Flexible and Printed Electronics - IOPscience

Flexible and Printed Electronics - IOPscience
Flexible and Printed Electronics
The OE-A
is the leading international industry association for flexible, organic, and printed electronics. The OE-A represents the entire value chain of this emerging industry. Our members are world-class global companies and institutions, ranging from R&D institutes, mechanical engineering companies and material suppliers to producers and end-users. 200 companies from Europe, Asia, North America, and Africa are working together to promote the establishment of a competitive production infrastructure for organic and printed electronics. The vision of the OE-A is to build a bridge between science, technology, and application. The OE-A is an international working group within VDMA. More than 3,600 member companies from the engineering industry make VDMA the largest industry association in Europe.
Korea Flexible Printed Electronics (KFPE)
is a representative academic association of Korea in the field of flexible printed electronics. Promoting the communication between academia and industry, KFPE contributes to the development of the related technology and industry. The conferences and the publications of journal may lead the technology to the front edge. The exhibitions are organized to enhance the technology of industry and the preparation for the future business related to flexible printed electronics like, display, solar cell and semiconductor.
Endorsed by
SUPPORTS OPEN ACCESS
Flexible and Printed Electronics
is a multidisciplinary journal devoted to publishing cutting edge research articles on electronics that can be either flexible, plastic, stretchable, conformable or printed.
Research related to electronic materials, manufacturing techniques, components or systems which meets any one (or more) of the above criteria is suitable for publication in the journal.
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Median submission to first decision before peer review
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Impact factor
3.2
Citescore
5.5
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The following article is
Open access
Review of digital printing technologies for electronic materials
Kye-Si Kwon
et al
2020
Flex. Print. Electron.
043003
View article
, Review of digital printing technologies for electronic materials
PDF
, Review of digital printing technologies for electronic materials
Direct printing methods have been used as manufacturing tools for printed electronics applications due to their cost effectiveness. In this review, the piezo-driven inkjet is discussed in detail since it is a mature technology and suitable for the production printing of printed electronics. In addition, other printing methods are considered for using higher viscosity ink and for producing smaller printed feature size. Various direct printing methods are compared in terms of jet mechanism, printing algorithm, and their applications. In particular high resolution printing methods using high viscosity inks, such as electrohydrodynamic jet, aerosol jet and micro-plotter are reviewed. To understand the recent status of industrial printing applications, display (liquid crystal display and organic light emitting diode) materials and printing issues are discussed. Finally, a brief overview of nano-particle metal based conductive inks is included because these inks have been widely used for printed electronics applications.
The following article is
Open access
The 2021 flexible and printed electronics roadmap
Yvan Bonnassieux
et al
2021
Flex. Print. Electron.
023001
View article
, The 2021 flexible and printed electronics roadmap
PDF
, The 2021 flexible and printed electronics roadmap
This roadmap includes the perspectives and visions of leading researchers in the key areas of flexible and printable electronics. The covered topics are broadly organized by the device technologies (sections 1–9), fabrication techniques (sections 10–12), and design and modeling approaches (sections 13 and 14) essential to the future development of new applications leveraging flexible electronics (FE). The interdisciplinary nature of this field involves everything from fundamental scientific discoveries to engineering challenges; from design and synthesis of new materials via novel device design to modelling and digital manufacturing of integrated systems. As such, this roadmap aims to serve as a resource on the current status and future challenges in the areas covered by the roadmap and to highlight the breadth and wide-ranging opportunities made available by FE technologies.
The following article is
Open access
Monitoring functional engagement of upper-limb prostheses using embedded sensors and machine learning in real-world contexts
Oindrila Sinha
et al
2026
Flex. Print. Electron.
11
025001
View article
, Monitoring functional engagement of upper-limb prostheses using embedded sensors and machine learning in real-world contexts
PDF
, Monitoring functional engagement of upper-limb prostheses using embedded sensors and machine learning in real-world contexts
Accurately monitoring upper-limb prosthesis use in daily life remains a major challenge in neurorehabilitation, as existing tools primarily measure wear duration without capturing functional engagement or task relevance. To address this gap, this work develops a multimodal sensing transradial prosthesis simulator equipped with embedded pressure, strain, and temperature sensors, enabling simultaneous tracking of mechanical and physiological interactions during natural use. Using data collected from able-bodied participants performing both structured tasks and unstructured daily activities, we train a random forest–based machine learning model to classify three distinct behavioral states: goal-directed active use, non-task use, and passive wear. The classifier trained on six multimodal features achieves 95% precision in distinguishing these states, with pressure-based sensors contributing the most discriminative information. Furthermore, a simplified variability-only model, using rolling standard deviation features from analog signals, accurately differentiates ‘Use’ vs. ‘Rest’ states with a balanced accuracy of 0.83 and an AUC of 0.913, demonstrating robust performance independent of absolute signal calibration. These findings highlight the feasibility of lightweight, interpretable, and scalable prosthesis monitoring systems that operate continuously in real-world settings, providing objective behavioral feedback for personalized rehabilitation and long-term prosthesis adaptation.
The following article is
Open access
Bio-based silver conductive ink for flexible printed electronics, and in-mold electronics
Tony Gerges
et al
2025
Flex. Print. Electron.
10
045012
View article
, Bio-based silver conductive ink for flexible printed electronics, and in-mold electronics
PDF
, Bio-based silver conductive ink for flexible printed electronics, and in-mold electronics
The development of environmentally friendly electronic circuits offers a sustainable alternative to conventional printed circuit board (PCB) manufacturing, which relies on chemically intensive and polluting processes. Screen printing of conductive inks is an effective and widely used method for fabricating flexible printed electronics (FPEs), and particularly well-suited for in-mold electronics (IMEs) applications. Screen printing of electronic circuits can be carried out on nearly all types of substrates, including recyclable and biodegradable polymers, thereby reducing the environmental impact. This paper presents the formulation of a silver conductive ink with stretchable properties, using poly(lactic acid) as the binder and Cyrene as the solvent, which are both biobased and biodegradable. Inks were formulated using silver flakes of different sizes (2.2
m–5.6
m) at a fixed content of 60%. Rheological behavior of the inks was measured to determine their printability, and resolution of printed patterns was tested using a scanning electron microscope. Thermal curing and photonic curing were used on the inks to study their electrical characteristics as functions of curing temperature and conditions. Among the latter tested formulations, the ink with a mixture of fine and large particles featured the best performance with an electrical resistivity of 34.77 ± 3.29
Ω · cm after heat treatment at 120 °C and 9.39  ± 0.17
Ω cm after photonic curing. This ink was also highly stretchable, with bending cycle tests showing an increase of electrical resistance only 8% after 1000 cycles, and the electrical continuity still intact even after 5000 cycles. Thermoforming tests confirmed electrical continuity at strains exceeding 30%. Demonstrators in FPEs and IME highlight the potential of these inks. This work shows that the developed ink exhibits electrical and stretchability properties equivalent to or even better than those of inks from previous research or commercial products, while reducing the environmental impact and enhancing user safety.
The following article is
Open access
Recent advances in encapsulation strategies for flexible transient electronics
Won Bae Han
et al
2024
Flex. Print. Electron.
033001
View article
, Recent advances in encapsulation strategies for flexible transient electronics
PDF
, Recent advances in encapsulation strategies for flexible transient electronics
Transient electronics, designed to dissolve, disintegrate, or degrade in a controlled manner after fulfilling their functions without remaining biologically and environmentally harmful byproducts, have emerged as a transformative paradigm with promising applications in temporary biomedical devices, eco-friendly electronics, and security applications. The success of this device development relies significantly on an effective encapsulation to protect their degradable active materials from environmental factors, such as biofluids and water, and secure reliable device functions throughout a desired lifespan. This review article provides an overview of recent advances in various encapsulation strategies for developing flexible, transient electronics. Details include materials selection, key characteristics, water-barrier capabilities, degradation mechanisms, and relevant applications, categorized into inorganic materials, synthetic/natural polymers, and hybrid composites. In addition, our insights into existing challenges and key perspectives for enhancing encapsulation performance are shared.
The following article is
Open access
Soft, wireless, technology-enhanced-dreaming patch for at-home sleep monitoring
Sung Hoon Lee
et al
2026
Flex. Print. Electron.
11
015013
View article
, Soft, wireless, technology-enhanced-dreaming patch for at-home sleep monitoring
PDF
, Soft, wireless, technology-enhanced-dreaming patch for at-home sleep monitoring
Sleep disorders are highly prevalent and often underdiagnosed due to the limitations of traditional polysomnography, which requires a long waiting time, wired sensor connections, and in-lab sleep. Here, this paper introduces a soft, wireless, technology-enhanced-dreaming (Tedream) patch for at-home sleep monitoring that avoids clinical supervision and multi-wired device mounting in a sleep lab. An experimental study demonstrates the mechanical reliability and biocompatibility of a wearable patch for continuous skin-signal detection. A set of three wearable devices, mounted on the forehead, chest, and forearm, measures wireless multiparametric physiological signals relevant to sleep staging and sleep apnea detection at home. Clinical evaluation across 8 subjects (4970 epochs) demonstrates that the Tedream system achieves 80% overall sleep-stage classification accuracy (Cohen’s
= 0.874) compared with PSG scoring. This class of technologies presented in this work offers a promising pathway toward widespread screening and long-term management of various sleep disorders in home environments.
The following article is
Open access
Recent advances in self-healing organic memristors and transistors for neuromorphic and flexible electronics
Sneha Bhise and Tae-Wook Kim 2026
Flex. Print. Electron.
11
013001
View article
, Recent advances in self-healing organic memristors and transistors for neuromorphic and flexible electronics
PDF
, Recent advances in self-healing organic memristors and transistors for neuromorphic and flexible electronics
The development of flexible and neuromorphic electronic devices relies on materials and systems that can sustain high performance despite mechanical deformation, fatigue, and environmental stress. Inspired by the self-repair mechanisms of human skin, self-healing materials present a promising approach to improving the durability, reliability, and lifespan of next-generation electronics. This review offers a comprehensive overview of self-healing processes in artificial materials, comparing them to biological healing. It discusses the fundamentals of biological synapses and their significance in neuromorphic computing and examines the intrinsic and extrinsic self-healing mechanisms used in electronic devices. Special emphasis is placed on designing and integrating self-healing functions into flexible transistors and memristors for neuromorphic applications, along with their role in creating resilient, adaptable, and stretchable flexible electronics. The key device requirements, current challenges, and future prospects for scalable manufacturing and material development are analyzed. By connecting biology-inspired strategies with flexible and neuromorphic electronics, self-healing technologies are set to significantly influence sustainable, reliable, and intelligent electronic systems across various fields.
The following article is
Open access
The role of printed electronics and related technologies in the development of smart connected products
C S Buga and J C Viana 2022
Flex. Print. Electron.
043001
View article
, The role of printed electronics and related technologies in the development of smart connected products
PDF
, The role of printed electronics and related technologies in the development of smart connected products
The emergence of novel materials with flexible and stretchable characteristics, and the use of new processing technologies, have allowed for the development of new connected devices and applications. Using printed electronics, traditional electronic elements are being combined with flexible components and allowing for the development of new smart connected products. As a result, devices that are capable of sensing, actuating, and communicating remotely while being low-cost, lightweight, conformable, and easily customizable are already being developed. Combined with the expansion of the Internet of Things, artificial intelligence, and encryption algorithms, the overall attractiveness of these technologies has prompted new applications to appear in almost every sector. The exponential technological development is currently allowing for the ‘smartification’ of cities, manufacturing, healthcare, agriculture, logistics, among others. In this review article, the steps towards this transition are approached, starting from the conceptualization of smart connected products and their main markets. The manufacturing technologies are then presented, with focus on printing-based ones, compatible with organic materials. Finally, each one of the printable components is presented and some applications are discussed.
The following article is
Open access
Cellulose nanofibril coated paper substrates for sustainable printed electronics and sensors
Gokulanand M Iyer
et al
2026
Flex. Print. Electron.
11
025004
View article
, Cellulose nanofibril coated paper substrates for sustainable printed electronics and sensors
PDF
, Cellulose nanofibril coated paper substrates for sustainable printed electronics and sensors
Internet of things (IoT) systems rely on the broad deployment of electronic devices and sensors in diverse environments. In some applications, including agriculture, packaging, and medical, there is a need for devices with relatively short lifetimes. Thus, there is growing interest in bio-based substrates for printed electronics and sensors that improve sustainability and minimize the environmental impact of IoT devices. Paper is a natural choice as a substrate for disposable printed devices; however, the high surface roughness and porosity of typical papers lead to printed structures with high variability. Here, we report a nanocellulose-infiltrated paper consisting of a cellulose nanofibrils (CNFs) film supported on a cardstock substrate. The CNF solution was coated onto the cardstock and then press-dried to form a smooth and dense surface. The CNF partially infiltrates the substrate, but forms a distinct film on the surface. The CNF coating process reduced the root mean square surface roughness of the cardstock from 4.3
m to 189 nm. This improvement in surface properties enables the screen-printing of silver patterns with geometric uniformity comparable to that of patterns printed on conventional polyimide substrates. The moisture sensitivity of these cellulose-based substrates can be exploited for moisture sensing, and the moisture absorption/desorption and resulting change in relative permittivity of these substrates are characterized.
The following article is
Open access
3D printing by direct ink writing (DIW) of UV-curable elastomers with embedded sensors for soft robotic and flexible electronic applications
Emrah Demirkal
et al
2025
Flex. Print. Electron.
10
035001
View article
, 3D printing by direct ink writing (DIW) of UV-curable elastomers with embedded sensors for soft robotic and flexible electronic applications
PDF
, 3D printing by direct ink writing (DIW) of UV-curable elastomers with embedded sensors for soft robotic and flexible electronic applications
The study focused on the direct ink writing (DIW) three-dimensional printing and characterization of UV-curable elastomers embedded with strain sensors for soft robotic applications. DIW was chosen due to its ability to precisely deposit multiple composite compositions in order to fabricate complex structures with varied spatial functionality. By leveraging a thiol–ene click chemistry, a range of elastomer compositions were developed using poly(mercaptopropylmethylsiloxane-co-dimethylsiloxane) and vinyl-terminated polydimethylsiloxane with varying molecular weights and photoinitiator concentrations. Rheological analysis demonstrated that photoinitiator concentration directly influenced viscosity, with a controlled range of 10–150 cP being optimal for DIW-based patterning. Upon UV exposure using a 5 W and 365 nm UV source, the elastomers exhibited rapid curing, with viscosity increasing significantly within ∼1 s, demonstrating high polymerization efficiency. A processing map was constructed, revealing the optimized printing speeds and UV source positioning to reduce excessive print spreading, thereby enhancing structural fidelity. Mechanical testing of printed dog-bone specimens printed with the optimal parameters showed a time-dependent increase in elastic modulus and tensile strength over seven days due to prolonged crosslinking. Additionally, silver-filled conductive polymer composites were embedded within the elastomer matrix to create strain sensors, exhibiting linearity (linear sensor output resistance to strain level) and demonstrating a stable cyclic response under 5% strain for 100 cycles. These results suggest that thiol–ene UV-curable silicone elastomers are promising materials for applications in the development of soft structures, particularly in the development of complex smart and multi-functional materials required for soft robotics and flexible electronics.
The following article is
Open access
Cellulose nanofibril coated paper substrates for sustainable printed electronics and sensors
Gokulanand M Iyer
et al
2026
Flex. Print. Electron.
11
025004
View article
, Cellulose nanofibril coated paper substrates for sustainable printed electronics and sensors
PDF
, Cellulose nanofibril coated paper substrates for sustainable printed electronics and sensors
Internet of things (IoT) systems rely on the broad deployment of electronic devices and sensors in diverse environments. In some applications, including agriculture, packaging, and medical, there is a need for devices with relatively short lifetimes. Thus, there is growing interest in bio-based substrates for printed electronics and sensors that improve sustainability and minimize the environmental impact of IoT devices. Paper is a natural choice as a substrate for disposable printed devices; however, the high surface roughness and porosity of typical papers lead to printed structures with high variability. Here, we report a nanocellulose-infiltrated paper consisting of a cellulose nanofibrils (CNFs) film supported on a cardstock substrate. The CNF solution was coated onto the cardstock and then press-dried to form a smooth and dense surface. The CNF partially infiltrates the substrate, but forms a distinct film on the surface. The CNF coating process reduced the root mean square surface roughness of the cardstock from 4.3
m to 189 nm. This improvement in surface properties enables the screen-printing of silver patterns with geometric uniformity comparable to that of patterns printed on conventional polyimide substrates. The moisture sensitivity of these cellulose-based substrates can be exploited for moisture sensing, and the moisture absorption/desorption and resulting change in relative permittivity of these substrates are characterized.
Thermoplastic-based composite embedding printed strain gauges for real time monitoring of battery casing deformations
Alexandre Pereira
et al
2026
Flex. Print. Electron.
11
025003
View article
, Thermoplastic-based composite embedding printed strain gauges for real time monitoring of battery casing deformations
PDF
, Thermoplastic-based composite embedding printed strain gauges for real time monitoring of battery casing deformations
The main critical indicators that ensure nominal batteries performances are energy storage density, charging capability and lifetime. These performances depend on the thermal conditions of use, the thermal history and the potential mechanical damages to the battery system. Over-heating of Li-Ion batteries (LIBs) due to over-voltage or over-current during use or charging may induce irreversible battery degradation, and even battery integrity. The primary function of the battery casing is to protect the battery cells against potential ground impacts. Besides, being generally located underbody, recurrent stone impacts and/or shocks can affect the battery casing mechanical integrity. It is therefore essential to monitor the integrity of the casing with dedicated sensors placed in critical areas, in order to optimize the lifetime of the battery-casing system. From an eco-circularity perspective, recording the deformations of composite-based casings can be highly valuable when considering their potential reuse. The ambition of this study is then to provide a lightweight battery casing with an integrated stress management to maximize the battery performance, safety, lifetime and reusability. In this context, printed strain gauges were designed and integrated into thermoplastic composite-based samples. Electrical measurements of the strain gauges signal variations were achieved using an experimental set-up that controlled the strain applied at different locations of the instrumented composite. Finite element-based mechanical simulations were also conducted to validate the magnitude of the deformations expected to be recorded by the printed gauges and to assess the potential of this instrumented casing for damage detection in LIBs.
Enhancing electroanalytical performance of flexible screen-printed electrodes through geometry-driven optimization and technological refinement
Tudor-Alexandru Filip and Marius-Andrei Olariu 2026
Flex. Print. Electron.
11
025002
View article
, Enhancing electroanalytical performance of flexible screen-printed electrodes through geometry-driven optimization and technological refinement
PDF
, Enhancing electroanalytical performance of flexible screen-printed electrodes through geometry-driven optimization and technological refinement
Screen-printed electrode (SPE)-based electroanalysis is widely employed in the development of wearable sensing devices due to its multiple advantages in probing interfacial phenomena in electrochemical systems. SPEs, as core elements of electrochemical biosensors as a result of their cost-effectiveness, versatility, and ease of mass production, are gaining popularity due to their facile integration and embedment with wearable devices. In spite of the multiple technological solutions for enhancing their electrochemical performance, the SPE geometry remains insufficiently explored, although the shape, dimension, and spacing of their functional components are known to play critical roles in influencing the accuracy, sensitivity, and reproducibility of electroanalytical results. Thus, our paper investigates the impact of six configurations related to various geometrical parameters of SPEs on the electrochemical performance, evaluated through three electrochemical techniques: cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. The experimental study focuses on emphasizing the effects of a tailored design on the charge transfer resistance, double-layer capacitance, and diffusion pathways. Significant electrochemical performance improvements were noted when optimizing the counter-electrode–working electrode distance and the width of the counter-electrode coupled with Na
CO
base activation.
The following article is
Open access
Monitoring functional engagement of upper-limb prostheses using embedded sensors and machine learning in real-world contexts
Oindrila Sinha
et al
2026
Flex. Print. Electron.
11
025001
View article
, Monitoring functional engagement of upper-limb prostheses using embedded sensors and machine learning in real-world contexts
PDF
, Monitoring functional engagement of upper-limb prostheses using embedded sensors and machine learning in real-world contexts
Accurately monitoring upper-limb prosthesis use in daily life remains a major challenge in neurorehabilitation, as existing tools primarily measure wear duration without capturing functional engagement or task relevance. To address this gap, this work develops a multimodal sensing transradial prosthesis simulator equipped with embedded pressure, strain, and temperature sensors, enabling simultaneous tracking of mechanical and physiological interactions during natural use. Using data collected from able-bodied participants performing both structured tasks and unstructured daily activities, we train a random forest–based machine learning model to classify three distinct behavioral states: goal-directed active use, non-task use, and passive wear. The classifier trained on six multimodal features achieves 95% precision in distinguishing these states, with pressure-based sensors contributing the most discriminative information. Furthermore, a simplified variability-only model, using rolling standard deviation features from analog signals, accurately differentiates ‘Use’ vs. ‘Rest’ states with a balanced accuracy of 0.83 and an AUC of 0.913, demonstrating robust performance independent of absolute signal calibration. These findings highlight the feasibility of lightweight, interpretable, and scalable prosthesis monitoring systems that operate continuously in real-world settings, providing objective behavioral feedback for personalized rehabilitation and long-term prosthesis adaptation.
Screen printable graphite–graphene hybrid ink for flexible electronics: correlating particle size and binary solvent system on conductivity and print quality
Naghmeh Gholamalizadeh
et al
2026
Flex. Print. Electron.
11
015015
View article
, Screen printable graphite–graphene hybrid ink for flexible electronics: correlating particle size and binary solvent system on conductivity and print quality
PDF
, Screen printable graphite–graphene hybrid ink for flexible electronics: correlating particle size and binary solvent system on conductivity and print quality
The large-scale production of flexible electronics requires cost-effective, high-precision printing processes and optimized conductive inks. Screen printing with carbon-based formulations offers uniformity, scalability, and low production costs; however, achieving the required balance between rheology, conductivity, and mechanical stability remains challenging. This work presents a formulation strategy for graphite–graphene hybrid ink designed for screen printing on PET substrates. We systematically investigate the effects of graphite particle size, graphene content, and a binary solvent system on rheological behavior, print fidelity, and electrical performance. The optimized ink-comprising 200-mesh graphite, 2 wt% graphene, and a 47:13 wt% mixture of cyclohexanone and ethyl acetate—exhibits pronounced shear-thinning (viscosity drop from 318.72 Pa.s to 8.16 Pa.s between 0.1 and 500 s
−1
), high thixotropic recovery (99.11%), strong adhesion (ASTM D3359, 5B), and a low resistivity of (1.19 ± 0.10) × 10
−3
Ω.m at 14.20 ± 2
m thickness. These features enable sharp pattern definition and mechanical robustness, with only 1.6% resistivity change after 300 bending cycles. The results highlight the synergistic role of particle size control, nanosheet incorporation, and solvent engineering in advancing carbon-based inks for scalable, high-performance flexible electronics.
MXene based flexible materials for energy harvesting and storage applications
Parika Mahajan
et al
2026
Flex. Print. Electron.
11
013003
View article
, MXene based flexible materials for energy harvesting and storage applications
PDF
, MXene based flexible materials for energy harvesting and storage applications
In the realm of flexible and wearable energy technologies, MXene, a family of two-dimensional transition metal nitrides, carbides, or carbonitrides, have emerged out as one of the most promising multifunctional materials owing to its high conductivity, excellent surface area to volume ratio, tunable surface functionality, mechanically flexible and layered structure. These unique features make MXene highly suitable to be integrated into a wide range of flexible energy harvesting and storage applications, including supercapacitors, batteries, solar cells, and triboelectric (TENGs) and piezoelectric nanogenerators. Consequently, MXene-based systems have been extensively investigated, and recent reports on fully printed MXene-based TENG represent one of the highest-performing MXene-based flexible energy harvesters reported to date, delivering output voltages of up to ∼252 V and power densities approaching 760 mW m
−2
, demonstrating both flexible energy harvesting and wearable motion sensing capabilities. In parallel, flexible MXene-based all-solid-state supercapacitors have shown volumetric capacitances up to 94.21 F cm
−3
, a volumetric energy density of ∼3.27 mWh cm
−3
, and a power density of ∼0.25 W cm
−3
under bending conditions, highlighting their strong potential for integrated flexible energy harvesting and storage applications. Building on these advances, nowadays, by integrating high-performance charge storage with effective energy conversion, MXene-based flexible materials support the development of sustainable, portable, wearable and self-powered hybrid energy platforms. Accordingly, this review comprehensively discusses the evolution and advancements of MXene-based flexible materials for next-generation energy storage and harvesting devices, focusing on their structural characteristics, synthesis strategies, and design approaches to enhance flexibility and performance of the devices. The review concludes by addressing the certain bottlenecks associated with MXene, including, oxidation stability, scalable synthesis, and prolonged stability, while providing future perspectives for the rational design of MXene-based flexible and advanced materials for futuristic energy applications.
Flexible memristors for next-generation electronics: materials, fabrication and applications
Soumyadip Paul
et al
2026
Flex. Print. Electron.
11
013002
View article
, Flexible memristors for next-generation electronics: materials, fabrication and applications
PDF
, Flexible memristors for next-generation electronics: materials, fabrication and applications
Flexible and printable memristors are emerging as transformative platforms at the intersection of materials science, electronics, and neuromorphic computing. By integrating mechanical flexibility with resistive-switching functionality, these devices open new opportunities for low-power, flexible, and next-generation wearable electronics. This review provides a comprehensive overview of recent advances in flexible memristors, highlighting progress in flexible substrates, scalable fabrication techniques, novel functional materials, and their diverse application domains. Key materials include polymer dielectrics, two-dimensional materials, metal oxides on flexible substrates, and organic–inorganic hybrids, engineered into thin films, nanosheets, nanorods, and nanocrystals through vapour deposition and solution-based routes. We discuss how material composition, deposition methodology, interface engineering, and nanostructuring approaches govern key performance metrics, including endurance, retention, switching speed, and mechanical robustness under bending or stretching. The evolution of switching mechanisms, from filamentary conduction to interface-mediated processes and ion migration, is contextualized with the emerging applications, including neuromorphic computing, flexible memory arrays, logic circuits, and bio-interfaced electronics, such as artificial skin and wearable health monitors. Further, we address the challenges associated with the practical applications of the flexible memristive devices and discuss the future directions of research that can be pivotal in shaping the future of intelligent, responsive electronics.
The following article is
Open access
Recent advances in self-healing organic memristors and transistors for neuromorphic and flexible electronics
Sneha Bhise and Tae-Wook Kim 2026
Flex. Print. Electron.
11
013001
View article
, Recent advances in self-healing organic memristors and transistors for neuromorphic and flexible electronics
PDF
, Recent advances in self-healing organic memristors and transistors for neuromorphic and flexible electronics
The development of flexible and neuromorphic electronic devices relies on materials and systems that can sustain high performance despite mechanical deformation, fatigue, and environmental stress. Inspired by the self-repair mechanisms of human skin, self-healing materials present a promising approach to improving the durability, reliability, and lifespan of next-generation electronics. This review offers a comprehensive overview of self-healing processes in artificial materials, comparing them to biological healing. It discusses the fundamentals of biological synapses and their significance in neuromorphic computing and examines the intrinsic and extrinsic self-healing mechanisms used in electronic devices. Special emphasis is placed on designing and integrating self-healing functions into flexible transistors and memristors for neuromorphic applications, along with their role in creating resilient, adaptable, and stretchable flexible electronics. The key device requirements, current challenges, and future prospects for scalable manufacturing and material development are analyzed. By connecting biology-inspired strategies with flexible and neuromorphic electronics, self-healing technologies are set to significantly influence sustainable, reliable, and intelligent electronic systems across various fields.
Flexible and printed electronics manufacturing in China
Yanqiao Pan
et al
2025
Flex. Print. Electron.
10
043001
View article
, Flexible and printed electronics manufacturing in China
PDF
, Flexible and printed electronics manufacturing in China
Flexible electronic devices, such as flexible displays, sensors, and thin-film solar cells, are defined by their thinness, expansive surface area, precision, and elasticity, demonstrating significant applications in optoelectronics, information technology, healthcare, and energy sectors. With ongoing industrial innovation and evolution, diverse heterogeneous flexible electronic devices have arisen, necessitating substantial progress in material adaptability, structural design innovation, and manufacturing techniques. Traditional manufacturing processes commonly face difficulties in simultaneously achieving preparation accuracy, efficiency, and the integration of heterogeneous components. This constraint impedes the vigorous advancement of the flexible electronics sector. A synergistic combination of diverse manufacturing processes, along with the upgraded collaborative development of manufacturing equipment, may provide a feasible solution. Currently, flexible electronics in China are addressing industry challenges and exhibiting remarkable research dynamism and industrial innovation. The study begins with an overview of industry and academic research in the field and explores the contributions of Chinese researchers in solving production challenges. Finally, it showcases domestically produced manufacturing equipment for various process types, aiming to consolidate Chinese flexible electronics-related resources and provide a comprehensive reference for future research.
A review of printed electrochemical sensors for pesticide sensing applications
Neethu Thomas
et al
2025
Flex. Print. Electron.
10
033001
View article
, A review of printed electrochemical sensors for pesticide sensing applications
PDF
, A review of printed electrochemical sensors for pesticide sensing applications
An electrochemical sensor (ECS) is one that converts the electrode-analyte interaction/chemical reaction events into detectable electrochemical signals that can be exploited for analyte detection. This review paper provides a perspective on ECSs for pesticide detection through a comprehensive literature study on diverse pesticide classes for different environmental contexts. Moreover, this review covers the fundamental working principles of ECS and their performance efficacy in terms of parameters such as sensitivity, selectivity, and practical utility. It also presents different sensing strategies incorporated with ECS for pesticide detection, with a particular focus on printed ECS and the various printing techniques in use for their fabrication. The review also discusses a wide range of active/functional nanomaterials used either directly as printed electrodes or deposited onto conventional electrodes. The printed sensors and sensor arrays provide the promise of the handling of small analyte volumes (from a few microlitres or less), which increases detection sensitivity due to a higher surface-to-volume ratio. The integration of printed electrodes with optical transparency and flexibility of both the electrodes and the substrates has resulted in the development of printed transparent flexible ECS (PTFECS). The development of ECS in the areas of electrode composition, printing-based fabrication, flexible/rigid geometry, surface modification type, and electrode optical transparency is paving the way for efficient pesticide detection and environmental monitoring. Moreover, their applications in environmental monitoring and food safety are addressing the UN’s 2030 sustainable development goals to enhance lives. The review also provides future directions, especially towards the development of PTFECS and its applications.
Optimization of film thickness and annealing for bending-stable flexible platinum thin-film temperature sensors
Danish et al
View accepted manuscript
, Optimization of film thickness and annealing for bending-stable flexible platinum thin-film temperature sensors
PDF
, Optimization of film thickness and annealing for bending-stable flexible platinum thin-film temperature sensors
Flexible platinum thin-film temperature sensors were designed and fabricated on polyimide substrates using a sputtered Ti/Pt bilayer to achieve high mechanical flexibility and thermal stability. The effects of film thickness (100–400 nm) and post-deposition annealing temperature (200–350 ◦C) on the microstructure and electromechanical response were systematically investigated. Field-emission scanning electron microscopy (FESEM) revealed uniform grain coarsening at 300 ◦C without microcrack formation, corresponding to enhanced bending resilience. Electrical characterization on flat and curved surfaces (12.7–25.4 mm radii) demonstrated that 100 nm films annealed at 300 ◦C exhibited the lowest bending-induced resistance variation (<0.7% under tensile and <0.5% under compressive curvature). In contrast, thicker or improperly annealed films showed higher strain sensitivity due to residual stress and microstructural defects. The results establish an optimized process window that minimizes deformation-induced resistance drift while preserving temperature accuracy, offering practical design and fabrication guidelines for mechanically robust platinum-based flexible temperature sensors suitable for wearable, robotic, and aerospace applications.
Study on the influence of drying time on the electrical resistance performance of AJP silver electrodes
li et al
View accepted manuscript
, Study on the influence of drying time on the electrical resistance performance of AJP silver electrodes
PDF
, Study on the influence of drying time on the electrical resistance performance of AJP silver electrodes
In response to the application requirements of aerosol jet-printed (AJP) silver electrodes in flexible electronic devices, this study employs a combined experimental and simulation approach to investigate the influence of pre-sintering drying time on their electrical resistance performance. In the experiments, a single batch of silver electrode samples was subjected to a precisely controlled drying-time gradient ranging from 0 to 45 min. Subsequently, all samples were co-sintered, and their electrical resistance was characterized using the four-point probe method. For the simulation, a finite-element model based on porous-media two-phase flow theory was constructed to quantify the solvent-evaporation kinetics and the degree of drying during the process. The results show that under 50 °C drying conditions, the critical drying time for AJP silver electrodes is 35 min, at which point the electrodes reach a completely dry state. The resistance of the sintered electrodes decreases with prolonged drying time and enters a stable plateau after 35 min; insufficiently dried samples exhibit resistance several times higher than that of sufficiently dried samples. SEM characterization reveals that insufficient drying leads to a porous, cracked structure that disrupts the continuity of the conductive network, whereas sufficient drying yields a dense, uniform electrode with well-fused particles. The solvent-content variation predicted by the simulation aligns closely with the experimental resistance-stabilization point and the structural transition observed via SEM, validating the reliability of the model. This work identifies a key process parameter for AJP silver electrodes, elucidates the drying-structure-performance relationship, and provides a theoretical basis and data support for process optimization in flexible electronics manufacturing.
Deep reinforcement learning-enabled closed-loop process optimization for aerosol jet printing
Zhang et al
View accepted manuscript
, Deep reinforcement learning-enabled closed-loop process optimization for aerosol jet printing
PDF
, Deep reinforcement learning-enabled closed-loop process optimization for aerosol jet printing
To address process instability in aerosol jet printing (AJP), this study proposes AeroOptima-DRL, a deep reinforcement learning–based closed-loop process optimization system. A data-driven virtual environment, termed NeuroPrintMapper, is developed to model the relationship between process parameters and printed line quality, enabling efficient agent training without extensive physical experiments. Based on this environment, a reinforcement learning agent is trained to autonomously generate optimal process parameters in real time. Experiments on silver nanoparticle ink deposition on polyimide substrates demonstrate that the proposed system achieves accurate line width control within a target range of 10-30 μm, with a mean absolute deviation of 0.19 μm and an average error rate of 1.09%. During a 5-hour continuous printing test, the closed-loop system effectively suppresses process drift, limiting resistance fluctuations to 2.5 times the initial value, compared to approximately 30-fold fluctuations under open-loop control. These results verify the effectiveness of DRL-based closed-loop optimization for improving the stability and consistency of high-resolution AJP processes.
In-situ electrospun nanofiber encapsulation for high-performance, breathable, and adhesive flexible dry electrodes
Liao et al
View accepted manuscript
, In-situ electrospun nanofiber encapsulation for high-performance, breathable, and adhesive flexible dry electrodes
PDF
, In-situ electrospun nanofiber encapsulation for high-performance, breathable, and adhesive flexible dry electrodes
Long-term continuous electrophysiological monitoring is crucial for accurate health assessment. However, the practical implementation of flexible dry electrodes is frequently constrained by difficulty of simultaneously achieving high stretchability, stable skin adhesion, and sufficient breathability. This work presents a flexible electrode encapsulation strategy utilizing an in-situ electrospinning process integrated with direct-write transfer to fabricate embedded flexible composite electrodes. A composite of poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) and silver nanowires was embedded within a poly(vinyl alcohol)–glycerol substrate, yielding epidermal electrodes exhibiting high conductivity, low Young’s modulus, and superior stretchability. The electrode exhibits low impedance (18 Ω) and biomimetic mechanical properties (Young's modulus of 1.23 MPa), with minimal resistance variation prior to exceeding 80% strain. Significantly, an in-situ nanofiber encapsulation technique was introduced to address the poor skin adhesion characteristic of dry electrodes. This approach achieves a breathability rate 3.5 times higher than that of medical polyurethane tape encapsulation while maintaining effective waterproofing. A 12-hour patch test on human skin revealed no irritation, confirming excellent biocompatibility. In practical use, the electrode enables stable acquisition of long-term electrocardiogram signals during continuous wear, offering a comfortable and user-friendly solution for wearable dry electrodes in prolonged electrophysiological monitoring.
The following article is
Open access
Direct ink writing of nickel nanowires/hexagonal boron nitride based capacitive pressure sensors using a water-based ink
Jois H S et al
View accepted manuscript
, Direct ink writing of nickel nanowires/hexagonal boron nitride based capacitive pressure sensors using a water-based ink
PDF
, Direct ink writing of nickel nanowires/hexagonal boron nitride based capacitive pressure sensors using a water-based ink
The advancement of next-generation flexible electronics relies on the development of high-performance components that are lightweight, conformable, and compatible with scalable additive manufacturing processes. Here, we report a fully 3D-printed capacitive pressure sensor featuring a novel dielectric composite ink composed of nickel nanowires (NiNWs), hexagonal boron nitride (h-BN), and polyethylene oxide (PEO). This eco-friendly, water-based ink was engineered for direct ink writing (DIW), enabling the fabrication of printed planar capacitive sensors, with dimensions of 1.5 cm x 0.6 cm, comprised of interdigitated silver electrodes topped with composite dielectric layer on flexible, polyimide substrates. The composite dielectric ink included: h-BN, a 2-D nanomaterial which served as a charge storing nanomaterial with low dielectric loss, and a PEO binder, which stabilized the nanosheets and provided to the necessary viscoelastic properties for print fidelity and structural stability. Adding a small concentration of NiNWs to the hBN/PEO composite enhanced the dielectric properties due to an increase in interfacial polarization. The printed capacitive sensors incorporating an hBN/PEO/NiNW dielectric layer exhibited reliable pressure-responsive behavior across a wide sensing range (0–466 kPa), with sensitivities of 0.024 and 0.008 kPa⁻¹ in low - medium, and high-pressure regimes, respectively; these sensitivities were 7 – 8 times higher than for similar devices with hBN/PEO dielectric layers without NiNWs. Sensors demonstrated fast response times, low hysteresis, mechanical durability over cyclic loading, and high signal fidelity under dynamic pressure. Furthermore, the sensors enabled real-time monitoring of physiological signals including pulse, voice, and motion, underscoring their applicability in wearable health diagnostics and soft human–machine interfaces.
The following article is
Open access
Cellulose nanofibril coated paper substrates for sustainable printed electronics and sensors
Gokulanand M Iyer
et al
2026
Flex. Print. Electron.
11
025004
View article
, Cellulose nanofibril coated paper substrates for sustainable printed electronics and sensors
PDF
, Cellulose nanofibril coated paper substrates for sustainable printed electronics and sensors
Internet of things (IoT) systems rely on the broad deployment of electronic devices and sensors in diverse environments. In some applications, including agriculture, packaging, and medical, there is a need for devices with relatively short lifetimes. Thus, there is growing interest in bio-based substrates for printed electronics and sensors that improve sustainability and minimize the environmental impact of IoT devices. Paper is a natural choice as a substrate for disposable printed devices; however, the high surface roughness and porosity of typical papers lead to printed structures with high variability. Here, we report a nanocellulose-infiltrated paper consisting of a cellulose nanofibrils (CNFs) film supported on a cardstock substrate. The CNF solution was coated onto the cardstock and then press-dried to form a smooth and dense surface. The CNF partially infiltrates the substrate, but forms a distinct film on the surface. The CNF coating process reduced the root mean square surface roughness of the cardstock from 4.3
m to 189 nm. This improvement in surface properties enables the screen-printing of silver patterns with geometric uniformity comparable to that of patterns printed on conventional polyimide substrates. The moisture sensitivity of these cellulose-based substrates can be exploited for moisture sensing, and the moisture absorption/desorption and resulting change in relative permittivity of these substrates are characterized.
The following article is
Open access
Monitoring functional engagement of upper-limb prostheses using embedded sensors and machine learning in real-world contexts
Oindrila Sinha
et al
2026
Flex. Print. Electron.
11
025001
View article
, Monitoring functional engagement of upper-limb prostheses using embedded sensors and machine learning in real-world contexts
PDF
, Monitoring functional engagement of upper-limb prostheses using embedded sensors and machine learning in real-world contexts
Accurately monitoring upper-limb prosthesis use in daily life remains a major challenge in neurorehabilitation, as existing tools primarily measure wear duration without capturing functional engagement or task relevance. To address this gap, this work develops a multimodal sensing transradial prosthesis simulator equipped with embedded pressure, strain, and temperature sensors, enabling simultaneous tracking of mechanical and physiological interactions during natural use. Using data collected from able-bodied participants performing both structured tasks and unstructured daily activities, we train a random forest–based machine learning model to classify three distinct behavioral states: goal-directed active use, non-task use, and passive wear. The classifier trained on six multimodal features achieves 95% precision in distinguishing these states, with pressure-based sensors contributing the most discriminative information. Furthermore, a simplified variability-only model, using rolling standard deviation features from analog signals, accurately differentiates ‘Use’ vs. ‘Rest’ states with a balanced accuracy of 0.83 and an AUC of 0.913, demonstrating robust performance independent of absolute signal calibration. These findings highlight the feasibility of lightweight, interpretable, and scalable prosthesis monitoring systems that operate continuously in real-world settings, providing objective behavioral feedback for personalized rehabilitation and long-term prosthesis adaptation.
The following article is
Open access
Soft, wireless, technology-enhanced-dreaming patch for at-home sleep monitoring
Sung Hoon Lee
et al
2026
Flex. Print. Electron.
11
015013
View article
, Soft, wireless, technology-enhanced-dreaming patch for at-home sleep monitoring
PDF
, Soft, wireless, technology-enhanced-dreaming patch for at-home sleep monitoring
Sleep disorders are highly prevalent and often underdiagnosed due to the limitations of traditional polysomnography, which requires a long waiting time, wired sensor connections, and in-lab sleep. Here, this paper introduces a soft, wireless, technology-enhanced-dreaming (Tedream) patch for at-home sleep monitoring that avoids clinical supervision and multi-wired device mounting in a sleep lab. An experimental study demonstrates the mechanical reliability and biocompatibility of a wearable patch for continuous skin-signal detection. A set of three wearable devices, mounted on the forehead, chest, and forearm, measures wireless multiparametric physiological signals relevant to sleep staging and sleep apnea detection at home. Clinical evaluation across 8 subjects (4970 epochs) demonstrates that the Tedream system achieves 80% overall sleep-stage classification accuracy (Cohen’s
= 0.874) compared with PSG scoring. This class of technologies presented in this work offers a promising pathway toward widespread screening and long-term management of various sleep disorders in home environments.
The following article is
Open access
Recent advances in self-healing organic memristors and transistors for neuromorphic and flexible electronics
Sneha Bhise and Tae-Wook Kim 2026
Flex. Print. Electron.
11
013001
View article
, Recent advances in self-healing organic memristors and transistors for neuromorphic and flexible electronics
PDF
, Recent advances in self-healing organic memristors and transistors for neuromorphic and flexible electronics
The development of flexible and neuromorphic electronic devices relies on materials and systems that can sustain high performance despite mechanical deformation, fatigue, and environmental stress. Inspired by the self-repair mechanisms of human skin, self-healing materials present a promising approach to improving the durability, reliability, and lifespan of next-generation electronics. This review offers a comprehensive overview of self-healing processes in artificial materials, comparing them to biological healing. It discusses the fundamentals of biological synapses and their significance in neuromorphic computing and examines the intrinsic and extrinsic self-healing mechanisms used in electronic devices. Special emphasis is placed on designing and integrating self-healing functions into flexible transistors and memristors for neuromorphic applications, along with their role in creating resilient, adaptable, and stretchable flexible electronics. The key device requirements, current challenges, and future prospects for scalable manufacturing and material development are analyzed. By connecting biology-inspired strategies with flexible and neuromorphic electronics, self-healing technologies are set to significantly influence sustainable, reliable, and intelligent electronic systems across various fields.
The following article is
Open access
Direct ink writing of nickel nanowires/hexagonal boron nitride based capacitive pressure sensors using a water-based ink
Meghana Jois H S and Anastasia L Elias 2026
Flex. Print. Electron.
View article
, Direct ink writing of nickel nanowires/hexagonal boron nitride based capacitive pressure sensors using a water-based ink
PDF
, Direct ink writing of nickel nanowires/hexagonal boron nitride based capacitive pressure sensors using a water-based ink
The advancement of next-generation flexible electronics relies on the development of high-performance components that are lightweight, conformable, and compatible with scalable additive manufacturing processes. Here, we report a fully 3D-printed capacitive pressure sensor featuring a novel dielectric composite ink composed of nickel nanowires (NiNWs), hexagonal boron nitride (h-BN), and polyethylene oxide (PEO). This eco-friendly, water-based ink was engineered for direct ink writing (DIW), enabling the fabrication of printed planar capacitive sensors, with dimensions of 1.5 cm x 0.6 cm, comprised of interdigitated silver electrodes topped with composite dielectric layer on flexible, polyimide substrates. The composite dielectric ink included: h-BN, a 2-D nanomaterial which served as a charge storing nanomaterial with low dielectric loss, and a PEO binder, which stabilized the nanosheets and provided to the necessary viscoelastic properties for print fidelity and structural stability. Adding a small concentration of NiNWs to the hBN/PEO composite enhanced the dielectric properties due to an increase in interfacial polarization. The printed capacitive sensors incorporating an hBN/PEO/NiNW dielectric layer exhibited reliable pressure-responsive behavior across a wide sensing range (0–466 kPa), with sensitivities of 0.024 and 0.008 kPa⁻¹ in low - medium, and high-pressure regimes, respectively; these sensitivities were 7 – 8 times higher than for similar devices with hBN/PEO dielectric layers without NiNWs. Sensors demonstrated fast response times, low hysteresis, mechanical durability over cyclic loading, and high signal fidelity under dynamic pressure. Furthermore, the sensors enabled real-time monitoring of physiological signals including pulse, voice, and motion, underscoring their applicability in wearable health diagnostics and soft human–machine interfaces.
The following article is
Open access
Materials and process optimizations for fabricating digital AM temperature and relative humidity sensor system circuits for use in high thermal stress environments
Emily Lamport
et al
2026
Flex. Print. Electron.
11
015009
View article
, Materials and process optimizations for fabricating digital AM temperature and relative humidity sensor system circuits for use in high thermal stress environments
PDF
, Materials and process optimizations for fabricating digital AM temperature and relative humidity sensor system circuits for use in high thermal stress environments
Additive manufacturing (AM) has experienced rapid growth across various industries owing to the advantages of AM technologies. However, the adoption of AM for sensor integrated circuits (ICs) in harsh environments remains limited due to insufficient high-temperature materials and lack of reliability data. This work demonstrates a wireless, conformal temperature and humidity sensor fabricated via multi-material AM using high-temperature-capable materials. Off-the-shelf components, including a microcontroller and sensor, are embedded in a 3D-printed SLA interposer with conformally printed silver interconnects and protective encapsulation. Additionally, these circuits were designed to communicate wirelessly via Bluetooth low energy (BLE) protocols. Process optimizations were made to manufacture AM sensor circuits efficiently and with high yield. The AM circuits were then electrically, thermally, and mechanically characterized to further optimize the performance of the sensors compared to those manufactured and connected via traditional methods. Key novelties of this approach include (1) fully conformal printing around a QFN-packaged IC, (2) an encapsulation strategy that enhances mechanical resilience of mounted components, and (3) integration of wireless data transmission into a rugged additively manufactured package. The AM sensor’s performance was also characterized and compared to conventional assemblies: results show stable operation from 25 °C up to 100 °C under cyclic humidity and significantly improved mechanical robustness of component interconnections due to encapsulation. This AM sensor demonstrates, to our knowledge, the first combination of conformal printed electronics, encapsulated packaging, and wireless communication for reliable operation in harsh environmental conditions.
The following article is
Open access
Metallization and laser sintering of electrical conductor tracks on microporous and temperature-sensitive natural fiber-reinforced plastic
Maximilian L Hupfer
et al
2026
Flex. Print. Electron.
11
015007
View article
, Metallization and laser sintering of electrical conductor tracks on microporous and temperature-sensitive natural fiber-reinforced plastic
PDF
, Metallization and laser sintering of electrical conductor tracks on microporous and temperature-sensitive natural fiber-reinforced plastic
Natural fiber-reinforced plastics (NFRP) composites are increasingly used as lightweight, bio-based structural materials in automotive and interior applications. To enable multifunctional components with integrated sensing, lighting or wiring, electrical conductor tracks need to be fabricated directly on NFRP surfaces. This is challenging, because NFRP exhibits pronounced surface roughness and porosity, while the polypropylene matrix imposes a restricted thermal budget that limits conventional high-temperature curing of conductive inks. In this work, we demonstrate the direct fabrication of silver conductor tracks on a hemp-fiber NFRP by combining a water-based starch filler layer with screen printing of a commercial thermoplastic polyurethane-based silver ink, followed by localized 808 nm laser sintering. The starch layer fills surface pores and smooths the NFRP surface while acting as an aqueous, bio-derived adhesive that can be dried at moderate temperatures, which is in line with the low-emission and moderate-temperature requirements of NFRP interior components and avoids the need for typical solvent-borne primers and higher curing temperatures that are less compatible with such substrates. We systematically compare track resistance and morphology on glass and on both sides of the NFRP and show that suitable pre-treatment of the NFRP surface, combined with laser sintering, enables low-resistance conductor tracks on the NFRP back side under process temperatures compatible with the polymer matrix. Localized near-infrared laser sintering further improves the conductivity without damaging the composite and enables continuous, low-resistance tracks to be realized on the NFRP substrate. To the best of our knowledge, this is the first study to demonstrate laser sintered, screen-printed silver conductors directly on an industrial natural fiber-reinforced polypropylene composite within its limited thermal budget using a water-based, starch-based filler layer. The results indicate a process- and environmentally compatible route towards multifunctional, lightweight NFRP components with integrated electrical functionalities.
The following article is
Open access
Real-time imaging-ellipsometry with a polarization camera in R2R-applications
Ferdinand Bammer
et al
2026
Flex. Print. Electron.
11
015005
View article
, Real-time imaging-ellipsometry with a polarization camera in R2R-applications
PDF
, Real-time imaging-ellipsometry with a polarization camera in R2R-applications
We present an inline imaging ellipsometer based on a polarization camera for real-time, full-area quality control of thin-film coatings in roll-to-roll (R2R) production. The system captures two-dimensional distributions of polarization-dependent intensity ratios reflected from the moving substrate with fixed illumination wavelength and angle of incidence. This measurement enables the detection of coating uniformity, shape, and defects, even those hardly visible by conventional optical means. Two simple calculation methods are proposed to estimate the spatial distribution of layer thickness from polarization data. A full 2D image is constructed by accumulating high-frame-rate line measurements across the web. The system is demonstrated for PEDOT-layers on PET and battery electrolyte coatings on copper foil, indicating its potential as a robust, real-time solution for inline thickness monitoring in R2R manufacturing.
The following article is
Open access
Electromechanical characterization of flexible screen-printed tracks
Juuso Puutio
et al
2026
Flex. Print. Electron.
11
015004
View article
, Electromechanical characterization of flexible screen-printed tracks
PDF
, Electromechanical characterization of flexible screen-printed tracks
To reduce the environmental impact of flexible printed electronics the most used material combination—silver-based ink on a plastic substrate—needs to be replaced. Carbon-based inks and paper substrates have the potential to do this, but their electromechanical reliability needs to be evaluated. This paper presents a systematic study of cyclic bending reliability for carbon-based inks on plastic substrates and silver-based inks on plastic and paper substrates, using a 9 mm compressive bending radius. Failure was defined as a 70% increase in resistance from the initial value, and carbon-based inks showed promising results as their resistance did not reach the failure criteria even after 30 000 bent cycles. Silver-based inks on plastic substrates failed by around 200 cycles as evaluated by the Weibull’s cumulative distribution function, but silver on a regenerated cellulose film lasted almost 30 000 cycles. However, for paper substrates, bending reliability showed significant variation. Therefore, silver-based inks on both substrate types were subjected to further characterization to study potential correlations among substrate surface roughness, substrate thickness, and substrate type. For paper substrates, a strong correlation was observed between surface roughness and the number of cycles to failure. Sustainable packing material failed around 40 cycles, likely due to the uneven distribution of silver, which contributed to failures. Smooth regenerated cellulose film on the other hand lasted almost 30 000 cycles. With plastic substrates no strong correlation was found as even the smoothest substrates failed relatively quickly. This study also demonstrates that low overall thickness of the substrate enhances bending reliability, especially with paper substrates, as the strain is decreased. Overall carbon-based inks and paper substrates show promising results in replacing the mainstream materials, but the lower conductivity of carbon compared to silver, and the effect of surface roughness on the reliability of paper substrates needs to be considered.
The following article is
Open access
Testing the durability of aerosol jet printed antennas on acetylated cellulose nanofiber substrates
Jenny Wiklund
et al
2026
Flex. Print. Electron.
11
015003
View article
, Testing the durability of aerosol jet printed antennas on acetylated cellulose nanofiber substrates
PDF
, Testing the durability of aerosol jet printed antennas on acetylated cellulose nanofiber substrates
The continually growing demand for electronic devices and consequently the increase in electronic waste have caused the need for more environmentally friendly materials and methods used when manufacturing the devices. In this paper, a coplanar waveguide-fed square slot antenna was aerosol jet printed onto acetylated cellulose nanofiber (ACNF) substrates and a poly(ethylene terephthalate) (PET) reference substrate, and the effects of photodegradation on these were studied. The functionality and print quality of the antennas were examined before and after photodegradation. In addition, changes in the color of the substrate and antenna were analyzed during the photodegradation process. Interestingly, the color of the ACNF substrate became whiter after photodegradation, while there were no significant changes in the color of the PET substrate, and the printed antennas became notably darker. The printed dimensions were quite accurate compared to the planned dimensions; there were, however, small differences in the horizontal and vertical directions. Additionally, the printed pattern on the PET substrate showed significantly more gaps in the pattern compared to the printed pattern on the ACNF substrate. The electrical properties of the antenna on the ACNF substrate were almost as good as those of the PET substrate. The photodegradation treatment significantly deteriorated the electrical properties of the antenna on the PET substrate, whereas the antenna on the ACNF substrate did not show any notable changes. Hence, this study shows that ACNF would be a suitable substitute for plastic as a substrate for printed electronics.
More Open Access articles
Principles of aerosol jet printing
Ethan B Secor 2018
Flex. Print. Electron.
035002
View article
, Principles of aerosol jet printing
PDF
, Principles of aerosol jet printing
Aerosol jet printing (AJP) has emerged as a promising method for microscale digital additive manufacturing using functional nanomaterial inks. While compelling capabilities have been demonstrated in the research community in recent years, the development and refinement of inks and process parameters largely follows empirical observations, with an extensive phase space over which to optimize. While this has led to general qualitative guidelines and ink- and machine-specific correlations, a more fundamental understanding based on principles of aerosol physics and fluid mechanics is lacking. This contrasts with more mature printing technologies, for which foundational physical principles have been rigorously examined. Presented here is a broad framework for describing the AJP process. Simple analytical models are employed to ensure generality and accessibility of the results, while experimental validation using a silver nanoparticle ink supports the physical relevance of the approach. This basic understanding enables a description of process limitations grounded in fundamental principles, as well as guidelines for improved printer design, ink formulation, and print parameter optimization.
The following article is
Open access
Review of digital printing technologies for electronic materials
Kye-Si Kwon
et al
2020
Flex. Print. Electron.
043003
View article
, Review of digital printing technologies for electronic materials
PDF
, Review of digital printing technologies for electronic materials
Direct printing methods have been used as manufacturing tools for printed electronics applications due to their cost effectiveness. In this review, the piezo-driven inkjet is discussed in detail since it is a mature technology and suitable for the production printing of printed electronics. In addition, other printing methods are considered for using higher viscosity ink and for producing smaller printed feature size. Various direct printing methods are compared in terms of jet mechanism, printing algorithm, and their applications. In particular high resolution printing methods using high viscosity inks, such as electrohydrodynamic jet, aerosol jet and micro-plotter are reviewed. To understand the recent status of industrial printing applications, display (liquid crystal display and organic light emitting diode) materials and printing issues are discussed. Finally, a brief overview of nano-particle metal based conductive inks is included because these inks have been widely used for printed electronics applications.
The following article is
Open access
Controlling and assessing the quality of aerosol jet printed features for large area and flexible electronics
Michael Smith
et al
2017
Flex. Print. Electron.
015004
View article
, Controlling and assessing the quality of aerosol jet printed features for large area and flexible electronics
PDF
, Controlling and assessing the quality of aerosol jet printed features for large area and flexible electronics
Aerosol jet printing (AJP) is a versatile technique suitable for large-area, fine-feature patterning of both rigid and flexible substrates with a variety of functional inks. In particular, AJP can tolerate ink viscosities between 1 and 1000 cP, with printing resolution of the order of 10
m, thus making it attractive for flexible and printed electronics. This work investigates in detail significant aspects of ink-substrate combination and substrate temperature that are highly relevant to AJP. In order to do this, thin conducting silver lines are printed using AJP on both rigid (glass and silicon) as well as flexible (polyimide) substrates. The correlation between the various deposition parameters and the ‘quality’ of the printed lines are evaluated, through measurements of electrical conductivity under different experimental conditions. Based on our findings, a framework is proposed through which the morphology of AJP lines can be controlled and assessed for applications in large area and flexible electronic devices.
The following article is
Open access
The 2021 flexible and printed electronics roadmap
Yvan Bonnassieux
et al
2021
Flex. Print. Electron.
023001
View article
, The 2021 flexible and printed electronics roadmap
PDF
, The 2021 flexible and printed electronics roadmap
This roadmap includes the perspectives and visions of leading researchers in the key areas of flexible and printable electronics. The covered topics are broadly organized by the device technologies (sections 1–9), fabrication techniques (sections 10–12), and design and modeling approaches (sections 13 and 14) essential to the future development of new applications leveraging flexible electronics (FE). The interdisciplinary nature of this field involves everything from fundamental scientific discoveries to engineering challenges; from design and synthesis of new materials via novel device design to modelling and digital manufacturing of integrated systems. As such, this roadmap aims to serve as a resource on the current status and future challenges in the areas covered by the roadmap and to highlight the breadth and wide-ranging opportunities made available by FE technologies.
A review of silver nanowire-based composites for flexible electronic applications
Neha Sharma
et al
2022
Flex. Print. Electron.
014009
View article
, A review of silver nanowire-based composites for flexible electronic applications
PDF
, A review of silver nanowire-based composites for flexible electronic applications
Silver nanowires (Ag NWs) have become a ubiquitous part of flexible electronic devices. The good electrical conductivity of silver, coupled with the excellent ductility and bendability exhibited by the wires make them ideal for flexible devices. Additionally, deposited films of Ag NWs are also found to be transparent due to the incomplete areal coverage of the wires. Thus, Ag NWs are widely used as transparent conducting electrodes (TCEs) for flexible and wearable electronics, replacing the traditionally used metal oxide based TCEs. The properties and functionality of NWs can be further improved by forming composites with other materials. Composites have been synthesized by combining Ag NWs with metals, metal oxides, and polymers. Both dry- and wet-techniques have been used to synthesize and deposit these composites, which have unique structural, chemical, and functional properties leading to myriad applications. This review focuses on recent developments in the field of Ag NW-based composites. An overview of the various fabrication techniques is provided, with a particular focus on coating and printing techniques, which are widely used for depositing Ag NWs. The application of the composites in diverse fields is also discussed. While the most common application for these composites is as TCEs, they are also used in sensors (physical, chemical, and biological), displays, and energy-related applications. The structural and environmental stability of the composites is also discussed. Given the wide interest in the development of printed flexible electronic devices, new Ag NW-based composites and application areas can be expected to be developed going forward.
Gravure-printed electronics: recent progress in tooling development, understanding of printing physics, and realization of printed devices
Gerd Grau
et al
2016
Flex. Print. Electron.
023002
View article
, Gravure-printed electronics: recent progress in tooling development, understanding of printing physics, and realization of printed devices
PDF
, Gravure-printed electronics: recent progress in tooling development, understanding of printing physics, and realization of printed devices
Printed electronics promises the realization of low-cost electronic systems on flexible substrates over large areas. In order to achieve this, high quality patterns need to be printed at high speeds. Gravure printing is a particularly promising technique that is both scalable and offers micron-scale resolution. Here, we review the tremendous progress that has recently been made to push gravure printing beyond its traditional limitations in the graphic arts. Rolls with far greater precision than traditional rolls and with sub-5
m resolution can be fabricated utilizing techniques leveraging the precision of silicon microfabrication. Physical understanding of the sub-processes that constitute the gravure process is required to fully utilize the potential of gravure. We review the state-of-the-art of this understanding both for single cells and patterns of multiple cells to print high-resolution features as well as highly-uniform layers. Finally, we review recent progress on gravure printed transistors as an important technology driver. Fully high-speed printed transistors with sub-5
m channel length and sub-5 V operation can be printed with gravure.
The following article is
Open access
Cork derived laser-induced graphene for sustainable green electronics
Sara L Silvestre
et al
2022
Flex. Print. Electron.
035021
View article
, Cork derived laser-induced graphene for sustainable green electronics
PDF
, Cork derived laser-induced graphene for sustainable green electronics
The demand for smart, wearable devices has been dictating our daily life with the evolution of integrated miniaturized electronics. With technological innovations, comes the impactful human footprint left on the planet’s ecosystems. Therefore, it is necessary to explore renewable materials and sustainable methodologies for industrial processes. Here, an eco-friendly approach to producing flexible electrodes based on a single-step direct laser writing is reported. A 1.06
m wavelength fiber laser was used for the first time to produce porous three-dimensional laser-induced graphene (LIG) on an agglomerated cork substrates. The obtained material exhibits the typical Raman spectra, along with an exceptionally low sheet resistance between 7.5 and 10 ohm sq
−1
. LIG on cork high electrical conductivity and the friendliness of the used production method, makes it an interesting material for future technological applications. To show its applicability, the production of planar micro-supercapacitors was demonstrated, as a proof of concept. Electrochemical performance studies demonstrate that LIG interdigitated electrodes, using PVA-H
SO
electrolyte, achieve an area capacitance of 1.35 mF cm
−2
(103.63 mF cm
−3
) at 5 mV s
−1
and 1.43 mF cm
−2
(109.62 mF cm
−3
) at 0.1 mA cm
−2
. In addition, devices tested under bending conditions exhibit a capacitance of 2.20 mF cm
−2
(169.22 mF cm
−3
) at 0.1 mA cm
−2
. Here, showing that these electrodes can be implemented in energy storage devices, also successfully demonstrating LIG promising application on innovative, green, and self-sustaining platforms.
Liquid metal polymer composites: from printed stretchable circuits to soft actuators
Carmel Majidi
et al
2022
Flex. Print. Electron.
013002
View article
, Liquid metal polymer composites: from printed stretchable circuits to soft actuators
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, Liquid metal polymer composites: from printed stretchable circuits to soft actuators
Soft polymers embedded with liquid metals like eutectic gallium-indium (EGaIn) exhibit unique combinations of mechanical, electrical, and thermal properties that are not possible with other material systems. For example, a soft silicone elastomer embedded with a percolating network of EGaIn microdroplets can function as a highly soft and elastic conductor that can be stretched to 600% strain without significant change in electrical resistance. Depending on the choice of polymer matrix and EGaIn microstructure, these soft material composites can be engineered to exhibit mechanical and electrical self-healing properties as well as high fracture toughness and resistance to tearing. Moreover, when solid filler particles like silver flakes are added to EGaIn-polymer composites, they can function as printable conductive inks that are fully elastic, non-marking, and non-smearing when cured. In this short review, we present different classes of EGaIn-polymer composites, discuss approaches to materials synthesis and patterning, and compare their properties with other material systems. Additionally, we will review applications of this emerging class of materials in domains ranging from wearable bioelectronics to soft robotics, shape programmable smart materials, as well as energy storage and harvesting devices.
Graphene-based wearable temperature sensor and infrared photodetector on a flexible polyimide substrate
Parikshit Sahatiya
et al
2016
Flex. Print. Electron.
025006
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, Graphene-based wearable temperature sensor and infrared photodetector on a flexible polyimide substrate
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, Graphene-based wearable temperature sensor and infrared photodetector on a flexible polyimide substrate
This paper describes an approach to the fabrication of flexible electronics i.e., a wearable temperature sensor and infrared (IR) photodetector on flexible polyimide (PI) substrate. Solar exfoliated reduced graphene oxide (SrGO) and graphene flakes are used as the sensing materials for developing the sensors on a PI substrate. PI, apart from being flexible and compatible with microfabrication processes, also helps in reducing the mobility and recombination of the photo-generated electrons of graphene due of its dielectric nature, thus enabling IR detection. Current responsivity and external quantum efficiency of IR photodetector for graphene flake- and SrGO-based devices were found to be 0.4 A W
−1
, 16.53% and 0.8 A W
−1
, 33.06% respectively which are higher than those of commercially available photodetectors. In addition, we demonstrate an ultrasensitive wearable human body temperature sensor in the temperature range of 35 °C to 45 °C, wherein both graphene flake- and SrGO-based devices exhibited a negative temperature coefficient of −41.30 × 10
−4
°C
−1
and −74.29 × 10
−4
°C
−1
respectively, which are higher than commercially available counterparts. Plausible underlying mechanisms to both IR sensing and temperature sensing have been studied. Furthermore, as a proof of concept, we investigated the effect of IR radiation emitted by a human hand on the device. Interestingly it was found that the device was very sensitive to it, indicating that the sensor can be used for motion detection which has potential applications in security, surveillance etc. The strategy presented here provides a new, simple, cost effective approach for the fabrication of next-generation wearable and bio-implantable devices based on a polyimide substrate that can be easily integrated onto the surface of a leaf, skin, paper, clothes etc owing to its versatile nature.
The following article is
Open access
Roll-to-roll processing of film substrates for hybrid integrated flexible electronics
Nagarajan Palavesam
et al
2018
Flex. Print. Electron.
014002
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, Roll-to-roll processing of film substrates for hybrid integrated flexible electronics
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, Roll-to-roll processing of film substrates for hybrid integrated flexible electronics
Roll-to-roll (R2R) processing on film substrates has been demonstrated to have the potential for achieving high throughput manufacturing of organic electronic systems at low cost. However, the ever-growing mobile devices market accompanied by the developments in information and communication technologies require high performance systems at very low power operation, sometimes on larger substrates having sizes in the range of a few metres. Organic electronics often fall short of fulfilling the required computing performance and power requirements of most of the common use cases. Hybrid integration of inorganic monocrystalline silicon chips on polymer films is a means to fulfil the aforementioned requirements. In this context, it is opportune to report our recent activities on R2R processing of plastic films for hybrid integration of flexible electronics. Hybrid integration can be performed with conventional, rigid surface mount devices as well as flexible, ultra-thin bare silicon chips. The first section of the paper is dedicated to a brief overview of R2R manufacturing of electronic devices with an example of production of radio frequency identification tags as well as to a discussion emphasising the targets for hybrid integration. Then, detailed descriptions about our processes for R2R manufacturing of metal wiring lines on films and hybrid integration are included. Three-dimensional integration of films and a temperature sensor label manufactured using hybrid integration process are also elaborated on. Furthermore, key results from fatigue reliability assessment of R2R metallised wiring lines are reported. Finally, some of the challenges in transferring the R2R processes for hybrid integration on film substrates from research labs to industrial manufacturing are highlighted.
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2015-present
Flexible and Printed Electronics
Online ISSN: 2058-8585