Papers by Keyword: Flexible Electronics

Abstract: The growing energy crisis and environmental challenges have spurred the development of sustainable energy storage solutions. This study synthesizes 3D porous Orange Peel-Lignin activated carbon (OPLAC) from orange peel waste and lignin using a two-step pyrolysis process with KOH activation. The OPLAC was combined with styrene-isoprene-styrene (SIS) and SUPER P conductive carbon black to create stretchable electrode composites with varying compositions (70:20:10, 60:30:10, and 50:40:10). Mechanical testing revealed that increasing the SIS content improved stretchability, with the 50:40:10 composition achieving 300% strain and retaining 95% durability after 100 cycles. However, higher SIS content reduced electrical conductivity, with the 70:20:10 composition showing the highest conductivity (12 S/cm) and the 50:40:10 the lowest (7 S/cm). The 60:30:10 composition offered a balance between flexibility and conductivity. These results demonstrate the potential of biomass-derived activated carbon for sustainable, high-performance supercapacitor electrodes, particularly for flexible electronics and wearable devices, while highlighting the valorization of agricultural and industrial waste in energy storage applications. Keywords: Stretchable electrode, activated carbon, orange peel waste, Lignin, flexible electronics

Abstract: Conductive inks composed of chemically sintered silver (Ag) nanoparticles were prepared. The enlargement of particle size was accompanied by the increase in conductivity of the Ag nanoparticle ink. The resistance of the as-prepared and sintered Ag nanoparticles printed on different substrates was measured, and results showed that the formulated conductive ink works best on glossy paper. This is due to the compatibility of the conductive ink with the porosity and surface roughness of the glossy paper. The conductive ink formulation was also used as printer ink, and results showed a decrease in resistance as the printing pass was increased.

Abstract: Flexible and transparent devices are expected to meet increasing consumer demands for upgrades in wearable devices, smart electronic and photonic applications. In this work, nano-manufacturing of a flexible and powerless silicon carbide nanowire network ultraviolet photodetector (SiCNW-network UVPD) prototype was investigated by a very cost-effective direct transfer method. Indeed, the powerless device exhibited a photo-to-dark current ratio (PDCR) of 15 with a responsivity of 5.92 mA/W at 254 nm wavelength exposure. The reliability and durability of the device was evaluated by bending tests. In fact, the PDCR of the device was still very good even after seventy-five bending cycles (~ 96 % of the rest state). In brief, our flexible, powerless SiCNW-network UVPD device with cost-effectiveness, good performance, and durability can provide feasible alternatives for new generation wearable optoelectronic products.

Abstract: Advancements in wearable technology and smart textiles have also opened new possibilities in the sports and medical fields. One of the examples of a relevant application case can be found in cycling. This paper expands on previous research on stretchable electronics on knit fabrics. It describes the development of stretchable circuits for the lower back position and motion tracking to prevent back pain in recreational (road) cyclists by combining electrical and textile engineering with insights generated in rehabilitation sciences and sports physiotherapy. The research process included developing and testing of the functional circuit integrated into a cycling jersey. Thermoplastic polyurethane films were used for the textile integration process to achieve maximum comfort and after-life disassembly possibility. Reliability tests, e.g. washing (ISO 6330-2012) and tensile tests, were conducted. It is concluded that while mechanical stress during washing cycles remains a serious concern for reliability and durability, the use of water-repellent thermoplastic polyurethane sealing seriously reduces the damage caused by water and detergents.

Abstract: The development of flexible electronics towards for the direction of bend ability, lightweight, portability, long life against falling. The performance of the substrate in the flexible electronics plays a very important role in the development of electronics. In this article, three preparation technologies of thin films are introduced, including CVD, PVD and ALD. The paper also introduces the research progress on the preparation of substrate barrier films, and one main challenge that may face by the preparation of thin film materials. In order to satisfy the development of flexible electronics, improving the substrate’s performance constantly is needed. Finally, the development of preparing barrier films is prospected.

Abstract: Recently, supercapacitors have attracted a tremendous amount of attention as energy-storage devices due to their high-power density, fast charge–discharge ability, excellent reversibility, and long cycling life. In this research work, we demonstrate a laser scribed super capacitor based on polyimide (PI) substrate for the storage of electrical energy. PI substrate of thickness 200μm and area 1cm × 1cm was reduced by a laser engraver with a 450 nm wavelength in the form of stackable supercapacitor electrodes. Although, PI itself exhibits non-conductive behavior; however, by laser irradiation we change the surface properties of PI and reduce its resistance. The chemical property of irradiated PI was characterized with XRD where the carbon peak was observed at 2*theta = 25.44, which confirms the reduction of PI material in to a graphene-like substance. The electrical conductivity was analyzed with a probe station and observed to be 1.6mS. Two conductive regions were assembled into a capacitor device by sandwiching a PVA/H₃PO₄ electrolyte in between. During the charging and discharging characterization of the capacitor device, current density was observed to be 1.5mA/cm². Capacitance versus voltage analysis was carried out and the device showed 75mF/cm² against a voltage sweep of ±2V. The galvanostatic charging and discharging curve shows a symmetric behavior with respect to time exhibiting the stability and durability of the device.

Abstract: Flexible electronics have drawn much attention due to vast application possibilities. Polyimide was the substrate of choice as a flexible substrate owing to its properties such as good mechanical strength, high temperature resistance, good dimensional stability, and low dielectric constant. The adhesion between metal and polymer substrate plays a crucial role for reliability of these applications and low adhesion was the cause for most failures. In this study, plasma surface treatments were applied on polyimide surface by inductively coupled plasma (ICP) treatment system. The results of contact angle measurements and atomic force microscopy (AFM) show a large increase in surface roughness with increasing treatment time. Complete wetting was found for both argon and oxygen plasma treatment. Analysis of chemical composition by FTIR reveals an increase in carbon-oxygen functional groups and the concentration of oxygen on the surfaces.

Abstract: This paper presents how geometrical and technological parameters of inductive angular position sensor, fabricated on flexible substrate, influence its characteristics. In our earlier work, the angular position sensor has been already presented but for 60° stroke. In presented work, the design and optimization have been performed for 90° stroke, which is extensively used, for example, in automotive applications. For three different designs of meander rolled coils, width of segments, substrate thickness and relative distance between outer and inner coils have been changed in order to find optimal sensor structure. The proposed sensor is low-cost, easily fabricated and its parameters can be adapted for different angular strokes and applications.

Abstract: Recent advances in mechanics and materials provide routes to integrated circuits that offer the electrical properties of conventional, rigid wafer-based technologies but with the ability to be stretched, compressed, twisted, bent and deformed into arbitrary, curvilinear shapes. This paper summarizes developments in this emerging field, with descriptions of application opportunities, fundamental aspects, representative devices, and particularly the effect of plastic deformation.

Abstract: We demonstrate a woven textile with an integrated humidity and temperature sensor on flexible PI substrates. We discuss the fabrication process of the smart textile and compare two methods of sensor fabrication, first conventional photo lithography and second printing using ink jet. The humidity sensor is based on a capacitive interdigitated transducer covered with a sensing layer while the temperature sensor is made of a resistive metallic meander. An encapsulation method protecting the sensors during dicing, weaving and operation has been successfully implemented. The fabricated structures are tested to bending strain, a main source of failure during the fabrication of textiles. We were able to bend bare electrodes and complete sensors down to a minimal bending radius of 100 μm without loss of functionality. The woven temperature sensor has a temperature coefficient of 0.0027 /° C for lithography made and 0.0029 /°C for printed sensors. The humidity sensor shows a repeatable behaviour in the tested humidity range between 20 to 70 %RH. The weaving process does not damage or change the behaviour of the fabricated sensors. This contribution will highlight the challenges and promises of printing and laminating processes for the large scale fabrication of smart polymeric stripes to be woven into textiles.