Phys.org September 18, 2023 The mechanical properties of the substrate elastomers are often poor due to the inherent performance of the materials. Researchers in China prepared a poly(vinyl alcohol) (PVA)-based self-healing material with high strength and good thermal stability by side-linked grafting modification of PVA with a one-step esterification reaction. Benefiting from the hydrogen bonds and ion coordination between iron ions and carboxyl groups, the synthesized elastomer exhibited excellent mechanical properties and good self-healing performance. The high sensitivity and self-healing performance of a silver nanowire-coated elastomer strain sensor demonstrated the wide potential applicability of the prepared PVA-based elastomers in health […]
Tag Archives: Flexible electronics
Toward perdurable flexible electronics
Nanowerk March 23, 20212 In wearable electronics, to acquire stability and simultaneously preserve stretchability, sensitivity, and scalability is of high significance yet challenging for practical device applications. Researchers in Japan developed a kirigami-structured graphene–polymer hybrid nanocomposite for strain sensors by a laser direct writing technique on a polyimide sheet. To protect the device, ecoflex polymer was applied as the passivation layer. Depending on the applications, ecoflex grid-wrapped and film-encapsulated have high stretchability and sensitivity. In demonstrations the sensor platform suffered almost no performance degradation even after >60 000 stretching cycle tests due to less strain within the sensor. As proof-of-concept for […]
Untwisting plastics for charging Internet-of-things devices
Nanowerk May 27, 2020 To use body heat to charge some types of micro-devices and sensors requires lightweight, non-toxic, wearable, and flexible thermoelectric generators. Researchers in Japan studied the thermoelectric properties of a highly conductive thiophene-based polymer, called PBTTT. They found that doping the polymer with a thin ion electrolyte gel improves conductivity and infiltrates the polymer successfully when a specific electric voltage is applied. Doping it with a critical amount of electrolyte untwists the highly twisted chain and creates links between its crystalline parts, improving electron conductivity. They are now looking into ways to optimize the thermoelectric performance of […]
Team develops foldable and washable luminescent film
Phys.org April 8, 2020 The conversion of invisible infrared or ultraviolet light into visible light allows us to intuitively see the data contained in the light, and thus enables the use of infrared or ultraviolet light for displays or imaging devices. As ultraviolet light is high in energy its conversion into visible light relatively easy and efficient. A team of researchers in South Korea made a square lattice array of silica microbeads decorated with up-conversion nanoparticles and metal structures. This configuration maximizes both the absorption of near-infrared light and the luminescence of visible light, thus increasing the efficiency of near-infrared-to-visible […]
Researchers identify breaking point of conducting material
EurekAlert March 4, 2020 Accurate predictions of the temperature when embrittlement occurs is crucial to design conducting polymers that are used in next-generation flexible electronics. An international team of researchers (USA – Pennsylvania State University, Germany) found a way to measure glass transition temperatures by keeping track of the mechanical properties as embrittlement occurs, laying the foundation for understanding the relationship between the glass transition and structure. Follow-up studies then determined the glass transition for 32 different polymers by measuring mechanical properties as a function of temperature. They showed the simple relationship between the chemical structure and the glass transition […]
Bending an organic semiconductor can boost electrical flow
Science Daily December 3, 2019 Slightly bending semiconductors made of organic materials can roughly double the speed of electricity flowing through them. An international team of researchers (USA – Rutgers University, UMass Amherst, Japan, South Korea) shows a very strong, anisotropic, and reversible modulation of the intrinsic (trap‐free) charge carrier mobility of single‐crystal rubrene transistors with strain, showing that the effective mobility of organic circuits can be enhanced by up to 100% with only 1% of compressive strain. This study lays the foundation of the strain engineering in organic electronics and advances the knowledge of the relationship between the carrier […]
Smart metamaterials that sense and reprogram themselves
Phys.com November 11, 2019 As proof of concept, an international team of researchers (USA – Duke University, UK, China) proposed and developed a smart digital-coding metasurface with self-adaptive capacity for reprogrammable functionality. A sensor on the metasurface detected specific features surrounding the construct in the environment and delivered them to a microcontroller unit (MCU) which independently determined reactions to these variations and then instructed the FPGA via coding patterns, to change the metasurface configuration in real time. The smart metasurfaces achieved self-adaptive reprogrammable functionality automatically based on the surface-installed sensing-feedback system and calculation software. The team envisions the preliminary work […]
Multitasking graphene ink printed into tiny flexible supercapacitors
Nanowerk January 23, 2019 Researchers in China developed an ink combining graphene and carbon black, both of which are conductive, with a polymer binder in a solvent. As it is applied, the force causes it to lose its viscosity, so it flows easily, but as soon as the force is removed, it thickens and keeps its shape. The ink can act as the microelectrodes, metal-free current collectors and interconnects, simultaneously. They applied the graphene ink to a substrate, such as glass or flexible PET plastic, using a patterned screen as a stencil. The resulting pattern includes all the conductive parts […]
Personalizing wearable devices
Harvard University February 28, 2018 Researchers at Harvard University used Bayesian optimization to identify the peak and offset timing of hip extension assistance that minimizes the energy expenditure of walking with a textile-based wearable device. Optimal peak and offset timing represents an improvement of more than 60% on metabolic reduction compared with state-of-the-art devices that only assist hip extension. The results provide evidence for participant-specific metabolic distributions with respect to peak and offset timing and metabolic landscapes, lending support to the hypothesis that individualized control strategies can offer substantial benefits over fixed control strategies… read more. TECHNICAL ARTICLE Harvard researchers […]