Technology
New triboelectric fabric generates charge from body movement
Researchers from the University of Fukui, Japan, and Nanjing University in China have developed all-fibrous composite-layer triboelectric nanogenerators (AF-TENG) that can easily be integrated into fabric. TENGs generate power from body movements to charge electronic devices such as mobile phones or wearables. TENGs do exist, largely in low-power devices such as LEDs and calculators, but not in wearables since they are not deemed “breathable” enough, making them uncomfortable to wear. Te new multilayered TENGs are made of electrospun fibres and silver nanowires with a polystyrene charge-storage layer, promising high electrical performance as well as wearability comfort. “With our work we aim to provide a new point
of view towards wearable energy harvesters and smart textiles,” says Dr Hiroaki Sakamoto, the study’s corresponding author. Te triboelectric effect is a phenomenon
where a charge is generated between two dissimilar materials when they are moved apart aſter being in contact with each other. TENGs use this effect to convert mechanical motion into electrical energy. Aimed at wearables, emphasis is on the TENG fabrics’ properties (especially the comfort of the material) as well as their charge- carrying capacity. Te triboelectric materials must be safe, biocompatible with the human body, flexible and breathable whilst maintaining high electrical output. Among the materials considered are electrospun fibres, since they
Caption
Polyvinylidene fluoride, nylon, silver nanowires and polystyrene have been spun into a fibrous composite nanogenerator that can be integrated into clothing
are lightweight and strong, with good electrical properties. Electrospinning is a technique by which
solutions of polymers are drawn into fibres using electrical charge. Tere are ongoing efforts to add metals to electrospun fibres to improve the electrostatic potential and charge- trapping capabilities. Te AF-TENG contains a triboelectric
membrane made of two layers of electrospun fibres – one of a material called polyvinylidene fluoride (PVDF) and the other of nylon. Silver nanowires cover these layers. Te researchers also added a layer of electrospun polystyrene fibres between
the silver nanowires and the triboelectric membrane, to store the charge. Te mechanical motion of the body whilst
walking or running causes the triboelectric layers to produce a charge. Normally, the charge buildup on the triboelectric surface is gradually lost or dissipated, reducing the surface charge density and the output performance of the nanogenerator. However, in this case, the added polystyrene membrane collects and traps the charge, retaining the surface charge density of the AF-TENG. Te researchers used the AF-TENG to light
126 commercial LEDs, each rated at 0.06W, demonstrating the commercial feasibility of the nanogenerator.
Polyn Technology demonstrates a brain-like chip
Polyn Technology, an Israeli fabless semiconductor company, has demonstrated a proof of technology for its Neuromorphic Analogue Signal Processor, or NASP. Based on Polyn’s brain-mimicking architecture and containing several neural networks, the chip is the first Tiny AI “true analogue” design to be used with sensors. Tiny AI is localised AI, which promises to speed up processes such as mobile- based medical image analysis or the reaction time of self-driving cars, as close to real time as possible. “Our chip represents the most advanced
technology for bridging analogue computations and the digital core. It is designed with
neuroscience in mind, replicating the pre-processing the primary cortical area of the human brain does at the periphery before learning at the centre,” said Aleksandr Timofeev, CEO and founder of Polyn Technology. Te chip is implemented in 55nm CMOS,
and Polyn’s proof of technology also confirms the chip’s scaleability and the efficiency of its design tools. Polyn’s Neural-Net-To-Chip automation tools support fast and cost-effective development of tailored Tiny AI solutions, which perform AI computations on-device. “Our first chip is created from trained neural networks by NASP compiler and synthesis
tools that generate a netlist and the silicon engineering files from the soſtware math model simulation. We will continue to refine our technology for creation of new generation chips,” said Yaakov Milstain, Polyn’s Chief Operating Officer. Te chip will be available to customers
early next year, followed by the first wearable product that fuses photoplethysmography (PPG) sensors – essential in monitoring cardiac functions, and inertial motion unit (IMU) sensors, which blend the data from sensors such as gyroscopes, magnetometers and accelerometers to calculate the exact force, angular rate and direction of a body.
www.electronicsworld.co.uk June 2022 05
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