Energy harvesting textiles for a rainy day:woven piezoelectrics based on melt-spun PVDF microfibres with a conducting core

Recent advances in ubiquitous low-power electronics call for the development of light-weight and flexible energy sources.The textile format is highly attractive for unobtrusive harvesting of energy from e.g.,biomechanical movements.Here,we report the manufacture and characterisation of fully textile piezoelectric generators that can operate under wet conditions.We use a weaving loom to realise textile bands with yarns of melt-spun piezoelectric microfibres,that consist of a conducting core surrounded byβ-phase poly(vinylidene fluoride)(PVDF),in the warp direction.The core-sheath constitution of the piezoelectric microfibres results in a—for electronic textiles—unique architecture.The inner electrode is fully shielded from the outer electrode(made up of conducting yarns that are integrated in the weft direction)which prevents shorting under wet conditions.As a result,and in contrast to other energy harvesting textiles,we are able to demonstrate piezoelectric fabrics that do not only continue to function when in contact with water,but show enhanced performance.The piezoelectric bands generate an output of several volts at strains below one percent.We show that integration into the shoulder strap of a laptop case permits the continuous generation of four microwatts of power during a brisk walk.This promising performance,combined with the fact that our solution uses scalable materials and well-established industrial manufacturing methods,opens up the possibility to develop wearable electronics that are powered by piezoelectric textiles.

Tunable flexible artificial synapses:a new path toward a wearable electronic system

The flexible electronics has been deemed to be a promising approach to the wearable electronic systems.However,the mismatching between the existing flexible deices and the conventional computing paradigm results an impasse in this field.In this work,a new way to access to this goal is proposed by combining flexible devices and the neuromorphic architecture together.To achieve that,a high-performance flexible artificial synapse is created based on a carefully designed and optimized memristive transistor.The device exhibits high-performance which has near-linear non-volatile resistance change under 10,000 identical pulse signals within the 515%dynamic range,and has the energy consumption as low as 45 fJ per pulse.It also displays multiple synaptic plasticity features,which demonstrates its potential for real-time online learning.Besides,the adaptability by virtue of its threeterminal structure specifically contributes its improved uniformity,repeatability,and reduced power consumption.This work offers a very viable solution for the future wearable computing.