Energy autonomous electronic skin

Energy autonomy is key to the next generation portable and wearable systems for several applications.Among these,the electronic-skin or e-skin is currently a matter of intensive investigations due to its wider applicability in areas,ranging from robotics to digital health,fashion and internet of things(IoT).The high density of multiple types of electronic components(e.g.sensors,actuators,electronics,etc.)required in e-skin,and the need to power them without adding heavy batteries,have fuelled the development of compact flexible energy systems to realize self-powered or energy-autonomous e-skin.The compact and wearable energy systems consisting of energy harvesters,energy storage devices,low-power electronics and efficient/wireless power transfer-based technologies,are expected to revolutionize the market for wearable systems and in particular for e-skin.This paper reviews the development in the field of self-powered e-skin,particularly focussing on the available energy-harvesting technologies,high capacity energy storage devices,and high efficiency power transmission systems.The paper highlights the key challenges,critical design strategies,and most promising materials for the development of an energy-autonomous e-skin for robotics,prosthetics and wearable systems.This paper will complement other reviews on e-skin,which have focussed on the type of sensors and electronics components.

Heterogeneous integration of contact-printed semiconductor nanowires for high-performance devices on large areas

In this work,we have developed a contact-printing system to efficiently transfer the bottom-up and top-down semiconductor nanowires(NWs),preserving their as-grown features with a good control over their electronic properties.In the close-loop configuration,the printing system is controlled with parameters such as contact pressure and sliding speed/stroke.Combined with the dry pre-treatment of the receiver substrate,the system prints electronic layers with high NW density(7 NWs/μm for bottom-up ZnO and 3 NWs/μm for top-down Si NWs),NW transfer yield and reproducibility.We observed compactly packed(~115 nm average diameters of NWs,with NW-to-NW spacing~165 nm)and well-aligned NWs(90%with respect to the printing direction).We have theoretically and experimentally analysed the role of contact force on NW print dynamics to investigate the heterogeneous integration of ZnO and Si NWs over pre-selected areas.Moreover,the contact-printing system was used to fabricate ZnO and Si NW-based ultraviolet(UV)photodetectors(PDs)with Wheatstone bridge(WB)configuration on rigid and flexible substrates.The UV PDs based on the printed ensemble of NWs demonstrate high efficiency,a high photocurrent to dark current ratio(>10^(4))and reduced thermal variations as a result of inherent self-compensation of WB arrangement.Due to statistically lesser dimensional variations in the ensemble of NWs,the UV PDs made from them have exhibited uniform response.