AUTHOR=Keller Kirill , Grafinger David , Greco Francesco 

TITLE=Printed and Laser-Scribed Stretchable Conductors on Thin Elastomers for Soft and Wearable Electronics

JOURNAL=Frontiers in Materials

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2021.688133

DOI=10.3389/fmats.2021.688133

ISSN=2296-8016

ABSTRACT=As printed electronics is evolving towards applications in biosensing and wearables, the need of novel routes to fabricate flat, lightweight, stretchable conductors is increasing in importance. A suitable strategy for creating soft yet robust and stretchable interconnections in the aforementioned technological applications is to use print-related techniques to pattern conductors on top of elastomer substrates. In this study some thin elastomeric sheets – two forms of medical grade thermoplastic polyurethanes and a medical grade silicone – are considered as suitable substrates. Their mechanical, surface and moisture barrier properties -relevant for their application in soft and wearable electronics- are first investigated. VariousDFour different approaches are tested to pattern conductors, based on: screen printing of (i) conducting polymer (poly(3,4 ethylenedioxythiophene): polystyrene sulfonate, PEDOT:PSS), or (ii) stretchable Ag ink, and (iii) laser-scribing of Laser Induced Graphene (LIG). The electromechanical properties of these materials are thoroughly investigated by means of tensile testing and concurrent electrical measurements up to a maximum strain of 100%. Performance of the different stretchable conductors is compared and rationalized, evidencing the differences in onset and propagation of failure. Selected materials are then used in a proof of concept application as connectors for a wearable tattoo biosensor.