Interfacial damage in flexible electronics with collagen substrate: effect of environmental conditions

Stretchable polymers such as polyethylene terephthalate, polyether sulfone etc. are widely used as substrates for flexible electronics. Though these materials are clinically approved and safe to employ for in-vitro applications, still, using collagen as an alternative would be beneficial thanks to its biocompatibility, biodegradability, non-toxicity and flexibility. Recently, some researchers were successful in fabricating sensors with collagen substrates; however, the softer collagen base attached to the stiffer metallic layers might create a mismatch in the interfacial properties and affect the device's performance. Therefore, it is essential to investigate the mechanical behaviour of collagen-metallic interfaces. It was observed that at lower strain levels (1.25%) the interfacial delamination between the collagen-and metallic layers is negligible while at higher strain (5%), a considerable delamination was noticed. The effect of environment should also be considered as the stress generated for both metallic layers and collagen substrates differed by two orders of magnitude compared to dry ones.