Strain- and Strain-Rate-Invariant Conductance in a Stretchable and Compressible 3D Conducting Polymer Foam

Advances in stretchable conductors have been one of the main driving forces behind the realization of wearable and epidermal electronics. However, retaining constant strain-property relationships under varying strain and strain rate remains a challenge. Here, we demonstrate a 3D structuring approach toward strain-accommodating, biocompliant conductors. In contrast to previous stretchable conductors, this method leads to polymeric materials with conductance that has zero dependence on (1) both tensile and compressive strain over an 80% strain range, and (2) strain rate from 2.5%/min to 2,560%/min. Their Young's moduli can be controllably tuned between 10 and 300 kPa. In addition, these conductors are ultra-lightweight and can be molded into virtually any shape and size. Their properties mimic the dynamic and softness of biological systems, rendering this a versatile platform for designing electronic materials that can potentially form intimate interfaces with humans.