Stretchable bioelectronics: Mitigating the challenges of the percolation threshold in conductive elastomers

Conductive polymer (CP)–elastomer composites have been proposed as an alternative to the metals conventionally used for bioelectronic devices. Being softer and more stretchable than metals such as platinum and gold, they can mitigate the adverse effects associated with mechanical mismatch and fatigue failure. Such composites are conventionally made by embedding CP particles inside an elastomeric matrix. However, to achieve such a structure, a high CP loading that reaches a percolation threshold is required. High percolation thresholds lead to the degradation of mechanical properties. This study presents an alternate approach designed to reduce the CP content while maintaining conductivity through the matrix. A poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) composite was produced by filling a CP aerogel with polydimethylsiloxane (PDMS). This approach successfully formed a stretchable, conductive material, with only 1.8 wt. % CP. While elastic behavior was observed at low strain, the composite displayed plastic deformation at high strain (>20%). Future improvements will focus on the modification of the PEDOT:PSS–PDMS interface, to improve interaction of the polymer components and, hence, mechanical stability within the construct.