Anisotropic Electrical Transport in Mechanically Responsive Silver-Coated Microparticle-Gel Composites for Flowable Semiconducting Materials.

Soft materials with reversible electrical and mechanical properties are critical for the development of advanced bioelectronics that can distinguish between different rates of applied strain and eliminate performance degradation over many cycles. However, the current paradigm in mechano-electronic devices involves measuring changes in electrical current based on the accumulation of strain within a conductive material that alters the geometry through which electrons flow. Attempts have been made to incorporate soft materials like liquid metals and concentrated solutions of conjugated polymers and salts to overcome materials degradation but are limited in their ability to detect changes in the rate of the applied strain. Herein, the anisotropic electrical performance of a soft semiconducting composite prepared with silver-coated microspheres dispersed within a swollen copolymer gel is demonstrated. This composite exhibits an electrical response proportional to the magnitude of the applied shear force to enable a rate-of-strain dependent conductivity. Furthermore, a 100-fold increase in the conductivity of the composite is observed when the electric field is oriented parallel to the flow direction. This improvement in the electrical response can be attributed to the enhanced alignment of microspheres in viscoelastic media and can be leveraged in the development of mechanically responsive electronic devices.