Characterizations and optimization of electrical contact between nanocomposite elastomer and metal

Nanocomposite elastomer is an exciting, emerging class of materials for polymer MEMS sensors and actuators . It is made by mixing electrically conducting particles (e.g., carbon nanotubes) in regular, nonconducting elastomer (e.g., PDMS) beyond percolation limit. The bulk resistance of the polymer is a function of particle doping concentration and other parameters (e.g., applied stress). The electrical contact between this material and patterned electrodes is crucial for future device performance but has not been systematically investigated in the past. In this work, we present comprehensive characterization of contact resistance between the nanocomposite elastomer and metal electrodes. We report the I-V and drift properties under different applied pressure. We discovered that liquid metal alloy (Galinstan: 68.5% Ga, 21.5% In, 10% Sn) could be used to drastically reduce the contact resistance and eliminate long term drift from 20% to below 2%.