Wafer-level fabrication of strain gauges on PDMS membranes for low-pressure sensing

A wafer-level fabrication process of polydimethylsiloxane (PDMS) membranes with integrated strain gauges for low-pressure sensing is developed. The device is proposed as an alternative approach and a first step towards a high-throughput platform to electrically monitor the contractility of heart cells on a silicon chip. Titanium strain gauges are successfully integrated on a 12 μm-thick PDMS membrane that acts as a flexible substrate for heart cells culturing. Electrical measurements show a relative resistance change of approximately 5% for membranes subjected to variable pressure up to 1 kPa. This demonstrates the suitability of the sensing principle for monitoring typical micron-range contractions of heart cells. Both the membranes and strain gauges are fabricated using conventional photolithography and MEMS fabrication techniques, providing high-throughput and IC manufacturing compatibility as required for its envisioned large scale application in drug testing and cell biology study.