A MEMS differential calorimeter for biomolecular characterization

This paper presents a MEMS differential calorimeter with integrated microfluidics for measuring structural transitions of biomolecules in solution. The device features two identical freestanding membranes, resistive temperature sensors and heaters, and a thermopile differential temperature sensor between the two membranes. Integrated with PDMS microfluidic channels and chambers, the calorimeter allows efficient handling and measurements of small volumes (∼1 μJ) of liquid samples. During measurements, the temperatures of the liquid sample and reference materials contained in the microfluidic chambers are scanned over a continuous range of temperatures with on-chip temperature control, and the differential thermal response is monitored by the thermopile, thus allowing differential scanning calorimetry (DSC). We have used the device to measure protein unfolding, one of the most important types of biomolecular structural transitions.