A Biomedical Microphysiometer

Abstract

We report on a micromachined silicon chip that is capable of providing a high-throughput functional assay based on calorimetry. A prototype twin microcalorimeter based on the Seebeck effect has been fabricated by using IC technology process steps in combination with micromachined postprocessing techniques. A biocompatible liquid rubber membrane supports two identical 0.5×2 cm2 measurement chambers, situated at the cold and hot junction sites of a thermopile. The thermopile consists of 666 aluminum/p+-polysilicon thermocouples. The chambers can house up to 106 eukaryotic cells cultured to confluence. The advantage of the device over microcalorimeters on the market, is the integration of the measurement channels on chip, rendering microvolume reaction vessels, ranging from 10 to 600 µl, in the closest possible contact with the thermopile sensor (no springs are needed). Power and temperature sensitivity of the sensor are 23 V/W and 130 mV/K, respectively. The small thermal inertia of the microchannels results in the short response time of 70 s, when filled with 50% of water.