A CMOS capacitance sensor that monitors cell viability

Abstract

We describe a CMOS capacitance sensor for measuring the capacitive behavior of living cells in a culture environment, in the presence of weak electric fields. The underlying physical phenomenon results primarily from polarization of the ionic cloud surrounding the cell in aqueous medium. The measured capacitance depends on a variety of factors including cell morphology, membrane integrity, medium pH and extra cellular ionic concentration and serves as an indicator of cell health. The capacitance sensor uses the principle of charge sharing and maps sensed capacitance values to voltages. The sensor chip has been fabricated in a commercially available 0.5 mum, 2-poly 3-metal CMOS technology. The sensors have been successfully used for long term monitoring of cell viability in vitro