CMOS capacitive sensor array for continuous adherent cell growth monitoring

In this paper we present a compact, low-cost and re-usable cell-based biosensor that can be employed as a versatile tool for cell detection and monitoring. The proposed biosensor consists of an array of 8×8 capacitive sensors working based on the fully differential charge-based measurement technique. The analog output voltage coming from readout interface is converted to bit-streams using a DC-input ΣΔ modulator. The bit-streams are then acquired by a data acquisition system for further processing and display. We validate the chip functionality using various organic solvents with different dielectric constants. Moreover, we show the response of the chip to different concentrations of Polytyrene beads that have the same electrical properties as the living cells. The experimental results show that the chip allows the detection of a wide range of Polystyrene beads concentrations from as low as 10 beads/ml to 100k beads/ml. Due to its compactness, fast response and low complexity, the device can be used as an efficient alternative to traditionally labor-intensive cell analyses processes and it can be advantageous in different fields of biology and medicine.