CMOS Electro-Chemical DNA-Detection Array with On-Chip ADC

We report on a CMOS-based microsensor array, featuring 576 electrodes and 24 channels, for label-free electrochemical detection of DNA hybridization. Each channel comprises a potentiostatic circuit that keeps the electrode at a defined potential and measures the respective electrical current. The readout channels rely on a first-order delta-sigma architecture, where the electrode-electrolyte capacitance is used as the integrator. This results in a very compact recording circuit inclusive of A/D conversion; the circuit consists of only the measurement electrode, a comparator, a feedback capacitance and a few switches. Biological experiments with short DNA samples and DNA extracted from human immunodeficiency virus (HIV) are presented.