Integrated DNA-sensor arrays typically check for probe-target strand hybridization by analyzing the sensed capacitance changes, normally off-chip in software. However,many applications like portable medical devices require only the detection of an event or of a substance. We reduce the area, power and computational overhead for this task manifold with simple regenerative analog and mixed-signal circuits, including a 9-b low-power regenerative rail-to-rail comparator and a winner-take-all (WTA) circuit. Simulation of a design targeted for implementation in a 0.35μm CMOS process is presented.