We demonstrate an elegant chemical and biological sensing mechanism that transduces chemical and biological signals to electrical signals with large intrinsic amplification not requiring complex on-chip microelectronics. The sensing mechanism employs dissolvable membranes separating a fluid chamber from an interdigitated capacitor initially in air. Dissolution of the membrane (here, a hydrogel membrane) in the presence of the target species (here, dithiothreitol) allows the target species to flow into the capacitor bringing about a change in its impedance. Using this mechanism, a simple circuit can generate 2.9 V DC output with 2.94 V DC supply. No DC power is consumed until the detection of the target species. A range of species can be sensed by defining membranes specific to the target species. The fabrication process is compatible with conventional IC fabrication technologies and is applicable to wireless microsensor networks.