Liquid Level Sensing Using Planar Inter-digitated Electrodes Employing CMOS Process

This article details liquid level sensing utilizing interdigitated electrodes topology fabricated using CMOS process steps. Layer of silicon strip with multiple electrodes is employed for characterization of different liquids based on the principle of capacitance change and thereby relative dielectric constant. Optimization of oxide thickness is carried out to minimize substrate capacitance effect. Fabricated strip is assembled, packaged and integrated with electronic circuitry. This handy device can be employed to characterize various liquids along with level sensing of the storage tank with electronic display. Various liquid levels are characterized by employing the proposed structure.