Over nearly a century, capacitive sensor readout has remained largely tied to absolute capacitance extraction and circuit-specific parameters. Here, we report a unified time-domain sensing framework that ingeniously leverages the intrinsic threshold voltage of microcontroller I/O pins, enabling a direct mapping between sensor charging dynamics and the desired physical quantities, without requiring any circuit knowledge. Circuit variations manifest primarily as time-axis scaling, and can be efficiently corrected using simple two-point anchoring. We experimentally validate the framework using non-contact liquid-level sensor, commercial capacitive humidity sensor, and linear displacement sensor. Despite substantial hardware differences, consistent sensor responses are recovered through two-point temporal anchoring, without re-identifying circuit parameters or recalibrating sensing models. By shifting the sensing representation from absolute capacitance to time-domain observables, this work challenges the long-standing capacitance-centric readout paradigm and points to a system-level paradigm shift toward robust, scalable, and platform-independent sensing. The proposed framework significantly reduces the complexity and maintenance overhead associated with capacitive sensors across diverse application domains, making it broadly applicable across nearly all industrial sectors.
Yan et al. (Sun,) studied this question.