Capacitively coupled contactless conductivity detection-based sensor for liquid level measurement and application to clinical infusion monitoring

Capacitively coupled contactless conductivity detection (C4D) is rarely reported for a liquid level sensor (LLS), especially for clinical infusion monitoring. In this paper, a facile model and theory of LLS based on the previous work of C4D has been proposed. The smartphone-based sensor was developed and applied to automatic monitoring of the clinical infusion process. In contrast to the currently -used LLSs, the developed C4D-LLS has the merits: (i) flexible, facile, and low cost of sensing section, fitting for containers of different shapes as well as making it easy for mass production and applications; (ii) variable and wide measurement ranges and application scopes, being suitable for various occasions and capable of measuring the level of liquid or solid materials; and (iii) contactless measurement, avoiding electrode polarization and contamination. All these results indicate the developed model, theory and sensor have the potential to process monitoring of liquid level in fields such as clinical pre -warning of healthcare.