Hydrogel-Based Real-Time Wireless Liquid Level Monitoring System for Size-Independent Infusion Bags

The monitoring of saline levels during medication has become a tedious process for practitioners. Regardless of the infusion bag size, real-time wireless monitoring is essential in the healthcare medical sector. This paper demonstrates a size-independent infusion bag liquid level monitoring system based on highly stretchable (>100% tensile strain) hydrogel-based electrodes. The sensor uses coplanar capacitive electrodes to sense changes in the liquid level and is integrated with a flexible printed circuit board (FPCB) to monitor the liquid level in real-time wirelessly. Regardless of the sensor's extensibility, the linear relationship between the ∆C/C₀ and the drop in liquid level, and the difference in the ∆C/C₀ values corresponding to liquid fill and empty states remained approximately the same. The sensor integrated with an FPCB delivered continuous liquid-level data to a mobile device in real-time without any obvious error.