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

Abstract

exposure of medical practitioners to pathogens while facilitating efficient consultation. With the help of wearable sensors, several basic but important information such as blood pressure, temperature, and electrocardiogram can be shared with doctors at any time over the Internet, which not only facilitate real-time diagnosis but also reduces the number of direct doctor consultation, hospital stay, and hospital readmission. Intravenous (IV) drip infusion is commonly used in hospitals to treat critically ill patients. However, this procedure is laborious and requires the constant monitoring or supervision of the administration because it can last for more than an hour. It is nontrivial to continuously examine the amount of IV fluid drip, which comprises a small curative tube called a catheter that infuses a saline-based electrolyte solution into the patient's bloodstream and provides readily available nutrition to assist in the patient's recovery. Typically, the fluid inside the drip bottle is monitored by the doctor or nurse visiting the patient's bed; health professionals must replace the drip bag just before the saline solution is depleted. This procedure is tedious, and in some cases, the nurse's tasks may be disrupted, and/or additional personnel or staff may be required. In the current COVID-19 pandemic, the situation is even more complex and not a good practice. To address this issue, wireless liquid-level sensors based on capacitive-type, [5][6][7][8] load cell, [9,10] optical, [11] and infrared sensors [12] have been proposed. In the case of capacitive-type liquid-level sensors, flexible conductive plates separated by a distance in a coplanar configuration are mostly adopted. On the other hand, hydrogel-based conductors are fascinating due to their electrical conductivity, transparency, self-healable, stretchability, and tunable to desired functionality by modifying the crosslinking chemistry. Considering their high stretchability (>100%), a positive attribute, size-independent infusion bag liquid-level monitoring can be realized. Hydrogel-based devices, considering their stretchability a major functionality, such as strain sensors, [13,14] triboelectric nanogenerators, [15,16] and supercapacitors [17] have been reported to date. To the state-of-art of hydrogel-based devices, there were no reports on liquid level sensors based on hydrogel electrodes in a coplanar configuration.This paper introduces a coplanar capacitive-type liquid level sensor based on stretchable hydrogel electrodes integrated with a flexible printed circuit board (FPCB). The sensor can be attached to the outer surface of an infusion bag for real-time wireless monitoring. Regardless of the size of the infusion bag,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 (...