High-Performance Metal Ion Coordination Polymer Humidity Sensor with High Sensitivity, Real-Time Monitoring, and Wide Range Measurements

Abstract

As the demand for environmental monitoring and industrial applications increases, the significance of humidity sensors in various fields has grown substantially. However, traditional humidity sensors are hindered by slow response times, substantial hysteresis, and inadequate stability, which limit their applicability in high-precision environments. To overcome these limitations, this study introduces an ion-capacitive humidity sensor based on poly(vinyl alcohol)-magnesium (PVA-Mg(II)). The sensor is fabricated using a straightforward solution-based method, and it leverages ion migration as the primary response mechanism, thereby significantly enhancing humidity response sensitivity compared to conventional electronic sensors. The PVA-Mg(II) sensor achieves a humidity response of up to 1420% within the 36% to 97% RH range, with a broad detection range spanning from 2% to 97% RH. The sensor exhibits response and recovery times of 15 and 2 s, respectively, with minimal hysteresis. Furthermore, the sensor demonstrates exceptional long-term stability, maintaining consistent performance for over 100 h within the 2% to 61% RH range, underscoring its superior humidity detection capabilities. By improving humidity response sensitivity through ion migration and exhibiting low hysteresis, the sensor effectively addresses the inherent limitations of traditional humidity sensors in terms of stability and response speed, offering significant potential for a wide range of practical applications.