High-Performance Three-Dimensional Go-Frame Electrode Design for Capacitive Humidity Sensors in Real-Time Human Respiration Monitoring

Abstract

The increasing need of environmental and physiological monitoring propels the development of humidity sensors, especially for applications aimed at personal health detection. Among the various types of humidity sensors, capacitive humidity sensors are particularly noted for their rapid response, low power consumption, and high sensitivity. However, conventional capacitive humidity sensors, including widely used planar interdigitated electrodes (IDE) and parallel plate (PP) structures, face challenges with achieving high sensitivity and producing stable output signals. Thus, this work introduces a novel 3D electrode configuration called the "Go-frame (GF)," designed to surmount these limitations by enhancing linearity, sensitivity, and stability. The GF humidity sensor consists of a pin structure on the bottom electrode, which is coated with a sensing material, and capped with a grid-shaped top electrode. The experimental findings demonstrate that the GF humidity sensor outperforms both IDE and PP structures, achieving a sensitivity of 65.27 fF/%RH, low hysteresis of 4.06%, and enhanced signal stability. Additionally, the 3D-structured humidity sensor exhibits high repeatability and long-term stability over a week. This advancement in electrode design represents a significant innovation in capacitive humidity sensing technology, promising widespread adoption in critical applications, including real-time human respiration monitoring.