# Detection of Low Humidity Using Three-Dimensional DMC Network Structure

## TL;DR

A new sensor using a 3D DMC network structure effectively detects low humidity levels with high sensitivity and fast response.

## Contribution

A novel 3D DMC/SiO2 composite microsphere structure for ultra-sensitive low humidity sensing is developed.

## Key findings

- The sensor achieves a high response of 13,544% in the 1–18.6% RH range.
- It exhibits short response and recovery times of 6 s and 10 s, respectively.
- The sensor has a small humidity hysteresis of 1.4% RH.

## Abstract

The detection of low humidity levels remains a great challenge in relative humidity (RH) sensing technologies. In this work, methacryloxyethyl trimethyl ammonium chloride (DMC) was coated around SiO2 microspheres to form DMC/SiO2 composite microspheres, which were self-assembled into a three-dimensional (3D) network structure for low humidity detection. The hydrophilic nature of the DMC component enhances the adsorption capacity for water molecules even at ultra-low humidity levels (1–18.6% RH), while the 3D network structure provides abundant channels for fast water molecule transport, facilitating rapid response and recovery processes. The optimized sensor shows high response (13,544%) in 1–18.6% RH, with short response/recovery time (6 s/10 s) and a small humidity hysteresis (1.4% RH). Such high performance shows that this type of sensor has great potential for application in widespread fields, such as electricity, semiconductor manufacturing, pure gas supply, aerospace, and pharmaceutical formulations.