Ultrafast resistive-type γ-Fe2O3–rGO nanohybrid-based humidity sensor – a respiratory monitoring tool

Abstract

The resistive-type sensing device has been fabricated by integrating a thin film of iron oxide–rGO nanohybrids on a flexible tempered glass substrate, providing an excellent tool for humidity sensing for different activities. The optimal nanohybrid demonstrates an ultra-high sensitivity as well as an ultrafast response and recovery time. The response/recovery speed of the sensor is 270 ms/298 ms for fast breathing and only 6 ms/7 ms when a finger touched the sensor surface. This sensor showed excellent potential for the monitoring of different breathing patterns such as normal, deep, fast and relaxed. It also demonstrated the capability to detect skin evaporation in a non-contact mode, exhibiting future prospects for developing next-generation tools/devices such as smart touchless switches and screens. A rapid sensing device for the human respiratory system based on resistivity measurement could also provide a promising way to assess COVID-19 stages in a patient.