Graphene Oxide-Based Resistive Humidity Sensor for Non-Contact Monitoring of Human Breathing Patterns

Abstract

This work presents a simple, low-cost, and effective resistive humidity sensor based on graphene oxide for monitoring human breathing patterns in a non-contact manner. The sensor was fabricated by drop-casting a graphene oxide suspension onto a commercial Zensor TE100 platform with printed electrodes. A voltage divider circuit paired with an op-amp was used to convert the sensor’s resistance changes into measurable voltage signals, which were recorded using MATLAB’s analog input interface. The sensor reliably detected various breathing patterns—mouth and nasal breathing, single and continuous cycles, and both low- and high-intensity airflow. Results show that exhaled humidity significantly decreases the sensor’s resistance, producing a clear signal during each breath. Notably, high-intensity exhalation led to baseline drift, likely due to deeper water molecule adsorption within the porous graphene oxide structure. This behavior highlights the material’s sensitivity and reveals both opportunities and challenges for long-term respiration monitoring. Overall, the study demonstrates the potential of graphene oxide humidity sensors for wearable or ambient respiratory health monitoring applications.