InGaN/GaN multi-quantum well nanowires: Enhanced trace-level NO2 detection for environmental and breath analysis

The World Health Organization highlights nitrogen dioxide (NO2) as a key atmospheric pollutant impacting air quality and human health. To date, several sensors have been proposed for NO2 detection and disease monitoring, but their effectiveness is limited because of low sensitivity and high operational temperatures. Herein, we propose a selective and sensitive NO2 sensor based on indium gallium nitride/gallium nitride multiple quantum wells (InGaN/GaN-MQWs). We explored different InGaN/GaN-MQWs configurations (InGaN/GaN-MQW1, InGaN/GaN-MQW2, InGaN/GaN-MQW3), developed through metal-organic chemical vapor deposition (MOCVD), to analyze their impact on gas sensing performance. Our findings reveal that the InGaN/GaN-MQW2 sensor at 150 degrees C exhibits a response 4.0, 3.1, and 1.65 times greater than GaN-NWs, InGaN/GaN-MQW1, and InGaN/GaN-MQW3 sensors, respectively. The limit of detection (LOD) for the InGaN/GaN-MQW2 sensor is 3 parts per billion (ppb), significantly lower than the NO2 threshold value of 53 ppb. Under ultraviolet (UV) light, the response of InGaN/GaN-MQW2 is 5.51-fold, 4.18-fold, and 1.82-fold higher than that of the GaN-NWs, InGaN/GaN-MQW1, and InGaN/GaN-MQW2 sensors, respectively. Importantly, our hybrid nanocompositebased electronic nose (e-nose) sensor arrays could distinguish between healthy and simulated unhealthy breaths with high accuracy, promising a new era of efficient, non-invasive disease detection through breath analysis.