Researchers have developed ultrathin IGZO nanofibers for wireless, real-time breath monitoring, paving the way for advanced health-tracking technologies.
IGZO nanofiber-based sensors are integrated with a flexible circuit to create a sensory face mask, thus featuring wireless and real-time monitoring capabilities. Image Credit: Wearable Electronics
Room-temperature (RT) gas sensors with high sensitivity are crucial for low-power Internet-of-Things (IoT) applications, such as smart devices, wearables, and mobile robotics. Among these, metal oxide semiconductor gas sensors stand out for their affordability, high sensitivity, and user-friendly design, making them suitable for detecting flammable, toxic, explosive, and exhaled gases. However, challenges like further reducing fiber diameter and integrating real-time monitoring remain underexplored.
In this study, the researchers introduced a novel sensor design. They developed ultrathin (~88 nm) amorphous indium gallium zinc oxide (IGZO) nanofibers for wireless and real-time breath monitoring.
IGZO nanofibers were created as the charge transport layer to enhance the surface area for gas diffusion using an electrospinning approach. The resulting field-effect properties demonstrated an average mobility of 2.2 cm²/V·s and an on/off ratio of 10⁵.
Qing Ma, Study Lead Author and Post-Doctoral Fellow, School of Electronic Science and Engineering, Southeast University
The team successfully monitored human breath in fast, normal, and deep states, demonstrating the sensor’s quick response and recovery times, as well as its stable performance.
By integrating the sensor with a flexible circuit board and mounting them on a face mask, we achieved wireless and real-time monitoring of respiratory status, highlighting its potential for practical applications in health monitoring.
Qing Ma, Study Lead Author and Post-Doctoral Fellow, School of Electronic Science and Engineering, Southeast University
The researchers noted that the electrical transport properties of IGZO nanofibers are influenced by oxygen vacancies, water vapor, and temperature. During a breath cycle, the sensor’s current dropped significantly when voltage was applied and recovered quickly, achieving a response and recovery time of about 0.7 seconds.
Co-corresponding author Binghao Wang highlighted the technology's promise in personalized healthcare and pandemic prevention.
An IGZO NF-based sensor integrated into a flexible circuit achieved a compact size of 15 × 35 mm², marking significant progress in the miniaturization efforts for smart mask technology. The recorded electrical signals can be visualized via a smartphone equipped with a customized mobile app, underscoring the potential for the widespread adoption of IGZO TFT-based sensors in wearable technology.
Binghao Wang, Senior and Co-Corresponding Author, School of Electronic Science and Engineering, Southeast University
Journal Reference:
Ma, Q., et al. (2024). Nanofibrous metal oxide semiconductor for sensory face masks. Wearable Electronics. doi.org/10.1016/j.wees.2024.09.001.