Humidity-Independent, Breathable and Wearable Chemiresistive Sensor Enables Exclusive Exhaled Ammonia Detection

Area of Science:

• Materials Science
• Chemical Sensing
• Biomedical Engineering

Background:

• Breath analysis is a noninvasive diagnostic method using volatile biomarkers.
• Current wearable sensors lack sensitivity, selectivity, and humidity resistance.
• Ammonia (NH3) is a key biomarker in exhaled breath.

Purpose of the Study:

• To develop a robust, humidity-resistant wearable sensor for detecting exhaled ammonia (NH3).
• To improve sensitivity and selectivity for practical breath analysis applications.
• To enable real-time, non-invasive health monitoring via mobile devices.

Main Methods:

• Fabrication of a self-supporting composite nanofiber film (YSZ/TiO2/PANI/SDBS).
• Utilizing a YSZ nanofiber network for mechanical flexibility.
• Employing PANI/TiO2 heterojunction for enhanced NH3 adsorption and signal transduction.
• Incorporating SDBS for hydrophobicity and humidity resistance.

Main Results:

• Achieved a low limit of detection (300 ppb NH3) for the wearable sensor.
• Demonstrated stable sensor performance in high humidity (≥80% RH) and presence of interfering gases.
• Successfully monitored simulated exhaled NH3 in real time using a wireless sensing platform and mobile terminal.

Conclusions:

• The developed sensor overcomes key limitations of existing wearable gas sensors.
• This advancement facilitates robust, humidity-resistant non-invasive health monitoring.
• The technology holds promise for early disease screening and personalized healthcare.