Embedded Transdermal Alcohol Detection via a Finger Using SnO₂ Gas Sensors

Area of Science:

• Materials Science
• Chemical Engineering
• Biomedical Engineering

Background:

• Conventional alcohol detection methods can be invasive or provide only intermittent readings.
• There is a need for continuous, non-invasive alcohol monitoring solutions.
• Transdermal alcohol sensing offers a promising alternative for real-time physiological monitoring.

Purpose of the Study:

• To fabricate and characterize a portable transdermal alcohol sensing device using tin dioxide (SnO2) chemoresistive gas sensors.
• To evaluate the sensor's performance for continuous, non-invasive alcohol monitoring.
• To validate the device's correlation with blood, breath, and perspiration alcohol concentrations.

Main Methods:

• Fabrication of SnO2 sensing layers via reactive radio frequency (RF) magnetron sputtering.
• Characterization of material structure and morphology using X-ray spectroscopy (XRD) and scanning electron microscopy (SEM).
• Testing sensor response to ethanol concentrations, stability under varying humidity, and transdermal alcohol monitoring in a human volunteer.

Main Results:

• Optimized annealing time significantly impacted sensor sensitivity.
• Sensors demonstrated high sensitivity, stability, and rapid detection times for ethanol.
• The device showed resistance to high relative humidity (50% and 70%).
• Transdermal alcohol monitoring in a volunteer showed a clear correlation with blood and breath alcohol levels.

Conclusions:

• A portable, low-cost, and non-invasive transdermal alcohol sensor was successfully developed.
• The SnO2-based sensor is suitable for continuous alcohol monitoring with good performance.
• The study validates the potential of this device for real-time alcohol level assessment.