Sniffing Entrapped Humans with Sensor Arrays

Area of Science:

• Chemical Sensing
• Environmental Monitoring
• Biomedical Engineering

Background:

• Earthquakes and building collapses pose significant risks, often trapping individuals.
• Rapid detection of trapped survivors is crucial for effective urban search and rescue (USaR).
• Current methods for locating survivors can be time-consuming and limited in scope.

Purpose of the Study:

• To develop and validate a compact, portable sensor array for detecting human metabolic tracers.
• To assess the array's sensitivity and selectivity for identifying signs of life in simulated entrapment scenarios.
• To provide a tool for accelerating USaR operations.

Main Methods:

• Utilized a sensor array comprising three nanostructured metal-oxide sensors (Si-doped WO3, Si-doped MoO3, Ti-doped ZnO) and commercial CO2 and humidity sensors.
• Tailored nanoscale sensor properties for high sensitivity and selectivity towards acetone, ammonia, and isoprene.
• Tested the sensor array on humans in plethysmography chambers to simulate entrapment conditions.

Main Results:

• The sensor array successfully detected sub-parts-per-million (ppm) concentrations of acetone, ammonia, and isoprene.
• Achieved high accuracy and precision in detecting these volatile organic compounds (VOCs).
• Results showed strong agreement (Pearson's correlation coefficients ≥0.9) with benchtop selective reagent ionization time-of-flight mass spectrometry (SRI-TOF-MS).

Conclusions:

• An inexpensive, portable sensor array capable of detecting key metabolic tracers has been developed.
• This technology offers a promising solution for rapid, on-site detection of trapped individuals in disaster scenarios.
• The sensor array can be integrated into hand-held or drone-based detectors for enhanced USaR capabilities.