A Wearable System for the Real-Time Ambient Gases Monitoring
School of Biomedical Engineering, Zhejiang University, Biosensor National Special Lab, Key Lab for Biomedical Engineering of Ministry of Education, Hangzhou 310027, China
Abstract：In order to monitor the indoor or outdoor hazard gases and evaluate the harmful impact of these gases to humans and environment, this study developed a wearable mobile system for the real-time ambient gases monitoring based on the metal oxide semiconductor (MOS) sensors array. We designed and produced a miniaturized hardware circuit to detect the sensor signals. The system can detect the realtime concentration of these environmental toxicants continuously for a long time. This study selected formaldehyde, benzene, total volatile organic compound (TVOC) as typical harmful gases for a preliminary test. The threshold range (0.01-0.5 mg/m3) was determined by detecting the standard gas. The correlation between the steady-state peak values and the corresponding concentration was analyzed, and the fitting curve was plotted as the calibration equation. We selected the detection sensors depending on the slope and fitting degree (R2) were both the best. Experiments of environmental monitoring were performed in multi-scene applications. The fuming cupboard simulated small closed space and the laboratory simulated indoor environment. The system can record the local concentration of formaldehyde, benzene or TVOC and achieve the goal of detecting the harmful gases in volatile environment with wave multi-sources and giving out sound and light alarm. The TVOC concentration can also be detected in different positions to draw the concentration space map for observing and analyzing big data while the system was moving in the outdoor campus. The sensor stable response time was 30 s and the system can set the data transmission interval at more than 30 s. The target gas concentration was transferred to one′s smartphone via the Bluetooth or to one′s computer via the serial port. We believe that this design has potential of being used in realtime detection of the environmental target gases in cars, indoor, outdoor and other scenes.
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