Sniffing Smartwatch for Online Monitoring of Selected Odorants

Monitoring chemical substances is of paramount importance in various industries and environmental contexts. In industrial settings, the presence of certain chemical substances may indicate leaks, spills, or malfunctioning equipment, posing immediate threats to both human health and the environment. Moreover, continuous monitoring of chemical compounds is crucial for ensuring compliance with safety regulations and environmental standards. In the context of air quality management, monitoring chemical compounds helps identify sources of pollution, assess the impact on public health, and implement effective pollution control measures. Timely detection and response to chemical compounds also play a vital role in preventing long-term environmental degradation. Overall, monitoring chemical substances is an indispensable component of proactive risk management, environmental stewardship, and the safeguarding of human well-being. The development of automatic and portable devices for online monitoring is an important need in the chemical industry. The smartwatch designed and presented is a home-developed prototype and built from commercially available components. All components of the smartwatch are protected with a plastic casing capable of allowing air to pass to the sensors, the device is also capable of measuring temperature and relative humidity, magnitudes that influence the detection of different odors or volatile compounds. This device is based on a microcontroller that offers low-power performance, integrated Bluetooth low energy at an affordable price, and the measurements of four digital MOX gas sensors, models BME680 SGP40, ENS160 and STC31 through I2C interface. Data are shown on a LCD display and also transmitted via Bluetooth to a smartphone at a sampling period time of 2 s. It is powered using a 3.7 V lithium polymer battery. The smartwatch has a graphical interface to show the user the data provided by the sensors. The designed smartwatch has been validated by measuring different industrial gases like toluene, xylene, and ethylbenzene at low concentrations. Toluene was measured at 6 ppm, xylene at 8 ppm, and ethylbenzene at 10 ppm. Good discrimination between the three different gases was achieved using Principal Component Analysis as multivariable analysis.