Waving Hand as Infrared Source for Ubiquitous Gas Sensing

Gases in the environment can significantly affect our health and safety. As mobile devices gain popularity, we consider to explore a human-centered gas detection system that can be integrated into commercial mobile devices to realize ubiquitous gas detection. However, existing gas sensors either have too long response delays or are too cumbersome. This paper shows the feasibility of performing gas sensing by shining infrared (IR) signals emitted from our hands through the gas, allowing the system to rely on a single IR detector. The core opportunity arises from the fact that the human hand can provide stable, broadband, and omnidirectional IR radiation. Considering that IR signals experience distinct attenuation when passing through different gases or gases with different concentrations, we can integrate the human hand into the gas sensing system to enable extremely low-power and sustainable gas sensing. Yet, it is challenging to build up a robust system directly utilizing the hand's IR radiation. Practical issues include low IR radiation from the hand, unstable optical path, impact of environmental factors such as ambient temperature, etc. To tackle these issues, we on one hand modulate the IR radiation from the hand leveraging the controllability of the human hand, which improves the hand's IR radiation. On the other hand, we provide a dual-channel IR detector design to filter out the impact of environmental factors and gases in the environment. Extensive experiments show that our system can realize ethanol, gaseous water, and CO2 detection with 96.7%, 92.1% and 94.2%, respectively.