Low-power, Chip-Scale, Carbon Dioxide Gas Sensors for Spacesuit Monitoring

摘要

N5 Sensors, Inc. and NASA, through a Small Business Technology Transfer program, are jointly developing an ultra-small, low-power carbon dioxide (CO2) gas sensor capable of monitoring CO2 gas concentrations inside a spacesuit. Measurement of key gases relevant to an astronaut’s safety and health, such as CO2, is quite challenging due to the unique environmental conditions within a spacesuit, (e.g., high humidity, large temperature, and pressure swings). Conventional non-dispersive infrared absorption-based CO2 sensors cannot be effectively implemented inside a spacesuit due to its size, weight, and power constraint. Metal-oxide-based sensors have been effectively miniaturized for several applications; however, detection of CO2 utilizing metal-oxide-based sensors is challenging due to the chemical inertness and high stability of CO2 at room-temperatures. To mitigate these limitations, engineers developed unique chip-scale, nanoengineered chemiresistive gas-sensing architecture to allow the metal-oxide sensors to operate inside a spacesuit. This design combines the selective adsorption properties of the nanophotocatalytic clusters of metal-oxides and metals, which allows for the increase of selectivivity for CO2 detection in high relative humidity conditions. The all-electronic design of the sensors provides a compact and low- power solution, which can be implemented for multipoint detection of CO2 inside a spacesuit. This paper describes a novel approach in refining the sensor architecture, development of new photocatalytic material for better sensor performance.