Optical Detection of Particulate Matter Growth on Exploration Air Pre-Filters

A new optical technique is being investigated to determine its feasibility in detecting gradual increases in particle deposition/loading on air pre-filters, a technology not available in the market. The proposed new technology will enhance the optimal use and replacement cycle of pre-filters and, specifically, will enhance the performance and detection capability of an exploration filter system developed under the Life Support Systems project under the Moon to Mars program. While pressure-drop sensors can also be used to monitor loading on pre-filters, their sensitivity may not be sufficient or accurate enough to detect changes in pressure drop under certain conditions. For example, the pressure drop may be too low to detect through a mesh screen loaded with fibrous particulate matter (PM) with a highly porous structure. In a recent 2024 International Conference on Environmental Systems (ICES) paper the authors presented preliminary results on a pre-filter coupon study using simulated fibrous simulant and different types of miniature optical sensors. This past work reported that the use of a miniature ambient light sensor correlated well with the PM layer buildup with sufficient sensitivity. The current work explores the use of additional sensors and light sources to increase the sensitivity and accuracy of the detection technique, and its implementation on a prototype flight filter.