Extravehicular activities (EVAs) are dangerous to astronauts for a number of reasons, including high levels of physical exertion, potential for impacts by space debris particulates that could puncture the spacesuit and cause depressurization, Moon dust exposure that is abrasive and possibly biologically harmful, harsh thermal environments (extreme variation from –150 to >120 ºC when directly exposed to the Sun), and extreme low pressure (≈0 atm). These harsh environmental conditions inevitably lead to emotional pressure and stress, which directly impact physiological condition and potentially affect performance and safety. Because many EVA operations are time-consuming, astronauts may be extremely uncomfortable for several continuous hours.

During future projected lunar and Martian EVA maneuvers, it will be critical for the crewmembers to monitor their own personal health status and make important mission type/duration decisions based on measured data. It is important that the measurement system providing these data is simplified in order to provide quick and reliable readings, and also indicate warnings and guidance during suit anomalies. To be comfortable and most efficient, the individual sensor devices/transducers should be low-profile, highly accurate, reliable, and fully integrated into astronaut clothing, with minimal added wiring and weight, and with no impact on astronaut range of motion or comfort. In the past, crewmembers have found that the use of medical instrumentation electrodes (with electrode gel and overtapes for attachment) are not ideal, due to a combination of effects including skin irritation, adhesion problems, non-reliability, stowage concerns, restrictive mechanical behavior, and limited lifetime use.

Comfortable garments with multiple integrated sensor functions for the monitoring of astronauts during long-duration space missions are under development. The feasibility of using Metal Rubber sheet and fabric materials as both sensor elements and highly flexible electrodes integrated into prototype instrumented garments has been demonstrated. Heart rate and EKG data taken using the Metal Rubber sensors are essentially identical to those obtained using standard biomedical instrumentation. The combined high electrical conductivity, low mechanical modulus, and environmental robustness of the Metal Rubber materials make them a lightweight, stretchy, and comfortable alternative to conventional metal wiring and cabling.

The Metal Rubber-Textile sensor garment system is a low-weight, non-invasive, reliable, and comfortable autonomous health-monitoring system for use by astronauts during long-duration space missions and EVAs. The smart sensor garment can be worn comfortably to continuously monitor the physiological status of the astronaut. The sensor shirt utilizes Metal Rubber sheet and fabric materials as both electrical and mechanical sensor elements, and flexible, low-weight electrical sensor interconnect materials. The instrumented health-monitoring garment consists of a fully interconnected, non-invasive, and wearable Metal Rubber- Textile shirt, which can be worn underneath a protective spacesuit (outer-vehicular wear) or by itself within the spacecraft or lunar/Martian shelter.

The textile may be spatially patterned to create a two-dimensional network of sensors and interconnects within the fabric itself by locally functionalizing the material and then growing the sensor array and network in place using ESA (electronically scanned array), by sewing on sensor patches and interconnect traces, or by weaving the conductive threads into required designs.

This work was done by Andrea Hill of NanoSonic, Inc. for Johnson Space Center. NASA is seeking partners to further develop this technology through joint cooperative research and development. For more information about this technology and to explore opportunities, please contact jsctechtran@ mail.nasa.gov. MSC-24838-1


NASA Tech Briefs Magazine

This article first appeared in the May, 2016 issue of NASA Tech Briefs Magazine.

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