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Biosensors for EVA: Improved Instrumentation for Ground-based StudiesDuring lunar excursions in the EVA suit, real-time measurement of metabolic rate is required to manage consumables and guide activities to ensure safe return to the base. Metabolic rate, or oxygen consumption (VO2), is normally measured from pulmonary parameters but cannot be determined with standard techniques in the oxygen-rich environment of a spacesuit. Our group has developed novel near infrared spectroscopic (NIRS) methods to calculate muscle oxygen saturation (SmO 2), hematocrit, and pH, and we recently demonstrated that we can use our NIRS sensor to measure VO 2 on the leg during cycling. Our NSBRI project has 4 objectives: (1) increase the accuracy of the metabolic rate calculation through improved prediction of stroke volume; (2) investigate the relative contributions of calf and thigh oxygen consumption to metabolic rate calculation for walking and running; (3) demonstrate that the NIRS-based noninvasive metabolic rate methodology is sensitive enough to detect decrement in VO 2 in a space analog; and (4) improve instrumentation to allow testing within a spacesuit. Over the past year we have made progress on all four objectives, but the most significant progress was made in improving the instrumentation. The NIRS system currently in use at JSC is based on fiber optics technology. Optical fiber bundles are used to deliver light from a light source in the monitor to the patient, and light reflected back from the patient s muscle to the monitor for spectroscopic analysis. The fiber optic cables are large and fragile, and there is no way to get them in and out of the test spacesuit used for ground-based studies. With complimentary funding from the US Army, we undertook a complete redesign of the sensor and control electronics to build a novel system small enough to be used within the spacesuit and portable enough to be used by a combat medic. In the new system the filament lamp used in the fiber optic system was replaced with a novel broadband near infrared LED light source. The compact grating spectrometer was replaced with a chip-scale spectrometer. With this new design, the sensor is 4 in 2 in 0.5 in, weighs 60 g, and no fiber optic cables are needed. The sensor, which contains the light source and the spectrometer, is adhered directly to the skin with medical grade adhesive. The sensor can be powered via the USB port of the laptop computer that controls the sensor operation. Alternatively, for studies in the spacesuit, the sensor can be powered by a small battery pack and operated by an ultra-portable hand-held computer. Both the handheld computer and battery pack will easily fit within the PLSS of the test spacesuit. System automation was significantly improved, to add features suggested by our colleagues in the Cardiovascular Laboratory and the NASA JSC Exercise Physiology and Countermeasures Project. The functionality and portability of this system were demonstrated in our UMass laboratory.
Document ID
20100001636
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Soller, B.
(Massachusetts Univ. Medical Center Worcester, MA, United States)
Ellerby, G.
(Massachusetts Univ. Medical Center Worcester, MA, United States)
Zou, F.
(Massachusetts Univ. Medical Center Worcester, MA, United States)
Scott, P.
(Massachusetts Univ. Medical Center Worcester, MA, United States)
Jin, C.
(Massachusetts Univ. Medical Center Worcester, MA, United States)
Lee, S. M. C.
(Wyle Integrated Science and Engineering Group Houston, TX, United States)
Coates, J.
(Reflectance Medical, Inc. Northboro, MA, United States)
Date Acquired
August 25, 2013
Publication Date
January 1, 2010
Subject Category
Instrumentation And Photography
Report/Patent Number
JSC-CN-19484
Meeting Information
Meeting: 2010 NASA Human Research Program Investigators'' Meeting
Location: Houston, TX
Country: United States
Start Date: February 3, 2010
End Date: February 5, 2010
Funding Number(s)
CONTRACT_GRANT: NCC9-5
CONTRACT_GRANT: W81XWH-08-C-10114
Distribution Limits
Public
Copyright
Other

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