A Microfluidic Bioreporter System for Space Flight Monitoring

Metabolic changes of a continuously-fed bacterial microculture are monitored as a potential means of understanding the effects of the space environment on life. A hand-held plastic device supports and monitors the metabolism of a 100 μl microculture of E. coli. Both a semi-permeable microdialysis fiber and a gas-permeable microbore silicone hollow fiber membrane (HFM) are threaded through the microculture. Microliter quantity solutions flow through the lumen of the microdialysis fiber to extract metabolic wastes and to deliver nutrients. A carbon dioxide absorbance-based indicator flows through the lumen of the silicone HFM to supply oxygen, remove carbon dioxide, and monitor carbon dioxide production. Carbon dioxide production, which is tracked as an indicator of metabolic response, is monitored with an optical sensor that has a response time of 15 minutes and a sensitivity of ±0.6 mmHg. We evaluated the device using ultraviolet light as a test stressor for the instrumentation. We were able to detect changes in metabolic activity by varying dialysis feed rate and stressing the cells with UV.