Wireless Gait and Respiration Monitoring Using Nanocomposite Sensors

Abstract

The measurement of posture, loading conditions, and physiological parameters during physical activity is key in human performance monitoring and assessment. Of particular interest in this study is the monitoring of these parameters during high intensity activities associated with firefighting. The objective is to capture various walking cycles using nanocomposite pressure sensors built into the backpack-type harnesses of a Self-Contained Breathing Apparatus (SCBA) unit. It was hypothesized that the sensor’s high stability, linearity, and sensitivity would allow this sensor to be used for human posture and activity monitoring. First, nanocomposite sensors were prepared by integrating piezoresistive graphene nanosheet thin films between elastomer layers. Two sensors were then integrated with the SCBA harnesses and mounted at symmetric locations to capture gait and respiration cycles. Second, a small, portable, wireless data acquisition unit was developed to non-intrusively monitor up to eight sensors and wirelessly transmit the data for external data storage and analysis. This sensing node included analog signal conditioning circuits alongside an ARM based microprocessor for analog to digital conversion, signal processing, and wireless transmission. Third, human participant tests were performed while wearing these harnesses. The participants performed various low intensity walking and respiratory cycles. The results confirmed that the wireless sensing unit was able to reliably acquire sensor measurements, while the sensing streams also exhibited unique features indicative of different activities and postures.