Physiological Sensor System for a wireless tactile display

Abstract

This research focuses on the development of a wearable Physiological Sensor System (PSS) that can be used with a wireless tactile control unit to monitor the physiological status of a mobile user. Two physiological variables, heart rate and respiration rate, were selected for initial study, and technologies that could be used to measure these variables were evaluated. The PSS was required to be non-invasive, lightweight, and low-power. Initial studies indicated that heart rate could be most effectively measured using infrared light technology and so this was implemented in a wrist strap. It was determined that respiration rate could be recorded using a novel implementation of conducting polymer strain gages. For this purpose, polypyrrole-coated Lycra was fabricated and a chest strap was made that incorporated this sensor for recording respiration rate. Both sensors were connected to the PSS unit that was designed to provide the necessary signal processing, such as filtering and amplification, as well as produce the digital output signals that could be analyzed by the microcontroller in the tactile control unit. The complete circuit design process is described, from initial prototype development and testing to final layout and printed circuit board fabrication.