A respiratory transducer array to exploit the ultra-sensitive temperature dependence of an acrylate-based composite for real-time respiration rate monitoring

Abstract

This work proposes a miniaturized respiratory transducer array that utilizes the sharp temperature dependence of the resistivity characteristic of acrylate-based composites with a positive temperature coefficient. The proposed device employs an array configuration consisting of three sensing elements with the composites of different glass transition temperatures to achieve a wide operational temperature range. The temperature transient responses caused by different breathing conditions were clearly resolved by the device, and the corresponding respiration rates were easily extracted. The transducer array was characterized in a room temperature range from 23 °C to 29 °C. In addition, the device effectively detected the respiration rate up to a distance of 30 cm. It was also demonstrated that the device is capable of quantifying the breathing rate over a practical range of frequencies (from 0.1 Hz to 2 Hz). The respiration rates measured by the proposed device were also in good agreement with the results measured simultaneously by using a commercially available nasal pressure transducer. Comparison of the results demonstrated an excellent linear correlation (r=0.953 and P < 0.001). The measured results suggest the feasibility of using this miniaturized device to monitor patients' respiration rates in clinical institutes and in other point-of-care applications.