A noninvasive method for monitoring respiratory rate of rats based on a microcantilever resonant humidity sensor

Respiratory rate is a vital physiological signal in laboratory rodents research. This paper presents a noninvasive method based on resonant humidity sensor for monitoring respiratory rate of rats. The sensor is composed of an aluminum nitride (AlN) resonant microcantilever coated with graphene oxide (GO) film. The sensor shows high sensitivity and good repeatability. By combining the sensor with a control circuit, a closed-loop respiration measurement system is realized for fast response. The system can monitor respiratory rate of rats in real time by detecting relative humidity difference between exhaled and inhaled breath. The method has advantages of fast response, small size and low cost. Furthermore, the respiratory rate of rats can be noninvasively monitored by integrating the sensor with a face mask.