Lifetime tracing of cardiopulmonary sounds with low-power sound sensor stick connected to wireless mobile network

A wearable wireless cardiopulmonary sound sensing system with a low-power sound sensor stick connected to the wireless mobile network is proposed in this work. The system is composed of three parts, namely, the wearable sound sensor stick attached to the user’s chest for cardiopulmonary sound recording, the portable base station (PBS) for wireless data transmission which is usually a smart phone, and a remote data center for long-term data storage and analysis. An effective signal processing method is developed for the data center to analyze the cardiopulmonary sounds for health information extraction such as the heart rate. A prototype system has been built to validate the proposed system for lifetime tracing of cardiopulmonary sounds. The prototype sound sensor stick weighs 29 g, and the battery life is over 48 h with a 130 mAh battery. Experimental results from the prototype system are given, including the signal processing results and the measured power consumption. The heart rate calculation error of this system is within ±1 %.