A novel wearable sensor device with conductive fabric and PVDF film for monitoring cardiorespiratory signals

This paper is concerned with the development of a novel wearable cardiorespiratory signal sensor device for monitoring sleep condition at home. The sensor device consists of a belt-type sensor head which is composed with a couple of conductive fabric sheets and a PVDF film, two signal acquisition circuits which are designed specially for conductive fabric and PVDF film to obtain clear cardiorespiratory signals, and a USB communication module which is used to transmit the signal to computer for data display and analysis. In order to design and construct the signal acquisition circuits efficiently and simply, modular design concept is adopted in this research. Three basic high quality and flexible modules, pre-amplifier module with 500 Hz low-pass filter, high quality band-pass filter module and VCVS band-rejection filter module, are designed and assembled together for satisfying each sensor. Furthermore, software data processing algorithms are also proposed for extraction of the reliable heartbeats and respiratory cycles from the obtained cardiorespiratory signals. To validate the performance and efficiency of the developed wearable belt-type sensor system, two commercial sensor devices, 3-lead ECG sensor and pneumography sensor, are used together in experimental test. The results demonstrated that the cardiorespiratory signals are obtained clearly and the information of the heartbeat and respiratory cycle are extracted successfully by the proposed simple data processing algorisms. In contrast to the commercial sensors, the developed belt-type sensor system shows a great potential to take over the commercial pneumography and 3-lead ECG sensors. (c) 2006 Elsevier B.V. All rights reserved.