A Novel Piezoelectric PVDF Film-Based Physiological Sensing Belt for a Complementary Respiration and Heartbeat Monitoring System

Human heartbeat and respiration signals were measured from a DAQ board interfaced with a homemade voltage-amplifier with specific frequency filtering function using an elastic textile belt imbedded with a poled-PVDF film, which is designated as a physiological sensing belt (PSB), as a piezoelectric sensor and analyzed. PSB sensor systems can be easily tied on the chest, abdomen, head, wrist, or ankle for comfortable fit. The sensitivity of the imbedded PVDF film sensor is highly dependent on the thickness of coated silicon rubber layer on both sides of the PVDF film. Both respiration and heartbeat signals could be isolated from the mixture signal measured from the chest and abdomen during respiration and pulse wave velocity could be calculated using time delay obtained from waveforms measured simultaneously at the two different body positions. Finally we found the feasibility of applying the PSB as a complementary respiration monitoring system to the traditional anesthesia activities or other types of patient respiratory monitoring such as polysomnography and telemedicine.