Film-type transducer materials PVDF and EMFi in the measurement of heart and respiration rates

Film-type transducer materials polyvinylidenefluoride (PVDF) and ElectroMechanical Film (EMFi) were used in the measurement of heart and respiration rates on the chest wall at rest. The aim here was to evaluate if the both materials are capable to measure the heart and respiration rates correctly and also to found out if there are differences between the results of PVDF and EMFi. The movements provided by the pulsation of heart and respiration were converted into an electrical signal by the sensors. The signals were amplified and transmitted to a computer. The data was analyzed with Matlab® software. The signals were filtered to reveal the heart pulsation and respiration components. Power spectral density (PSD) spectrum was computed to determine the heart and respiration rates. ECG was used as a reference signal for the heart rate and a thermistor for the respiration rate. Both transducer materials provided good results and no differences between PVDF and EMFi were found. The heart rates measured with PVDF and EMFi sensors corresponded to the values calculated from the ECG signal. Also the respiration rates correlated with the values determined with the thermistor. To conclude, both materials provided reliable results in the measurements of heart and respiration rates.