Ferroelectret film‐based patch‐type sensor for continuous blood pressure monitoring

A thin, flexible and skin‐attachable sensor for continuous monitoring of blood pressure is reported. The sensor was fabricated as a layered structure of ferroelectret film, specially designed electrodes and a flexible electronic circuit, which together enable simultaneous measurement of ballistocardiogram and an electrocardiogram on the human chest with minimal discomfort. To investigate the feasibility of continuous blood pressure monitoring, systolic blood pressure was estimated using the RJ interval, which is computed as the time delay between the R peak of the electrocardiogram and the J peak of the ballistocardiogram. The results indicate that the estimated systolic blood pressures are in excellent agreement with the reference values, achieving an intraclass correlation coefficient of 0.95 ( P < 0.01), and complying with the recommended guidelines from the Association for the Advancement of Medical Instrumentation in the United States and the British Hypertension Society.