Development of a piezopolymer pressure sensor for a portable fetal heart rate monitor

• Published in: IEEE transactions on biomedical engineering Vol. 40; no. 9; pp. 963 - 969
• Main Authors: Zuckerwar, A.J., Pretlow, R.A., Stoughton, J.W., Baker, D.A.
• Format: Journal Article
• Language: English
• Published: Legacy CDMS IEEE 01.09.1993
• Subjects: Acoustic sensors; Acoustic testing; Belts; Biosensing Techniques; Calibration; Equipment Design; Female; Fetal heart rate; Fetal Monitoring - instrumentation; Heart rate measurement; Heart Rate, Fetal - physiology; Humans; Life Sciences (General); Membranes, Artificial; Performance evaluation; Polyvinyls; Pregnancy; Pressure; Sensor arrays; Sensor phenomena and characterization; Space life sciences; Standards development; Wearable sensors
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/10.245618

A piezopolymer pressure sensor has been developed for service in a portable fetal heart rate monitor, which will permit an expectant mother to perform the fetal nonstress test, a standard predelivery test, in her home. Several sensors are mounted in an array on a belt worn by the mother. The sensor design conforms to the distinctive features of the fetal heart tone, namely, the acoustic signature, frequency spectrum, signal amplitude, and localization. The components of a sensor serve to fulfill five functions: signal detection, acceleration cancellation, acoustical isolation, electrical shielding, and electrical isolation of the mother. A theoretical analysis of the sensor response yields a numerical value for the sensor sensitivity, which is compared to experiment in an in vitro sensor calibration. Finally, an in vivo test on patients within the last six weeks of term reveals that nonstress test recordings from the acoustic monitor compare well with those obtained from conventional ultrasound.< >