<Session 4: Biomedical Application>Fetal Signal Telemetry with Suction-Cup Mounted Transducer and Bluetooth Transmitter to Monitor Mainframe or Networked PDA

Abstract

We devised a fetal cardiac signal acquisition and telemetry system mounted within a suction-cup which can stick and keep on to gravidae's abdomen for itself with mild negative pressure. For prototyping we use fetal phonocardiography microphone with necessary filter and amplifier and lithium polymer battery, followed by a Bluetooth downlink transmitter to send the signal to monitor mainframe (HP8041A) externally equipped with Bluetooth receiver. The suction cup used for prototyping is glass or hard-plastic one driven by external pump to initiate to suck and stick action. They are coming from acupuncture device in China or Korea or Japan. However, with our early experience, we believe a soft, silicone rubber made, deformable self-sucking cup performs better and more patient friendly. In model environment using adult heart activity the system works almost equivalent to wired system, while real gravidae trial is yet to be performed soon. For monitor mainframe we are attempting to replace legacy excellent HP8041A with just a networked PDA like an Android smart-phone to have extended connection to central database for gravidae group management. Also, ultrasound Doppler will certainly outperform phono, at cost of complex and power consumption, for future challenge. The connection reach distance of the Blue-Tooth transceiver used in prototyping is more than sufficient for home, self-managed NST (non stress test), a lower RF power, lower battery drain device is desired for power hungry environment like this application.