A miniature pressure system with a capacitive sensor and a passive telemetry link for use in implantable applications

摘要

A miniature telemetric pressure-measuring system is presented in this paper. The system uses passive telemetry to transfer power to the transponder and pressure data to the remote base unit. Such telemetric systems are becoming ever more important in the biomedical field as the interest for in-vivo measurements of different biological parameters both of humans and animals is increasing. A novel capacitive-type pressure sensor based on an SiGeB diaphragm is used as a sensing element. The merits of combining a capacitive pressure sensor and passive telemetry lies in the inherent low-power consumption of the sensor and the continuous availability of power through induction. The pressure sensor is connected to an integrated interface circuit, which includes a capacitance to frequency converter and an internal voltage regulator to suppress supply voltage fluctuations on the transponder side. In addition, the sensor and accompanying interface circuit take up very little space so as to be suitable for implantation.