engleski

Low Power Telemetry Transmitters for Measurement of Physiological Parameters

For measurement of physiological parameters inside the human body or on small animals or birds, miniature, low-power measuring transmitters are desirable. They can be implanted or swallowed as endosondes for investigating intestinal tract. Simple LC-oscillator that operates with intermittent oscillations, with short bursts of oscillations and a long-lasting quiescent interval, is analyzed. It is found out that duration of this interval is in linear relationship with resistance and capacitance in the transistors base circuit. Besides, the limits for highest or lowest resistance or capacitance, when intermittent oscillations cease or become continuos, are determined. Instead of resistor or capacitor, a resistive or capacitive sensor can be used. Resistive sensors are preferable because they can be applied in the range from a few k to 2.5M. Capacitive sensors usually have small capacitance, which is not allowed to be less than 40pF in this particular case. In this paper we are also considering conditions for the lowest current consumption and battery voltage. The voltage measurement can be realized as well, when instead of sensing resistor a FET is used. Bioelectrical activities can be measured in this way using special low-power amplifiers. The results obtained by measurements are presented as a proof.

Low power RF biotelemetry

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