Multichannel, programmable, microprocessor based strain gauge telemetry system

The development of improved implantable devices and materials requires knowledge of their in vivo behavior. However, little is known about the actual loads borne by implanted devices in vivo. Direct load measurement would provide extremely valuable information, for the improvement of device designs, and for the rapid rehabilitation of individuals in which devices have been implanted. Multichannel telemetry systems, combined with strain gauges, can provide this information. Ideally, these systems should possess the flexibility that microprocessor based data acquisition can provide; including: programmable, channel specific gain, digital filtering, power conservation through multiplexing, transmission error detection, and programmable sweep rates. To achieve these advances, we have developed a multichannel, microprocessor based strain gauge telemetry system which maintains small size and low power consumption. Our completed transmitters used only four surface mount ICs, were 14 mm by 30 mm in size, and consumed only 2.8 milliamps at 3 volts DC