Implementation of multichannel sensors for remote biomedical measurements in a microsystems format.

A novel microelectronic "pill" has been developed for in situ studies of the gastro-intestinal tract, combining microsensors and integrated circuits with system-level integration technology. The measurement parameters include real-time remote recording of temperature, pH, conductivity, and dissolved oxygen. The unit comprises an outer biocompatible capsule encasing four microsensors, a control chip, a discrete component radio transmitter, and two silver oxide cells (the latter providing an operating time of 40 h at the rated power consumption of 12.1 mW). The sensors were fabricated on two separate silicon chips located at the front end of the capsule. The robust nature of the pill makes it adaptable for use in a variety of environments related to biomedical and industrial applications.

An on-chip programmable instrumentation microsystem for gastrointestinal telemetry applications.

We have developed an integrated circuit microsystem instrument using a design methodology akin to that for system-on-chip microelectronics. The microsystem is optimised for low-power gastrointestinal telemetry applications and includes mixed-signal sensor circuits, programmable digital system, a feedback clock control loop and RF circuits that were integrated on a 5 mm x 5 mm silicon chip using a 0.6 microm, 3 V CMOS process. Unintended signal coupling between circuit components has been investigated and current injection into sensitive instrumentation nodes has been minimised. Tests show that the wireless instrument-on-chip worked as intended.