An Implantable Telemetry Platform System With ASIC for in Vivo Monitoring of Gastrointestinal Physiological Information

This paper presents a multiple channel, implantable biotelemetry platform, suitable for in vivo monitoring of gastrointestinal (GI) physiological information. This system consists of a wireless capsule, a portable data recorder, and a workstation; it can digitalize and transmit up to four analog signals coming from different sensors. Several design challenges involving system miniaturization, sensor-precision improvement, and power-dissipation reduction were resolved by employing optimized architecture, microsensors, and a low-power application-specific integrated circuit (ASIC) that applied a very large scale integration architecture of three-stage clock management, power management, and an 18-bits full-differential input sigma-delta analog-to-digital converter. pH, temperature, and pressure sensors were manufactured and assembled with the ASIC and the transmission circuit into an elliptical capsule. The capsule measured 25 mm in length and 11 mm in diameter to ensure that it would be easy for patients to swallow yet able to transmit GI physiological information wirelessly. Because of the implementation of the low-power ASIC, the capsule can work normally for 136 h with three 1.5 V 22-mA button batteries. The system performances were assessed through several vivid tests. In addition, results from 22 cases of application in humans are reported in this paper.