Implementation of radiotelemetry in a lab-in-a-pill format

Abstract

A miniaturised lab-in-a-pill device has been produced incorporating a temperature and pH sensor with wireless communication using the 433.92 MHz ISM band. The device has been designed in order to enable real time in situ measurements in the gastrointestinal (GI) tract, and accordingly, issues concerning the resolution and accuracy of the data, and the lifetime of the device have been considered. The sensors, which will measure two key parameters reflecting the physiological environment in the GI (as indicators for disease) were both controlled by an application specific integrated circuit (ASIC). The data were sampled at 10-bit resolution prior to communication off chip as a single interleaved data stream. This incorporated a power saving serial bitstream data compression algorithm that was found to extend the service lifetime of the pill by 70%. An integrated on–off keying (OOK) radio transmitter was used to send the signal to a local receiver (base station), prior to acquisition on a computer. A permanent magnet was also incorporated in the device to enable non-visual tracking of the system. We report on the implementation of this device, together with an initial study sampling from within the porcine GI tract, showing that measurements from the lab-on-a-pill, in situ, was within 90% of literature values.