Micro Electronic Pill

Temperature Channel Performance

        The linear sensitivity was measured over a temp. range from 0˚C to 70˚C & found to be 15.4 mV/˚C. This amplified signal response was from the analog circuit, which was later implemented in the ASIC. The sensor (fig 7a) a)), once integrated in the pill, gave a linear regression of 11.9 bits/˚C , with a resolution limited by the noise band of 0.4 ˚C (Fig 7 a) b)). The diode was forward biased with a constant current (15 µA) with the n-channel clamped to the ground, while p-channel was floating.

Sensor chip 1

        An array consisting of both temperature sensor & pH sensor platforms were cut from the wafer & attached onto 100-µm- thick glass cover slip cured on a hot plate. The plate acts as a temporary carrier to assist handling of the device during level 1 of lithography when the electric connections tracks, electrodes bonding pads are defined. Bonding pads provide electrical contact to the external electronic circuit.

Abstract

               A “Microelectronic pill” is a basically a multichannel sensor used for remote biomedical measurements using micro technology. This has been developed for the internal study and detection of diseases and abnormalities in the gastrointestinal (GI) tract where restricted access prevents the use of traditional endoscope. The measurement parameters for detection include real – time remote recording of temperature, pH, conductivity and dissolved oxygen in the GI tract.

Radio Transmitter

        It’s assembled prior to integration in the capsule using discrete surface mount components on a single-sided PCB. It’s designed to operate at a transmission freq. of 40.01 MHz at 20˚C generating a signal of 10 kHz. BW. A second crystal stabilized transmitter was also used. This unit is similar to the free running STD transmitter, having a transmission freq. limited to 20.08 MHz at 20˚C, due to crystal used. Pills incorporating the STD transmitter are Type 1, where as the pills having crystal stabilized unit is Type 2. The transmission range was measured as being 1 m & the modulation scheme FSK, with a data rate of 1 kb/s.

 Other applications

        The generic nature of microelectronic pill makes it adaptable for use in corrosive environments related to environmental & industrial applications, such as the evaluation of water quality, pollution detection, fermentation process control & inspection of the pipelines.

Introduction

        The invention of transistor enabled the first use of radiometry capsules, which used simple circuits for the internal study of the gastro-intestinal (GI) [1] tract. They couldn’t be used as they could transmit only from a single channel and also due to the size of the components. They also suffered from poor reliability, low sensitivity and short lifetimes of the devices. This led to the application of single-channel telemetry capsules for the detection of disease and abnormalities in the GI tract where restricted area prevented the use of traditional endoscopy.

Conclusion

        We have therefore described about the multichannel sensor, which has been implemented in remote biomedical using micro technology, the micro electronic pills, which is designed to perform real time measurements in the GI tract providing the best in vitro wireless transmitter, multi channel recordings of analytical parameters.