We are familiar with a wide range of sensors in the field of electronics. They are used widely in the various experiments and research activities too. This microelectronic pill is such a sensor with a number of channels and is called as a multichannel sensor. As the name implies this sensor is a pill. That is it is meant to go inside the body and to study the internal conditions.
Earlier it was when transistor was invented, that radiometry capsules were first put into use. These capsules made use of simple circuits for studying the gastrointestinal tract. Some of the reasons that prevented their use was their size and their limitation of not to transmit through more than a single channel. They had poor reliability and sensitivity. The lifespan of the sensors were also too short. This paved the way for the implementation of single channel telemetry capsules and they were later developed to overcome the demerits of the large size of laboratory type sensors. The semiconductor technologies also helped in the formation and thus finally the presently seen microelectronic pill was developed.
These pills are now used for taking remote biomedical measurements in researches and diagnosis. The sensors make use of the micro technology to serve the purpose. The main intention of using the pill is to perform an internal study and recognize or detect the abnormalities and the diseases in the gastrointestinal tract. In this GI(gastrointestinal) tract we cannot use the old endoscope as the access is restricted. A number of parameters can be possibly measured by these pills and they include conductivity, pH temperature and the amount of dissolved oxygen in the gastrointestinal tract.
The design of the microelectronic pill is in the form of a capsule. The encasing it has is biocompatible. Inside this are multi- channel (four channel) sensors and a control chip. It also comprises of a radio transmitter and two silver oxide cells. The four sensors are mounted on the two silicon chips. In addition to it, there are a control chip, one access channel and a radio transmitter.
The four sensors commonly used are a temperature sensor, pH ISFET sensor, a dual electrode conductivity sensor and a three electrode electrochemical oxygen sensor. Among these the temperature sensor, the pH ISFET sensor and the dual electrode conductivity sensor are fabricated on the first chip. The three electrode electrochemical cell oxygen sensor will be on chip 2. The second chip also consists of a NiCr resistance thermometer which is optional.