Silicon integrated-circuit temperature sensor

The principle discussed above has been used to develop an electronically adjustable miao chemostat valve allowing feedback control to keep constant concentration of certain species in solution. " The chemostat consists of silicon-based upper and bottom plates as well as a circuit card for the elertric connection to the PC-controlled power supply. The upper plate carries a platinum temperature sensor and contains a hydrogel chamber ((600 x 600 x SSOjpm ), which is covered by a perforated membrane. The bottom plate has similar con-stmction with an integrated platinrrm heating element (Figure 36(a)). ... 

The architecture of a wireless capsule system named the lab-in-a-pill (LIAP) is presented in Fig. 7.13 [113]. It consists of pH and temperature sensors and a custom-made application-specific integrated readout circuit. The pH sensor is a micro-fabricated ISFET with Ag/AgCl reference electrode. The temperature sensor is an n-channel silicon diode. The system consumes 15.5 mW. The circuit has a power saving feature to operate it for 42 h. 

Micro-Electromechanical Systems The measure of the intelligence of this and other systems is both the range and time of response to changes in the monitored equipment or environment. This is most often ensured by micro-electromechanical systems (MEMS), miniature components which measure and process such parameters as acceleration, pressure, distance, temperature, light and the chemical composition of an atmosphere. The heart of MEMS is a processing unit (microprocessor) made in the form of an integrated circuit on a silicon board. The board is then chemically etched and layers of other materials are deposited to make a sensor. Typical features of a MEMS fabricated in this way are shown in Fig. 7.5. Thanks to their small size, sensors in MEMS are characterised by low inertia, which makes it possible to quickly start and stop their functions. Moreover, thanks to their integration with the microprocessor in one substrate, their response to external stimuli is sent to the microprocessor almost immediately. 

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