Sensors for Environmental and Medical Monitoring

摘要

In environmental monitoring and in branches of clinical surveillance there have been impressive advances in sensors and associated instrumentation. The principles employed in sensor design are very similar in these overlapping topics. Measurement of chemicals is an important need in both areas. Here principles of electrochemistry, optics, acousto-optics, piezo-transduction, are all employed. Radiation measurement is often more conveniently carried out with semiconductor sensors than with, say, Geiger-Muller tubes. The fabrication of sensors must be matched to their specific application. In environmental instruments extended sensor life-time is important; typically 2 yrs. In medical applications one class of sensors must be implanted within the patient. This demands miniaturisation, high reliability, biocompatibility and safety, although the period of use may be only a few hours or days. In a second class the sensor is merely placed on the surface of the patient; so-called non-invasive measurement. In this case sensors may be passive, collecting the species of interest or detecting energy emitted by some event or process. Alternatively the sensors may be active, in that they require interrogation with external energy. With the advent of small sensor-based instruments there is an increased need for rigorous calibration and quality control.