Currently, devices to measure temperature, pressure, torque, acceleration, rotational velocity, humidity, sound, magnetic fields, radiation, and optical, biological, biomedical, and chemical parameters are either in production or at advanced stages of research. Individual devices vary from simple ones where the mechanical part does not move to much more complex ones involving several moving elements. Microsensors can be regarded as miniature transducers, since they convert energy in the form of a measured mechanical signal into energy in electrical form. The defining feature of any MEMS device is an element with some sort of mechanical functionality integrated with microelectronics. Typical sizes of microsensors range from 10 μm (0.01 mm or 10 −5 m) up to 5 mm. They are part of the wider class of micro-electro-mechanical-systems (MEMS) devices that also includes microactuators. Microsensors are two- and three-dimensional micromachined structures that have smaller size, improved performance, better reliability, and lower production costs than many alternative forms of sensor. Morris, Reza Langari, in Measurement and Instrumentation (Third Edition), 2021 13.12 Microsensors (MEMS sensors) To date, there has been limited testing of these devices with noisy chemical backgrounds under operational conditions however, the handheld ‘FIDO' system, based on amplifying fluorescent polymers (AFP), was field-tested against certified explosive detection canines for the detection of TNT-based land mines using a wide-area screening methodology and was reported to share similar detection capabilities with canines. ![]() Other electronic nose technologies under development include the use of fiber optics and sensor beads, polymeric thin films, nanocluster metal-insulator-metal ensembles (MIME), and fluorescent polymers using amplifying chromophore quenching methods. This array of independent microsensors would be seen to mimic the array of glomeruli in the olfactory system. The hope is that, in the future, hundreds of such microcantilevers, coated with suitable coatings, may be able to achieve sufficient selectivity to provide a cost-effective platform for detecting explosives in the presence of potentially interfering compounds in real environments. ![]() Promising microsensors include surface acoustic wave (SAW) detectors normally coated with different semi-selective polymeric layers and microelectromechanical systems (MEMS) including microcantilever sensors. Microsensors have the potential for selective GC detectors and also as remote sensors when combined in arrays often referred to as ‘electronic noses'. Furton, in Counterterrorist Detection Techniques of Explosives, 2007 3.1.1 Electronic noses
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