Mass sensor is an essential and important device which has immense applications in the diversified fields such as medicine, chemical analysis, biochemistry etc. An ideal mass sensor can perform real-time detection and measurement of mass of organic and inorganic materials. Small sized mass sensors are available in the market which is in a chip form with some onboard processing circuitry. Latest category of mass sensors usually called as smart sensors makes use of microprocessor. Since surface acoustic waves are used in a smart sensor, it also called as surface acoustic wave sensor or SAW sensor. Here a piezoelectric substrate acts as both transmitter and receiver of a surface acoustic wave of frequency around 100 MHz. These waves are then allowed to travel through a chemically adsorbed film which results in a mass change at the surface of the crystal. The attenuation or loss suffered by the acoustic wave is a measure of the gas mass adsorbed by the film. The same device when we use for bulk materials, it is known as bulk acoustic wave (BAW) devices. These devices are nowadays extensively used for the mass measurement of ketones, alcohols, aromatic hydrocarbons and organophosphates chlorinated hydrocarbons.
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