ABSTRACT
A sensor is used to transform a nonelectrical stimulation to an electrical response that is suitable to be processed by electrical circuits. Sensors are related with everyday life, such as automobiles, airplanes, radios, and countless other applications. Piezoresistive effect describes the changes of electrical resistance when the material is mechanically deformed. It occurs in crystals that have no polar axes and is well represented in semiconductors. Physically, piezoresistance comes from the anisotropic distribution of energy levels in the k-space of the angular wave vector. Thermoelectric effect is called Seebeck effect in honor of East Prussian scientist Thomas Johann Seebeck. He observed that an electrical current was present in a series circuit of two different metals that were contacted and at different temperatures. Piezoelectric effect is the property of certain crystals that can generate a voltage subjected to a pressure and conversely generate a pressure due to an applied voltage.
