The fact that the electrical resistivity of a material changes when mechanical pressure or strain is applied to the material is called the piezoresistive effect. This effect enables pressure measurement with piezoresistive pressure sensors. They are usually based on a silicon membrane bonded with four strain gauges. The strain gauges are arranged in such a way that two of them respond to the strain under pressure with a positive change in resistivity and two with a negative one. This creates a voltage that can be used as a measuring signal.