Handbook of Silicon Based MEMS Materials and Technologies

1.1.4.2. Piezoresistive Effect in Silicon

General Piezoresistive Effect

The change in the resistance of metal devices due to an applied mechanical load was first discovered by Lord Kelvin in 1857. With the large-scale use of single-crystal silicon in the making of semiconductor circuits, a much stronger piezoresistive effect was discovered in silicon [25]. This discovery forms the basis for practically all piezoresistive MEMS applications.

Strain

When a sample is subjected to physical force, the force yields a change in length, dL, that follows the well known Hooke’s law F = kΔL, where k is a material constant. The stress is defined as the applied force per unit area. Stress (σ) is thus given by(1.1)where ε^L denotes the differential deformation, ...