Elastoresistance Effect

a change in the electrical resistivity of a solid conductor, such as a metal or semiconductor, as a result of deformation. The magnitude of the relative change in the tensor components of the resistivity, Δρ_ik/ρ_ik, is related to the deformation tensor u_lm through the fourth-rank tensor λ_iklm: Δρ_ik/ρ_ik = Σλ _iklm u_lm. In practice, the concept of elastosensitivity k = (Δρ/ρ)/(Δl/l) is used, where Δl/l is the relative change in the length l of the sample under the load applied in a certain direction and Δρ/ρ is the relative change in the resistivity ρ in this direction. In metals, k is of the order of unity, whereas in semiconductors, for example, Ge and Si, it is tens or hundreds of times greater.

The elastoresistance effect is related to the change in interatomic distances upon deformation, which involves a change in the structure of the energy bands of the crystal. This change in structure causes a change in the concentration and effective mass of the current carriers (conduction electrons and holes) and a redistribution of the carriers between the energy maxima in the conduction band and the minima in the valence band. In addition, deformation affects the process of carrier scattering (the appearance of new defects and a change in the phonon spectrum). The elastoresistance effect is used in elastoresistive sensors for measuring deformations.