Cantilever sensor using both the longitudinal and the transversal piezoresistive coefficients

摘要

The present invention relates to a sensor comprising least one sensor unit e.g. a cantilever. The sensor unit comprises a capture surface area and a piezoresistive detection system, for direct detection of stress change of the sensor unit when applying an electrical field over the piezoresistive element. The piezoresistive element has a longitudinal direction in the current direction and a transverse direction perpendicular there to. The longitudinal direction and the transverse direction each has a stress composant and a current composant. The piezoresistive element is of an anisotropic material, and is arranged so that the numerically value of the sum of the longitudinal piezoresistive coefficient pi₁ and the transverse piezoresistive coefficient pi_t along at least 25% of the length, of the piezoresistive element is at least 10^-10 Pa^-1xP, such as 2x10^-10 Pa^-1xP. such as 3x10^-10 Pa^-1xP, such as 4x10^-10 Pa^-1xP, wherein P is the piezoresistance factor, and wherein the piezoresistive coefficients pi₁ and pi_t are determined as composants in the coordinate system used to determine the longitudinal direction.