Patent ID: 7284452

Claim:
A sensor comprising at least one sensor unit shaped as a cantilever, said sensor unit comprises a capture surface, and a piezoresistive element with a pair of wires for applying an electrical field over the piezoresistive element, the distance between the wires along the piezoresistive element being defined as the length of the piezoresistive element, the piezoresistive element has a longitudinal direction and a transverse direction along the length of the piezoresistive element when an electrical field is applied over the piezoresistive element and the piezoresistive element is subjected to a stress, the longitudinal direction is defined as a direction which is one of the axis x, y or z of a coordinate system and wherein there is a stress component and a current component, the transverse direction is perpendicular to said longitudinal direction, said piezoresistive element being of an anisotropic material, and being arranged so that the numerical value of the sum of the longitudinal piezoresistive coefficient π l and the transverse piezoresistive coefficient π t along at least 25% of the length, of the piezoresistive element being at least 10 −10 Pa −1 ×P, wherein P is the piezoresistance factor, and wherein the piezoresistive coefficients π l and π t are determined as components in the coordinate system used to determine the longitudinal direction.