ENHANCEMENT OF THE SENSITIVITY OF A PIEZORESISTIVE SENSOR USING SCR’S ORIENTATION

Abstract

The sensitivity of a piezoresistive sensor holds great importance in case of bio-medical applications. In this paper, we will discuss how to enhance the sensitivity of a cantilever based piezoresistive sensor. The methodology behind this enhancement is, creating Stress Concentration Region (SCR) on the beam. These SCRs are created by introducing defects on the beam. When these Stress Concentration Regions are introduced in the cantilever beam through any means of fabrication process; they distribute the surface stresses present on the cantilever beam under load. This distribution increases the surface stresses around the defect. As the defect is near to the piezoresistive layer; diffused or deposited on the cantilever beam; the surface stress will tend to increase the strain and longitudinal deflection around the piezoresistive surface. This increase in the strain will ultimately lead to increase in change in resistivity. After plotting the change in resistance against the applied load, the slope of the curve will give us the sensitivity of the piezoresistive sensor. This paper will discuss the methods to enhance the sensitivity to optimal level without critically damaging the peizoresistive sensor. With the introduction of an optimal defect (Star design), selecting the optimal geometrical aspects or parameters of the defect and in comparison with the previous defects, this paper will lead to an enhanced sensitive piezoresistive sensor.