The sensitivity of a piezoresistive sensor holds great importance in case of bio-medical applications. In this paper, we will discuss about 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 SCR's are created by introducing defects on the beam. As the Stress Concentrated Region elements increases the stresses, the deformation will increase which will lead to the enhancement of the sensitivity of piezoresistive sensor. With introduction of a Optimal defect (Star design) and in comparison with the previous defects, this paper will lead to a enhanced sensitive piezoresistive sensor.