This work presents a SU-8 based Flexure-FET biosensor to achieve ultra-sensitive response. Here, gate of the FET is replaced with the fixed-fixed beam. Beam is biased near to pull-in instability (Vpi,) and FET channel is biased in sub-threshold regime (Vth) to take advantage of non-linear response of beam and FET respectively. We simulated the beam using polySi, gold and SU-8 as beam material in real environment using Coventorware to compare their Vpi. After selecting SU-8 as beam material, we optimized the dimensions of beam to achieve low Wpi using Coventorware and then modeled the FET whose Vth Vpi. We simulated the electromechanical coupling using COMSOL Multiphysics. The non-linear deflection in beam due to biomolecules causes the change in potential of channel which results upto 4th order change in I a of FET i.e. Id at equilibrium is 1.1 pA and due to biomolecules, Id becomes 17.3 nA. This result can be used for ultrasensitive detection of malignant molecules. Copyright 2015 by TechConnect. All rights reserved.