Polymer Based Hybrid Membrane-Flexure Nanomechanical Piezoresistive Sensor

In this paper, a novel Hybrid Membrane-Flexure Nanomechanical (HMF-NM) Piezoresistive Sensor with SU-8 as structural material and Indium Tin Oxide (ITO) as piezoresistor is designed and simulated using commercial finite element analysis (FEA) software. SU-8/ITO microcantilever has been fabricated to electromechanically extract the piezoresistive property of ITO which has been considered for simulation. The simulated device consists of a circular membrane coated with receptor layer suspended by inverse trapezoidal flexures with embedded piezoresistors. Surface stress induced on the membrane due to target binding is transduced as a uniaxial stress in the flexures which is then sensed using piezoresistors. A conventional polymer U-shaped piezoresistive cantilever is also designed and simulated for comparison. The surface stress sensitivity of HMF-NM sensor is extracted as 4.01 ppm/[mN/m] which is more than 20 times that of a conventional cantilever.