Analysis of MEMS cantilever sensor for sensing volatile organic compounds

Increased concentration of Volatile Organic Compound (VOC) in environment can cause severe health issues and create the ozone layer at ground level. The increased concentration of ozone at the ground level creates the smog which will affect the biodiversity of mother earth, environment and human health in many ways. Many re-searchers have persuaded the continuous research on miniaturized sensors to detect the VOC with high sensitivity and selectivity. This paper presents the design and fabrication of MEMS cantilever sensor to sense VOCs viz., acetone (C3H6O) and Isopropyl alcohol (C3H8O). Here, the metal oxide films of Poly-vinyl-pyrrolidone (PVP) and Amino-propyl-tri-ethoxy-silane (3-APTES) having 600 nm thickness is deposited on oxidized p-type Si surface by RF sputtering process. The cantilever structure of 128 mu m length, 80 mu m width and thickness 600 nm is designed having a sensor area of 10,240 mu m(2). With this design specification the sensor is simulated in COMSOL Multiphysics software. Then, the sensor is fabricated using surface micromachining technique. The detection of VOCs is carried out by omnicant instrument. Here, the detection sensitivity of PVP and 3-APTES towards Acetone and Isopropyl alcohol are analyzed. The experimental results show that, PVP coated sensor performs 39% increase in sensitivity as compared to 3-APTES coated sensor to detect acetone, and 3-APTES coating sensor exhibit 7.5% increase in sensitivity to detect Isopropyl alcohol as compared to PVP coated sensor.