A COMSOL® Based Illustrative Study on SAW Sensor VOC Detection for Human Respiratory System
Volatile Organic Compounds (VOC) are a wide range of carbon based organic chemical compounds which evaporate easily at room temperature referred as volatile in nature. Human exhaled breathe consists of carbon dioxide (CO2) along with more than 3000 Volatile Organic Compounds exists like acetone, methanol, ethanol, and butane and formaldehydes etc. Out of existing several invasive methods, Exhaled breath analysis is a non-invasive technique through which most preferable pain less procedures can be adopted for the purpose of diagnosing respiratory track issues. Estimation of acetone detection is seriously considered and most preferred techniques should be adopted for improving the mortality rate by overwhelming serious breath related diseases. In order to achieve, SAW Sensor is designed and simulated by using COMSOL Multi Physics 5.0. Estimation Of gas sensor adsorption rate and conductivity is observed based on electric potentials, Frequency response is analysed at various Eigen values, depends on the results obtained further characterization and fabrication of bio Sensor to detect VOC thereby Human exhaled breathe Analysis can be estimated.
Key words: Volatile Organic Compounds, SAW Sensor, Breath biomarkers,
Results obtained from COMSOL Multiphysics® 5.0 based SAW Sensor Simulations are as follows which are explained in detail in the Research conference Paper.
Analysis of SAW sensor is fabricated by COMSOL Multiphysics® 5.0 The use of periodic boundary condition implies that the frequencies of interest will correspond to wavelengths that are integer fractions of the width of the geometry. The lowest SAW Eigen mode has its wavelength equal to the width of the geometry of 3 to 4 μm. Using the Rayleigh wave velocity for the given piezoelectric substrate material, estimation of resonance frequency is the main theme of this work. The information can be used in the Eigen frequency solver, from COMSOL Multiphysics software which will help to find out the resonance frequencies. In this model, a YZ-cut LiNbO3 whose Rayleigh wave velocity (v) is around 3300 m/s. This gives an estimate of the lowest SAW frequency (f0) to be 848MHz and maximum Eigen value obtained is 972 MHz Thus, COMSOL multiphysics results are represented as shown in fig  and fig  for Eigen frequency Vs Total Displacement with switch mode 1 & switch mode 0 respectively.