Electrode Of Microstructure Gas Sensor Optimized Design And Finite Element Simulation

The performance of Micro-structure Gas Sensor mainly depend on the active development of sensitive materials, the sensitive materials working temperature usually between 300 ℃ ~ 400 ℃, thus, a heater is needed for the materials to reach working temperature. The heating electrode is an important part of the micro-hotplate and the key of heat production. Heating electrodes’ energy consumption includes: Convection, Conduction, and Radiation.This article offers theories for designing micro-hotplate electrodes based upon the calculation of its size. Three electrode structures had been designed based on the above theory, the size(width and thickness) of micro heating electrodes can be preliminarily set through the theoretical calculation for each electrodes’ structural design. The ANSYS Finite Element analysis software is then required to analyze the different electrode arrangements’ heating distribution for more accurate simulation, and further validates the validity of the design for micro hotplate electrodes.1. Two-fingers shaped design for heating electrodesDesign an electrode arrangement with an “Two-fingers” shaped heating electrode, with a size of 0.56×0.66 mm2 for the micro hotplate, use thermal power loss relationship with the resistance and the formula of resistance.setting the electrode’s thickness around 300 nm and 20 μm in width. Simulate using the ANSYS finite element analysis software to get the heat generation rate at 6′1011 W/m2 under 25 ℃, thus reaching an evenly distributed working temperature of 346 ℃.2. Snake-shaped design for heating electrodesArrange the heating electrodes in a “Snake” pattern on micro hotplate with a base size of 0.64×0.66 mm2,get the resistance variable R through the use of the power variable P, then calculate the electrodes? thickness and widthusing variable R, which is 300 nm in thickness and 20 μm in width. After obtaining the electrode model, simulate with the ANSYS finite element analysis software to conclude that with a set heat generation rate of 6 ′ 1011W/m2, the average working temperature is at 321 ℃, evenly distributed.3. Claw-shaped electrode designDesign a heating electrode on a 0.74×0.6 mm2 micro hotplate. The measured thickness for Si is 300 μm, and the thickness for Si O2 is 300 nm.Through calculating the total power consumption P, conclude and set the electrode’s width and thickness at 20 μm and 300 nm.Simulate using the ANSYS finite element analysis software with a heat generation rate of 6′1011W/m2 under load, the average working temperature is evenly distributed at364 ℃.Above three kinds of micro hot-plate heating electrode designs are able to meet the requirements of sensitive materials working temperature.viewed by structure,under the same working conditions,the claw heating electrode configuration area of substrate proportion is the largest.so the substrate heating area is the largest. It increases the sensitive materials coating area and reduces the difficulty of the coating and increase the sensitivity of the microstructure gas sensors.