| Electronic nose,as a gas sensing system with intelligent recognition capability,it’s core component is an array of gas sensors.Some gas sensors require heaters for high-temperature operation.However,nowadays,many heated sensors are discrete type,which limits the concentration and type of gas detected due to their large size and high power consumption,while the MEMS technology based micro hot plate sensors have the advantages of small size,low power consumption and easy integration.It has more advantages than traditional ones.In micro hot plate gas sensors,the micro hot plate serves as a heat source to provide a working temperature for gas sensitive materials,and the working temperature can affect the performance of the gas sensor.Therefore,providing a stable temperature and uniformly distributed micro hot plate is one of the hot spots in sensor research.In this thesis,a cantilever beam type micro heat plate based on MEMS technology is proposed.The finite element method was used to analyze and optimize design parameters,and apply the micro heat plate to the array.The specific content is as follows:(1)A cantilever beam type micro heat plate based on MEMS technology was designed.Steady state thermal simulation was conducted using the COMSOL finite element analysis software for different thicknesses of the support layer,different widths of the cantilever beam,and different thicknesses of the heating electrode at a temperature of 350 ℃.Based on the rules of low power consumption,good temperature uniformity and good structural stability,the support layer thickness of the micro heat plate was found to be 6μm.Cantilever beam width is 4μm.The heating electrode is 200 nm,and the power consumption of the micro heating plate is 1.86 m W,with a deformation of 1.27μm.The membrane stress is 424 MPa.At the same time,the plane filling curves of fractal geometry——Hilbert curve and Peano curve are introduced into the design of heating electrode morphology and structure,and the feature of fractal curves are used to optimize the performance of the heater.Compared to traditional geometric curve based on heating electrodes,the temperature distribution uniformity of fractal heaters is improved effectively with the best one being by 44.7%,and the temperature increases by at least 30 ℃ with the same power consumption.(2)A PCB based heater was designed to verify the accuracy of COMSOL software simulation.Infrared camera temperature tests showed that the test temperatures of the double helix curve and Hilbert curve PCB heaters under 1.2A and 1.5A conditions were 74.7℃,107.2℃,114℃,and 78.5℃,respectively,which were basically consistent with the simulation temperatures of 72.5 ℃,106 ℃,78.9 ℃,and114.2 ℃,demonstrating the effectiveness of the simulation results(3)A micro heat plate array based on the above micro heat plates was designed.The contact of each micro heat plate with each other will cause a temperature rise.Under the same heating electrode conditions and 0.6V power supply voltage,the maximum temperatures of the 2× 2 and 4×4 micro heat plate arrays are increased by 26 ℃ and 44 ℃,respectively.By adjusting the spacing between each micro heat plate at 50μm,each micro heat plate in the 2×2 and 4×4 arrays achieved temperature independence from each other. |
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