Research On The Key Technologies Of Quartz Tuning Fork Resonance Temperature Sensor

Quartz crystal temperature sensors based on the piezoelectric resonators thermalsensitivity to temperature, which have the advantages of high precision, smallhysteresis, good stability and digital signal output, plays an importment role in thefields of the high precision temperament measurement.Based on piezoelectric effect of quartz crystal, the resonant frequencytemperature dependence of quartz resonators has been used for the measurement oftemperature for a long time, as quartz crystal sensor Since quartz is an anisotropicmedium, it is necessary to select the optimal crystal cut which yields the bestperformance for a quartz crystal temperature sensor.Quartz tuning fork resonance temperature sensors is a branch of quartz crystaltemperature sensors. The basis of the quartz tuning fork resonance temperaturesensor is that an environmental temperature change leads to a change in the measuredfrequency change of the quart tuning fork resonance temperature sensor, which havethe advantages of high resolution, small bulk, low cost, low consumption, highprecision, Strong anti-interference ability，good stability and digital signal output.Quartz tuning fork resonance temperature sensor have always been an importantbranch in the field of temperature sensors research.In this paper, a novel MEMS quartz tuning fork resonance temperature sensorwas improved. By utilizing the novel thermal cut, the thermal sensitivity of quartztuning fork resonance temperature sensors was obviously higher than that of thetraditional quartz tuning fork temperature sensor. The researches about the theory, thedesign, the fabrication, and the detecting were performed. The main contributions ofthis work are listed as following:1. The research status of different kinds of quartz temperature sensors werefirstly studied. And then the quartz resonant temperature sensors based onpiezoelectric principles were reviewed in detail. Motivated by the aboveobservation， the stratagem of the quartz tuning fork temperature sensors were taken out. The research objectives and contents of this work were developedrespectively.2. The basic structure and operation principle of the quartz tuning forkresonance temperature sensors were introduced. By utilizing the H shape tuning forkand reasonable electrodes configuration to improve the quality factor and SNR of thesensor. Based on the piezoelectric principles and the elastic mechanics theory, thevibration model of the quartz tuning fork piezoelectric cantilever was established, thedifferential equation was derived and the frequency of the quartz tuning forkresonator was solved by using the variable separation method.3. Based on the resonant sensor theory, the theatrical analysis model offrequency temperature coefficients of quartz under double rotation angle wasestablished. A novel thermal cut was designed, and the sensitivity was calculated as–2Hz/°C.4. The structure of the was designed based on piezoelectric effect andelectromechanical coupling theory, and optimized by using finite element method.The cantilever beam structure was designed and simulated by ANSYS software， itsreliability was demonstrated. The fabrication process layout was designed and theexperimental sensor prototype was fabricated.5. The parasitic circuit capacitor compensation oscillation circuit wasimplemented to drive the quartz tuning fork and then the detecting platform wasformed. The relationships of between the outputted frequency and the inputtedtemperature of experimental QTFR temperature sensor was detected in operationfrom–20to100°C. Experimental results show that sensitivity of–1.9Hz/°C, linearityof1.8%and resolution of0.0125℃were obtained respectively.