Research On The Characteristics Of Silicon-based Integrated Heating/magnetizing Porous Alumina Humidity Sensor

This thesis designed AAO humidity sensor integrated with heating and magnetic function using MEMS processing.The humidity sensor includes humidity sensing structure and heating/magnetic structure,the humidity sensing structure comprises platinum interdigitated electrodes and AAO humidity sensing membrane.Water molecules absorbed on AAO membrane with various quantities at different humidity level,result in different capacitance of interdigitated electrodes to implement humidity measurement.The heating structure consists of platinum heating resistor,using the serpentine heating resistor to raise the temperature of the area where AAO sensing membrane located.The magnetic structure is composed of permenant magnetic material,it can generate certain strength external appied magnetic field.Anodic oxidation method was employed first,to prepare AAO membrane in oxalic solution as humidity sensing film,through optimized anodization conditions,the diameter of AAO pores are range from 30 nm to 70 nm.Then finite element analysis software COMSOL Multiphysics was adopted to construct simulation model and conduct simulation analysis,studied the influences of thickness of AAO membrane,dimension of electrode,et al,to the performances of humidity sensor,and optimized structure design parameters.On that bases,utilizing Tanner EDA L-Edit to complete design of chip layout,and MEMS processing was employed to complete fabrication of AAO humidity sensor.In this thesis,saturated salt solution and LCR meter is adopted to set up humidity sensor testing environment,at ambient temperature condition,measurement voltage and frequency are 1 V and 100 Hz,repectively.The sensitivity,hysteresis and response time of sensor are 1.727 pF/%RH,5.1% F.S.,24 s,respectively.When heating temperature is 60 ?,the hysteresis of sensor reduced to 0.50%F.S.,the sensitivity reduced to 0.155 pF/%RH,the response time shrank to 14 s.When magnetic flux density of external appied magnetic field is 358 Gs,the sensitivity of humidity sensor is 2.331 pF/%RH.