Research On Electrohydrodynamic Jet Deposition Of PZT Piezoelectric Micro Structure And Device

PZT thick film microstructures and PZT composite microstructures with excellent piezoelectric properties are designed as ultrasonic transducers,energy harvesters,micro-mass detection sensors and underwater acoustic transducers and so on which are widely used in medical,military,biological and chemical fields.Electrohydrodynamic Jet Deposition technology is an additive manufacturing technique that can be used to fabricate various micro-nano functional structures using a variety of functional materials on different substrates.This thesis is concerned with the difficulty of PZT thick film complex structure and device fabrication.Electrohydrodynamic Jet Deposition experimental platform for preparing the planar/spherical PZT thick film microstructure is constructed and PZT composite suspension composed of PZT sol and PZT powder was prepared.Experimental studies on PZT thick film micropatterns,spherical PZT thick films and PZT thick film microcantilevers with different shapes and sizes were developed.In addition,experimental studies also have been conducted on electrode preparation and poling treatment of PZT microstructure.Firstly,a PZT thick film microstructures Electrohydrodynamic Jet Deposition experimental platform and a high-quality PZT composite suspension was constructed.A precision stainless steel PZT thick film deposition template was prepared by precision laser machining technology.20?m-thick PZT thick film micropatterns with different shapes were prepared with the aid of the template and the minimum size is about 58?m.In addition,these microstructures were also annealed and crystallized.The electric field distribution between the needle and the planar/spherical substrate was simulated and analyzed.Based on the analysis results,a three-axis rotating experimental platform was designed and added to prepare the spherical PZT thick film with a diameter of 5mm and a thickness of 30?m.Subsequently,the electrodes preparation and polarization treatment method of PZT microstructures were studied.Ti/Pt electrodes were prepared on the surface of planar/spherical PZT thick film by magnetron sputtering technique and the influence of the transition layer on the bonding ability of the electrode was compared.The surface of PZT composite wafer was polished,cleaned and degreased,then the surface electrode was prepared by magnetron sputtering.The test results showed the weldability of the electrode is good and the average bonding strength of the electrode can reach 7.69 MPa.Finally,the working mode and polarization of spherical PZT thick film were analyzed,The PZT microstructure polarization platform was constructed and the polarization of the planar/spherical PZT piezoelectric thick film was completed.Finally,the structure of the PZT thick film microcantilever sensor was designed and the resonance characteristic of it is theoretically analyzed.Different sizes of stainless steel microcantilever array,stainless steel PZT thick film deposition template and stainless steel PZT thick film microcantilever upper electrode preparation template were prepared by precision laser machining technology.A PZT thick film functional layer with a thickness of 10?m and a minimum width of 40 ?m was prepared on the stainless steel microcantilever by template-assisted Electrohydrodynamic Jet Deposition.Then,the PZT thick film functional layer was subjected to high temperature annealing treatment.Ti/Pt upper electrode of PZT thick film microcantilever was prepared by magnetron sputtering technique combined with electrode preparation template.The PZT thick film functional layer was polarized and tested for its piezoelectric constant and dielectric constant.Its d33 is 54 pC/N,the relative dielectric constant and dielectric loss at 1 kHz are 184 and 0.033,respectively.The resonance characteristics of PZT thick film microcantilever sensor were simulated and the resonance characteristic and amplitude of it were also tested and analyzed by a precision impedance analyzer and a Doppler laser vibrometer,respectively.The results show that first four-order resonant frequency is 6 kHz,39 kHz,106 kHz and 205 kHz with good consistency with the simulation results.Further,when the excitation voltage is 5 V,the amplitudes are about 44 nm,38 nm,20 nm,and 8 nm,respectively.