| Micro-/nanomechanical resonators have been highlighted for their capability to detected quantities like surface stress,stiffness or particle mass with extraordinary sensitivities.They have become a fundamental sensing tool used in either material science to determine the elastic properties of prepared nanomaterials usually in form of thin film or mass spectrometry to estimate the mass of various chemical and biological molecules.Since these films have thicknesses of several tens of nm,their material properties,including density,significantly deviate from the known bulk values.As such,determination of ultrathin film material properties requires usage of highly sophisticated devices that are often expensive,difficult to operate,and time consuming.The present study seeks for simple method to determine the deposited thin film material properties and various molecules by micro-/nanomechanical resonator.Specifically,the work considers of i)ultrathin film material properties determination using microcantilever immersed in air,ii)single-mass spectrometry of heavy analytes and large biological clumps by monitoring Q-factor changes of nanomechanical resonator in solution,iii)thin film elastic properties determination and mass spectrometry utilizing phase transformation shape memory alloy-based resonators.The first portion of present study found out the accessible expressions needed to calculate the ultrathin film density,the Poisson's ratio,the Young's and shear moduli from measured changes in the microcantilever resonant frequencies,and quality factors.This procedure is based on detecting changes in the static deflection,flexural and torsional resonant frequencies,and the corresponding quality factors of the microcantilever vibrating in air before and after film deposition.The validity and potential of the present procedure in material testing is demonstrated by i)extracting the Young's modulus of atomic-layer-deposited Ti O2 films coated on a SU-8 microcantilever from observed changes in frequency response and without requirement of knowing the film density,and ii)comparing the shear modulus and density of Si3N4 films coated on the silicon microcantilever obtained numerically and by present method.The second portion of the work demonstrate that the single mass spectrometry of heavy analytes including large biological clumps can be realized without a need for highly challenging analysis of the analyte position,stiffness and/or binding effects just by monitoring changes in the resonator quality factor of only a single mode frequency.Theory with a detailed procedure of mass extraction from changes in quality factor is developed.Validity and universality of present method is demonstrated by extracting the mass of heavy(light)analyte made of protein or E.coli bacteria cells(ragweed pollen particle)adsorbed on the microcantilever,of which Q-factors of the torsional mode in air were previously measured.Present results open a doorway for single-mass spectrometry of even heavy analytes like large biological clumps near their native environments by utilizing current nanomechanical resonators.The final portion of this dissertation focuses on the extraordinary capability of shape memory alloy(SMA)based nanomechanical resonator operating in vacuum,air or viscous fluid to determine both i)the elastic properties of ultrathin film,and ii)the attached particle mass from only the frequency response of resonator loaded by an investigated quantity.Besides,we also show that the SMA based resonators enable a significant improvement of the achievable Q-factor and,consequently,they allow a notably large increase in the resonator sensitivity.Present results demonstrate the outstanding potential and capability of high frequency operating SMA based nanomechanical resonators in sensing applications that can be rarely achieved by current resonators. |
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