Method and apparatus for sensing the natural frequency of a cantilevered body

摘要

A method and apparatus for measuring the natural resonant frequency of a spring element by monitoring a phase difference between an output signal from the spring element and an input signal to the spring element and by adjusting frequency of the input signal until a detected phase difference signals that the natural resonant frequency has been reached. The method and apparatus are applied to a micro-cantilevered elements used to measure gas compositions and concentrations. Such elements are provided with coatings that absorb gas to cause deflections and changes in the mass or spring constant of the cantilevered element. These changes correspond to changes in the natural resonant frequency of the cantilevered element which are measured using the method and apparatus described herein.