Non-contact evaluation of the resonant frequency of a microstructure using ultrasonic wave  

作　　者：X. Kang X. Y. He C.J. Tay C. Quan 

机构地区：[1]Department of Applied Mechanics, Nanjing University of Science and Technology, 210094 Nanjing, China [2]Institute of Engineering Mechanics, Southeast University,210096 Nanjing, China [3]Department of Mechanical Engineering, National Universityof Singapore, 9 Engineering Drive 1, 117576 Singapore, Singapore

出　　处：《Acta Mechanica Sinica》2010年第2期317-323,共7页力学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(10772086 and 10727201);the National University of Singapore(R-265-000-140-112)

摘　　要：This paper presents a novel non-contact method for evaluating the resonant frequency of a microstructure, Firstly, the microstructure under test is excited by ultrasonic waves. This excitation method does not impose any undefined load on the specimen like the electrostatic excitation and also this is the first actual use of ultrasonic wave for exciting a microstructure in the literature. Secondly, the amplitudes of the microstructure are determined by image edge detection using a Mexican hat wavelet transform on the vibrating images of the microstructure. The vibrating images are captured by a CCD camera when the microstructure is vibrated by ultrasonic waves at a series of discrete high frequencies （〉30 kHz）. Upon processing the vibrating images, the amplitudes at various excitation frequencies are obtained and an amplitude-frequency spectrum is obtained from which the resonant frequency is subsequently evaluated. A micro silicon structure consisting of a perforated plate （192 × 192 μm） and two cantilever beams （76 × 43 μm） which is about 4 μm thickness is tested. Since laser interferometry is not required, thermal effects on a test object can be avoided. Hence, the setup is relatively simple. Results show that the proposed method is a simple and effective approach for evaluating the dynamic characteristics of microstructures.This paper presents a novel non-contact method for evaluating the resonant frequency of a microstructure, Firstly, the microstructure under test is excited by ultrasonic waves. This excitation method does not impose any undefined load on the specimen like the electrostatic excitation and also this is the first actual use of ultrasonic wave for exciting a microstructure in the literature. Secondly, the amplitudes of the microstructure are determined by image edge detection using a Mexican hat wavelet transform on the vibrating images of the microstructure. The vibrating images are captured by a CCD camera when the microstructure is vibrated by ultrasonic waves at a series of discrete high frequencies （〉30 kHz）. Upon processing the vibrating images, the amplitudes at various excitation frequencies are obtained and an amplitude-frequency spectrum is obtained from which the resonant frequency is subsequently evaluated. A micro silicon structure consisting of a perforated plate （192 × 192 μm） and two cantilever beams （76 × 43 μm） which is about 4 μm thickness is tested. Since laser interferometry is not required, thermal effects on a test object can be avoided. Hence, the setup is relatively simple. Results show that the proposed method is a simple and effective approach for evaluating the dynamic characteristics of microstructures.

关 键 词：NON-CONTACT Microstructure· Resonant frequency Ultrasonic wave Image processing 

分 类 号：TQ320.1[化学工程—合成树脂塑料工业] TB552[理学—物理]