Reliability of cyclically actuated silicon microcantilevers in liquid environments

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Microstructures are exposed to a variety of liquid environments in applications such as biosensors, BioMEMS, and microfluidic devices. Environmental interactions between the liquids and microstructures can undermine the reliability of MEMS in liquid environments. In this paper, reliability of silicon microcantilevers is investigated in two common liquids, de-ionized water and saline solution, and contrasted with results in air. These single crystal silicon microcantilevers have a magnetic Permalloy tip and are magnetically actuated. The microcantilevers are subjected to long-term cyclic actuation (108-109 cycles) in a liquid filled enclosure. Reliability of the microcantilevers is evaluated by periodically monitoring changes in resonance frequency. The microcantilevers are subjected to peak stresses of ∼5 MPa, which is typical for MEMS applications in liquids, e.g. AFM tips and biosensors. Since the tensile strength of silicon (1-3 GPa) is much higher than the applied stresses, structural fatigue failures were neither expected nor observed in air, water or saline. Changes in resonance frequencies of microcantilevers tested in air and water were insignificant to within the limits of experimental accuracy. However, environmental interactions influenced the reliability of microcantilevers tested in saline as indicated by a gradual decrease in resonance frequency. This decrease in resonance frequency is attributed to gradual mass adsorption of ionic species on the microcantilevers from the saline solution as indicated by scanning electron microscope imaging and electron dispersive spectroscopy.

Original languageEnglish (US)
Title of host publicationProceedings of 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006 - Microelectromechanical Systems
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Print)0791837904, 9780791837900
DOIs
StatePublished - Jan 1 2006
Event2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006 - Chicago, IL, United States
Duration: Nov 5 2006Nov 10 2006

Publication series

NameAmerican Society of Mechanical Engineers, Micro-Electro Mechanical Systems Division, (Publications) MEMS
ISSN (Print)1096-665X

Other

Other2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006
CountryUnited States
CityChicago, IL
Period11/5/0611/10/06

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