A Linearized Method to Measure Dynamic Friction of Microdevices

Corwin, Alex D.; Boer, Maarten P. de

doi:10.1007/s11340-008-9158-9

Cited by 3 publications

(2 citation statements)

References 21 publications

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“…Hence, there is good evidence that FOTAS is chemically attached, and it is expected to act as a dry boundary lubricant. The measured value of dynamic coefficient of friction with the same device was μ d = 0.25 [25], [26], in accordance with this expectation. The FOTAS surface is hydrophobic with a water contact angle of 106 • ; capillary condensation in laboratory air due to ambient moisture is not expected.…”

Section: Device and Test Proceduressupporting

confidence: 84%

Frictional Aging and Sliding Bifurcation in Monolayer-Coated Micromachines

Corwin

Boer

2009

J. Microelectromech. Syst.

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Using a high-performance polycrystalline-silicon micromachined actuator that also functions as a friction tester, we have found frictional forces that cannot be explained by Amontons' law with a constant coefficient of friction. In our friction test, a constant tangential force is applied while normal load is ramped down at a rateḞ n after a hold time t h at a hold load F h . When coated by a monolayer of FOTAS (CF 3 C 5 F 10 C 2 H 4 Si(N(CH 3 ) 2 ) 3 ), we find that there is no unique coefficient of static friction μ s , but instead that μ s depends on all three of these parameters. The dependence on t h implies static friction aging, but the rate of static friction aging can be suppressed by greater hold force. When sliding motion begins, we have identified a critical normal force to shear force ratio such that any motion initiating above the critical ratio proceeds with time-dependent frictional creep over several hundred nanometers, whereas any motion initiating below the critical ratio proceeds with a large inertial jump. These effects demonstrate that contact aging effects extend from the micrometer to the nanometer scale and are relevant to micromachined interfaces.[2008-0174]

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Section: Device and Test Proceduressupporting

confidence: 84%

Frictional Aging and Sliding Bifurcation in Monolayer-Coated Micromachines

Corwin

Boer

2009

J. Microelectromech. Syst.

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“…The data presented here is for oxide-coated devices, which were found [32] to have shorter lifetimes than monolayer-coated devices. Other work we have reported [23,24,[34][35][36][37] was taken on nanotractors monolayer coatings applied according to the procedure detailed by Hankins et al [33]. For those tests, friction results are highly consistent in the first few hundreds of tests.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Wear Characteristics and Frictional Behavior in MEMS Devices

2010

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A surface-micromachined nanotractor device has been used to investigate the tribological behavior of MEMS devices made of polycrystalline silicon. An accelerated wear test, spanning several hundreds of thousands of cycles, was developed to monitor the evolution of wear characteristics and frictional behavior during its operational lifetime. Postmortem microscopic observations of the wear surfaces revealed features that can be categorized into two regimes of wear: (i) adhesion-dominated wear and (ii) third-body wear. The former was characterized by asperity blunting, plastic deformation of asperity peaks, and smearing of fine wear debris into a thin-surface film. With an increased number of wear cycles, the wear mechanism transitioned to the latter regime which consisted of debris agglomeration and material removal through scratches induced by these agglomerates. Finally, it was theorized that one of the agglomerates grows to a large size, adheres to one of the contact surfaces and causes severe wear in a localized region on the counter surface to lock the two surfaces and cause device failure.

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