Fully compressible low-Mach number simulations of carbon-dioxide at supercritical pressures and trans-critical temperatures

In this paper, we report on the influence of capillary condensation on the sliding friction of sidewall surfaces in polycrystalline silicon micro-electromechanical systems (MEMS). We developed a polycrystalline silicon MEMS tribometer, which is a microscale test device with two components subject to sliding contact. One of the components can be heated in situ by Joule heating to set the temperature of the contact and thereby control the capillary kinetics at the MEMS sidewalls. We used an optical displacement measurement technique to record the stick–slip motion of the slider with sub-nanometer resolution, and we assessed the friction force with nanonewton resolution. All friction measurements were performed under controlled ambient conditions while sweeping the contact temperature from room temperature to 300 (cid:3) C, and from 300 (cid:3) C to room temperature. We were able to distinguish the two ways in which energy is dissipated during sliding: the ‘semi-statically’ dissipated energy attributed to asperity deformation and contact yield, and the dynamically dissipated energy ascribed to the release of the tension in the slider during slip events. We observed an increase in the dynamically dissipated energy at 80 (cid:3) C while sweeping down in temperature. This increase is caused by higher adhesion due to capillary condensation between the conformal surfaces. Our study highlights how energy is dissipated during the sliding contact of MEMS sidewalls, and it is helpful in overcoming friction in multi-asperity systems.

[1]  W. V. Spengen,et al.  Improved analysis and visualization of friction loop data: unraveling the energy dissipation of meso-scale stick–slip motion , 2017 .

[2]  W. V. Spengen,et al.  Controlling adhesion between multi-asperity contacting surfaces in MEMS devices by local heating , 2016 .

[3]  Federico Buja,et al.  In-Plane Displacement Detection With Picometer Accuracy on a Conventional Microscope , 2015, Journal of Microelectromechanical Systems.

[4]  J. Krim,et al.  Surface science, MEMS and NEMS: Progress and opportunities for surface science research performed on, or by, microdevices , 2013 .

[5]  B. Poelsema,et al.  Surface adhesion and its dependence on surface roughness and humidity measured with a flat AFM tip , 2012 .

[6]  Jonathan R Felts,et al.  Controlling nanoscale friction through the competition between capillary adsorption and thermally activated sliding. , 2012, ACS nano.

[7]  L. Qian,et al.  Role of tribochemistry in nanowear of single-crystalline silicon. , 2012, ACS applied materials & interfaces.

[8]  J. Frenken,et al.  The description of friction of silicon MEMS with surface roughness: virtues and limitations of a stochastic Prandtl–Tomlinson model and the simulation of vibration-induced friction reduction , 2010, Beilstein journal of nanotechnology.

[9]  R. Ritchie,et al.  Micron-Scale Friction and Sliding Wear of Polycrystalline Silicon Thin Structural Films in Ambient Air , 2008, Journal of Microelectromechanical Systems.

[10]  J. Frenken,et al.  The Leiden MEMS Tribometer: Real Time Dynamic Friction Loop Measurements With an On-Chip Tribometer , 2007 .

[11]  Tjerk H. Oosterkamp,et al.  A sensitive electronic capacitance measurement system to measure the comb drive motion of surface micromachined MEMS devices , 2007 .

[12]  R. Ritchie,et al.  An electron microscopy study of wear in polysilicon microelectromechanical systems in ambient air , 2007 .

[13]  Seong H. Kim,et al.  Effects of adsorbed water layer structure on adhesion force of silicon oxide nanoasperity contact in humid ambient. , 2006, The Journal of chemical physics.

[14]  J. Frenken,et al.  Capillary condensation in atomic scale friction: how water acts like a glue. , 2006, Physical review letters.

[15]  W. R. Ashurst,et al.  Evidence for pre-sliding tangential deflections in MEMS friction , 2003, TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664).

[16]  L. Sirghi.  Effect of capillary-condensed water on the dynamic friction force at nanoasperity contacts , 2003 .

[17]  E. Riedo,et al.  Kinetics of capillary condensation in nanoscopic sliding friction. , 2002, Physical review letters.

[18]  S. Granick,et al.  Rate-dependent slip of Newtonian liquid at smooth surfaces. , 2001, Physical review letters.

[19]  Michael Thomas Dugger,et al.  Friction and wear in surface-micromachined tribological test devices , 1997, Photonics West - Micro and Nano Fabricated Electromechanical and Optical Components.

[20]  D. F. Evans,et al.  Structure and Frictional Properties of Self-Assembled Surfactant Monolayers , 1996 .

[21]  Jan H. J. Fluitman,et al.  The electrostatic shuffle motor , 1995 .

[22]  C. Mate,et al.  Influence of capillary condensation of water on nanotribology studied by force microscopy , 1994 .

[23]  R. Puers,et al.  A physical model to predict stiction in MEMS , 2006 .

[24]  William D. Cowan,et al.  Effect of surface chemistry on the tribological performance of a MEMS electrostatic lateral output motor , 2001 .

[25]  K. Kendall,et al.  Inadequacy of Coulomb's friction law for particle assemblies , 1986, Nature.