Modeling the Effect of Surface Roughness on the Adhesion, Contact and Friction in Micro-Electro-Mechanical Systems (MEMS) Interfaces

2003 ◽  
Author(s):  
Noureddine Tayebi ◽  
Andreas A. Polycarpou
Keyword(s):  
Surface Texturing ◽  
Static Friction ◽  
Normal Operation ◽  
Root Mean Square Roughness ◽  
Adhesion Forces ◽  
Sensors And Actuators ◽  
Micro Electro Mechanical Systems ◽  
Friction Forces ◽  
Normal Forces ◽  
Adhesion Contact

It has been experimentally shown that surface texturing (roughening) decreases the effect of intermolecular adhesion forces that are significant in MEMS applications. These forces can hinder normal operation of sensors and actuators as well as micro-engines where they might increase friction, which could be catastrophic. In this paper, a model that predicts the effects of roughness, asymmetry, and flatness on the adhesion, contact, and friction forces in MEMS interfaces is presented. The three key parameters used to characterize the roughness the asymmetry and the flatness of a surface topography are the root-mean-square roughness (RMS), skewness and kurtosis, respectively. It is predicted that surfaces with high RMS, high kurtosis and positive skewness exhibit lower adhesion and static friction coefficient, even at extremely low external normal forces.

scholarly journals Friction force microscopy of tribochemistry and interfacial ageing for the SiO x /Si/Au system

2018 ◽  
Vol 9 ◽  
pp. 1647-1658 ◽  
Author(s):  
Christiane Petzold ◽  
Marcus Koch ◽  
Roland Bennewitz
Keyword(s):  
Friction Force ◽  
Static Friction ◽  
Chemical Bonds ◽  
Friction Force Microscopy ◽  
Adhesion Forces ◽  
Low Friction ◽  
Friction Forces ◽  
Force Microscopy ◽  
Static Contact ◽  
Wear Friction

Friction force microscopy was performed with oxidized or gold-coated silicon tips sliding on Au(111) or oxidized Si(100) surfaces in ultrahigh vacuum. We measured very low friction forces compared to adhesion forces and found a modulation of lateral forces reflecting the atomic structure of the surfaces. Holding the force-microscopy tip stationary for some time did not lead to an increase in static friction, i.e., no contact ageing was observed for these pairs of tip and surface. Passivating layers from tip or surface were removed in order to allow for contact ageing through the development of chemical bonds in the static contact. After removal of the passivating layers, tribochemical reactions resulted in strong friction forces and tip wear. Friction, wear, and the re-passivation by oxides are discussed based on results for the temporal development of friction forces, on images of the scanned area after friction force microscopy experiments, and on electron microscopy of the tips.

Relations of Microstructure, Piezoelectricity, and Surface Forces at Nanoscale

2007 ◽  
Author(s):  
Hyungoo Lee ◽  
Rodrigo Cooper ◽  
Bartosz Mika ◽  
Hong Liang
Keyword(s):  
Polyvinylidene Fluoride ◽  
Polymer Surface ◽  
Electrical Potential ◽  
Mechanical Systems ◽  
Adhesion Forces ◽  
Surface Adhesion ◽  
Micro Electro Mechanical Systems ◽  
Friction Forces ◽  
Β Phase ◽  
Dipole Structure

In small devices such as micro-electro-mechanical systems (MEMS) and nano-electro-mechanical systems (NEMS), adhesion and friction forces make them less reliable with unacceptable performance [1]. These forces need to be completely understood to make advances in the systems. In our previous research, it has been proven that using a functional material, polyvinylidene fluoride (PVDF), both stiction and friction could be modified or turned on-off. The phase of the polymer affects the adhesion and friction forces. β phase contents reduced the adhesion forces due to its less electrostatic forces. With higher phase difference, higher roughness of the polymer surface got higher friction forces. In this research, we continue our investigation in understanding microstructure aspects of the PVDF, its dipole structure, and piezoelectricity on surface adhesion and friction. Doing so, we used an atomic force microscope (AFM) with an external potential to study the piezeoelectrical behavior. The effects of the electrical potential on adhesion and friction force were tested. It was shown that when the electrical potential increases, the surface roughness increases under the AFM, however not with a profilometer. Changes were also found in adhesion. This paper discusses the mechanisms of nanoscale adhesion and friction of the PVDF with an AFM tip along with the microstructures and dipole structures. This article contributes to understanding in fundamental adhesion and friction forces at a nanometer length scale.

scholarly journals Slipping–rolling transitions of a body with two contact points

2021 ◽  
Author(s):  
Mate Antali ◽  
Gabor Stepan
Keyword(s):  
Rigid Body ◽  
Contact Point ◽  
Static Friction ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Friction Forces ◽  
Contact Points ◽  
Body Dynamics ◽  
Coulomb Model ◽  
Rigid Surfaces

AbstractIn this paper, the general kinematics and dynamics of a rigid body is analysed, which is in contact with two rigid surfaces in the presence of dry friction. Due to the rolling or slipping state at each contact point, four kinematic scenarios occur. In the two-point rolling case, the contact forces are undetermined; consequently, the condition of the static friction forces cannot be checked from the Coulomb model to decide whether two-point rolling is possible. However, this issue can be resolved within the scope of rigid body dynamics by analysing the nonsmooth vector field of the system at the possible transitions between slipping and rolling. Based on the concept of limit directions of codimension-2 discontinuities, a method is presented to determine the conditions when the two-point rolling is realizable without slipping.

Flexure based gripper to grasp hollow objects by internal surface interaction

2021 ◽  
pp. 095440622110498
Author(s):  
Rajesh Kumar ◽  
Harsh Yadav ◽  
Varan Gupta ◽  
Jitendra P Khatait
Keyword(s):  
Internal Surface ◽  
Surface Interaction ◽  
Design Development ◽  
Friction Forces ◽  
Normal Forces ◽  
Inner Surface

The paper focuses on the design, development, and evaluation of a gripper intended to hold hollow objects by interacting with the inner surface. The gripper moves towards the inside of the hollow object and grips it using the friction forces applied on the surface of the object. The design also ensures the application of variable normal forces on the surface of the object to be grasped. The mathematical architecture is verified using prototypes and experiments.

Electric Control of Friction on Silicon Studied by Atomic Force Microscope

NANO ◽  
2015 ◽  
Vol 10 (03) ◽  
pp. 1550038 ◽  
Author(s):  
Yan Jiang ◽  
Lili Yue ◽  
Boshen Yan ◽  
Xi Liu ◽  
Xiaofei Yang ◽  
...  
Keyword(s):  
Atomic Force Microscope ◽  
Bias Voltage ◽  
Electrostatic Force ◽  
Adhesion Forces ◽  
Friction Forces ◽  
Type Silicon ◽  
Atomic Force ◽  
Electric Control ◽  
Before And After ◽  
Track Line

We investigated friction on an n-type silicon surface using an atomic force microscope when a bias voltage was applied to the sample. Friction forces on the same track line were measured before and after the bias voltages were applied and it was found that the friction forces in n-type silicon can be tuned reversibly with the bias voltage. The dependence of adhesion forces between the silicon nitride tip and Si sample on the bias voltages approximately follows a parabolic law due to electrostatic force, which results in a significant increase in the friction force at an applied electric field.

Adhesion and Pull-Off Forces for Polysilicon MEMS Surfaces Using the Sub-Boundary Lubrication Model

2002 ◽  
Vol 125 (1) ◽  
pp. 193-199 ◽  
Author(s):  
Allison Y. Suh ◽  
Andreas A. Polycarpou
Keyword(s):  
Surface Roughness ◽  
Boundary Lubrication ◽  
Intermolecular Forces ◽  
Contact Forces ◽  
Root Mean Square Roughness ◽  
Magnetic Storage ◽  
Smooth Surfaces ◽  
Adhesion Forces ◽  
Disk Interface ◽  
Adhesion Model

Miniature devices including MEMS and the head disk interface in magnetic storage often include very smooth surfaces, typically having root-mean-square roughness, σ of the order of 10 nm or less. When such smooth surfaces contact, or come into proximity of each other, either in dry or wet environments, then strong intermolecular (adhesive) forces may arise. Such strong intermolecular forces may result in unacceptable and possibly catastrophic adhesion, stiction, friction and wear. In the present paper, a model termed sub-boundary lubrication (SBL) adhesion model is used to calculate the adhesion forces, and an elastic-plastic model is used to calculate the contact forces at typical MEMS interfaces. Several levels of surface roughness are investigated representing polished and as-deposited polysilicon films that are typically found in MEMS. The SBL adhesion model reveals the significance of the surface roughness on the adhesion and pull-off forces as the surfaces become smoother. The validity of using the SBL adhesion model to estimate the pull-off forces in miniature systems is further supported by direct comparison with experimental pull-off force measurements performed on silicon and gold interfaces. Finally, the significance of the interfacial forces as relate to the reliability of MEMS interfaces is discussed.

Influence of the Powder Particle Size on the Denudated Zone Width at Selective Laser Melting

2020 ◽  
Vol 989 ◽  
pp. 816-820
Author(s):  
Roman Sergeevich Khmyrov ◽  
R.R. Ableyeva ◽  
Tatiana Vasilievna Tarasova ◽  
A.V. Gusarov
Keyword(s):  
Particle Size ◽  
Selective Laser Melting ◽  
Powder Particle ◽  
Powder Particle Size ◽  
Adhesion Forces ◽  
Laser Melting ◽  
Friction Forces ◽  
Single Bead ◽  
Powder Particles

Mass transfer in the laser-interaction zone at selective laser melting influences the quality of the obtained material. Powder particles displacement during the formation of the single bead is experimentally studied. The so-called denudated zone was visualized by metallography. It was determined that increasing the powder particle size leads to widening the denudated zone. This can signify that the adhesion forces between powder particles prevail over the friction forces.

Temperature-induced switchable interfacial interactions on slippery surfaces for controllable liquid manipulation

2019 ◽  
Vol 7 (31) ◽  
pp. 18510-18518 ◽  
Author(s):  
Zubin Wang ◽  
Quan Xu ◽  
Lili Wang ◽  
Liping Heng ◽  
Lei Jiang
Keyword(s):  
Interfacial Friction ◽  
Adhesion Forces ◽  
Interfacial Interactions ◽  
Friction Forces ◽  
Temperature Responsive ◽  
Slippery Surface

The interfacial friction forces and adhesion forces are directly detected and controllable liquid sliding is achieved on a temperature-responsive slippery surface.

Measurements of Forces Between a Synchronous Belt and a Pulley

2000 ◽  
Author(s):  
Martin Distner ◽  
Tomas Johannesson
Keyword(s):  
Load Distribution ◽  
Contact Forces ◽  
Automotive Application ◽  
Friction Forces ◽  
Running Time ◽  
Application Range ◽  
Normal Forces ◽  
Belt Speed ◽  
Pitch Difference ◽  
Static Conditions

Abstract In modern belt profiles, power is transmitted by both normal forces and friction forces. To control the load distribution between a belt and a pulley, avoiding power circulation and local tooth load peaks, it is necessary to take into account both types of forces. An analytical model for the load distribution has previously been presented by the authors. This work also introduces the effective pitch difference, EPD, which is the actual pitch difference between a pulley and a loaded belt. To examine these matters and verify the model, a series of 270 experiments was carried out in a two-pulley test rig. Parameters investigated are: torque, tension, belt speed, pitch difference and running time. All of the measurements were conducted under quasi-static conditions. The equipment used included a specially designed measurement pulley that can measure four different engagement forces. Experiments show that belt speed within automotive application range has no effect on load distribution, apart from engagement and disengagement peaks. Tooth flank normal forces and land area friction forces often work against each other. Belts with dissimilar pitch difference give rise to great differences in load distributions. Even a short running time causes a redistribution of the friction forces, although their sum remains constant. The results show that it is possible to tailor the load distribution by adjusting the EPD. This offers an opportunity to avoid power circulation and unnecessary high contact forces. Changing the EPD for the correct load distribution at each interaction is easily achieved by individual adjustment of the pulley radius.

Chemical Force Microscopy

1997 ◽  
Vol 3 (S2) ◽  
pp. 1253-1254
Author(s):  
Charles M. Lieber ◽  
Dmitri Vezenov ◽  
Aleksandr Noy ◽  
Charles Sanders
Keyword(s):  
Functional Groups ◽  
Adhesive Contact ◽  
Adhesion Forces ◽  
Friction Forces ◽  
Force Microscopy ◽  
Chemical Force Microscopy ◽  
Water Solvent ◽  
Assembled Monolayers ◽  
Adhesive Interactions ◽  
Chemical Force

Chemical force microscopy (CFM) has been used to measure adhesion and friction forces between probe tips and substrates covalently modified with self-assembled monolayers (SAMs) that terminate in distinct functional groups. Probe tips have been modified with SAMs using a procedure that involves coating commercial Si3N4 cantilever/tip assemblies with a thin layer of polycrystalline Au followed by immersion in a solution of a functionalized thiol. This methodology provides a reproducible means for endowing the probe with different chemical functional groups.A force microscope has been used to characterize the adhesive interactions between probe tips and substrates that have been modified with SAMs which terminate with COOH and CH3 functional groups in ethanol water solvent. Force versus distance curves recorded under ethanol show that the interaction between COOH/COOH > CH3/CH3 > COOH/CH3. The measured adhesive forces were found to agree well with predictions of the Johnson, Kendall, and Roberts (JKR) theory of adhesive contact, and thus show that the observed adhesion forces correlate with the surface free energy

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