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.

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.

The Changes in Particle Distribution Over the Polymer Surface Under the Dielectric Barrier Discharge Plasma

2019 ◽  
Vol 18 (03n04) ◽  
pp. 1940079 ◽  
Author(s):  
V. A. Lapitskaya ◽  
T. A. Kuznetsova ◽  
G. B. Melnikova ◽  
S. A. Chizhik ◽  
D. A. Kotov
Keyword(s):  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Polymer Surface ◽  
Film Surface ◽  
Adhesion Forces ◽  
Surface Adhesion ◽  
Temperature Plasma ◽  
Dielectric Barrier ◽  
Force Microscopy ◽  
Barrier Discharge Plasma

Surface properties of a two-layer polymer PMF-351 film exposed to the dielectric barrier discharge (DBD) low-temperature plasma have been studied by atomic force microscopy. It is established that such treatment leads to an increase of surface adhesion. The largest adhesion forces of about 165[Formula: see text]nN were achieved after 5[Formula: see text]min of treatment at the distance of 2[Formula: see text]sm, power of 30[Formula: see text]W and nitrogen flow of 3.1[Formula: see text]L/min. SiO2 nanoparticles with diameters of 10–20[Formula: see text]nm were distributed over the treated polymer film surface from a suspension by centrifugation and they formed uniform rounded formations with the diameters of 50–100[Formula: see text]nm.

scholarly journals Adhesion Behavior between Multilayer Graphene and Semiconductor Substrates

2018 ◽  
Vol 8 (11) ◽  
pp. 2107 ◽  
Author(s):  
Qi Zhang ◽  
Xin Ma ◽  
Yulong Zhao
Keyword(s):  
Critical Velocity ◽  
Bonding Strength ◽  
Energy Levels ◽  
Mechanical Systems ◽  
Semiconductor Surface ◽  
Multilayer Graphene ◽  
Adhesion Forces ◽  
Micro Electro Mechanical Systems ◽  
Graphene Layers ◽  
Topmost Layer

A high bonding strength between graphene and a semiconductor surface is significant to the performance of graphene-based Micro-Electro Mechanical Systems/Nano-Electro Mechanical Systems (MEMS/NEMS) devices. In this paper, by applying a series of constant vertical upward velocities (Vup) to the topmost layer of graphene, the exfoliation processes of multilayer graphene (one to ten layers) from an Si semiconductor substrate were simulated using the molecular dynamics method, and the bonding strength was calculated. The critical exfoliation velocities, adhesion forces, and adhesion energies to exfoliate graphene were obtained. In a system where the number of graphene layers is two or three, there are two critical exfoliation velocities. Graphene cannot be exfoliated when the Vup is lower than the first critical velocity, although the total number of graphene layers can be exfoliated when the Vup is in the range between the first critical velocity and second critical velocity. Only the topmost layer can be exfoliated to be free from the Si surface if the applied Vup is greater than the second critical velocity. In systems where the number of graphene layers is four to ten, only the topmost layer can be free and exfoliated if the exfoliation velocity is greater than the critical velocity. It was found that a relatively low applied Vup resulted in entire graphene layers peeling off from the substrate. The adhesion forces of one-layer to ten-layer graphene systems were in the range of 25.04 nN–74.75 nN, and the adhesion energy levels were in the range of 73.5 mJ/m2–188.45 mJ/m2. These values are consistent with previous experimental results, indicating a reliable bond strength between graphene and Si semiconductor surfaces.

Optical phase modulators using deformable waveguides actuated by micro-electro-mechanical systems

2011 ◽  
Vol 36 (7) ◽  
pp. 1089 ◽  
Author(s):  
Wei-Chao Chiu ◽  
Chun-Che Chang ◽  
Jiun-Ming Wu ◽  
Ming-Chang M. Lee ◽  
Jia-Min Shieh
Keyword(s):  
Mechanical Systems ◽  
Micro Electro Mechanical Systems ◽  
Optical Phase ◽  
Phase Modulators ◽  
Optical Phase Modulators

scholarly journals Wash Testing of Electronic Yarn

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1228 ◽  
Author(s):  
Dorothy Anne Hardy ◽  
Zahra Rahemtulla ◽  
Achala Satharasinghe ◽  
Arash Shahidi ◽  
Carlos Oliveira ◽  
...  
Keyword(s):  
Research Group ◽  
Copper Wire ◽  
Mechanical Systems ◽  
Consumer Products ◽  
Temperature Sensing ◽  
Micro Electro Mechanical Systems ◽  
Acoustic Sensing ◽  
Protective Polymer ◽  
Wash Durability

Electronically active yarn (E-yarn) pioneered by the Advanced Textiles Research Group of Nottingham Trent University contains a fine conductive copper wire soldered onto a package die, micro-electro-mechanical systems device or flexible circuit. The die or circuit is then held within a protective polymer packaging (micro-pod) and the ensemble is inserted into a textile sheath, forming a flexible yarn with electronic functionality such as sensing or illumination. It is vital to be able to wash E-yarns, so that the textiles into which they are incorporated can be treated as normal consumer products. The wash durability of E-yarns is summarized in this publication. Wash tests followed a modified version of BS EN ISO 6330:2012 procedure 4N. It was observed that E-yarns containing only a fine multi-strand copper wire survived 25 cycles of machine washing and line drying; and between 5 and 15 cycles of machine washing followed by tumble-drying. Four out of five temperature sensing E-yarns (crafted with thermistors) and single pairs of LEDs within E-yarns functioned correctly after 25 cycles of machine washing and line drying. E-yarns that required larger micro-pods (i.e., 4 mm diameter or 9 mm length) were less resilient to washing. Only one out of five acoustic sensing E-yarns (4 mm diameter micro-pod) operated correctly after 20 cycles of washing with either line drying or tumble-drying. Creating an E-yarn with an embedded flexible circuit populated with components also required a relatively large micro-pod (diameter 0.93 mm, length 9.23 mm). Only one embedded circuit functioned after 25 cycles of washing and line drying. The tests showed that E-yarns are suitable for inclusion in textiles that require washing, with some limitations when larger micro-pods were used. Reduction in the circuit’s size and therefore the size of the micro-pod, may increase wash resilience.

Micro-spectrophotometer based on micro electro-mechanical systems technology

2008 ◽  
Vol 3 (1) ◽  
pp. 37-43
Author(s):  
Lianqun Zhou ◽  
Yihui Wu ◽  
Ping Zhang ◽  
Ming Xuan ◽  
Zhenggang Li ◽  
...  
Keyword(s):  
Mechanical Systems ◽  
Micro Electro Mechanical Systems
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