Diamond-Like Carbon Films for Silicon Passivation in Microelectromechanical Devices

1995 ◽  
Vol 383 ◽  
Author(s):  
M. R. Houston ◽  
R. T. Howe ◽  
K Komvopoulos ◽  
R. Maboudian
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Microelectromechanical Systems ◽  
Adhesion Force ◽  
Contact Angles ◽  
Vacuum Arc ◽  
Diamond Like Carbon ◽  
Adhesion Forces ◽  
Water Contact

ABSTRACTThe surface properties of diamond-like carbon (DLC) films deposited by a vacuum arc technique on smooth silicon wafers are presented with specific emphasis given to stiction reduction in microelectromechanical systems (MEMS). The low deposition temperatures afforded by the vacuum arc technique should allow for easy integration of the DLC films into the current fabrication process of typical surface micromachines by means of a standard lift-off processing technique. Using X-ray photoelectron spectroscopy (XPS), contact angle analysis, and atomic force microscopy (AFM), the surface chemistry, microroughness, hydrophobicity, and adhesion forces of DLC-coated Si(100) surfaces were measured and correlated to the measured water contact angles. DLC films were found to be extremely smooth and possess a water contact angle of 87°, which roughly corresponds to a surface energy of 22 mJ/m2. It is shown that the pull-off forces measured by AFM correlate well with the predicted capillary forces. Pull-off forces are reduced on DLC surfaces by about a factor of five compared to 10 nN pull-off forces measured on the RCA-cleaned silicon surfaces. In the absence of meniscus forces, the overall adhesion force is expected to decrease by over an order of magnitude to the van der Waals attractive force present between two DLC-coated surfaces- To further improve the surface properties of DLC, films were exposed to a fluorine plasma which increased the contact angle to 99° and lowered the pull-off force by approximately 20% over that obtained with as-deposited DLC. The significance of these results is discussed with respect to stiction reduction in micromachines.

scholarly journals Surface Properties of Pine Scrimber Panels with Varying Density

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 397 ◽  
Author(s):  
Jinguang Wei ◽  
Qiuqin Lin ◽  
Yahui Zhang ◽  
Wenji Yu ◽  
Chung-Yun Hse ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Lower Surface ◽  
Contact Angles ◽  
High Density ◽  
Water Contact ◽  
Change Rate ◽  
Hydrophilic Material ◽  
Wood Grain

Coating quality for scrimber products against exterior conditions is largely dependent on the surface properties. The wettability, morphology, and chemical composition of pine scrimber surfaces were investigated to better understand the surface properties. The scrimber was found to be a hydrophilic material because the water contact angles were less than 90°. The panels with a density of 1.20 g/cm3 had the largest angle change rate (k = 0.212). As the panel density increased, the instantaneous contact angle of each test liquid (i.e., water, formamide, and diiodomethane) on the panels decreased, and so did surface free energy. Panels with higher density showed lower surface roughness. Surface roughness across the wood grain was greater than that along the grain. SEM observations showed the high-density panels had a smoother surface with fewer irregular grooves in comparison with the low-density panels. X-ray photoelectron spectroscopy (XPS) analysis indicated that more unoxygenated groups appeared on the surface of high-density panels.

scholarly journals Adhesion to Bile Drain Materials and Physicochemical Surface Properties of Enterococcus faecalis Strains Grown in the Presence of Bile

2002 ◽  
Vol 68 (8) ◽  
pp. 3855-3858 ◽  
Author(s):  
Karola Waar ◽  
Henny C. van der Mei ◽  
Hermie J. M. Harmsen ◽  
John E. Degener ◽  
Henk J. Busscher
Keyword(s):  
Surface Properties ◽  
Enterococcus Faecalis ◽  
Photoelectron Spectroscopy ◽  
Surface Protein ◽  
Lower Surface ◽  
Contact Angles ◽  
Surface Proteins ◽  
Water Contact ◽  
Zeta Potentials ◽  
Aggregation Substance

ABSTRACT The aim of this study is to determine whether growth in the presence of bile influences the surface properties and adhesion to hydrophobic bile drain materials of Enterococcus faecalis strains expressing aggregation substance (Agg) or enterococcal surface protein (Esp), two surface proteins that are associated with infections. After growth in the presence of bile, the strains were generally more hydrophobic by water contact angles and the zeta potentials were more negative than when the strains were grown in the absence of bile. Nitrogen was found in lower surface concentrations upon growth in the presence of bile, whereas higher surface concentrations of oxygen were measured by X-ray photoelectron spectroscopy. Moreover, an up to twofold-higher number of bacteria adhered after growth in bile for E. faecalis not expressing Agg or Esp and E. faecalis with Esp on its surface. E. faecalis expressing Agg did not adhere in higher numbers after growth in bile, possibly because they mainly adhere through positive cooperativity and less through direct interactions with a substratum surface. Since adhesion of bacteria is the first step in biomaterial-centered infection, it can be concluded that growth in bile increases the virulence of E. faecalis.

The Wetting of Insect Cuticles by Water

1955 ◽  
Vol 32 (3) ◽  
pp. 591-617 ◽  
Author(s):  
M. W. HOLDGATE
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Surface Properties ◽  
Surface Composition ◽  
Contact Angles ◽  
Aquatic Species ◽  
Water Contact ◽  
Calliphora Erythrocephala ◽  
Wetting Properties ◽  
Wide Range

1. The water contact angles of insects show a wide range of variation, which is broadly correlated with surface roughness and with habitat. 2. The contact angles of species inhabiting stored products or carrion are greatly modified by contamination. This produces large variations between apparently similar individuals. 3. In terrestrial insects surface roughness increases the contact angles to very large apparent values. Detailed analyses of its effect have been made in the pupa of Tenebrio molitor and the adult Calliphora erythrocephala. In some aquatic insects surface roughness leads to a reduction in the contact angles; this has been studied in the nymph of Anax imperator. 4. Prolonged immersion in water causes a lowering of the contact angles of all the insects examined, and the low angles of many aquatic species may therefore be the direct effect of their environment. In some aquatic species there is evidence of the active maintenance of a large contact angle during life. 5. Changes in contact angle accompany processes of cuticle secretion and will occur at any moult if changes in roughness or habitat take place. 6. The observed variations of surface properties can be explained without assuming any variation in the chemical composition of the cuticle surface. Wetting properties are of little value as indicators of cuticle surface composition. 7. The biological aspects of insect surface properties are briefly discussed.

scholarly journals Influence of Surface Properties on Adhesion Forces and Attachment ofStreptococcus mutansto ZirconiaIn Vitro

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Pei Yu ◽  
Chuanyong Wang ◽  
Jinglin Zhou ◽  
Li Jiang ◽  
Jing Xue ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Properties ◽  
Biofilm Formation ◽  
Adhesion Force ◽  
Contact Angles ◽  
Adhesion Forces ◽  
Force Microscopy ◽  
Early Attachment ◽  
Atomic Force ◽  
Initial Adhesion

Zirconia is becoming a prevalent material in dentistry. However, any foreign bodies inserted may provide new niches for the bacteria in oral cavity. The object of this study was to explore the effect of surface properties including surface roughness and hydrophobicity on the adhesion and biofilm formation ofStreptococcus mutans(S. mutans) to zirconia. Atomic force microscopy was employed to determine the zirconia surface morphology and the adhesion forces between theS. mutansand zirconia. The results showed that the surface roughness was nanoscale and significantly different among tested groups (P<0.05): Coarse (23.94±2.52 nm) > Medium (17.00±3.81 nm) > Fine (11.89±1.68 nm). The contact angles of the Coarse group were the highest, followed by the Medium and the Fine groups. Increasing the surface roughness and hydrophobicity resulted in an increase of adhesion forces and early attachment (2 h and 4 h) ofS. mutanson the zirconia but no influence on the further development of biofilm (6 h~24 h). Our findings suggest that the surface roughness in nanoscale and hydrophobicity of zirconia had influence on theS. mutansinitial adhesion force and early attachment instead of whole stages of biofilm formation.

End-Blocked Silanization of Side-Chain Fluoroalkyl Oligoether and its Surface Properties

2018 ◽  
Vol 71 (11) ◽  
pp. 855
Author(s):  
Lei Wang ◽  
Lei Chen ◽  
Zhanxiong Li
Keyword(s):  
Contact Angle ◽  
Photoelectron Spectroscopy ◽  
Contact Angles ◽  
Side Chain ◽  
Chemical Compositions ◽  
Silicon Substrates ◽  
Water Contact ◽  
Molecular Weights ◽  
Self Assembled ◽  
Surface Morphologies

In this study, three novel side-chain fluoroalkyl oligoethers with different molecular weights were synthesised via a ring-opening reaction of 2,2,3,3,4,4,5,5,5-nonafluoropentyloxirane. The fluorooligoethers were then silanized and characterised by FT-IR,1H, and 19F NMR spectroscopies. These silanlized fluorooligoethers were used to fabricate hydrophobic coatings on silicon substrates, which were pre-treated with O2 plasma, by the method of liquid phase deposition. The chemical compositions and structures of the film surfaces were analysed by X-ray photoelectron spectroscopy and the results showed that silanized fluorooligoethers formed self-assembled films on the silicon wafer. The surface wettability of the coatings was measured by water contact angles. It is noted that the annealing process can improve the hydrophobicity with the highest water contact angle being 115.2 ± 1° and hexadecane contact angle being 67.2 ± 1°. The surface morphologies and roughness of the self-assembled films were measured by atomic force microscopy (AFM), as a result, the surface was found to be rougher with the increment of the molecular weight of the fluorooligoethers.

scholarly journals Experimental Study of the Influence of the Adsorbate Layer Composition on the Wetting of Different Substrates with Water

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Michaela Heier ◽  
Rolf Merz ◽  
Stefan Becker ◽  
Kai Langenbach ◽  
Michael Kopnarski ◽  
...  
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Photoelectron Spectroscopy ◽  
Contact Angles ◽  
Water Contact ◽  
X Ray ◽  
Cleaning Agents ◽  
Adsorbate Layer ◽  
Titanium Substrates ◽  
Layer Composition

Wetting is strongly influenced by adsorbate layers, which are omnipresent on surfaces. The influence of the composition and thickness of adsorbate layers on the water contact angle of sessile drops on different substrates was systematically investigated in the present work. Measurements were carried out for gold-sputtered substrates. These new results are compared to results from a previous study, in which corresponding measurements were carried out for technical steel and titanium substrates. In all experiments, different pretreatments of the samples were used to obtain variations of the adsorbate layer. The samples were either exposed to an oil bath or not, and different cleaning agents were used. The analysis of the adsorbate layer was carried out with X-ray photoelectron spectroscopy (XPS). The results for the different substrates reveal that the water contact angle depends mainly on the composition of the adsorbate layer. The substrate has only an indirect influence, as it influences the composition of the adsorbate layer. The thickness of the adsorbate layers was between 1.4 and 14 nm and was large enough to prevent a direct influence of the substrate on the water contact angle. It is shown that using the information on the adsorbate layer composition from XPS and the results for the water contact angle obtained for the gold samples alone, the water contact angles on the steel and titanium samples can be predicted.

Effects of Surface Treatments of Polycaprolactone Scaffolds on their Properties

2013 ◽  
Vol 747 ◽  
pp. 178-181 ◽  
Author(s):  
Wasana Kosorn ◽  
Boonlom Thavornyutikarn ◽  
Wanida Janvikul
Keyword(s):  
Contact Angle ◽  
Plasma Treatment ◽  
Alkaline Hydrolysis ◽  
Photoelectron Spectroscopy ◽  
Atomic Ratio ◽  
Contact Angle Measurement ◽  
Contact Angles ◽  
Angle Measurement ◽  
Water Contact ◽  
Oh Groups

Polycaprolactone (PCL) was surface modified with alkaline hydrolysis by NaOH and/or low pressure oxygen (O2) plasma treatment. The hydrolysis was conducted in two different stages: one was performed prior to PCL scaffold fabrication by a high pressure supercritical CO2 technique; the other was carried out after the fabrication. The resulting hydrolyzed PCL scaffolds, with pore sizes in the range of 150-250 μm, were denoted as pre-HPCL and post-HPCL, respectively. Both non-hydrolyzed and hydrolyzed PCL scaffolds were subsequently subjected to the plasma treatment, to further enhance the hydrophilicity of the scaffolds. The surface morphology, wettability and chemical composition of all PCL scaffolds were analyzed by scanning electron microscopy (SEM), water contact angle measurement, and X-ray photoelectron spectroscopy (XPS), respectively. It was found that the surface of the scaffolds turned from fairly smooth to highly rough after the hydrolysis and plasma treatment, particularly when both treatments were in use. The post-hydrolysis induced more surface roughness, compared to the pre-hydrolysis. In addition, the water contact angles on the scaffolds enormously reduced after the treatments; plasma treatment, however, showed a more prominent effect than the alkaline hydrolysis. Although expressing a zero-degree contact angle, the plasma-treated pre-HPCL scaffold was wetted more readily than the plasma-treated post-HPCL. These were in good agreement with the XPS results; interestingly, the plasma-treated pre-HPCL scaffold exhibited the greatest O/C atomic ratio among the PCL scaffolds. This indicated its highest extent of PCL chain oxidation, a degradation of ester groups into-COOH and-OH groups.

Laser-Induced Nanocarbon Formation for Tuning Surface Properties of Commercial Polymers

2020 ◽  
Author(s):  
Moataz Abdulhafez ◽  
Angela J. McComb ◽  
Mostafa Bedewy
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Surface Characterization ◽  
Surface Engineering ◽  
Surface Hydrophobicity ◽  
Contact Angles ◽  
Structure Property ◽  
Water Contact ◽  
Wide Range ◽  
Commercial Polymers

Abstract The growth of laser-induced nanocarbons, referred to here are LINC for short, directly on polymeric surfaces is a promising route toward surface engineering of commercial polymers. This paper aims to demonstrate how this new approach can enable achieving varied surface properties based on tuning the nanostructured morphology of the formed graphitic material on commercial polyimide (Kapton) films. We elucidate the effects of tuning laser processing parameters on the achieved nanoscale morphology and the resulting surface hydrophobicity or hydrophilicity. Our results show that by varying lasing power, rastering speed, laser spot size, and line-to-line gap sizes, a wide range of water contact angles are possible, i.e. from below 20° to above 110°. Combining water contact angle measurements from an optical tensiometer with LINC surface characterization using optical microscopy, electron microscopy, and Raman spectroscopy enables building the process-structure-property relationship. Our findings reveal that both the value of contact angle and the anisotropic wetting behavior of LINC on polyimide are dependent on their hierarchical surface nanostructure which ranges for isotropic nanoporous morphology to fibrous morphology. Results also show that increasing gap sizes lead to an increase in contact angles and thus an increase in the hydrophobicity of the surface. Hence, our work highlight the potential of this approach for manufacturing flexible devices with tailored surfaces.

On the Wettability of Nanocomposite Amorphous Carbon Films

2005 ◽  
Vol 23 ◽  
pp. 67-70
Author(s):  
P. Zhang ◽  
B.K. Tay ◽  
G.Q. Yu ◽  
S.P. Lau
Keyword(s):  
Contact Angle ◽  
Surface Energy ◽  
Amorphous Carbon ◽  
Photoelectron Spectroscopy ◽  
Contact Angles ◽  
Atomic Scale ◽  
Vacuum Arc ◽  
Polar Component ◽  
Metal Composite ◽  
Obvious Effect

Nanocomposite Si containing amorphous carbon (a-C:Si) and metal containing amorphous carbon (a-C:Me) films including a-C:Al, a-C:Ti, and a-C:Ni were prepared by the filtered cathodic vacuum arc (FCVA) technique The metal-carbon (5 at.% metal) composite targets were used. The VCA Optima system was used to measure the contact angle. Three types of liquid were used to study the changes in the surface energy. X-ray photoelectron spectroscopy (XPS) was employed to analyze the composition and chemical state of the films. The surface morphology and roughness of the films were determined by atomic force microscopy (AFM). The Al containing films show the highest contact angle with water, which reaches as high as 101.26°. The Si containing films show the lowest contact angle around 64°. The contact angles of Ni, and Ti containing films are around 83°, 96.5°, respectively. The absorption of oxygen on the surface play an important role on the polar component of the a-C:Me films. The formation of Al-O, and Ti-O bonds is responsible for the lower polar component. The metal state Ni results in higher polar component. The Si-O bond contributes to the high polar component of a-C:Si film. As all films are atomic scale smooth, the RMS roughness is below 0.5 nm, the roughness does not have obvious effect on the surface energy.

Characterisation of surface properties of chemical and plasma treated regenerated cellulose fabric

2012 ◽  
Vol 82 (20) ◽  
pp. 2078-2089 ◽  
Author(s):  
Zdenka Peršin ◽  
Alenka Vesel ◽  
Karin Stana Kleinschek ◽  
Miran Mozetič
Keyword(s):  
Plasma Treatment ◽  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Research Work ◽  
Contact Angles ◽  
Alternative Activation ◽  
Oxygen Plasma Treatment ◽  
Regenerated Cellulose ◽  
Water Contact ◽  
Chemical Treatments

The aim of this research work was to study the surface properties and sorption characteristics of differently treated regenerated cellulose fabrics. Surface modifications of viscose, modal and lyocell samples caused by using standard chemical pre-treatment procedures were compared to an alternative activation procedure by applying low pressure oxygen plasma treatment. The elemental chemical composition of the modified fabric surfaces was investigated using X-ray photoelectron spectroscopy (XPS), while hydrophilic/hydrophobic properties were evaluated by determining the water contact angles, as well as thoroughly analysed using Owens–Wendt surface energy (SFE) and surface polarity investigations. Standard chemical and also plasma treatments changed the surface chemistry of cellulose. Bleaching and alkaline treatments increased the surface carboxylic acid content by approximately 4.8% while plasma treatment increased it by approximately 9.7%. As a consequence, higher hydrophilicity arises as proved by water contact angle decrease; i.e. 24% (61°) after standard chemical treatments and 70% (20°) after plasma treatment. Both chemical treatments increase the SFE and polar components, while the reduction of dispersive components was less pronounced. The oxygen activation treatment has the greatest influence on the SFEs of the samples as well as on polarity of the samples.

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