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Abstract: Poly(dimethyl siloxane) (PDMS) has been focused on recently due to its variety of applications specifically in microsystems technology. Many companies market two-component PDMS, which is comprised of a base component and a curing agent. Widely known and used for microsystems applications is Sylgard 184 from Dow Corning. Present work deals with two-component Room Temperature Vulcanized (RTV) PDMS from three different companies. They are Sylgard 184 from Dow Corning, RTV 615 from GE Silicones and RTV 141 from Rhodia Chemicals. Temporary increase in wettability of these three different types of PDMS by oxygen plasma by varying the plasma power and exposure time has been studied and compared with results available in literature. The hydrophobic recovery of the modified surfaces was monitored as a function of time and quantified. The surfaces were characterized using contact angle measurements and ATR-FTIR and XPS spectroscopy, their behavior analyzed in term of free surface energy and work of adhesion. [Copyright &y& Elsevier]

The cutting edge radius is a significant parameter of a micromachining tool. When it is not sufficiently sharp, ploughing, which affects the whole machining process and workpiece quality, will occur. It is then essential to be able to estimate the value of the cutting edge radius accurately. In this paper, a three-dimensional strategy that can be used to measure the microturning tool edge radii is presented. The strategy is based on robust cylinder fitting that is applied to a 3D point cloud of the tool. It is implemented in C++ with Open Computer Vision and Point Cloud Library. It was validated using a virtual point cloud, resulting in errors of 0.42% and 1.11% without noise and with noise, respectively. Additionally, uncertainties of 0. 045 μ m and 0. 082 μ m were obtained. It was successfully applied to six microturning inserts: three unused tools and three used tools. The point clouds were obtained with two different 3D surface reconstruction techniques, focus variation with a photon microscope and a multi-view stereo with a scanning electron microscope. The obtained results were more coherent, i.e., they were less dispersed; for example, in non-used tools, the range was [ 3. 11 μ m– 3. 90 μ m] and for the conventional circle fitting the range was [ 2. 62 μ m– 4. 38 μ m]. The traditional method is indirect: the 3D point cloud is sliced into 2D point clouds (profiles) fitted with circles. This 3D-2D process might result in errors. The proposed method is a direct 3D approach with no slicing step. • Importance of tool edge radii in the overall quality of micromachining. • Development of a method for accurate measurement of micro turning tool edge radii from 3D point cloud. • A method based on robust 3D fitting that avoids the 3D-2D process, which is a potential source of errors. • A semi-automatic and practical tool edge radii measurement method. [ABSTRACT FROM AUTHOR]

Abstract: We report on two approaches to achieve ultra-smooth structures on lithium niobate (LiNbO3) substrates. The first method relies on ICP-RIE (inductively coupled-reactive ionic etching) or on RIE, and is exploited here for the fabrication of rods with smooth etched surfaces. A series of tests have been performed with fluorine gases. Nanometric rods with 200, 400 or 600nm diameters, with a periodicity of 400, 800 and 1200nm respectively and etched angles close to 68° for the RIE process and 75° for the ICP-RIE process have been fabricated. The second process is based on “optical grade dicing” and is dedicated to the fabrication of deep-etched ridge waveguides. First optical characterization results are reported. They show optical propagation losses value close to 0.1dB/cm. [Copyright &y& Elsevier]

A metal-containing polymer has been prepared by electropolymerization of an homoleptic Ru(II)-terpyridine complex bearing pyrrole heterocycles. The polymer is obtained as a thin film at the surface of electrodes, and has been characterized by electrochemical measurements, XPS and microscopy. It has been shown that this polymer acts as an active gas sensitive layer since it enables the detection of an ammonia gas flow through layer’s resistivity measurements. [ABSTRACT FROM AUTHOR]

Abstract: Polyethyleneimine films have been deposited on platinum electrode surfaces by electrochemical oxidation of ethylenediamine H2N–CH2–CH2–NH2 (EDA) in acetonitrile solutions. This electrochemical synthesis was realized by cyclic voltammetry and gravimetry techniques. Then, the characterization of the thin solid polyethyleneimine film was performed using X-ray photoelectron spectroscopy and infrared spectroscopy. It was also shown, using atomic force microscopy, that the solid polymeric coating has a granular and homogeneous structure. The influence of EDA concentration on the electropolymerization process was studied leading to the conclusion that the reaction is easier for high EDA concentration. Then, the influence of the nature and concentration of the supporting salt was investigated, showing that its nature is not very important, contrary to its concentration. [Copyright &y& Elsevier]