The purpose of this study is to prepare the thin film of C-type parylene (C-type polyxylylene, parylene-C) with improved biocompatibility for the biomedical applications, since in spite of the popularity, the parylene-C has been known to have the less biocompatibility than the N-type or D-type parylene. To prepare the welldesigned parylene films through the chemical vapor deposition (CVD) process and the subsequent plasma surface treatment, the parameters of deposition and surface modification were controlled to obtain optimized physical and surface properties. Using CVD, the thin films of parylene-C as thick as 5 lm were prepared under different deposition pressures. When increasing the deposition rate of parylene film or the deposition pressure, the tensile strength of film increased, whereas the properties such as the surface contact angle and permeability, and the elongation decreased. The deposition rate could be controlled to optimize the physical and physiochemical properties of films. The hydrophilicity of the parylene-C film increased after plasma surface treatment by showing the larger water contact angle than untreated one. When the radio frequency power was above 100 W in the plasma process, the thin film obtained reveals an excellent cytotropism. It shows the improved biocompatibility with living cells.

The biomechanical interaction between the leg stump and the prosthetic socket is critical in achieving close-to-normal ambulation. Although many investigations have been performed to understand the biomechanics of trans-tibial sockets, few studies have measured the socket interface pressure for transfemoral amputees. Furthermore, no report has examined how the residual muscle activities in the transfemoral stump affect the socket interface pressure characteristics during gait. In this study, an experimental method was developed to measure the trans-femoral socket interface pressures and EMG of muscles in the stumps of two trans-femoral amputees. Also, the measurement of three-dimensional prosthetic locomotion was synchronized to understand detailed socket biomechanics. Based on the experimental results, a significant correlation (P 5 0.05) was found between the measured temporal EMG amplitude and the interface pressure at the knee flexor (biceps femoris) and extensor (rectus femoris). Therefore, the residual muscle activity of a trans-femoral amputee's stump could be an important factor affecting socket-interface pressure changes during ambulation.

ABSTRACT:The character and performance of a new ionic polymer-metal composite (IPMC) prepared with a melt-processable fluorinated acrylic copolymer were examined. The fluorinated acrylic copolymer was synthesized by the copolymerization of fluoroalkyl methacrylate (DuPont Zonyl) and acrylic acid, and it was compression molded to attain membranes of various thicknesses. The current and displacement responses by electric stimulus were measured to study the effects of the ionic concentration, thickness, and countercation on the actuation of the IPMC. The ionic center of the acrylic copolymer was essential for the actuation of the IPMC; however, too much ionic center induced excessive water uptake, which caused adverse effects on the performance of the IPMC. When the applied voltage was 5 V, the largest current and displacement responses were observed with the IPMC prepared by a fluorinated acrylic copolymer containing 11.8 wt % acrylic acid.

ABSTRACT:We studied the preparation of antimicrobial silicone rubbers of improved interfacial strength, which could be formed with the ion beam assisted deposition (IBAD) technique for coating metallic or inorganic materials (silver (Ag), Copper (Cu), and Hydroxyapatite(HAp)/TiO 2 ) on the silicone surface. Those coating materials provide high product safety as well as outstanding antimicrobial activity. The deposition methodology is composed of pre-etching with oxygen gas, vaporizing the coating materials, and posttreatment with Ar ion. With the evaporation of the coating materials, the Ar beam was focused on the substrate to assist deposition. It was found out that the ion assisting depositions in the IBAD process give a prominent enhancement in adhesion between silicone rubbers and coatings of Ag and Cu. The HAp/TiO 2 coating layer was easily dissolved in aqueous saline solution. All deposited layers display high antimicrobial activities against Staphlococcus aureus (ATCC 6538) and Escherichia coil (ATCC 25,922), showing 99.9% reduction of bacteria, respectively. In a cytotoxicity test, the Ag and HAp/TiO 2 coated silicone shows a decrease of cytotoxicity, while the Cu coating leads to a slight increase of cytotoxicity. The result on the surface modifications of silicone rubber will be employed in further study for applications of medical or rehabilitation devices.

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