Yasuharu Ohgoe

Diamondlike carbon film deposition on a polycarbonate-tube inner wall using a cylindrical electrode with radio frequency glow discharge plasma

Radio frequency (rf) plasma chemical vapor deposition (CVD) process is very useful for film deposition. However, common rf plasma CVD techniques using planar electrodes make it difficult to apply to three-dimensional insulator structures. In this study, to deposit diamondlike carbon (DLC) films on a polycarbonate-tube inner wall (ϕ 11mm, length 100mm), we have developed the cylindrical electrode plasma process. This process could be adapted to cylindrical substrates such as polymeric tubes. In investigating the availability of this process, under helium (He) gas pressures (50, 100, and 150Pa), the plasma states of the rf power at 30W were measured using a double-probe method. The He plasma was generated bright as a stable, hollow cathode discharge inside the polycarbonate tube. As a result, the cylindrical electrode process was expected to have applications for cylindrical materials such as polymeric tubes. In actual deposition of DLC film (CH4 gas at 10Pa, rf power at 30W, and deposition time at 10min), ...

13.56 MHz radio frequency plasma properties on hemispheric electrodes and diamond-like carbon films deposition on three-dimensional polyurethane diaphragms

The characteristics of the radio frequency (rf) plasma that could hold an entire hemispheric polyurethane diaphragm generated using the hemispheric-type electrode were investigated. The plasma states were measured using Langmuir probe. Although the common rf plasma chemical vapor deposition technique using planar electrodes makes it difficult to apply uniform plasma to three-dimensional structures, the hemispheric-type electrode process could uniformly hold a hemispheric polyurethane diaphragm at self-bias voltage. As a result, this process could uniformly keep the ion sheath on the diaphragm. In case of using this process for diamond-like carbon (DLC) film deposition, the DLC film was deposited uniformly on the diaphragm at approximately 300nm. Besides electron temperatures and electron number of densities were similar to the behavior of common rf plasma. This means that the characteristics of plasma are kept in the same states even if the plasma form is controlled using such a hemispheric-type electrode...

Biocompatibility of Diamond-Like Carbon Coated NiTi Orthodontic Wire and Acrylic Resin Teeth

A variety of dental devices such as orthodontics, artificial teeth are implanted in oral cavity for long term. The implant coated with protective films, which can reduce corrosion and wear, may prevent the problems described above and extend the lifetime of implants to the benefit of the patients. Diamond-like carbon films have extreme hardness, low friction coefficients, chemical inertness, and high-corrosion resistance. Moreover, these properties make the good candidates as biocompatible coatings for dental devices. In this study, DLC films using the plasma CVD method deposited on acrylic resin and orthodontic archwires have investigated to detect the Ni release from the wires and to estimate cell growth in E-MEM immersed acrylic plates. After 6 months, the concentration of the nickel release from DLC-coated wire and Non-coated wire was 150 [ppb] and 933 [ppb], respectively. Results indicated DLC films inhibit the release of these materials, and prevent degradation of these materials in the solution.

Hemocompatibility of DLC coating for blood analysis devices

The studies of Diamond-Like carbon (DLC) coated medical devices have reported possibility for developing blood analysis devices. DLC film is a surface modification technique for biomaterials due to their hemocompatibility, low friction, and reasonableness. We have deposited DLC film on silicon (Si), cyclic olefin polymer (COP), polycarbonate (PC), SU-8 and polydimethylsiloxane (PDMS) by using r.f. plasma enhanced chemical vapor deposition (r.f.-PECVD) method. These materials have been used extensively in micro-channel devices. The hemocompatibility, chemical composition, structure, wettability, roughness, and surface morphology of the samples have been investigated by in-vitro test with sheep blood, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman), a contact angle measurement, atomic force microscopy (AFM). The result indicated that the satisfied hemocompatibility was obtained for the DLC on COP and PDMS. Moreover, it was observed that hemocompatibility was influenced by surface conditions of sample DLC coating to COP and PDMS are expected as a surface modification technique for the micro-channel with hemocompatibility.

Cytocompatibility of modified a-C:H film deposited on complicated polymeric medical apparatus

In this study, in order to biologically evaluate the surface condition of the a-C:H film which was deposited on a complicated polymeric medical apparatus by using rf plasma chemical vapor deposition technique with a special three-dimensional-type electrode, we have investigated the cytocompatibility to the a-C:H film with and without plasma post-treatment. The a-C:H film surface was modified with argon (Ar) and oxygen (O2) plasma post-treatment to change the surface condition of the a-C:H film. The effects of the plasma post-treatment of a-C:H film deposited on a complicated object were estimated by using an Ar-laser Raman microscopy (Raman), a wettability measurement, a x-ray photoelectron spectrometer, and an atomic force microscopy. Additionally, the cellular adhesions of a-C:H film with and without plasma post-treatments were carried out under cell culture by in vitro studies. As results, The surface properties of a-C:H film on a complicated polymeric medical apparatus were controlled by surface modif...

Atomic-layer-deposited Al 2 O 3 -nano-coated segmented polyurethane sheet and its blood compatibility

Alumina(Al₂O₃)-coated segmented polyurethane (SPU) sheet is prepared for the application to bioengineering by using both preparation methods of atomic layer deposition for Al₂O₃ coating and electrospinning for SPU scaffold sheet. Its fine blood compatibility was performed on in-vivo test during long term.

Improvement of surface properties on microfluidic devices by Diamond-Like Carbon coatings

Studies of Diamond-Like Carbon (DLC) coated medical devices have reported possibility for developing blood analysis devices. DLC film is a surface modification technique for biomaterials due to their hemocompatibility, low friction, and reasonableness. To estimate the hemocompatibility of DLC films on microfluidic devices, we have coated DLC film on silicon (Si), and SU-8 by using RF plasma chemical vapor deposition system. Si and SU-8 have been used extensively in microchannel devices[1-3]. The hemocompatibility, chemical composition, structure, wettability, chemical stability, and surface morphology of the samples have been investigated by in-vitro test, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman), a contact angle measurement, immersion test, scanning electron microscopy (SEM). The result indicated that the satisfied hemocompatibility and chemical stability was obtained for the DLC on SU-8. DLC coating is expected as a surface modification technique for the microchannel of microfluidic devices.

Improvement of a-C:H film adhesion for medical instruments using plasma technique

Summary form only given. Amorphous hydrogenated carbon (a-C:H) films provide low friction, extreme hardness, chemically inertness, and good biocompatibility. a-C:H films have been expected a surface modification coating to medical appliances. However, poor adhesion of a-C:H film onto medical instruments which is metallic material limits their application. In order to improve the adhesion, the most typical method is deposition of interlayers between the metallic material surface and a-C:H film. Therefore, we have focused on plasma pre-treatment as a simplification plasma technique where it is possible to deposit strong adhesion a-C:H film to metallic materials which are used in medical instruments like clamps or surgeons knife etc.In this study, a-C:H film was deposited on SUS 304 material without interlayer by only r.f. plasma CVD technique. Before the film deposition, the surface of the metallic materials was modified with H2 plasma and N2 plasma as a pre-treatment to improve the adhesive strength of the film. The pre-treatment was carried out under the following conditions: H2 and N2 gas pressure at 10 Pa with a treatment time of two and four minutes, respectively. After the pre-treatment, the r.f. plasma decomposed CH4 gas (10 Pa), and deposited a-C:H film with a deposition time of 10 minutes. To investigate the effect of the plasma pre-treatments, chemical conditions of the interface were analyzed by XPS. It was observed that the pre-treatment removed hydroxide, and the SUS substrate surface became N-rich. Moreover, the a-C:H film structures and adhesion strength were investigated by Raman spectroscopy, XPS and scratch tests. From these results, the a-C:H film was completely deposited with strong adhesion without interlayer by using the r.f. plasma CVD technique. This technique has the effect of aC:H films adhesion onto metallic materials which are used in medical instruments the same as using an interlayer.

Diamond-like Carbon Film Deposition on an Artificial Heart Blood Pump Using a Flexible Type Electrode with r.f. Plasma CVD Processing

Diamond-like carbon (DLC) film was deposited uniformly on an irregular structure such as a polyurethane artificial heart blood pump using a special 3-dimensional type electrode. Process of applying the DLC film coating is accomplished by inserting a large number of small metallic balls (φ0.8 mm chromium balls). It is then possible to adjust the shape of the electrode in such a way that the DLC film coating can be applied to the irregular surface of the artificial heart. In investigating the availability of the electrode, under helium (He) plasma, the plasma states were measured using double probe analysis. Lateral profiles of the electron temperature were higher in the centre and decreased towards the edges of the electrode. On the other hand, the plasma density profiles were lower in the centre part than at the edges. The electrode kept ion sheath on the artificial heart blood pumps surface at self-bias voltage uniformly. The results were that the DLC film was deposited completely on the artificial heart blood pump at the film thickness of approximately 350 - 380 nm. Additionally the film structure was uniform.