N. Huang

Characteristics and anticoagulation behavior of polyethylene terephthalate modified by C2H2 plasma immersion ion implantation-deposition

Acetylene (C2H2) plasma immersion ion implantation-deposition (PIII-D) is conducted on polyethylene terephthalate (PET) to improve its blood compatibility. The structural and physicochemical properties of the modified surface are characterized by, Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), and static contact angle measurement. Atomic force microscopy discloses that the average roughness (Ra) of film surface decreases from 58.9 nm to 11.4 nm after C2H2 PIII-D treats PET. Attenuated total reflection Fourier transform infrared spectroscopy shows that the specfic adsorption peaks for PET decrease after ion implantation and deposition. Raman spectroscopy indicates that a thin amorphous polymerlike carbon (PLC) film is formed in the PET. The effects of the surface modification on the chemical bonding of C, H, and O are examined by XPS and the results show that the ratio of sp3 C–C to sp2 C=C is 0.25. After C2H2 PIII-D, the polar component γp of surface energy increases from 2.4 mN/m to 12.3 mN/...

Corrosion resistance and antithrombogenic behavior of La and Nd ion implanted stainless steels

Lanthanide ions such as lanthanum (La) and neodymium (Nd) were implanted into 316 stainless steel samples using metal vapor vacuum arc to improve the surface corrosion resistance and antithrombogenic properties. X-ray photoelectron spectroscopy shows that lanthanum and neodymium exist in the +3 oxidation state in the surface layer. The corrosion properties of the implanted and untreated control samples were investigated utilizing electrochemical tests and our results show that La and Nd implantations enhance the surface corrosion resistance. In vitro activated partial thromboplastin time (APTT) tests were used to evaluate the antithrombogenic properties. The APTT time of the implanted samples was observed to be prolonged compared to that of the unimplanted stainless steel control. La and Nd ion implantations can be used to improve the surface corrosion resistance and biomedical properties of 316 stainless steels.

Effect of electrochemical etching current on prepared perforated silicon structures for neutron detectors

Neutron detector based on perforated silicon structures backfilled with neutron converting materials could be operated at a low voltage and improves the detection efficiency of thermal neutron. It is found that the intrinsic detection efficiency of thermal neutron is affected by a lot of factors such as the geometry, size, and depth of the perforation and so on. In this study, the perforated silicon was prepared by electrochemical etching. Effect of etching current on geometry, size, and depth of the perforated silicon structures for neutron detectors was also reported.

Study in the porosity of the TiO 2 films prepared by magnetron sputtering deposition

Nano-crystalline TiO2 films with an anatase phase were deposited by reactive medium frequency magnetron sputtering deposition. Such TiO2 films as anode for the dye-sensitized solar cells should be with a suitable porosity, two methods were used. One is change the tilt angle, i.e., the angle between sputtering beam direction and normal of the substrate, during film deposition. Another is regulating the total pressure during film deposition. Cross-section morphologies of SEM observation and measurements in optical property of the TiO2 films were used to check the porosity of the deposited TiO2 films. The result shows that increasing the tilt angle and increasing the total pressure are both effective to increase the porosity of the TiO2 films. And the results from both checking analyses are very coincident.

Surface Modification of Blood Contacting Biomedical Implants by Plasma Processes

Surface modification is becoming an increasingly popular method to Improve the surface properties of biomedical materials and implants. Among the techniques plasma processes have been attracting attention because of their high effect and low cost. In this paper some application of plasma processes such as plasma modification, plasma polymerization, films synthesis, and plasma based ion implantation etc to modify blood contacting biomaterials and implants are presented. The authors work on the surface modification of artificial heart valves, stents and catheter etc. are provided. The further development of this discipline is discussed.

Behaviors of the different dispersers on the morphology of the porous TiO 2 films

TiO<inf>2</inf> films with nano-particles dispersed by using three different additives such as acetylacetone, Emulsifier OP-10 and polyethylene glycol (PEG) respectively. It is found that the TiO<inf>2</inf> films produced at appropriate amount of Emulsifier OP-10 are no re-aggregation of TiO<inf>2</inf> nano-particles with pores of about 5–15 nm. By adding PEG, the pores of the TiO<inf>2</inf> films could be at about 50 nm to 200 nm. But, by using acetylacetone, aggregations of TiO<inf>2</inf> nano-particles always exist in the TiO<inf>2</inf> films. The related mechanism on the aggregation of nano-particles in the TiO<inf>2</inf> slurries is discussed.

TiN synthesized by filtered arc deposition combined with electron cyclotron resonance

Summary form only given. Titanium nitride thin films possess many good properties including blood compatibility but the properties are strongly dependent on the fabricating process. In this work, TiN films were deposited on 316L substrate using filter arc deposition (FAD) combined with and without electron cyclotron resonance (ECR), and the properties of the two types of films were evaluated. The first group TiN films were deposited using the Ti ion beam produced by a filtered arc source in a nitrogen ambient, whereas the second set of samples were deposited using FAD with an ECR-sustained nitrogen plasma. X-ray diffraction (XRD) was employed to determine the structure, nano-indentation measurements were used to evaluate the hardness, atomic force microscopy (AFM) was utilized to evaluate the surface morphology and pin-on-disk tribology tests were employed to assess the wear resistance.

The effect of amorphous carbon films deposited on polyethylene terephthalate on blood compatibility

Summary form only given. Acetylene (C/sub 2/H/sub 2/) plasma immersion ion implantation and deposition (PIII-D) was performed on polyethylene terephthalate (PET) at different bias voltages from -5 KV to -15 KV. The surface structure of the treated PET is determined by Rutherford backscattering spectrometry (RBS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results show the formation of thin hydrogenated amorphous carbon (a-C:H) films with different structures and chemical bonds on the PET surface. Atomic force microscopy (AFM) shows that the reduced average surface roughness (R/sub a/) decreases from 33.1 nm to 11.4 nm by depositing the amorphous carbon film. The wettability of the films is investigated by contact angle measurement. After C/sub 2/H/sub 2/ PIII-D, the surface energy increases from 43.3 mN/m to 47.1 mN/m and the ratio of polar component /spl gamma//sub p/ to dispersive component /spl gamma//sub d/ increases from 0.06 to 0.35. Platelet adhesion and coagulation factor experiments are conducted to examine the blood compatibility in vitro. Scanning electron microscopy (SEM) and optical microscopy reveal that the amounts of adhered, aggregated and morphologically changed platelets are reduced on all amorphous carbon films. The number of platelet adhered on the amorphous carbon film deposited under -10 KV is reduced by almost 75% compared to the amount of platelets on the untreated film. The thrombin time (TT), prothrombin time (PT) and activated partial thromboplastin time (aPTT) of the modified PET are longer than those of the untreated PET. Our result thus shows that the amorphous carbon film deposited on the PET surface by C/sub 2/H/sub 2/ PIII-D improves platelet adhesion and activation. A possible reason for the good hemocompatibility is that the amorphous carbon coating minimizes its interactions with plasma protein and slightly changes the conformation of adsorbed plasma proteins.

Competitive protein adsorption and platelet adhesion on poly(ethylene terephthalate) surface modified by plasma grafting

Summary form only given, as follows. We report a study involving different molecular weight polyethylene glycol (PEG) chains grafted on poly(ethylene terephthalate) (PET, Dacron) films by plasma surface grafting modification.

Fabrication of duplex coatings on biomedical titanium alloys by plasma nitriding, metal plasma immersion ion implantation, and reactive plasma oxidation

Summary form only given. In order to make titanium oxide films that possess good blood compatibility and can withstand a high contact stress, we are using a novel hybrid plasma fabrication technique combining plasma nitriding and plasma immersion ion implantation (PIII). The titanium alloys are first nitrided in a nitrogen plasma and then the TiO/sub x/ coating is produced by plasma immersion ion implantation utilizing titanium metal plasma and reactive plasma oxidation. The Ti-N layer produced by plasma nitriding can withstand a high contact stress and the titanium oxide coating generated by PIII yields improved biocompatibility and tribological properties. In this paper, the plasma fabrication processes are described. In addition, the tribological properties are assessed by measuring the microhardness and wear resistance, whereas the microstructures and surface characteristics are evaluated by using glancing X-ray diffraction, atomic force microscopy, and transmission electron microscopy. Our results show that titanium alloys with surface duplex PIII-TiO/sub x//Ti-N films have better load bearing capacity than that of PIII-TiO/sub x/ films.