A simple dielectric barrier discharge（DBD） jet array was designed with a liquid electrode and helium gas.The characteristics of the jet array discharge and the preliminary polymerization with acrylic acid（AA） monomer were presented.The plasma reactor can produce a cold jet array with a gas temperature lower than 315 K,using an applied discharge power between 6 W and 30 W（V dis × I dis）.A silk fibroin film（SFF） was modified using the jet array and AA monomer,and the treated SFF samples were characterized by atomic force microscopy（AFM）,scanning electron microscopy（SEM）,Fourier transform infrared spectroscopy（FTIR）,and contact angle（CA）.The deposition rate of the poly acrylic acid（PAA） was able to reach 300 nm/min,and the surface roughness and energy increased with the AA flow rate.The FTIR results indicate that the modified SFF had more carboxyl groups（-COOH） than the original SFF.This latter characteristic allowed the modified SFF to immobilize more quantities of antimicrobial peptide（AP,LL-37） which inhibited the Escherichia coli（E.Coli） effectively.
Polytetrafluoroethylene films are treated by room temperature helium atmospheric pressure plasma plumes, which are generated with a home-made single liquid electrode plasma device. After plasma treatment, the water contact angle of polytetrafiuoroethylene fihn drops from 114° to 46° and the surface free energy increases from 22.0 mJ/m2 to 59.1 mJ/m2. The optical emission spectrum indicates that there are reactive species such as O2＋, O and He in the plasma plume. After plasma treatment, a highly crosslinking structure is formed on the fihn surface and the oxygen element is incorporated into the film surface in the forms of C O-C-, -C=O, and O C=O groups. Over a period of 10 days, the contact angle of the treated film is recovered by only about 10°, which indicates that the plasma surface modification is stable with time.
The microarc oxidation（MAO） coatings produced at different current frequencies on AZ91 D magnesium alloys were studied systematically. The morphologies, thickness, corrosion performances, and tribological properties of the coatings were investigated by the scanning electron microscopy, the electrochemical measurement system, and MS-T3000 friction test rig, respectively. The results show that the structure of the coatings becomes denser, and thickness becomes thinner with the increase of the current frequency. It is also found that the corrosion resistance of the coatings produced at higher frequency is improved greatly and the difference of the corrosion current density becomes small with increasing current frequency, which is similar to that of the coating thickness. The tribological test shows that the friction coefficient decreases with increasing the current frequency and the wear resistance of the coatings is influenced by both the thickness and structures. All these results were explained by analyzing the growing process of the MAO coating.
Nano-Ag incorporated hydroxyapatite/titania （HA/TiO2） coatings were deposited on Ti6A14V substrates by the plasma electrolytic oxidation process. Compared with the substrate, the deposited coatings display attractive mechani- cal and biomedical properties. First, the coatings have stronger wear resistance and corrosion resistance. Second, they show a strong antibacterial ability. The mean vitality of the P. gingivalis on the coating surfaces is reduced to about 21%. Third, the coatings have good biocompatibility. The mean viability of the fibroblast cells on the coating surface is increased to about 130%. With these attractive properties, Ag incorporated HA/TiO2 coatings may be useful in the biomedical field.
