Non-equilibrium Plasmas and Their Applications to Biomaterials and Nanofabrication.pdf

1、In this thesis the study of non-equilibrium plasmas generated under low and atmospheric pressure conditions along with their applications to biomaterials and nanofabrication has been carried out. Non-equilibrium low pres

2、sure plasmas have been generated by using 150 W power from RF magnetron sputtering at working pressures of 3 and 5 Pa，with no substrate bias，and at 3 Pa with a substrate bias of -50 V. These plasmas have been utilized fo

3、r depositing the nanostructured TiO2 thin films on silicon substrates. For characterizing these nanostructured TiO2 films，x-ray diffraction for surface structure，atomic force microscopy for surface roughness and for wett

4、ability analysis，the water contact angle measurements have been used. X-ray diffraction (XRD) analysis divulges that TiO2 films fabricated on unbiased as well as biased substrates are all amorphous. Surface properties，fo

5、r instance，surface roughness and wettability of TiO2 films developed in a plasma environment，under biased and unbiased substrate conditions and the working pressure have also been described. Primary rat osteoblasts (MC3T

6、3-E1) cells have been cultured on nanostructured TiO2 films deposited at different working pressures and substrate bias conditions. The impacts of surface roughness and hydrophilicity on the cell density and cell spreadi

7、ng of nanostructured TiO2 films have also been described.
　　Non-equilibrium atmospheric pressure microplasmas produced by a DC source from the mixtures of He-N2 and Ar-N2 gases have been elucidated by investigating th

8、e rotational and vibrational temperatures of molecular nitrogen under varying discharge conditions. At a varying gap distance of 1-3 mm (with a step of 1 mm) from the exit of the capillary to the water surface，the averag

9、e rotational temperature of N2 has been observed to be increasing from 983-1250 K while the analogous vibrational temperature of N2 has been found to be reducing from 4875-3099 K. Subsequently，the average vibrational to

10、rotational temperature ratio of N2 is reduced from 4.96-2.48. Extending the capillary inner diameter from 100-200 mm，the average rotational temperature of N2 is raised from 891-1090 K whereas the average vibrational temp

11、erature of N2 is declined from 4662-3646 K and hence，the ratio of vibrational to rotational temperature of N2 is decreased from 5.23-3.34. Furthermore，with the addition of more nitrogen into the flow，i.e.，by enhancing th

12、e flow rate of N2 from 0-15 sccm (with an interval of 5 sccm)，the average rotational temperature of N2 is increased from about 942-1404 K，whereas the corresponding vibrational temperature of N2 is reduced from 5011-3254

13、K. As a result，the corresponding ratios of vibrational to rotational temperature of N2 have been dropped from 5.3-2.3. With regard to the Ar-N2 microplasma，by widening the gap distance from 1-3 mm，the average rotational

14、temperature of N2 progresses from 1743-1808 K while the corresponding vibrational temperature decreases from 2748-2528 K. This variation in the rotational as well as vibrational temperatures with the gap distance re

15、sults in the decrease of the corresponding values of vibrational to rotational temperature ratios of N2，which are changing from 1.57-1.39. With the increase of the diameter of capillaries from 100-300 μm，the average rota

16、tional temperature of N2 increases from about 1817-1821 K，whereas the average vibrational temperature of N2 decreases from 2677-2394 K. Owing to this reason，the ratio of the average values of vibrational to rotational te

17、mperatures of N2 falls from 1.47-1.31. The results reveal that the surface area to volume ratio of microplasma and also the gas conductivities have a substantial effect on the non-equilibrium nature of He-N2 and Ar-N2 at

18、mospheric pressure microplasmas.
　　Moreover the colloidal Ag nanoparticles have also been synthesized utilizing atmospheric pressure microplasma interfaced with AgNO3 aqueous solution. The pH value，solution conductivi