**5. Diamond, DLC, DLN for biomedical applications**

Diamond, Diamond-like Carbon(DLC) and Diamond-like Nanocomposite (DLN) thin films have high hardness, high wear resistance, high corrosion resistance and chemical inertness, low coefficient of friction, very low surface roughness, very good infrared light transparency. All of these properties are ideal for any material as a biocompatible materials. As a biocompatible material it's can be applicable for orthopedic, cardiovascular, contact lenses, catheter, prosthetic replacement etc. The biomaterial can be determine by the

Diamond, DLC and DLN are potential materials for RF-MEMS applications. The RF-MEMS switches have potential for RF communications because of their high isolation and low power consumption. The RF switches, which usually based on electrostatic actuators. This RF switch can be used as diamond switch [69-73]. The boron doped diamond can be considered as semiconductor with wideband gap for fabricate the electronic device. Diamond materials are ideal candidate for RF power electronics where the important factors are like high speed, high power density, effective thermal management and passive matching components with low loss at microwave frequencies. So surface area is needed for passive component, active device, waveguide circuits and heat dissipation. The substrate needs for monolithic integrated RF power electronics in gigahertz frequency range. Leaky diamond films used in RF capacitive MEMS switches with low RF loss up to 65 GHz have excellent electronic properties of the diamond layers [74]. Leaky diamond mode can trapped the charges and eliminating the charge injection and increases the switches reliability. Fig. 17 shows the single anchored cantilever in coplanar waveguide for ON and OFF switching of microwave signals. Where the centre line is bridge by the switch need to content the contact in series. In the first figure (left side) the switch was staying perpendicular way on to the waveguide. This switching is quite low because of air damping [75-76]. The very large

 Fig. 17. Electrostatic actuators with coplanar RF waveguide. (a)The cantilever actuator closes a gap in a signal line from the side (left fig.) (b) The signal line is part of the beam itself

In right side of the figure where cantilever is the part of coplanar waveguide pattern. The RF

Diamond, Diamond-like Carbon(DLC) and Diamond-like Nanocomposite (DLN) thin films have high hardness, high wear resistance, high corrosion resistance and chemical inertness, low coefficient of friction, very low surface roughness, very good infrared light transparency. All of these properties are ideal for any material as a biocompatible materials. As a biocompatible material it's can be applicable for orthopedic, cardiovascular, contact lenses, catheter, prosthetic replacement etc. The biomaterial can be determine by the

(right fig.), ([52], permission to reprint obtained from John Wiley & Sons, Ltd.).

line of ground plane act as a electrode of the parallel plate actuator [63].

**5. Diamond, DLC, DLN for biomedical applications** 

**4.4 Diamond films for RF-MEMS application** 

surface area can provide the high switching speed.

reaction of materials in biological environment [77]. The biomaterial, to apply our human body, should be chemically and biologically inert to the surrounding cells and our body fluids. In these diamond structure, they have two phase. One is sp2 hybridized carbon atoms in hexagonal ring formed by graphite structure. It is the disorder of bond angle, resulting due to disappearance of the long range translation symmetry of polycrystalline graphite and amorphous carbon lms. On the other hand, the C-C stretching vibration of sp3 hybridized carbon atoms in both the rings and chains. Which indicate the disorder diamond phase. In the films if percentage of sp3 carbon is much more, then films should be good mechanical properties. The diamond and DLC films have good orthopedic applications. In our human body, the hip and knee joint are subjected the friction and wear, as a result which forms the polyethylene debris at a rate of 1010 particulates per year [78]. These phagocytosed particulates forms osteolysis, granulomatosis lesions and bone resorptions which causes the aseptic loosening of the prosthesis and pain. In last couple of years researchers are trying to apply this diamond, DLC, and DLN films coating for knee and hip replacement to decrease the wear rate. The DLC with Co-Cr alloy can reduce the significant wear rates of both sliding surfaces [79]. The amorphous diamond coatings which can improve the wear and corrosion resistance by a factor of millions compare to conventional materials [80].

The biocompatibility of DLC and DLN films have determined by the interaction of cells with DLC and DLN surface. The biocompatibility of the films can be performed by characterization of cytotsicity, protein adsorption or microphase adhesion property of the films. In the study of cell adhesion on different substrates, the increase of number of cell adhesion onto the substrate indicates that the cell have greater chance to adhere onto the substrate.

Fig. 18 shows fluoresce microscopic image of the different cells growth on different surface and Fig. 19 shows the corresponding scanning electron microscope (SEM) image of cell growth on different surface. From both of these figures, the PC 12 cells growing characteristic in neuronal process. This process interact with platinum and ultrananocrystalline diamond (UNCD) diamond surface. In silicon surface the cells formation as like closed packed islands formation.

The PC 12 cells growth on the platinum and UNCD surface exhibiting distinctive outgrowth of axons and dendrites on the surface. The growth of the PC 12 cells on the surfaces are quite less compare to HeLa cells. The figure shows that, PC 12 cells growth on UNCD surface most suitably compared to other surfaces. The area cover by PC 12 cells is almost highest in UNCD surface compared to another material surface. Which indicates that the UNCD surface have much more biocompatibility compared to other surfaces. Finally the maximum cells attachment, cell spreading and nuclear area coverage of the cell in UNCD surface is much more compered to other surfaces [81].

In medical application DLC can coat over the stent. Where a stent is a metal tube that inserted permanently into an artery. Stent helps to open an artery for blood circulation through it. Recently, the use of cardiovascular implantation of stent increasing in the world. The side effect of the artery stent lies in its release of metal ions and thrombogenecity. So it is desirable in such a material that can prevent the release of metal ions and that materials also will be hemocompatible, very high corrosion resistance and long lasting in human blood environment [82]. DLC coat stent are suitable for this pour pose. Some of the companies are made the DLC coted stent for medical purpose use. Fig. 20 shows the multilayer nanocomposite coated with DLC as an intermediate layer under the name biodiamond stent [83].

Diamond, Diamond-Like Carbon (DLC)

**6. Conclusions** 

medical purpose needs more *vivo* and *vitro* experiments.

and Diamond-Like Nanocomposite (DLN) Thin Films for MEMS Applications 477

The variety of studied of biocompatibility of Diamond, DLC, DLN films shows that, the materials is potentially applicable in biomedical purpose. The characterization of these materials and determination of its surface properties are necessary to correlate the different in *vitro* and in *vivo* results. The diamond coating, due to use of its long term commercially in

Fig. 20. A bio-diamond stent ([83], permission to reprint obtained from Elsevier).

In this chapter, we have described mainly the characterization technique of diamond, Diamond-Like Carbon (DLC) and Diamond-Like Nanocomposite (DLN) thin films and their application in MEMS devices. From HRTEM, FTIR, Raman Spectroscopy analysis, we conclude that the hydrocarbon groups are bonded with two interpenetrating networks (a-C:H and a-Si:O) of DLN films. And also from HRTEM analysis, DLN films contain Si3N4, SiC and SiOx nanoparticles within amorphous matrix, which help to reduce the compressive stress of the films. Raman Spectroscopy shows that the DLN films should have higher concentrations of sp3 carbon than the conventional DLC films. High sp3 contents influence the mechanical properties of the films as a result, hardness and elastic modulus will increase due to higher sp3 content. From our all characterize technique we can conclude that diamond, Diamond-Like Carbon (DLC) and Diamond-Like Nanocomposite (DLN) thin films have very high hardness, high modulus of elasticity, high tensile strength, high thermal conductivity, very less surface roughness, low coefficient of friction low thermal expansion and good wear properties. All of these properties are unique material properties for application in MEMS/NEMS device. The excellent tribological properties of the diamond films are very useful to improve the stiction, friction and wear resistance of MEMS/NEMS based microcomponent. The chemical inertness and high temperature withstanding capability of this films can be useful for biosensor and microfluidic devices. In our microfabrocation part we discussed different thin film deposition technique with different pattern like lift-off, electroplating, thin film etching and substrate etching technique. Finally we have discussed the diamond film patterning and their application in

Fig. 18. Florescence microscopic image of cell attachment in platinum (first column), silicon (second column) and UNCD (third column) surfaces, ([81], permission to reprint obtained from Springer).

Fig. 19. Scanning Electron Microscope image of cell attachment on platinum (first column), Silicon (second column) and UNCD (third column) surfaces, ([81], permission to reprint obtained from Springer).

The variety of studied of biocompatibility of Diamond, DLC, DLN films shows that, the materials is potentially applicable in biomedical purpose. The characterization of these materials and determination of its surface properties are necessary to correlate the different in *vitro* and in *vivo* results. The diamond coating, due to use of its long term commercially in medical purpose needs more *vivo* and *vitro* experiments.

Fig. 20. A bio-diamond stent ([83], permission to reprint obtained from Elsevier).
