Humberto Gomez

Study of the Adhesion and Biocompatibility of Nanocrystalline Diamond (NCD) Films on 3C-SiC Substrates

The unique material characteristics of silicon carbide (SiC) and nanocrystalline diamond (NCD) present solutions to many problems in conventional MEMS applications and especially for biologically compatible devices. Both materials have a wide bandgap along with excellent optical, thermal and mechanical properties. Initial experiments were performed for NCD films grown on 3C-SiC using a microwave plasma chemical vapor deposition (MPCVD) reactor. It was observed from the atomic force microscopy (AFM) analysis that the NCD films on 3C-SiC possess a more uniform grain structure, with sizes ranging from approximately 5 – 10 nm, whereas on the Si surface, the NCD has large, non-unioform inclusions of grains ≈1 μm in size. The in vitro biocompatibility performance of NCD/3C-SiC was measured utilizing 2 immortalized neural cell lines: H4 human neuroglioma (ATCC #HTB-148) and PC12 rat pheochromocytoma (ATCC #CRL-1721). MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to measure viability of the cells for 96 hours and live/ fixed cell. AFM was performed to determine the general cell morphology. The H4 cell line shows a good biocompatibility level with hydrogen treated NCD as compared with the cell treated polystyrene control well, while the PC12 cells show decreased viability on the NCD surfaces.

Life Cycle Analysis of Diamond Coating of Machining Tools

To begin to identify the environmental impacts of coated cutting tools, lathe cutting inserts were coated with a thin film of diamond. To assess the environmental impacts of the coating process on the life cycle analysis (LCA) of a cutting tool, all chemical processes, including pre- and post-deposition processes and energy expenditures were monitored and recorded for entry into SimaPro LCA software. For the conditions evaluated, the primary deposition process was found to have a carbon footprint of 6.6 equivalent kilograms of carbon dioxide, and the etching process was found to be responsible for 96.8 equivalent grams of carbon dioxide.Copyright

Chapter 12 – Nanocrystalline Diamond for RF-MEMS Applications

This article presents thermally actuated nanocrystalline diamond bridges for microwave and high power RF applications. The growth process along with the seeding technique for generating the diamond films has been discussed. RF applications which include mechanical resonators and electrostatically actuated switches demonstrated by other researchers is presented. The diamond bridges are integrated in CPW and microstrip topologies to operate as a switch and tunable inductor. In addition to small signal measurements, high power measurements in the range of 24-47 dBm are performed for the switches integrated in the microstrip topology.

Structural-property relationship of nanocrystalline diamond films and its applications

The importance and interest of diamond synthesis is based on the unique properties that can be achieved using this material in several applications. Micro and nanocrystalline diamond (NCD) films were deposited by microwave plasma enhanced chemical vapour deposition (MPECVD). The structural properties were characterised by SEM, TEM, Raman spectroscopy and NEXAFS. Nitrogen incorporated NCD films were grown to produce electrically conductive films. Ohmic contacts to n-NCD films were formed by Ti/Au or Cr/Au metal electrodes. NCD based vibrating MEMS cantilever devices have been fabricated.