Tuesday, February 5, 2008

Ultrananocrystalline Diamond Thin Films Applications

Currently, three specific applications enabled by UNCD are under development. The first is wear-resistant, low friction coatings for mechanical components, including mechanical seals for fluid pumps. UNCD films as thin as 1 micron can change the performance of state-of-the-art silicon carbide seals and dramatically reduce the friction and wear at the seal face, increasing the lifetime of the pump for applications in chemical refineries, ethanol production, petroleum exploration and pharmaceutical processing. Since mechanical seals are found in most fluid pumps, it is estimated that reducing friction could save trillions of BTUs of energy annually. The same UNCD films can be used as a tribological coating in other industrial settings.

The second important application area for UNCD is as a structural material in MEMS, including AFM probes, RF MEMS filters, oscillators and switches. These applications leverage the greatest number of diamond's superlative bulk and surface properties, since the performance and long-term stability of MEMS devices depend on the chemical stability of the exposed surface. For RF MEMS, such as resonators, UNCD acts like a tuning fork, vibrating at a set frequency that cannot vary with time, temperature or other environmental conditions. UNCD, like natural diamond, has a chemically inert, hydrophobic, low stiction surface that allows devices to function without the need for expensive die-level hermetic packaging.
By leveraging the high acoustic velocity and surface stability of UNCD, devices for X- and Ka-band (2-20 GHz) wireless communication systems can be developed that allow for smaller, more energy efficient and less expensive RF front-ends for radios in mobile phones, base stations and military applications. UNCD-based atomic force microscopy (AFM) probes,· which are simple forms of MEMS devices, entered the market in late 2007.
The third application area includes bio-implants and sensors, with the goal of creating functional devices that integrate both passive and active UNCD elements combining diamond's bio-inertness and bio-compatibility with the ability to covalently immobilize biomolecules on the surface (see Figure 5). Active electrochemical-based sensors using conductive UNCD thin films can enable implantable devices that conduct real-time monitoring of blood chemistry (e.g., glucose, alcohol, cholesterol). This advancement will enable a new generation of biosensors that work in real-time in devices that are both compact and light enough to wear as jewelry. Imagine the life-changing and potential life-saving impact of wearing a "watch" that automatically monitors and administers insulin continuously via a wireless link to an implanted UNCD-based biosensor. Such biomedical applications will take additional effort to overcome many fundamental technical challenges. However, diamond has finally come of age in a platform technology suitable for broad integration into numerous applications, and UNCD is being developed into commercially available products to turn the idea of diamond for use as an engineering material into a reality. See previous post for more on UNCD.