Porous Metal for Medical Applications

Porous metal has been widely used in advanced technology applications, and has a number of uses in the design and manufacture of medical devices. Porous metal is ideal for providing highly dependable filtration performance, controlling fluid flow, as well as diffusion and metering of fluids and drugs. It can be manufactured in many different shapes, sizes, and metallurgies. Rigid and robust, porous metal affords designers novel and unique properties that are often the solution for challenging medical and life sciences applications.

Porous metal is available in materials known to be biocompatible including stainless steel and titanium. Mott Corp. routinely supplies components in 316L, 304, 310, and 400 series stainless steels, unalloyed titanium (ASTM 1580-07), as well as a number of other common and exotic metallurgies including zirconium, molybdenum, niobium, and precious metals including gold, silver, palladium, and others.

The company also offers an all-metal membrane that meets ASTM F838-05 for bacterial retention. Mott sterilizing grade membranes are supplied in 316L stainless steel or titanium. This technology is available in a variety of form factors from very small discs or tubes for drug delivery applications to larger 10-inch cartridges for biotechnology and pharmaceutical processing. This proprietary membrane is able to withstand aggressive chemistries and drug cocktails without the potential for leaching, outgassing, or other adverse reactions.

Mott porous metal components are available with filtration ratings from sub-micron (0.1mum) to coarser filtration ratings, including 0.2mum sterilizing grade media. Mott also produces specialized gas filters that can achieve 99.9999999 percent efficiency for particles as small as .003mum.

Porous metal flow restrictors have been used for decades to precisely meter the flow of critical gases in medical and non-medical applications. Mott has sophisticated modeling and calibration capability that enables us to calibrate the flow of a gas to accuracies of plus or minus 2 percent at a given inlet and outlet condition. Porous metal can also be designed to permit the controlled diffusion of liquids or gases, which is desirable for certain drug delivery and fluid metering applications.

Mott Corp. has also developed a proprietary nanotechnology, which utilizes nano-powders in metals including stainless steel and titanium to produce ultra-fine, all-metal, filtration membranes.

Although Mott's processes can often produce net shaped components, porous metal can be machined using modified techniques such as TWEDM, laser, or other methods. Mott has developed an array of machining processes that prevents the contamination or occlusion of the porous structure.

Joining porous metal to mating components for medical and life sciences applications can be accomplished in a variety of ways. Porous metal can be welded (laser, ebeam, or TIG) to mating hardware, sinter-bonded, or press fit. Over-molding using PEEK and other polymers is also a possibility depending on the component configuration and can afford exceptional strength as there is some "knitting" of the polymer to the mating porous component.

— Thomas N. Fahey is vice president of sales and marketing for Mott Corp.

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