Originally Published EMDM January/February 2005
Product Update
Focus on suppliers of filters |
Mott Corp.
All-metal filters and porous-metal products are suitable for medical applications requiring exact flow specifications, biocompatibility, and resistance to high temperatures and aggressive chemicals. Mott Corp. (Farmington, CT, USA) has developed porous-metal medical devices such as biocompatible porous-titanium filters, implantable products, and metal filters for use in test stands.
Exacting flows are essential to the medical device industry in applications such as drug- delivery systems and anaesthesia flow control, says marketing manager Patty Dillon. “Our porous metal prevents spikes in these flows, which would be dangerous to the patient,” adds Dillon.
Mott’s product line includes porous-metal shapes, air bearings and vacuum devices, flow restrictors, and gas and liquid spargers. It also includes a range of filtration products, such as precision filter elements, sampling filters, polymer filters, high-purity filters, and large industrial and instrumentation filters. The company specializes in stainless steel and corrosion-resistant alloys, and avoids low-melting-point materials such as bronze and brass.
Vacco Industries
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Photoetched perforated metal screens use conical through holes to optimize fluid flow rates. Vacco Industries (South El Monte, CA, USA) uses a photochemical etching process to create custom-shaped holes as small as 70 µm. Manufactured mostly from stainless- steel and titanium materials, the screens can vary in thickness from 0.0002 to 0.125 in.
The screens were developed to solve problems involving flow rate and particle entrapment, says product development manager Jeff Bjork. Customer specifications for the through holes, as well as open-area percentages, are used to design metal screens that direct materials through the funnel-shaped through holes quickly and effectively for maximal flow rates. The photochemical etching process creates a burr-free surface, making it easy to clean and back-flush the filter.
Product applications include pressure testing, liquid analysis, and screening of medical waste products. The screens can also be used as a sieve to sort particulate materials.
Filtrona Fibertec
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A fibrous media with DNA-collection capabilities is bonded into geometric shapes to fit into pipette tips, spin columns, and microtiter wells. The DNA capture media from Filtrona Fibertec (Colonial Heights, VA, USA) uses a dual approach to DNA isolation: the fibre has a natural affinity with DNA; the bonded-fibre structure functions as a size-
exclusion filter.
“The media is designed to allow solid contaminants to flow through the fibre structure rather than to collect this unwanted debris,” states Bennett C. Ward, vice president of R&D. “This feature is particularly interesting for genetic-based diagnostic assays, and allows much higher DNA extraction efficiency than competitive technologies.”
The company’s work in creating fibres with reactive characteristics yielded materials with amine and carboxyl functionality. As a result, Filtrona Fibertec opted to create two types of DNA capture media with reactive sites, one with high-density amine and the other with high-density carboxyl.
Metoxit AG
Ceramic filters for the treatment of liquids or gases can be used in a variety of chemical and pharmaceutical processes. Available from Metoxit AG (Thayngen, Switzerland), the filters are designed according to customer specifications. Typical pore sizes can be adjusted between 10 and 70 µm, and outside dimensions may go up to 300 ¥ 300 ¥ 60 mm.
Ceramics are generally very resistant to changes in temperature, mechanical load, and harsh chemicals, making them a viable alternative to polymers, according to Martin Schmidt, director of marketing and sales. The company’s ceramic filters were developed in response to the pharmaceutical industry’s need for filters that withstand repeated autoclaving and aggressive cleaning procedures.
Tech-Etch Inc.
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Filtering screens are manufactured by Tech-Etch Inc. (Plymouth, MA, USA) using photoetching technology. Unlike stamping, photoetching yields a burr-free product, resulting in clean, efficient screens. Possible uses for the screens include applications that need frequent cleaning or devices where there is mechanical contact. The filter screens feature high-tolerance hole sizes and fixed openings. Designers can request tapered holes to aid in liquid filtration and backflow cleaning. Hole sizes start at 0.003 in.
The screens are primarily produced from stainless steel; other materials are available. The company offers a standard line of screens with holes in a 60° or 90° pattern available with a maximum guaranteed perforated area of 18 ¥ 21 in. Other sizes and custom shapes are also offered.
Sefar Inc.
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Precision-woven fabrics are suitable for infusion and transfusion sets, arterial filters, oxygenators, and venous and cardiological reservoirs. The Medifab product line from Sefar Inc. (Ruschlikon, Switzerland) “was developed specifically to meet the high cleanliness requirements of the healthcare industry,” says healthcare product manager Helen Vogt.
Consisting of raw materials that comply with US FDA regulations, Medifab exhibits low pyrogen levels and has no haemolytic effects. All Medifab filter media can be surface treated and custom fabricated to meet the exact needs of medical device OEMs.
The company is working on filters and fabrics that incorporate textile sensors to monitor bodily functions, states Vogt. It is also developing permanent hydrophilic and hydrophobic coatings, as well as filters made from PEEK and other high-performance materials.
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