Medical Device Link.

Product Update

Filters and Filtration Media:

Suppliers Diversify to Satisfy Market Demand

Lori Bryan

In response to the increasing sophistication of medical devices, reductions in health-care budgets, and related challenges, suppliers of filters and filtration materials are making adjustments.

As manufacturers demand more flexibility and greater performance from the filters and filtration materials they build into their devices, suppliers are scrambling to develop new equipment, implement new services, and offer product enhancements that set them apart in a competitive market. Meanwhile, health-care budget reductions that force manufacturers to maintain a low unit cost provide a very real obstacle for filtration suppliers to overcome. For each supplier, the solutions are different.

"Because medical devices in general have become a lot more sophisticated, our customers have become more sophisticated about what a membrane can do for them," says Donna Gasper of Millipore Corp. (St.-Quentin Yvelines, France). "Customers come to us very well prepared to define what they need in terms of a membrane, and that means we have to be equally well prepared and have a good variety of membranes to meet their needs." From a range of media for use with liquids and gases to recent innovations in membrane design for diagnostic assay kits, Millipore is one of the many OEM suppliers attempting to keep up with an expanding market. "The range of needs today," explains Gasper, "goes anywhere from vent membranes on a packaging device to very novel membranes that are used in implants."

With medical devices becoming more intricate and requirements for filtration getting stricter, some suppliers are compelled to expand their manufacturing capabilities. "Because requirements are tougher than they were," explains Deirdre Thom of Whatman International (Maidstone, Kent, UK), "we are putting in new equipment to enable us to meet those challenges." Such new equipment includes machinery with coating capabilities or machines that can bind additives to impart, for example, hydrophobic properties to membranes. "At Whatman, we have improved our technology in order to give better results, but also more reproducible results," adds Thom. "Customers are perhaps more concerned than before about the reproducibility of filtration materials. From an economic standpoint, customers want media that handle well in production but with low losses, so breakages or product failures do not occur during the process."

While device manufacturers are seeking filtration products that act reliably during production, they are also concerned with cost containment. Shrinking health-care budgets are making it extremely important for manufacturers to choose the right filtration supplier at the outset of a project. "Very fancy configurations are often specified for our filter media, which can make the unit cost extremely high," says Franco Mondini of SaatiTech S.p.A. (Veniano, CO, Italy). "When manufacturers consult us at the beginning of projects, we are often able to recommend slight modifications that can enable more standard manufacturing, hence a lower unit cost."

Device manufacturers looking for filters or filtration media might begin by contacting one of the suppliers detailed in this section. Each is dedicated to the improvement of filters and related products for the medical marketplace.

Precision woven mesh offers accurate and predictable filtration properties, high flow rates, and batch-to-batch consistency. Saatifil filtration media, manufactured by SaatiTech S.p.A. (Veniano, CO, Italy), can be used in blood filters, cardiological devices, oxygenators, and diagnostic kits, for particle classification, and as backing material to support finer, more delicate media. Designed to stop or trap defined particle sizes, the calibrated meshes are composed of monofilament fibres and can be easily custom fabricated. This ability to fabricate filtration products to customer specifications is a core activity, explains sales manager Franco Mondini. "For the medical industry, I would say that 90% of the material we deliver is custom fabricated in our Class 10,000 cleanroom."

Committed to improving the performance of filtration media, the ISO 9001­certified company recently introduced plasma-treated fabrics. "Very often the overall surface of a filtration device is underused," notes Mondini. "Thanks to plasma treatment, we can improve the wettability of the filter media and thereby improve the filtration capacity of both the media and the filter itself." Saatifil plasma-processed products offer the physical attributes of conventional fabrics, while leaving the undersurface properties completely unaffected. "Plasma treating is performed in a vacuum chamber into which gas is entered; plasma charges develop within the vacuum, thus activating the surface of the mesh," says Mondini. Enhanced wettability of the treated surface enables a faster and more uniform spread and penetration of the liquids. Because the treatment process modifies surface tension, adhesion between the treated fabric and plastic or metal parts is also improved, providing device designers with increased freedom for innovation.

Gelman Sciences (Northampton, UK), a developer of filtration and separation products with 40 years' experience in OEM partnerships, recently merged with Pall Corp., an international manufacturer of filtration and separation solutions. "As part of the Pall family," says Tom Ramsey, marketing manager for OEM health-care devices, "Gelman now has the broadest array of filtration media and housings available in the industry. Our products range from depth media to liquid filtration membranes, and to a number of proprietary vent media as well."

A new filtration device specifically engineered for sterile-gas delivery in health-care applications is the first product to have been launched since the merger. Optimized for high flow rate and low pressure drop, Pall Gelman's Intervene gas filter (pictured) provides complete utilization of the filter membrane's surface while maintaining a hydrophobic barrier. The unit is well suited for insufflation, blood oxygenation, vacuum protection, and oxygen concentration applications. The filter's rectangular, low-profile housing design incorporates an effective filtration area of 18.5 cm² of either PTFE membrane or a proprietary hydrophobic glass media. "We were already putting high-quality media into our medical devices," notes Ramsey, "but now we have some very distinct Pall products that we can incorporate into our existing devices to better serve our customers."

Specializing in the development of small custom filtration units for reproducible low-volume applications, Millipore S.A. (St.-Quentin Yvelines, France) supplies its products to original equipment manufacturers for incorporation into their own equipment.

"One of our premiere products," says Millipore's Donna Gasper, "is an intravenous filter called IV Express." Composed of a material that is compatible with specialty pharmaceuticals, IV Express is a vented 0.22-µm filter that can be used for 96 hours for the retention of particulates and microorganisms. "This filter would be used on an in-line IV," says Gasper. "Typically it is used with antibiotic solutions or in an application where a nurse or IV professional is concerned about particulates or multiple admixtures being aligned. The user wants to ensure that sterile product is received by the patient."

The company's range of liquid filtration membranes also includes a vented in-line device for pump-driven filtration of total nutrient admixture (TNA) with lipids, and a low-hold up-volume, small-diameter, hydrophobic vent membrane for pediatric and ambulatory outpatient IV therapy.

In addition to its liquid- and gas-filtration products, the company supplies Quick Release media for diagnostic assay kits.

"Our focus at Whatman really is on heat and moisture exchangers, breathing circuit filters, and more recently, vent materials," says Deirdre Thom of Whatman International Ltd. (Maidstone, Kent, UK). "Very often, OEM customers have special requirements for certain thicknesses, flow rates, and pore sizes and we will try to modify or adapt a product--or design a completely new product--to suit those requirements."

New to the company's product line, a hydrophobic/oleophobic glass-fibre filter has been designed specifically for original equipment manufacturers of snap-fit IV vents. The product features high bacteriological efficiency with a low pressure drop. Because of its high water repellency and oleophobic properties, the filter is well suited for both water-based and fat- and lipid-based IV-vent applications. "We have designed the filter to have a particularly high airflow rate combined with bacterial retention," explains Thom.

The company's capabilities include the treatment of papers to impart hydrophobicity, strength, and/or oleophobicity; the development of microporous, track-etched, and hollow-fibre membranes; and the development and production of medical device filters.

"We have a standard range of filtration products from 0.1 to 500 µm," says Massimo Scagliarini of GVS S.r.l. (Zola Predosa, BO, Italy). "One of the most important things we can do for our clients is insert mould filter materials, membranes, or any other kind of tissue. With our devices you have all the advantages of a screen, as well as a surrounding solid body composed of any kind of plastic." The company offers screens, filters, and air vents with pore sizes from 0.2 to 270 µm for blood, parenteral, and enteral solutions. A complete range of services from product design and prototype moulding to high-volume injection moulding are conducted according to good manufacturing practices and ISO 9001 standards. A team of engineers and technicians can develop prototype filters with the technical characteristics and design features to accommodate specific requirements. "We have not only insert moulding technology," explains Scagliarini, "but we also have ultrasonic-, RF-, and heat-sealing expertise, and related friction- or mechanical-assembly capabilities."