Technology news
Company Develops Antimicrobial Composites
A family of composite materials developed by Implemed (Watertown, MA, USA) destroy microbes by electrochemically releasing silver ions from the material into the immediate surrounding environment. The company believes that Oligon, which has been shown to be effective against gram negative and gram positive bacteria, fungi, and antibiotic-resistant strains, can contribute to a dramatic reduction in hospital-acquired infections.
Oligon can be applied as a coating or made integral to the base material, stresses John Vandegrift, director of worldwide sales at Implemed. The release of silver ions from the material is produced by means of oligodynamic iontophoresis, which achieves more sustained ion release than technologies that rely on the solubility of silver to achieve antimicrobial effectiveness. According to the company, tests have shown that catheter tubing with a silver coating allowed microorganisms to grow within the first four hours whereas Oligon polymer tubing remained bactericidal. "By using the silver ion as the antimicrobial agent, Oligon offers the advantages of being long lasting, having a broad spectrum of effectivity including against drug-resistant strains such as MRSA and VRE, and the capability of releasing the silver ions from all device surfaces including the lumen," says Vandegrift.
The technology has been developed with various base polymers, but it can also be applied to ceramics and fibres. Products suitable for Oligon include catheters, wound dressings, vascular grafts, cannulae, periodontal products, introducer sheaths, orthopaedic products, and contact lens cases.
In addition to developing partnerships and licensing opportunities, the company markets a line of peripherally inserted central venous catheters made with Oligon. The catheters, which recently received the CE mark, are distributed in Europe through Vygon S.A. (Ecouen, France), a distributor of vascular access products.
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Injection Moulding Machine for Microparts Offers A Short Cycle Time
To overcome many of the problems associated with moulding parts that weigh less than 0.1 g, Battenfeld (Melnerzhagen, Germany) has developed a two-station injection moulding machine. The Microsystem 50/2 SE, which features the company's Unilog B4 control system, minimizes cycle time and energy consumption for the manufacture of medical products including microsensors, micropumps, and microsurgical instruments.
"The production of microparts requires a short cycle time to protect the material from chemical degradation," says Martin Ganz, manager of the company's microtechnology division. "A standard injection moulding machine usually has only one mould," says Ganz, "and time is lost when removing the parts. So, in the Microsystem, we have introduced a rotary table clamp system, which has one station for producing the plastic parts and another for taking the parts out of the mould." Suction cups keep the tiny parts separate and correctly oriented for packaging and quality control.
Also responsible for the injection moulding machine's short cycle time is its 5-mm-diam plunger injection system. "The new injection system works like a plunger, and this plunger reaches the splitting line of the mould," explains Ganz. "This means that we are able to inject the plastic very close to the cavity, creating a very small sprue." By keeping waste to a minimum, explains Ganz, manufacturers have less volume to cool down, thus shorter cooling times.
Cleanroom conditions are maintained within the system enclosure, making the machine suitable for the production of medical components. "We have reduced the cleanroom area to the machine itself," says Ganz. "A cleanroom box covers the entire unit and filters harmful dust and particulates out of the air."
Products that have been produced by the system include a high-precision polycarbonate sensor housing with a part weight of 0.002 g, which was designed for implantation under the skin of the human ear.
The Microsystem was developed by Battenfeld with the Technical College of Wiener Neustadt, Zumtobel Staff, Arge HMA, HB-Plastik, and the Institute for Microsystems and Precision Engineering of the Technical University of Vienna.
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Display Produces CRT-Quality Images in Flat-Panel Architecture
Field emission displays (FED) combine the visual advantages of phosphor-based imaging typical of cathode ray tubes with the convenience of flat panels as thin as 2.5 mm. The technology was developed by PixTech S.A. (Rousset, France), which recently received a purchase order for 50,000 displays from a US medical equipment manufacturer.
FED technology involves the deposition of millions of micron-sized tips on metal strips placed on the bottom of a glass plate. These strips form the columns of a matrix-addressed display. Another set of metal strips with holes, or "gates," is placed across the microtips. As voltage is applied to the microtips, electrons are emitted and they are attracted to a phosphor screen, creating coloured light.
According to Jean-François Gros, FED presents several advantages over LCDs and other flat-panel display technologies. "Unlike LCDs, PixTech's FEDs have natural viewing angles. Brightness, contrast, and colours are unchanged at horizontal and vertical viewing angles greater than 160°," says Gros. In addition, he notes that modules can operate in temperatures ranging from 45° to 85°C and that they consume 30% less power than LCDs and feature a 20-microsecond response time. Consequently, even very fast sonographic images will not smear or blur. Because it couples uniform high brightness at all viewing angles with true video speed and low power consumption, medical equipment manufacturers can finally make the switch from CRT-based systems without accepting the performance limitations inherent in other flat-panel technologies, says PixTech president Dieter Mezger.
FEDs are available in standard, high-brightness, colour, and low-power and low-temperature versions. The company recently initiated a technology development program with a Japanese manufacturer of CRTs to develop 15-in. and larger displays using FED technology.
