Technology News
Materials
Gamma-Stable Copolymer Has Clear Advantages in Medical Applications
A methyl-methacrylate copolymer that exhibits surprising clarity for a multiphase plastic also features impact resistance even at low temperatures and the capability to withstand EtO and gamma sterilization. Cyrolite, supplied by Röhm GmbH (Darmstadt, Germany), traditionally has been used in the fabrication of injection ports, connectors, luer locks, filter housings, and dialyzer housings. The recent introduction of a GS90 grade of the USP Class VI copolymer is likely to make the material even more attractive to device manufacturers.
"The GS stands for gamma stable," explains product manager Axel Zajonz. "When the material is exposed to common radiation levels of around 25 kGy, it will show a slight yellowing. After one week, however, GS90 reverts to its original clarity."
Another advantage of the GS90 grade, according to Zajonz, is its chemical resistance. While all the Cyrolite grades exhibit very good resistance toward a raft of different agents, "GS90 surpasses even the resistance properties of polycarbonate," he adds. "In particular, its resistance to alcohol was enhanced."
GS90, like the standard G20 and G20 HIFLO grades, features good flow characteristics, thereby ensuring easy processibility. In addition, "products made from Cyrolite can be welded together," says Zajonz, "enabling manufacturers to avoid the use of adhesives, solvents, or binders that may be physiologically offensive." Because the material supports welding, it is routinely used to manufacture housings for blood filters as well as other filtration devices used in chemical, biological, pharmaceutical, and medical laboratories. If required, Cyrolite can also be bonded to polyvinyl chloride or other Cyrolite parts in a matter of seconds by the use of solvents.
Cyrolite is supplied as uniform pellets and is suitable for either injection moulding or extrusion.
Röhm, which specializes in methacrylate chemistry, supplies monomers, special products, moulding compounds, and semifinished materials. The firm is certified to DIN EN ISO 9001.
Electronic Components
Low-Cost Power Supplies Developed for Medical Applications
A range of open-frame, switched-mode power supplies for non-patient-connected medical applications was recently introduced by Philips Power Systems (Wavre, Belgium). The low-cost PE35XX-M line currently comprises three single-output models rated 5V/8A, 12V/2A, and 24V/1.7A. Units with alternative output voltages and power ratings can be developed upon request.
All PE35XX-M power supplies share the features of standard industrial PE 35 models, such as a universal 90260-V-ac input. Outputs feature overvoltage protection, while current-limiting overload protection prevents the unit from overheating or burning out in the event of a short circuit. Reliability, as expressed by the mean time between failures, can exceed 300,000 hours, depending on the model.
The power supplies meet all relevant standards including EN 60601 and UL 544.
Analytical Instruments
Spectrophotometer Features Plug-and-Play Electronics
Varian Associates Inc. (Crawley, W Sussex, UK) recently introduced what is reportedly the first plug-and-play spectrophotometer. Controls for the Cary 50 UV-visible spectrophotometer are housed on a circuit board that plugs into a PC. Because the unit has few system elements, reliability is enhanced and potential problems are minimized. If the circuit board should fail, the user can replace it as he or she would a PC networking, video, or sound card.
The Cary 50 can be used to calculate the uniformity of drug dosage, analyze DNA for therapeutic drug uses, and measure the colours of powders and pastes. With its superconcentrated beam, the Cary 50 is particularly suited for fibre-optic work. "Technicians can use the Cary 50 to measure and analyze the creation of optics such as lenses," says product manager Alan Marks. Chemical companies can also employ the spectrophotometer to ascertain the purity of their products, and to follow the progress of chemical reactions in resins and adhesives.
A single xenon pulsed lamp source enhances the performance of the spectrophotometer. Because the lamp is switched on only during a reading, lamp life is prolonged and energy is saved. Unlike a diode array that exposes a sample to the entire wavelength range with each reading, the xenon lamp flashes only when acquiring a data point. As a result, degradation of photosensitive samples is eliminated. The Cary 50 can measure samples up to 3 Abs with a data collection rate of 80 points per second. The narrow, intense light beam provides optimal noise performance even if microcells are being used.
Accessories such as heaters and probes can be supplied for Cary spectrophotometers. "One of the unique aspects of the Cary 50 is its ability to make measurements of liquid samples quickly and easily with a fibre-optic dip probe," says Marks. When analyzing liquids, chemicals, or pharmaceuticals, the user can get a reading almost instantly by dipping the probe into the sample.
Varian Associates Inc., which is based in Palo Alto, CA, USA, operates manufacturing facilities in North America, Europe, Asia, and Australia, and has sales offices worldwide. The company has core businesses in health-care systems, analytical instruments, and semiconductor manufacturing equipment, and provides products and services to international markets.
