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Polymers In Healthcare: How Are They Different?

The potential for polymers in the medical and pharmaceutical industries is endless as new materials come on stream. Cost effectiveness is becoming a big factor in current development. The home healthcare market is expanding as patients receive medical support locally for convenience and to relieve the load on the hospital system: this is leading to more stylish casings and visible components.

Quality And Properties
  • The quality controls in place in the medical device industry are stringent for reasons of patient safety. The whole industry relies on timely communication between suppliers and manufacturers. Most manufacturers require around a 2-year lead time for a change of polymer.

  • Monitoring shelf-life of polymers is important for performance. Tests for material performance include gel permeation chromatography (GPC) for molecular weight, capillary for viscosity, melt flow index for ease of flow, differential scanning calorimetry (DSC) for thermal transitions and qualitative analysis, and Fourier Transform Infrared Spectrometry (FTIR) for contamination and identification.

  • Many factors can affect materials including transport and storage conditions.

  • The specialist knowledge-base for this industry is now focused in three locations in USA, Europe and Asia, all of which are ISO13485 certified.

  • Sterilization procedures are designed to kill pathogens such as bacteria and fungi, however there can still be problems with chemical and particulate contaminants on medical devices, which are not removed by these methods.

  • Sterilization affects materials in different ways depending on the technique, from ethylene oxide and gamma irradiation to autoclave. The rewards are seeing a device operational and improving the quality of life for patients.

  • Approvals include good manufacturing practice and control of materials supplies to ensure consistent products.

  • Material specification includes mechanical, chemical, biocompatibility, electrical and thermal properties, as well as Processibility. It is expensive to take a new device to market because of the cost of design and tests to obtain performance data, as well as FDA approval.

  • Key performance measures include substrate adhesion, durability and mechanical properties, thickness and swelling in body fluids, particle and leachable release, biocompatibility and degradation of implants.

  • Blood contact polymers should not: absorb protein, release additives into the bloodstream, carry infection, cause clots or cancer, or provoke an immune response or irritation.

Recent Trends

  • Biodegradable plastics have a role in temporary medical devices providing a function until the body is able to recover, for example in tissue scaffolding.

  • In the past the material did not contain stabilizers or processing aids. Now a few antioxidants have been approved.

  • Current healthcare trends include minimally invasive surgery: device developments include a silicone-access port for multiple instruments; micro endoscopes; and remote handgrips that simulate real hand feeling.

  • Coatings are used on medical devices for protection and to improve biocompatibility. Coatings are applied by dip coating, spray coating, brush, roll or blade.

  • Silicones are used in applications varying from catheters to surgical instruments. Silver ions are incorporated, which are toxic to the bacteria, by destabilizing the cell membrane, deactivating sulphur-containing proteins and blocking oxygen-transport enzymes.

  • The melt filtration of polymers is used for catheters and balloons. This can remove more than 80% of gels and other contaminants while retaining polymers’ inherent mechanical properties.

  • More advanced medical devices to perform minimally invasive surgeries with greater precision, the demands on polymer components and materials continue to escalate. This is particularly evident in vascular stent delivery and related devices.

  • Today’s vascular devices require catheter shafts that are smaller in diameter with thinner walls to reach new areas of the body with complex surgical tools.

  • Thin wall polymer balloons are attached to the end of these shafts and used to expand vascular pathways and to deliver stents for permanent support. Manufacturing these thin wall polymer shafts and balloons requires advanced melt extrusion techniques which are dependent on polymers with substantially greater consistency and quality.

  • Melt filtration process improves the quality of vascular catheters and balloon products, which will improve clinical performance and reduce the risk of product failure.

  • Specifically formulated for precision catheter components, the custom polymers feature superior color accuracy and surface quality as compared to traditional generic color concentrates.

  • New radiopaque fillers offer superior quality that translates to improved performance at the extrusion step of the supply chain. It allows improved yields and thinner wall thicknesses, thereby pushing the limits of product design.

  • Radiopaque fillers are added to polymers to make catheters and other medical devices visible under fluoroscopy or X-ray imaging. The filler affects the degree of contrast and the sharpness of the image to the extent that it influences the attenuation of X-rays passing through the body and the device.

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