There are four leading classes of biomaterials used in implantable applications, including metals, ceramics, composites and polymers. The use of one material type over the other varies greatly based on a range of criteria, including functional use, performance requirements and cost.
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Prior to marketing a device, the FDA requires biological evaluation to determine potential toxicity resulting from contact of component materials with the body. The intention of such testing is to ensure device materials do not produce adverse local or systemic effects; are not carcinogenic; or, do not produce adverse reproductive and developmental effects. The specific
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Polyethylene terephthalate (PET) is most commonly used in medical devices such as sutures and implantable textiles. Polybutylene terephthalate (PBT), an alternative thermoplastic polyester, is also used in medical devices such as injection molded connectors for pulse oximeters, tips for electrosurgical instruments and clips for breathing masks. Polyesters are produced by reacting terephthalic acid with alcohol.
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Fluoropolymers are commonly used for the construction of medical catheters. Polytetrafluoroethylene (PTFE) is the material of choice for low friction, inner liners of guide catheters used in cardiology and neurology. Fluorinated ethylene propylene (FEP) is used for vascular access sheaths and shrink tubing. Although used in state-of-the-art medical devices, these materials are not new. The
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Enhancing strength and rigidity of polymers used for non-medical applications is often achieved by adding glass, carbon, and other fibrous materials to the polymer during melt compounding. These fillers are too large for the extremely small geometries and thin wall sections of minimally invasive medical devices. In such applications, nano clay reinforcement of polymers is
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Changes in formulations of materials used for manufacturing patient-contacting medical devices or device components often require submission of a new 510(k) by the device manufacturer. This is because formulation changes can affect the biocompatibility, material properties and performance of a device. The FDA defines material formulation changes to include the following: – Changes to the chemical composition
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Silicones are widely used in medical devices because they are biocompatible, biodurable (do not degrade over time), do not produce extractables (a concern with leaching plasticizers from flexible PVC), and are unlikely to cause allergic reactions (a concern with latex). Medical applications for silicones are far ranging from wound care gels to flexible drainage tubes
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Two common criteria for catheter shafts are pushability and navigation. Pushability refers the force applied by a physician to advance the catheter to the designated therapeutic site. Navigation refers to the ability of the catheter shaft to move freely through the non-linear vascular pathway. To advance a vascular catheter, sufficient push force must be exerted
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Plastics are generally considered insulators, but can transmit some electrical energy at higher frequencies. The effectiveness of a material as an insulator is usually measured by dielectric constant and dissipation factor properties. Dielectric constant measures how well an insulator stores electrical energy so as to isolate electrical elements from each other and the ground. This
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The Food and Drug Administration (FDA) requires that medical device manufacturers establish and follow quality systems to help ensure products consistently meet applicable requirements and specifications. The quality system regulations (QSR) for FDA regulated products are known as current good manufacturing practices (CGMP). These requirements were first implemented in 1978 under the Federal Food, Drug
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