Medical polymers devices

Composite Devices. Composites made of active-phase PZT and polymer-matrix phase are used for the hydrophone and medical imaging devices (see Composite materials, polymer-matrix Imaging technology). A usehil figure of merit for hydrophone materials is the product of hydrostatic strain coefficient dj and hydrostatic voltage coefficient gj where gj is related to the dj coefficient by (74)... 

The protection of microelectronics from the effects of humidity and corrosive environments presents especially demanding requirements on protective coatings and encapsulants. Silicone polymers, epoxies, and imide resins are among the materials that have been used for the encapsulation of microelectronics. The physiological environment to which implanted medical electronic devices are exposed poses an especially challenging protection problem. In this volume, Troyk et al. outline the demands placed on such systems in medical applications, and discuss the properties of a variety of silicone-based encapsulants. 

The main requirement imposed on all polymer biomaterials applied in medicine is a combination of their desired physicochemical and physicomechanical characteristics with biocompatibility. Depending on particular applications, the biocompatibility of polymers can include various requirements, which can sometimes be contradictory to each other. Thns, in the case of artificial vessels, drainages, intraocular lenses, biosensors, or catheters, the interaction of the polymer with a biological medium should be minimized for the rehable operation of the corresponding device after implantation. In contrast, in the majority of orthopedic applications, the active interaction and fusion of an implant with a tissne is required. General requirements imposed on all medical polymers consist in non-toxicity and stability. 

Biocompatibility is a very critical, basic safety requirement for medical polymers in medical device applications. For this, it is essential that ... 

Polymer blends could be irradiated for the same purpose as polymers. For example, polymer devices for medical applications have been sterilized by irradiation for many years. Irradiation could also be used to obtain a polymer material suitable to foam by modifying its structural parameters (macromolecular mass, branch content). " For such an application, even if the irradiation of polymer blends is more complex than the irradiation of a pure polymer, the main objectives are the same in both cases. Thus, the following part will consider only the specific applications of irradiated polymer blends. 

PolyhydroxyaUcanoates (PHAs) are the biopolymers possessing the material properties ranging from rigid and highly crystalline to flexible, amorphous, and elastomeric. Because of such properties and inherent biodegradability, PHAs have attracted the world-wide attention of scientists and researchers as environment-friendly alternative to the conventional petroleum-based polymers. Polyhydroxybutyrate (PHB) and polyhydroxyoctanoate (PHO) have been found to possess biocompatibility in mammalian systems. Such biomaterials have got great potential as medical implantation devices [78-81]. 

Research, G.V., 2014. Medical Polymers Market Analysis by Product (Resins Fibers, Elastomers, Biodegradable Plastics), by Application (Devices and Equipments, Packaging) and Segment Forecasts to 2020. http //www.grandviewresearch.com/industry-analysis/medical-polymers-market. 

The discovery of strong piezoelectricity in PVDF has led to the development of numerous polymer based acoustic sensors, in particular the spot poled membrane hydrophone design in its various embodiments. These hydrophones have become the primary devices for characterizing biomedical ultrasound fields. Their development has made possible the quantification of medical ultrasound exposure levels, and so enabled standards organizations to adopt a rational and systematic approach to address the problems of field measurements and device safety. Significant measurement challenges remain, particularly in the area of therapeutic ultrasound, but it is clear that PVDF will continue to play a pivotal role in the characterization of medical ultrasound devices. 

The sterihsation of implantable devices is a subject of great concern for the medical industry. Since ionising radiation is preferentially used for this purpose, attention must be paid to possible effects on the structural and mechanical properties of polymers (through chain scission or cross-linking). L. A. Pruitt from UC Berkeley has reviewed the specific behaviour of the different medical polymer classes to y- and high-energy electron irradiation and environmental effects. The biocidal efficiency refies on free radical formation and on the ability to reduce DNA rephcation in any bacterial spore present in a medical device. 

A wide range of resins used in medical devices were included in this study and are listed in Table 1. These included an ABS resin manufactured by BASE, a polycarbonate resin manufactured by Bayer Polymers, and a polymethyl methacrylate (PMMA) resin manufactured by Gyro. In addition, a series of medical polymers manufactured by Eastman Chemical Company were included in this study. These included a propionate cellulosic formulation, a copolyester/polycarbonate blend, a polyethylene terephthalate homopolymer (PET), and a series of Eastman Coplyesters. All four of the... 

In addition to conventional applications in conducting polymers and electrooptical devices, a number of recent novel applications have emerged. Switching of DNA electron transfer upon single-strand/double-strand hybridization fonns the basis for a new medical biosensor teclmology. Since the number of base pairs of length 20... 

Ferroelectric—polymer composite devices have been developed for large-area transducers, active noise control, and medical imaging appHcations. North American Philips, Hewlett-Packard, and Toshiba make composite medical imaging probes for in-house use. Krautkramer Branson Co. produces the same purpose composite transducer for the open market. NTK Technical Ceramics and Mitsubishi Petrochemical market ferroelectric—polymer composite materials (108) for various device appHcations, such as a towed array hydrophone and robotic use. Whereas the composite market is growing with the invention of new devices, total unit volume and doUar amounts are small compared to the ferroelectric capacitor and ferroelectric—piezoelectric ceramic markets (see Medical imaging technology). 

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