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Conventional Pressure Sensors
Published in J G Webster, Prevention of Pressure Sores, 2019
Packaging of such sensors must be as biocompatible as possible. It must be noninflammatory, nontoxic, nonallergenic, and noncarcinogenic. The material must be mechanically durable and chemically stable. Silicon crystal is a good material for biosensors because of its biocompatibility (Hynecek 1975, Ko et al 1979). Good choices for wires include Elgiloy (a nickel-cobalt alloy), stainless steel, platinum-iridium, copper, or nickel. For insulation and/or encapsulation, Teflon, silicone rubber, and titanium have been found to have desirable qualities (Regnault and Picciolo 1987). Ko et al (1979) used Hysol W-795 epoxy for attachment of components and Silastic silicon rubber for encapsulation.
An overview of translational research in bone graft biomaterials
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Vijay Shankar Kumawat, Sanchita Bandyopadhyay-Ghosh, Subrata Bandhu Ghosh
Metallic bone grafts are considered as the oldest and widely used biomaterials in the load-bearing orthopaedic surgeries to replace the defective bone tissues and to provide the support during bone remodelling and healing process [25]. To date, there are several biocompatible metallic materials such as stainless steel, titanium, tantalum, magnesium, etc. and their alloys, which are used in bone grafts [94]. They have received vast popularity because of their excellent mechanical properties and good machinability. Among them, stainless steel (316 L; ASTM F138), cobalt-chromium based alloys (MP35 N, L-605, Elgiloy, ASTM F75 and F799), nickel-titanium (Nitinol) and titanium alloy (CP titanium, Ti-6Al-4V: ASTM F67 and F136) are the most frequently used standard bone grafts during orthopaedic surgeries, owing to their superior mechanical properties and long-term stability under highly-reactive in-vitro and in-vivo conditions [95–98]. However, metallic materials contain ingredients that can be cytotoxic or allergenic. They also have the tendency to release the unwanted metallic ions in highly-aggressive microenvironment due to corrosion, wear and friction, which may induce inflammatory reactions, with gradual osteolysis of adjacent tissues leading to further damages of the local tissues. These conditions imply to implant (graft) failure, and often the patients with metallic bone grafts undergo corrective (revision) surgeries, which may lead to surgery related complications.
Biocompatibility of titanium from the viewpoint of its surface
Published in Science and Technology of Advanced Materials, 2022
In the field of orthopedics, a cast Co–Cr–Mo alloy known as ‘Vitallium’ (ASTM F75) is utilized for artificial knee joints and artificial hip joints, in particular, the heads. ASTM F79 Co–Cr–Mo alloy is produced by refining the grain of F75 using hot rolling. The F99 alloy has twice the tensile strength and yield strength of the F75 alloy. To improve the workability of Co–Cr–Mo alloy, ASTM F90 as ‘HS25’ or ‘L-605’, used for orthopedic wire, is developed by reducing the C content and adding W and Ni, resulting in a workability of 44% and a strength after working that is more than double that of F75 alloy. ASTM F562 Co–Ni–Cr–Mo alloy as ‘MP35N’ is used in cardiovascular surgery for stents with superior strength, elasticity, and corrosion resistance, and tensile strength exceeding 1600 MPa. This alloy, along with the ASTM F90 alloy, has a high elastic modulus, which makes it advantageous for use as a stent. On the other hand, ASTM F1058 Co–Cr–Ni–Mo–iron (Fe) alloy, also known as ‘Elgiloy’, is utilized for artificial heart springs and aneurysm clips. Co–Cr–Mo alloy is utilized in dentistry for removable partial dentures with clasp, crowns, and bridges [34].
Mechanical properties and performances of contemporary drug-eluting stent: focus on the metallic backbone
Published in Expert Review of Medical Devices, 2019
Ply Chichareon, Yuki Katagiri, Taku Asano, Kuniaki Takahashi, Norihiro Kogame, Rodrigo Modolo, Erhan Tenekecioglu, Chun-Chin Chang, Mariusz Tomaniak, Neville Kukreja, Joanna J. Wykrzykowska, Jan J. Piek, Patrick W. Serruys, Yoshinobu Onuma
Compared with stainless steel, cobalt chromium alloys have higher elastic modulus and tensile strength resulting in a better radial strength and the ability to have thinner struts (Table 1). One bench study demonstrated the improvement of mechanical performance of the cobalt-chromium DES when compared with stainless steel DES [36]. Other than better mechanical properties, the cobalt chromium alloys are more radiopaque and their fluoroscopic visibility is better than stainless steel due to its higher density. Another advantage of this alloys is its low ferromagnetic nature which makes this alloys safe for MRI. Although artifacts on MRI signal was lower in cobalt alloys, platinum and nitinol than stainless steel [37], in vitro and in vivo studies demonstrated no substantial heating or motion of coronary stents in the magnetic field [38,39]. The cobalt chromium alloys commonly used in the manufacturer of coronary stents are L605, cobalt-nickel-chromium alloy (MP35N), and Phynox/Elgiloy. Among these three kinds of alloys, L605 is commonly used due to its highest density and elastic modulus. Current DES using cobalt-chromium alloys as a stent platform are listed in Table 2.