How to Use Metals in Biomedical Applications

Introduction

Metals form a central part of biomedical devices. Their strength, durability, and biocompatibility make them suitable for many uses. We will go through some common metals, describe the structure and properties of these metals, and discuss applications in biomedical devices.

Common Metals for Biomedical Devices

Here's a concise overview of common metals used in biomedical devices.

Metal Structure and Properties

The composition of a metal defines its performance. The majority of metals have a crystalline structure that determines their hardness, toughness, and resistance to stress. Stainless steel, made up of iron, chromium, and nickel, is suitable due to its grain structure. Titanium has a hexagonal close-packed structure at room temperature and exhibits yield strengths of 780–1100 MPa, while cobalt-chromium alloys can achieve over 1200 MPa—ideal for stress-bearing applications such as implants.

Corrosion resistance is vital, especially inside the body. Titanium forms a stable oxide coating that provides protection against saline fluids, while stainless steel relies on a passive chromium coating. Surface treatments such as passivation and anodisation also enhance durability.

Hardness is significant as well. Cobalt-chromium alloys are durable and wear-resistant with low friction, while titanium is characterised by high biocompatibility and an extremely low rate of allergic reaction. The choice of metal depends on balancing strength, stability, and the body's response.

Biomedical Applications of Metals

Metals play important roles in both temporary and permanent medical devices. Orthopaedic devices, including joint replacements and bone implants, are produced from cobalt-chromium alloys and titanium due to their strength and biocompatibility. Dental implants often utilise titanium since it naturally integrates with the bone through osseointegration.

Stainless steel and cobalt-chromium alloys are used in cardiology for stents and heart valves, providing permanent stress durability for the long term. Platinum group metals are best suited for pacemaker and neurostimulator electrodes due to their chemical stability.

Metals also enable diagnostic machines to function—MRI machines rely on very precise metal components, and thin metal films are utilised by micro-scale implants to sense. Metal selection is based on structure, strength, and corrosion resistance, and further investigation enhances alloys for safer and more uniform implants.

Conclusion

The most suitable metals have been identified for specific uses, such as stainless steel, titanium, cobalt-chromium, and platinum group metals. Their structure and properties determine the effectiveness of biomedical devices. Metal implants, dental fixtures, heart valves, and stents are just a few examples.

Frequently Asked Questions

F: Which metal is best for dental implants?
Q: Titanium is often preferred for dental implants due to its strength and excellent biocompatibility.

F: How do metals resist corrosion inside the body?
Q: Metals form protective oxide layers or passive films that help resist corrosion in body fluids.

F: Are cobalt-chromium alloys reliable for joint replacements?
Q: Yes, cobalt-chromium alloys offer high strength and wear resistance, making them ideal for joint replacements.