Medical grade adhesives have revolutionised the safety and efficiency of medical devices. These adhesives are used in the manufacturing process of medical devices such as blood filters and blood pressure transducers. These adhesives help connect different components of medical devices securely to each other, such as electronic circuits, sensors and electrodes.

Adhesives are also much better suited for putting together medical devices than any other alternative, as they are lightweight, provide better bonding strength and flexibility, and cause minimal damage to the equipment.

When choosing the right adhesives for medical device manufacturing, you have to consider various factors. In this blog, we will discuss not only the factors that you should consider when choosing medical-grade adhesives, but also the types of adhesives used in building medical devices.

 

A] Types Of Adhesives Used In Medical Devices

1. Epoxies

Epoxies are the most widely used adhesives in medical manufacturing due to their excellent bonding strength and durability. They are known for their chemical and thermal stability, making them perfect for medical devices that come into contact with hazardous chemicals and heat. Epoxies are available in both one-part and two-part compositions, both of which are used in bonding medical devices together.

2. Light-Cure Adhesives

Light-cure adhesives, also known as UV-cure adhesives, exhibit rapid curing properties upon exposure to ultraviolet (UV) light. They are usually used to bond clear plastics and optical components and seal transparent materials, which need quick curing. Generally, the light-cure adhesives cure within 30 seconds of exposure to UV lights and adhere well to metals, glass and plastic

3. Moisture-Curing Cyanoacrylate

Moisture-curing cyanoacrylates are solvent-free and fast-curing adhesives that form rigid bonds when exposed to moisture. They bond and cure rapidly, hence they are used in fast assembly and repairing devices. Moisture-curing cyanoacrylates are used in the same way as light-curing adhesives, however, they have the drawback of being brittle, which can be solved by making some changes to the formula.

4. Polyurethanes

Polyurethanes are one of the most widely used adhesives for healthcare devices as they provide excellent structural bonding and flexibility. Polyurethanes can be used for a number of different materials including plastics, and metals as a result, they are used to connect various components of medical devices including, medical electronic systems. Polyurethane adhesives are also used for potting applications as they do not shrink, cure in low temperatures and are durable at low temperatures.

5. Pressure Sensitive Adhesives

Pressure-sensitive adhesives (PSAs) form strong bonds with the surface under light pressure without the need for other curing mechanisms such as heat or solvents. These pressure-sensitive adhesives are used to assemble medical devices such as wearable sensors and also wound dressings and transdermal patches. They provide good adhesion with easy removal when required.

 

B] Factors To Consider When Selecting Medical Device Adhesives

1. Disposable Or Reusable Device

The first factor to consider is the inherent characteristics of the device, specifically whether it is designed to be disposable or reusable. Disposable devices might require medical adhesives that are initially strong however can later be safely removed and disposed of. While reusable devices require strong adhesives that do not degrade even after multiple sterilisation processes.

2. Nature Of Contact With The Human Body

It is important to consider if the device will come into contact with the human body and if yes, then where. Skin-friendly adhesives are used for devices that are attached to the human body, either externally or inside the body, ensuring there are no adverse reactions. Biocompatible adhesives for medical devices are changing the way adhesives are used in the medical sector.

3. Type Of Sterilisation

The method by which the device is sterilised might impact the adhesive’s performance, hence, it is also essential to keep this in mind. Different sterilisation techniques, such as steam autoclaving and gamma radiation can disrupt various mechanical, chemical and physical properties of the adhesive.

4. Surface Adhesion

The adhesive selection process necessitates careful consideration of the surface compatibility of different adhesives. Adhesives exhibit varying degrees of adhesion to different types of surfaces, making it crucial to assess the compatibility between the surface material and the specific adhesive being used. Understanding the substrate’s compatibility with the adhesive is important for achieving a strong adhesion and avoiding errors in manufacturing.

5. Surface Texture

The texture of the surface also plays an important part in selecting adhesives for medical device assembly. A rough or uneven surface requires more adhesives compared to a smoother surface. Textured surfaces also provide better adhesion than smooth surfaces.

6. Surface Cleanliness

A clean surface is important for good adhesion, and not cleaning the surface before applying the adhesive is a common mistake that should be avoided. The components of the medical device need to be cleaned and sterilised so the contaminants do not become a barrier between the surface and the adhesive.

7. Humidity

Moisture and humidity have detrimental effects on the adhesive’s functionality, affecting its durability and strength. While certain adhesives may rely on humidity as a catalyst for curing, in most cases, excessive humidity can degrade the quality of the adhesive, resulting in a foamy appearance. It is crucial to consider the environmental conditions in which the device will be used before selecting an adhesive, as the presence of high humidity can adversely affect the adhesive’s performance and overall quality.

8. Surface And Environment Temperature

Certain adhesives, such as thermosetting adhesives tend to bond well in higher temperatures, while some melt and lose their integrity when exposed to heat for too long. You need to consider the environment where the device is going to be used and it’s the average temperature. Understanding the temperature requirements will help to choose the right adhesive for medical devices.

 

C] Regulatory Considerations

Medical-grade adhesives refer to industrial adhesives specifically formulated and manufactured for use in medical applications. These adhesives, once fully cured, are non-toxic, ensuring their safety when utilised for medical purposes. There are certain certificates and regulatory restrictions posed on medical-grade adhesives, which differentiate them from industrial adhesives.

These certifications are provided by the International Organisation of Standardisation(ISO). While choosing the adhesives, look for ISO 10993, which is the standard of biocompatibility of a medical device and ISO 13485, which is the standard quality of medical devices. Continuous testing of the adhesives before manufacturing can also help to ensure the highest standards of medical adhesive.

 

D] Best Practices For Adhesive Selection Criteria For Medical Devices

Listed below are some additional factors and best practices for selecting medical adhesives for you intended applications:

1. Chemical Resistance

Medical devices come into contact with various chemicals, such as disinfectants, solvents, or bodily fluids. These chemicals can alter the adhesive’s properties, making it weaker over time. Hence, it is essential to choose an adhesive with chemical-resistant properties.

2. High-Temperature Resistance

Certain medical devices are exposed to high temperatures more often than others. High temperatures can ruin the chemical properties of certain adhesive materials, rendering them structurally weak. Thermosetting adhesives or adhesives with high thermal resistance can work better for these medical devices.

3. Resistance To Sterilisation Process

It is important to consider the adhesive’s compatibility with the sterilisation process as the sterilisation process affects certain adhesives weakening their structural integrity. The sterilisation process can include steam autoclaving, ethylene oxide (EtO) sterilisation, or gamma irradiation, these processes can affect the chemical and mechanical properties of the adhesives, hence it is important to choose an adhesive that can withstand multiple sterilisation processes.

4. Medical Grade Certifications

Ensuring the safety of medical devices and their compatibility with the human body is of utmost importance when selecting an adhesive. So, you should check for compliance with ISO 10993 for biocompatibility and other certifications that ensure that the adhesive has been tested and deemed safe for use in medical devices.

5. Curing Process

Different adhesives require different curing environments, such as heat, UV light, or moisture. Consider your medical device manufacturing conditions to select the adhesive having appropriate curing properties. The adhesive should allow for an efficient and reliable assembly process and provide a strong bond.

Here are some more questions to analyse while selecting an adhesive so you can make an informed decision.

E] Conclusion

Medical Adhesives ensure the safety of the patient, the durability and longevity of the device, and an efficient manufacturing process. Consider the above points to check if the adhesive has the desired mechanical and chemical properties.

Choosing the correct adhesive for medical device assembly is critical for providing patients with reliable, safe, and effective medical devices. Adhesives are also lighter, secure and biocompatible compared to other binding methods.

If you are looking for a high-quality bespoke medical-grade adhesive, contact us today! Kohesi Bond offers high-quality adhesives subjected to rigorous testing to ensure high quality and meet industry standards.