The medical industry is constantly developing new devices to help people in their diseases of injuries. Medical devices can be characterized by their complex form and high demands towards safety and material. That is very natural since some of them come in direct contact with people and can stay in that contact for long years. This is why medical devices must pass a number of strict clinical trials. A reliable way to successfully complete those trials is to develop a way to design and manufacture medical device prototypes rapidly with a considerable number of reiterations.
Medical Devices Requirements:
All medical devices can be divided into 3 categories by danger risk.
1st category devices are just generally used for medicinal purposes and have to meet only the basic requirements such as that their material must be non-allergic and they have to fulfill their purpose. An example of such device is a syringe or a scalpel.
2nd category products are more complex and may pose some threat to the patient who is using them. For such products, additional requirements are put into action. They may differ depending on the purpose of the device but they mean the second stage of tests and certifications in every case. An example of 2nd category medical device is a wheelchair.
3rd category devices are mostly things whose malfunction will bring considerable harm to the person. This type of devices mostly consists of different prostheses or capillary stints, things, inserted into the human body. They are the hardest to get certification for as they require a Pre-market approval. It means that after the first two testing stages, you have to make a small batch (around 100 to 1000 pieces) and test it in real life on some patients.
Now, consider the fact that an error may occur at any stage of the product certification, which will demand to redesign the product and remanufacturing the prototype as fast as possible. This can happen a number of times too. This is why rapid manufacturing of medical prototypes is such a vital task.
Medical Device Materials:
As it was mentioned earlier, material plays a large role in medical devices. Prototype manufacturers must be able to produce prototypes of the specified material for the certification to be possible. In many ways, the material determines the manufacturing process.
For example, titanium is one of the most widely used metals for prostheses. It is lightweight, resistant to corrosion and most importantly, it does not react with human tissue. Creating complex parts by machining titanium is a very complex job, so other methods of prototyping need to be considered.
Another popular material in medical is plastic. Nylon and urethane are ideal for clinic purposes. One of them soft, the other rigid, they are non-allergic and very neutral, so they can come into contact with human skin or even tissue.
Most first category medical devices are used from steel for the best efficiency and the wide range of different properties steel can offer. Those types of devices don’t come into contact with human tissue at all or for a small amount of time so there is no need to concern yourself with allergies and steel is still the most widely used industrial alloy.
Manufacturing Medical Prototypes:
Manufacturing medical prototypes are somewhat harder than creating prototypes for other industries. The reason for that is the strict certification that the design must undergo to be eligible for commercial use. You see, the prototypes are tested as if they were an exact representation of the end-product. You can’t make any changes in the design after the certification has been approved, so the part must be aimed at mass production from the start which is most often not necessary in other products (prototypes can be simplified in order to just test their performance in some areas of use). It is often possible to create mockup models from other materials just to see the product in real life. This will not stand for medical devices too. One material may not cause reactions to human tissue while another will.
Fortunately, materials used in medical industry can be processed by a large variety of the Rapid prototyping technologies. For example, urethane and nylon parts can be cast into a special silicone solution. The casting forms made of silicone are really easy to make and can be used a number of times to manufacture even the most complex of parts.
Additive manufacturing is another rapid prototyping method that is currently gaining popularity among medical device manufacturers. Not only does it enable a considerably rapid prototype production of parts made from the hardest of materials ( titanium, for example), it actually broadens the designing horizons for medical device developers. The reason for that is the unusual way of manufacturing parts. A fine metal powder is spread over a working plate and sintered layer-by-layer in accordance with the 3D-model cross-sections of the part. This enables the manufacturing of very complex parts without a large amount of preparation. Additive manufacturing can create prostheses that are close to real bones in structure (bones have porous cellular structure, which makes them really strong, yet lightweight).
CNC machining is a very viable method when post-processing additively manufactured or cast parts as those processes have lower precision. It is also useful as a standalone method. If the material has good machinability, it is much easier just to cut it out from a blank stock by creating a machining program. This method is the oldest and the best researched of the three, so properties of the manufactured part can be predicted better. Despite that, it is also the slowest method, which is the reason why it is currently backing off when compared to rapid prototyping technologies.
Developing and manufacturing medical devices is a complex and time-consuming process because of the strict requirements and the number of certification tests that the product must pass in order to be used commercially. This is why rapid manufacturing of high-quality device prototypes is absolutely necessary to conduct test iterations faster and bring the product to market.