Medical Archives - Page 2 of 4 - Perfect 3D Printing Filament

Exploring Exotic 3D Printing Materials Used in Prosthetics

Those familiar with 3D printing materials know that polylactic acid (PLA) is an extremely popular material. It’s strong, inexpensive, and easy to print with. PLA is is great for a wide range of applications, but there are other material options out there as well. Nylon is known for its toughness, but it is notoriously difficult to print successfully. Other plastics like polyvinyl alcohol (PVA) can be dissolved in water, making it the perfect choice for support material because it can be so easily removed.

In the prosthetics industry, 3D printing is starting to become a viable manufacturing process. Since a high level of quality is required, there are some situations where PLA and other common materials don’t quite cut it. Prosthetics and bionics companies are looking at using more exotic materials so that they can improve their products.

Above all else, prosthetic limbs must be lightweight and comfortable. If a prosthetic is powered either electrically or mechanically, it is considered a bionic prosthetic. It is beneficial for bionic products to be as simple as possible, so flexible parts may be desired to reduce the complexity. Bionic prosthetics can also feature sensory capabilities for user-feedback, so electronics may be required. All of these design criteria can be achieved by using special materials that do a little bit more than just your average PLA.

Carbon Fiber Reinforced Filament

Carbon fiber reinforced (CFR) filament is a 3D printing material that contains short strands of carbon. It is stiffer than most filaments, and it is a great material choice if weight and rigidity need to be optimized. One such application is in the socket for prosthetic legs. The socket is the part that connects the person’s leg to their prosthesis. People with leg amputations need their prosthesis to be both lightweight and rigid, and CFR filament fits both of these criteria.

This material consists of short carbon strands suspended in a plastic such as PLA or Nylon. These plastics are all classified as thermoplastics, which means they can be remelted. This material property can be quite beneficial. Typically, an amputee’s residual limb will change shape slightly over the course of months or years. This can lead to discomfort if their socket does not change shape. If modifications to the socket need to be performed, CFR filament can simply be heated up to soften it and then reshaped.

Carbon fiber composite material is different from CFR filament. It consists of woven carbon sheets glued together with epoxy. It does not soften with heat. This is because epoxy is classified as a thermoset polymer. That means it undergoes a chemical reaction as it cures which causes it to permanently harden.

Prosthetic sockets made from carbon fiber composite are in fact stronger than 3D printed carbon fiber material but they are expensive, hard to manufacture, and difficult to re-shape. This is why some prostheses are now made by 3D printing with CFR filament. With a 3D scan of the amputee’s residual limb, a socket can be 3D printed which very accurately captures every detail. This makes for a more comfortable fit. 3D printing a socket is much quicker and also less expensive than the traditional method of creating a prosthetic socket.

Flexible Filament

Unlike most 3D printing materials, thermoplastic polyurethane (TPU) is soft and flexible. This material is perfect for creating flexible joints, and it sees use in applications like prosthetic fingers and as soft liners for prosthetic sockets.

Prosthetic sockets which are made from rigid materials (such as CFR filament) can become uncomfortable if pressure is not evenly distributed. Introducing a soft inner liner can provide cushioning and support, improving comfort for the user. Because 3D printing can create complex shapes, a mesh-like structure can be printed which allows airflow throughout the socket. This ventilation is very necessary because moisture build-up can cause discomfort.

TPU is also being used in bionic hands as a material for flexible fingers. Instead of using a rigid mechanism, using flexible and compliant mechanisms to transfer forces can result in a more natural motion. Using flexible materials in compliant mechanisms reduces the number of parts, removes the need for lubrication, and greatly speeds up the assembly and manufacturing process.

Conductive Filament

3D printing is usually used to produce mechanical components, but certain filaments are electrically conductive and can be used in a variety of interesting electronics applications. Magalie Darnis (M.Eng), made this the topic of their master’s thesis. Magalie used a material known as ETPU to create 3D printed sensors.

ETPU combines carbon powder and TPU to develop a flexible and electrically conductive polymer that can be 3D printed. Although ETPU contains carbon, it is very different from CFR filament. This is because it uses graphene powder instead of short carbon fibers. Graphene easily conducts electricity, but it does not add much mechanical strength. Other types of conductive filaments exist, but they are rigid and sometimes brittle. In other applications, this may be desired, but for bionics, the flexibility that comes with ETPU allows for flexible, form-fitting sensors to be embedded in wearable products.

Currently, 3D printed sensors are only found in bionics prototypes, but ETPU has proven to be effective in applications such as touch sensors in bionic fingertips. To create a touch sensor, two ETPU surfaces are printed with a small air gap between them. These surfaces will move closer together when pressure is applied to the fingertip. When these surfaces make contact, it closes a circuit, and this signal can be used to let the user know when they’ve firmly grasped an object.

This binary (on/off) touch sensor is one of the most basic 3D printed sensors, and it can be modified to make more complex sensors such as deformation sensors, vibration sensors, and force sensors.

One of the main benefits of 3D printing sensors is that it simplifies and speeds up production. With 3D printed sensors, pre-built components do not need to be manually attached to an object. The sensors can instead be part of the printing process itself.

Want to find out how Shapeways can help fulfill your medical industry needs? Contact our team today to get a personalized consultation.

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GE Healthcare Partners With Formlabs To Improve Anatomical Model 3D Printing

If you’ve ever laid in an MRI or CT machine, you’ve probably stared at the GE logo on the equipment as there’s not much else to do while the images are taken. GE makes a lot of the imaging equipment used by radiologists and other healthcare providers so they make the perfect choice for Formlabs […]

How Surgical Residents Can Benefit from 3D Printing

The traditional way for surgical residents to learn and improve at procedures is to use cadavers (human corpses) that were donated to science and perform practical surgery training on them. However, the overreliance on cadavers is a burden on surgical training due to short supply. At Mayo Clinic in Florida, one resident thought outside the […]

Webinar On High-Temperature Polymers

High-temperature polymers are all the rage right now in 3D printing, and for good reason. Materials like PEEK, PEKK, and ULTEM are reshaping the manufacturing space with their high strength-to-weight ratios, chemical resistance, and high operating temperatures. As a manufacturer of 3D printers designed for industrial applications, AON3D prepared a webinar to give you the […]

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Life-Size 3D Printed Models Aid Doctors in Canada

With the help of the University Health Network’s Peter Munk Cardiac Centre, doctors in Canada are creating accurate, life-size 3D printed models for better pre-operative preparation. The models mimic hearts, spines and other body parts, giving doctors a better understanding of a patient’s condition prior to surgery. These models also provide better training methods and medical visualizations. […]

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Creating Prosthetic Limbs With 3D Printing

The tedious process of creating comfortable prosthetic limbs is well-researched, but new technology is always around the corner, and 3D printing is slowly making its way into the field of prosthetics. Traditionally, vacuum forming and cast-making have been used to create prosthetic limbs and sockets, but 3D printing is proving to be a viable alternative. Especially when the task is as complex as fitting a prosthesis to a patient, low-volume manufacturing with high accuracy and customizability is favored. Quite a few companies are finding success with 3D printing components for their prosthetic and bionic limb replacements.

Since prosthetics companies and start-ups design 3D-printable prostheses from scratch, there is a design phase that has to occur before a prosthesis can be tested and medically certified. Like any new product, bionics and prosthetics require iterating through many prototypes. Since 3D printing is accurate, affordable, and able to quickly produce quality parts, it is perfect for rapid prototyping.

Prototyping

Research teams make extensive use of 3D printing when creating prostheses and bionics prototypes. Since bionic limb replacements can be complex devices, many tweaks and adjustments need to be made before a final design is reached.

Some prototypes are made to test functionality, and others are made to judge form and aesthetics. Take a prosthetic hand, for example. A functional prototype might aid in testing the motion of the fingers as they clench, while an aesthetic prototype might be used to visualize the overall shape of the prosthesis. For both of these purposes, 3D printing is the perfect prototyping solution. 3D printing allows design teams and researchers to quickly and efficiently crank out the next iteration of their project, making it easier to move their product into production.

After a base design is reached, a prosthesis still needs to be fitted to every patient individually, and this is when the prosthetic socket is required.

What is a Prosthetic Socket?

Prosthetic sockets connect patients to their prosthesis. Sockets are the interface between the skin of the patient and the rest of the prosthesis, so they must be comfortable for the patient while providing rigidity and support.

Sockets are typically designed by qualified prosthetists. Prosthetists are medical professionals who can design sockets that fit comfortably while meeting the specific needs of each patient. Traditionally, producing a socket begins with a lengthy visit with a prosthetist, where measurements are taken and specific needs are addressed. Then over the course of a few weeks, a test socket is created, the fitting is tested by the patient, and then a permanent socket is created based on the feedback from the user, as well as the observations of the prosthetist.

This production process is shifting toward the use of more advanced technologies, such as 3D scanning, in order to more easily capture the complex shape of a patient’s limb.

Custom Manufacturing

3D printing isn’t just good for creating prototypes. Some bionics companies include 3D printed components in their flagship products. For example, Open Bionics has developed a medically certified bionic arm named the “Hero Arm”.

The Hero Arm is a partially 3D printed bionic arm that is fitted to each patient on an individual basis. It allows users to select from a variety of grip patterns and it works by closing its fingers when it senses muscle contractions in the patient’s residual arm tissue.

Since the Hero Arm has to be custom-fitted to each patient, there are some components that need to be custom-made. One of these components is a flexible, ventilated socket that attaches the Hero Arm to the user’s remaining forearm.

Creating a custom 3D printed socket is achieved with a unique approach. Initially, a cast of the patient’s arm is created by a prosthetist. This cast captures every detail and will fit the patient without being too tight or too loose. This cast is then 3D scanned. The 3D scan is then sent to Open Bionics. Designers at Open Bionics will use the 3D scan and computer-aided design (CAD) software to create a custom socket model for each patient. This model is then 3D printed, and attached to the rest of the arm.

Many patients choose to get unique colors, textures, or even superhero designs on their arms, and this is also easily achieved with the help of 3D printing.

Prosthetics for Infants

Most prosthetic limbs are designed for older children, teens, and adults. For infants though, there are currently very few options. Infants and toddlers grow very rapidly, and they’ll quickly outgrow most prostheses. Many children also reject the use of a prosthetic limb, as they can be uncomfortable and frustrating to use. Children with early prosthetics experience will benefit later on because they will retain muscle function in their residual limb. They’ll also more easily adapt to new prosthetics later in life. As a former psychology teacher, Ben Ryan, the founder of Ambionics, knew all about the importance of early prosthesis training. Ben wanted his child Sol (who unfortunately lost most of his left arm) to be able to grow up using a controllable prosthetic hand.

The Ambionics arm is mostly 3D printed. It uses a unique, human-powered hydraulic mechanism, and it is designed for children who are quickly growing. Using 3D scanning technology and 3D printing, new arm sockets can be created and delivered within just a few weeks. This method is accurate and much faster than traditional methods which typically involve a long visit to the prosthetist and over a month of waiting before getting a socket which might not even fit correctly.

Ambionics (now partnered with Glaze Prosthetics) has the goal of delivering affordable, functional prosthetic hands to children and infants.

Looking to 3D print your medical parts? Shapeways offers a variety of materials that are perfect for both prototyping and end-use medical products.

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Newcastle Hospitals Set Up In-House 3D Printing Lab For Anatomical Models

Orthopaedic and Spinal Surgeons at Newcastle Hospitals NHS Foundation Trust are setting up a new in-house 3D printing facility for the creation of anatomical models. The facility will cater to multiple hospitals in the region and provide patient-specific models for better patient-care and surgical planning. The use of 3D printing is set to drastically reduce […]

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Kumovis R1: 3D Printer with an Integrated Cleanroom

Munich-based Kumovis released its debut 3D printing system, gearing it towards medical applications and products. The company is touting the printer’s ability to convert the build chamber into a cleanroom, effectively eliminating concerns of contamination during the production process. Kumovis also intends for the printer to provide economically accessible production that caters to patient-specific needs. […]

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3D Printed Meshes Mimic Ankle Tissue-Like Mechanics

Medical 3D printing has always taken cues from biology to develop new functional parts and prosthetics. With the advanced engineering capabilities the technology allows, researchers have developed “externally worn and implantable tissue-support devices, such as ankle or knee braces, and hernia repair mesh“. These 3D printed meshes and supports mimic tissue mechanics and help support […]

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Biocompatible Resins Launched by Zortrax

Zortrax has just launched a new line of biocompatible resins for medical and dental applications. These new materials are especially useful for bridges, crowns, surgical and prosthetic goods. Zortrax has also optimised these materials for use with their Inkspire 3D printer, allowing for precise and quick development of crucial medical devices using their LCD printing […]

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