Nov 19, 2019

3D Printing Medical Devices: Considerations for Wearables and Implants

3d printing medical devicesAdditive manufacturing systems are already forcing systems designers, manufacturers, and scientists to rethink how they create new systems and develop advanced materials for futuristic products. The medical implant and wearable fields are no exception. What use to be confined to dental models and other body models has now expanded to devices like hearing aids, orthopedic and cranial implants, surgical instruments, dental restorations, and external prosthetics.

Wearable devices and some implants, especially those intended for real-time monitoring of chronic health conditions, require a flexible electronics platform that is biocompatible and compact enough to fit in the human body. 3D printing of medical devices will soon span beyond body models and prosthetics as more advanced electronic materials and additive manufacturing platforms become available. This enables the creation of unique electronic medical implants and other devices from a broad range of biocompatible materials.

3D printing medical devices, organ models, and prosthetics

Prosthetics and organ models are already popular 3D printed medical devices

The Current State of 3D Printing Medical Devices

If you’ve recently received a new pair of electronic hearing aids from your doctor, they were most likely produced with a 3D printer. Additive manufacturing is also being used elsewhere in the medical field to produce a range of unique medical devices. These include:

  • Patient-specific prosthetics. Any prosthetic must be crafted specifically to the patient. Working with a 3D printer allows these customized medical devices to be uniquely tailored to patients with lower cost and production time. Hands and arms are the most common 3D printed prosthetics, and organizations like the e-NABLE Community are focused on providing the world with a library of low cost, open-source 3D printable prosthetics.
  • Customized biodegradable stents. Patients with arterial diseases sometimes require a biodegradable stent to keep blocked arteries open. The most cutting-edge research has been used to produce 3D printed sugar-based stents for assisting surgical procedures and for drug delivery.
  • Patient-specific implants. Every patient is unique, and adapting an implant to a specific patient’s body can be a complicated, expensive process. 3D printing allows an implant to be adapted to the patient’s body by conforming the implant to a 3D model. These 3D models can be generated using standard medical imaging technologies, such as nuclear magnetic resonance imaging (NMRI) and computer tomography (CT). One excellent example is a titanium alloy implant from Ortho Baltic Implants, which can be 3D printed using a direct metal laser sintering (DMLS) process.
  • Surgical tools. 3D printed surgical instruments provide significant design flexibility with minimal production time. These instruments can be easily fabricated to suit particular functions. As an example, a group of US Army and Navy researchers produced a 3D printed surgical kit containing a Kelly hemostat, needle driver, tissue forceps, retractor, scalpel handle, and scissors from an engineered plastic modified with silver. 3D printing these tools helps solve some acute supply chain issues.

As such, 3D printing medical devices certainly has massive potential for innovation and creative problem solving for long-standing, difficult medical difficulties. 

Challenges in 3D Printing Medical Devices: Implants and Wearables

The areas outlined above illustrate how additive manufacturing systems have been used to print primarily mechanical medical devices. Expanding beyond the current range of medical devices carries a number of challenges. Advances in additive manufacturing processes have progressed alongside development of new useful materials, but these materials are not biocompatible. Other polymer materials for external use (i.e., in wearables) require repeated sterilization with a solvent or with heat, which causes these materials to slowly break down over time. This is known to cause premature failure of these devices.

This illustrates a primary challenge in expanding the use of 3D printing for medical devices. The range of useful materials needs to expand to include more biocompatible and biodegradable materials. 3D printing processes will also need to be specialized to work with these particular materials. Multiple companies are pushing to develop higher grade, sanitation-resistance biocompatible materials for 3D printing medical devices. These include polyether ether ketone (PEEK) filaments, graphene inks for organ scaffolds and electronics, and other biomaterials.

As the range of 3D printable biocompatible materials and their deposition processes expand, one can expect to see unique 3D printed electronic medical devices used in more human patients. This requires working with an additive manufacturing system that is adapted to 3D printing electronics with any geometry.

3D Printed Electronics for Medical Devices

The next frontier is electronic medical implants and wearable devices. Use of these devices provides can provide significant benefits to patients and to doctors, and they have the potential to reduce costs by eliminating some expensive medical procedures. 

This class of medical devices can enable real-time monitoring of chronic medical conditions and transmission of data to a patient’s mobile device. This data can then be sent to the patient’s medical provider for further analysis, or the data can be analyzed to warn the patient of an upcoming episode before it becomes serious. One example is 3D printed heart monitors that are equipped with an array of 3D printed embedded sensors.

3D printing medical devices and human jaw from unique materials

3D printed human jaw from a photopolymer using stereolithography

Electronic medical devices, whether they are wearable or implants, require a PCB with unique architecture. Standard planar PCBs are not suitable for every medical device as these rigid boards use materials that are not biocompatible, thus they cannot be used as implants. Rigid boards can be used in a number of wearables, but they cannot conform to a patient’s body. Flexible PCBs help solve this issue somewhat, but standard PCB fabrication processes still involve materials that are not biocompatible, thus these flex boards could not be used in implants.

3D printing medical devices helps solve both of these problems. Working with a 3D printer that is adapted specifically for unique electronic devices allows a PCB to be printed with nonplanar architecture and complex shapes that are not possible with standard PCB manufacturing processes. This allows electronic medical devices to be adapted specifically to a patient’s body, making these devices more user-friendly. Once the materials challenges noted above are addressed, this will allow 3D printing electronic medical devices with unique architecture and functionality.

In order to make these devices sufficiently small for use in the human body, new additive manufacturing processes will need to be adapted for use with these materials. Currently, commercial inkjet 3D printers provide among the highest resolution for 3D printing medical devices with electronic components. Some upcoming processes, such as multi-photon lithography (TPL) techniques, will allow 3D printing medical devices and electronic implants with sub-micron resolution. More guidance from regulatory agencies, the FDA being chief among them, is required before we see widespread use of 3D printed medical electronics.

3D printing medical devices is soon to be commonplace, and designers can 3D print electronics for these unique devices with the right additive manufacturing system. The DragonFly LDM system from Nano Dimension is ideal for on-demand fabrication of complex electronics with a planar or non-planar architecture. Read a case study or contact us today to learn more about the DragonFly LDM system.

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