Article Focus:
• Developer objectives
• Medical device innovation comes from small and nimble firms
• How best to harness new 3D-printing technologies

Developing and prototyping medical devices is increasingly critical and competitive. Most innovation presently comes from smaller niche companies. These specialist companies subsequently are absorbed by larger multinational firms capable of significant market capture. The smaller entrepreneurial firms need to focus on their core competency in innovation, but wearing many hats while growing a small company can occasionally drag that core focus down. To overcome this problem, it can be helpful to outsource physical prototyping to a 3D-printing bureau. It is also advisable to reduce tooling costs, speed up design iteration, and tap into the latest and greatest materials and technologies without needing deep pockets. For smaller firms, having something prototyped and in hand sooner rather than later helps keep investors interested, optimistic, and confident.

Medical device and surgical automation expert Martin Sklar, president and CEO, of Automated Medical Instruments Inc, Needham, MA, says device developers have to prove that the device works better than existing devices while meeting user requirements; it saves time or money; and it is different and worth the cost of bolstering education and training to drive adoption.

Developers may be proving this to doctors, companies, or investors concurrently, and need to be agile enough to keep up with market shifts while the device is in development.

Prototyping has come a long way, says Sklar. In the past, prototypes were simply for observation, then function. Today, moving mechanical assemblies are being printed without any assembly needed, thanks to 3D print processes that need no finishing after printing.

Perhaps the ultimate change has been the advent of “direct digital” or “additive manufacturing” which accounts for 3D printed parts ready for actual use. This past year, there has been a large uptick in the number of surgically installed implants for orthopedic repair, reconstructive surgery, and prosthetic development worldwide. Examples include direct metal laser sintering (DMLS) or electron beam sintered (E-Beam) metal knee and hip joints. The availability of polymer printed parts, metals, and ceramic parts through 3D print bureaus has given everyone from the largest corporations down to a single inventor in his or her garage access to precise, complex, and custom parts. This phenomenon has been called “the democratization of design.”

Global sandbox

Arlen Meyers, professor of Otolaryngology, Dentistry and Engineering at the University of Colorado, Denver, is head of the Society of Physician Entrepreneurs (sopenet.org), a nonprofit organization that, as he puts it, is “a global sandbox” that provides medical professionals in active practice access the tools and support for bringing new ideas and devices to reality. Pairing doctors and surgeons with thermal, mechanical, electrical, and environmental development issues, SoPE can accelerate innovation by allowing better communication between the problem finders (doctors) and solution providers (engineers). Why? Because engineers may not fully understand the medical problem and vice-versa. Also it’s important that engineers can convey to entrepreneurs what technologies (such as 3D printing) and materials may be available to build the best prototype to prove function and then interest investors for a commercial venture.

Meyers feels that the way device development (and healthcare in general) should move forward and promote innovation is to use patient-driven R&D. An analogy is Proctor and Gamble, which uses customer feedback along with agile processes to develop consumer products. “However, current medical-device developers may be developing products 98% in-house and only minimally soliciting patient feedback because profit comes directly from health institutions,” says Meyers. “The current flawed system is unfortunately arranged with a flow from medtech and biotech to regulators and then to payers. This approach forgoes two crucial players — doctors and patients.”

As Meyers points out, there are approximately 950,000 doctors in the US, but only 4% of them may be in university research. The remainder are doctors “in the trenches” who are ideally situated to see problems and often solutions. SoPE aims to help these practitioners bring their ideas to fruition and advance medical treatment and prevention with innovations from a doctor and patient perspective.
Design cycles

Craig Lanning, instructor, Dept. of Bio-Engineering, at CU Denver, heads a new department there specializing in medical-device prototyping in conjunction with researchers at the university and medical professionals from University Hospital and Children’s Hospital in Colorado. The state-of-the-art 3D-printing facility can produce polymer and metal sintered prototypes from a variety of processes. Over the last year and a half, the department has had great success in developing new devices. So much so that spin-off companies have collected in a business incubator also located at the campus.

Lanning has been involved with medical-device development including heart pumps, staple guns, and retractors, shape memory stents, and spinal fusion devices. Medical devices prototyped through the bio-engineering department have supported the creation of numerous startup companies, which have raised millions of dollars in investment funding.

Lanning is familiar with the synergy between 3D printing and physician entrepreneurs. He describes doctors as being surprised at the speed and high quality of prototypes that were 3D printed to test device ideas. He says, “Rapid prototyping may have increased the number of design cycles, but it also has dramatically decreased the cycle time.” He cites as an example a pediatric-heart-pump prototype that was constructed in two months at CU Denver with four iterations. He suggests that this project could otherwise have taken at least a year and would have been prohibitively expensive.

Devices are generally a mixture of off-the-shelf components such as screws and custom-printed parts. Sizes can range from millimeters to half a meter. Components can be larger by designing several parts to fit together. This might accommodate devices such as a spine board that needs to be full-size to test. For small or micron scale parts, for example, those in ophthalmology, new technologies are emerging such as two-photon lithography, recently developed in Vienna, Austria.

3D printing and the FDA

There are now several 3D printing materials that are USP class VI approved for the lowest possible levels of biological reactivity. This approval (although different from biocompatibility) means that materials have passed certain toxicological requirements for body and skin contact. Craig Carder, principal engineering consultant, C3 Medical Device Consulting (c3mdc.com), Boston, describes the difficulties when designing and testing an electromechanical device which may be inserted into the body in terms of moisture sealing and enclosure design. Often the PCB design happens independently or after enclosure design, and this can be a problem if hard tooling or molds already exist. Encapsulation is sometimes used for the electronics, but when the enclosure must be sealed, newer techniques, such as Objet’s (objet.com), Billerica, MA, Polyjet for 3D printing multimaterials simultaneously, can build-in rubber-like O-ring seals, which can be useful in prototype iteration. Of course, good communication between all parties in the design can help, as does rapid iterations of a design to iron-out fit issues and sealing problems that can happen prior to locking in the design for FDA regulation stages.


New approach tospinal fusion

Dana Carpenter, assistant professor, Mechanical Engineering at CU Denver, and Lillian Chatham, research assistant, will soon be publishing a paper on a new approach to spinal fusion that takes full advantage of patient scanning, FEA analysis, and state-of-the-art 3D printing with PEEK material for an interbody fusion device. The devices are used to support a spine by inserting screws into vertebrae, using an interbody spacer to maintain alignment, and anchoring a cage of rods that then holds the spine in position. The traditional approach is to perform the operation using off-shelf surgical screws and rods and relying on the scans and surgeon experience to decide the best spots to drill and mount the fusion cage. Also needed may be bone grafts to provide spacer support in between the vertebrae.

In contrast, the new approach being investigated is to first use a new software model to input patient-specific data such as height and weight. This data is coupled with patient scans to custom size the screws, rods, and support spacers that will then be 3D printed from a material closely resembling bone, such as PEEK. FEA will be used to verify the screws have the right stiffness and strength and help to provide direction to the surgeon on where best to insert them. For strength testing and validation of the method, it was decided not to use actual bone vertebrae to mount to because every bone is different, and variations in density or degradation pockets could have thrown-off the test repeatability.

Instead, patient-specific vertebrae for testing the mounts were 3D printed, and the rods, screws, and spacers were also 3D printed. Testing is ongoing, but results may lead to a new and improved system for spinal fusion, which offers longer implant integrity, shorter surgeries, and reduced cost by virtue of fewer patient complications down the road.

Device conserves anesthesia

In addition, Ron Farrell, chief operations officer of European device developer Sedana Medical AB (sedanamedical.com) Sweden and Germany, says the company has patented an anesthetic conserving and delivery device called “AnaConDa,” which delivers both sevoflurane and isoflurane and is used inline with a standard ventilator (i.e. no special anesthesia respirator equipment is required). The palm-sized device is qualified and doing well in Germany, and Sedana Medical looks forward to gaining FDA approval in the near future.

Farrell describes modifying the AnaConDa for broader application by adjusting the “dead space” volume in the device to accommodate a range of tidal-flow respiration. The problem was how to accomplish this without modifying existing production tooling. Engineers looked to 3D scanning and 3D printing to reach this goal.

When looking to alter the dead space without affecting the capabilities of the device, engineers experimented with clay filler pieces to approximate shape. They were then able to take a 3D scan of the new interior, convert to CAD, and create 3D printed versions for air-flow tests without having to modify any existing tooling or interrupt production. Once a new or alternate version of the device is successfully tested this way on their simulation respirator, a new tooling insert can be created for subsequent production injection molding that allows for huge cost saving over a new mold or iterations in tool steel. As Sedana Medical look towards rolling out more AnaConDa’s in more countries, this high-tech approach vastly shortens the design cycle, and allows for more freedom to experiment with design while reducing tool costs.