Designing medical products is typically a time consuming and expensive process. Challenged with rapidly designing a manual intraosseous infusion device for the developing world, San Francisco-based design firm LUNAR leveraged Carbon’s Digital Light Synthesis™ technology. With support from Carbon, the firm eliminated conventional molding and production to dramatically reduce development time and meet their goal of a production-ready release in four months. The benefits of Carbon’s 3D Manufacturing approach can be applied to a wide range of medical devices, suitable for both the developed and developing world.
An intraosseous infusion device rapidly delivers life-saving fluids to patients with severe trauma. If veins have collapsed and cannot accept an intravenous (IV) infusion line, this device creates venous access by drilling into the marrow of a long bone and placing a cannula for line insertion [Figure 1]. Traditional devices employ either a spring loaded or battery powered drill and typically cost $300 upfront, with a per use cost of about $100.
Figure 1: Real-world application of an intraosseous device.
LUNAR, an award-winning design firm now part of McKinsey Design, faced the challenge of designing a manually operated single-use device for the Indian market. The high costs of existing devices create a barrier for end-use, and LUNAR was tasked with solving this problem by creating a simple, low-cost solution, which invited the integration of 3D Manufacturing.
- Speed: Conventional design cycles take many months, with up to 16 weeks of lead time when the design iterations require retooling in the manufacturing process. Using this method yields a dramatically accelerated time to market.
- Simplicity: To be useful in developing countries, the device needed to be simple to assemble and cost-effective to manufacture.
- Biocompatibility: From a functional standpoint, the material needed to be biocompatible for skin contact, compatible with multiple sterilization methods including ethylene oxide (EO), and have robust mechanical properties consistent with the forces the drill would be required to withstand.
- Functionality: The handle needed to provide excellent grip for stability during insertion of the needle.
- Rapid design iterations: Leveraging Carbon’s Digital Light Synthesis™ technology, LUNAR engineers could iterate the product design daily without incurring expensive tooling costs. Ultimately three iterations were developed within four weeks, a process that would typically take four to six months with conventional manufacturing technologies.
- Reduced complexity: Carbon and LUNAR designers partnered to reduce the complexity of the final device by consolidating a multi-part assembly into a simpler design with fewer parts. Doing so not only reduced complexity, but it also reduced potential points of failure. The final device was printed in a single material and assembled in a matter of minutes.
- Material selection: Carbon offers a wide range of functional materials for end use parts. For this particular application, LUNAR designers selected Rigid Polyurethane (RPU) 70 material for its biocompatibility, its strength and durability (1.9 GPa modulus and 22 J/m impact strength), and its compatibility with multiple sterilization methods.
- Digital texturing: Additionally, Carbon’s end-to-end digital manufacturing workflow enabled LUNAR designers to easily add texture to the surface of the handle in order to improve grip and product performance. No retooling or post finishing was required.
RAPID DESIGN ITERATIONS
LUNAR’s design and engineering team were able to exchange ideas, digital files, and printed parts with a team of engineers in India. Each design iteration was tested in cadaver studies by the Stanford Biodesign team in India.
Carbon’s technology enabled the LUNAR team to quickly reimagine their existing design into durable printed parts, testing new features to improve usability, reducing cost and complexity on an almost daily basis. This agile manufacturing feedback loop simplified and improved the final product without incurring expensive tooling costs or adding lengthy lead times when testing new designs or features.
“We spend so much time designing for the prototyping process and then we have to do it again for the manufacturing process… With Carbon, it is possible to design, iterate, and manufacture on the same means of production.”
The original LUNAR design was created with only prototyping in mind. Carbon examined the design and collaborated with LUNAR to redesign the part for 3D Manufacturing. The team reduced the number of parts and the complexity of assembly, all with a mindset of manufacturing using Digital Light Synthesis™ technology. With each design iteration, the complexity and the cost of the device were reduced.
By modifying the original design to optimize the handle for 3D Manufacturing, the handle was simplified, eliminating an interior feature and two set screws [Figure 2 – 3]. The next iteration of the design incorporated the cog mechanism directly into the handle, which removed the interior handle and set screws. This integrated mechanism would have been very difficult to produce using traditional manufacturing methods such as injection molding. The new design simplified assembly as well as reduced the number of components.
Figure 2: A better handle on the design.The initial concept for the drill handle was a three-piece design that included an outer handle, an end cap, and a bushing for the cog to limit motion to only one drive direction. This bushing would be inserted into the handle and secured with two set screws.
Additionally, the LUNAR team realized that the product performance could be improved by adding texture to the handle [Figure 4]. This straightforward change to the CAD file was implemented with the single push of a print button, with no additional tooling or post-processing costs.
Using Carbon’s DLS™ technology, McKinsey Design firm LUNAR and Carbon were able to collapse multiple manufacturing steps and rapidly iterate on a design for a life-saving product.
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