Pro Tips for Prototypes: The Smart Way to Manage Device Iterations

There’s something about hitting the prototype stage of the development cycle that makes everything finally seem real. This is the point at which there is finally an object to hold in your hands—a physical representation of the vision, investment, and commitment a medical device developer has to improving patient lives.

This is the critical benchmark phase in the product development cycle. It’s the ultimate check for the feasibility of a concept. This is where we answer a crucial question, “Is it manufacturable?” With all the snazzy design software packages out there, an engineer might design something unable to be manufactured in a reasonable time for a reasonable cost—I’ve seen it happen. This phase also allows different stakeholders the chance to actually see the physical example representing what everyone’s working toward.
But it can be a little confusing.

As is so often the case with industry jargon, we often find ourselves separated by a common language. “Prototype” can mean anything from a clay model to a final version with medical-grade materials submitted for review to the U.S. Food and Drug Administration (FDA).

At Empirical Machine, our company offering prototyping and small-batch manufacturing, we break initial manufactured devices down into two basic categories: the feasibility version and the first-production run.

The feasibility model is also known around the shop as a “touchy-feely” version, said Meredith May, vice president of Empirical Consulting. This is an early rendering of a device intended for demonstration purposes. It will allow surgeons to get a feel for how they might use an instrument, for example. A marketing team can also start crafting messaging around this model. It doesn’t have to actually work, however, and can’t be used in a clinical environment such as surgery. These can be made out of anything that gets the job done, because that particular job doesn’t have anything to do with how it fits into the human body.

“Those are the easy ones,” May said. “They don’t have to necessarily function, they can be quickly done, you probably don’t need manufacturing engineering, you can create a model and send it to a 3D printer and something will come out. You need almost no documentation of things like materials, processes, inspections, etc.”

This is a version with very limited use. It’s not something that will factor into reporting and testing to be shared with regulatory agencies, she said.

“They don’t need to be made out of the right materials,” she said. “That’s where people get confused. ‘Touchy-feely’ cannot be used for any verification or validation of your design. They’re strictly for internal and marketing use.”

Still, these are an important part of the big picture because they basically give shape to the dream. The first-production run is much more important from a regulatory standpoint, May said.

“A first-production run prototype for me is a device that’s manufactured from the same or extremely similar materials as your finished device,” she said. “It’s manufactured with the same process. The difference between a prototype and a finished device is documentation and certification.”

At this point, the term used to describe your sample is important.

“By calling it a ‘first-production run’ instead of final prototype, you’re giving the FDA reviewer confidence that part was manufactured to your full standard and you did not cut any corners,” she said. “By calling it a first-production run, it feels more real and you don’t have to worry that the FDA will say you’re not allowed to test on prototypes.”

Keep in mind, these parts can’t be used as a final device in surgery if the material is not certified as medical-grade, she said. But for this phase in the cycle, you can save time and money without using medical-device grade materials. She cited the example of polyetheretherketone (PEEK).

“Medical-grade PEEK is expensive,” May said. “Industrial PEEK doesn’t have any certification and can’t be used in an implant. But it’s identical to medical grade PEEK except that it’s not manufactured with medical grade equipment.”

At about half the price, you can craft a prototype fitting FDA requirements for mechanical testing and other aspects of device development, she said.

“It’s OK because it’s not going into bodies, but it will behave identically to medical PEEK that will eventually go into bodies, which is what makes it perfect for prototyping,” she said. “Anodizing, laser marking—all of those things can be done without being certified for a vendor.”

As a general rule, the less documentation involved, the lower the price, May said. In many cases, you can actually go dumpster diving for materials acceptable for mechanical testing that will not be used for a 510(k), she noted.

“This is the perfect use of your manufacturing scrap and bar ends,” May said. “You don’t need to know the lot number. You don’t need certification. That prototype will be a functional prototype.”

She advised finding cost savings anywhere possible, because small-batch production is more expensive per piece.

“This is the device as it would go into a human body,” May said. “It will have a full design history record. It’s probably the most expensive piece you’ll ever make in the life of the project. Because you’re making a limited run, it’s more expensive per item because you’re not manufacturing to scale.”

This is a version a surgeon can use in a cadaver lab, package distribution testing, bench testing, and more. Even sterilization validations can be performed on this model. You can use this to write the surgical technique guide 510(k) submissions require.

“Pretty much the only thing you can’t do is biocompatibility,” she said.

Still, you’re getting a lot of bang for your prototyping buck by knowing which materials will get through a particular aspect of the cycle. Know the jargon for reporting and documentation purposes, and know which phase of the cycle you’re in to save time and money as you hone the vision for a final product. 

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Dawn Lissy is a biomedical engineer, entrepreneur, and innovator. Since 1998, the Empirical family of companies (Empirical Testing Corp., Empirical Consulting, LLC, and Empirical Machine, LLC) has operated under Lissy’s direction. Empirical offers the full range of regulatory and quality systems consulting, testing, small batch and prototype manufacturing, and validations services to bring a medical device to market. Empirical is very active within standards development organization ASTM International and has one of the widest scopes of test methods of any accredited independent lab in the United States. Because Lissy was a member of the U.S. Food and Drug Administration’s Entrepreneur-in-Residence program, she has first-hand, in-depth knowledge of the regulatory landscape. Lissy holds an inventor patent for the Stackable Cage System for corpectomy and vertebrectomy. Her M.S. in biomedical engineering is from The University of Akron, Ohio.