In consumer products, there is a sharp divide between the materials, processes and people used to create parts and assemblies during design and engineering, and those used to create the final product. The first is "prototyping", the second is "manufacturing". Prototyping is for exploration, for learning, and for making engineering decisions as efficiently as possible. Manufacturing is an extreme exercise in cost optimization while meeting an unchanging specification.
This sharp black and white split goes gray in medical device. No doctor would feel comfortable telling a patient in a pacemaker clinical trial that they were about to implant a "prototype" in their chest. Yet, the few hundred devices produced for a clinical trial are created using methods that no traditional "manufacturing" expert would willingly refer to as "manufacturing".
Rather than a binary "prototype" and "final product", there are eight distinct categories of builds that a medical device will pass through on its way from concept to full manufacture. According to most professionals' definition of "manufacturing", only the last two stages really qualify. However, new medical devices experience a rapid escalation in documentation and quality control measures starting from phase 2, both for mitigating clinical risk (ensuring safety during first in human cases) and production risk (minimizing scrap rates as volumes shoot up).
Because of this peak in documentation and controls, the drivers of fabrication decisions do not make a clean spectrum of tradeoffs from one end of the design process to the other. In Medical, there is a "messy middle" that is difficult for resources who specialize at one end or the other of the spectrum to meet. This is a short term, but high-risk time-point. For part and service providers, it lacks the long-term profitability of final manufacturing, while carrying a much higher reputational risk than not delivering on a handful of cheap mockups. This business reality makes it an unpopular product stage for fabrication companies to support. Start-up founders and new product managers often discover this when they find themselves stuck at the limit of their prototype shop's capabilities, while still too early to reach the interest of the full production manufacturers.
The period of technical and clinical validation (Phases V and VI), when the company is seeking its critical regulatory approval, is the period of highest spending a company will meet pre-revenue. This is the not the time for a design team to start chasing down material sources and onboarding brand new manufacturing partners. Because the stakes get higher, and delivery of correct documentation is just a critical as accurate parts, suppliers take longer to provide an actionable quote. This quote time is added to the "new customer" onboarding process time. Depending on financing terms and the size of the order, this may include credit checks and references. Add in the actual production time, and a last-minute re-sourcing of a critical custom component can delay a critical milestone by 4-6 months. With even the leanest start-ups running a burn rate in the mid to high six figures during pivotal clinical trials, that is a multi-million dollar mistake.
This potential company-ending risk is why laying out a build strategy across the entire development process, rather than just "prototype" and "manufacturing," is so critical in medical devices. Most start-up founders are aware of planning around financial, clinical, regulatory and legal milestones. When can they expect to raise new funding? When will they have their first clinical evidence? When will they receive their patents, incorporate, and hire their first employees? These are often planned out in detail at the earliest stages of a company. This same planning needs to occur around finding, validating and onboarding resources for the different stages of product development. If parts or assemblies need to be in hand to meet financial, clinical or regulatory goals at a certain date, sourcing them needs to start at least 4-6 months beforehand.
This planning, like any part of an evolving entrepreneurial plan, does not have to start with great detail or accuracy, but it should be started early. While total part count, part geometry, assembly order, material and coating selections are all sure to change, managers can still create a rough list of the types of materials, parts and processes you will need. Once there is a rough list, a method for filling that need can be marked out for each of the approximate 8 phases of the product development.
This table gives some examples of common components, and how the sourcing can evolve differently for each.
Most concept prototypes are mock-ups, since often the feedback being looked for (size, weight, overall interactions) can be obtained without the time and expense of functional components.
Mature prototypes are generally produced using entirely off the shelf (MP-Mass Produced) components purchased through resellers, or are custom assembled by the design team (such as a prototype electronics breadboard). In the case of something as ubiquitous as a rubber push button, purchasing a 99 cent calculator for parts (repurposing) often beats the retail pricing of component resellers in small volumes.
The components most critical to achieving engineering and clinical functions start appearing as custom, small batch run parts during engineering unit builds. These are exceedingly early units with minimal cost optimization to meet the final product price needs for commercial launch.
When units being used to generate regulatory submission data, (V&V Testing, Pivotal Clinical Trials) prototype fabrication methods (such as 3D printing and hand assembled electronic boards) give way to controlled processes that can meet the performance and documentation requirements. While the intention of this phase is to prove the clinical efficacy and safety of the final product to be sold on the market, small changes (such as custom buttons or color changes to better match company branding) are frequently made before the product actually goes to market.
Assuming a successful launch and growing demand, many device companies undergo resourcing projects to drive down costs after the product demonstrates commercial viability. This may include redesigning certain parts to reduce their manufacturing costs, replacing a mass-produced part with a custom one to reduce a failure risk, or simply seeking out a larger scale partner capable of meeting the larger volumes.
The emphasis on limiting risk in medical can give early decisions in methods, materials and partners a long, long legacy. A design that completes clinical trials, but then requires sweeping changes to reach commercial viability, faces the risk of repeating those clinical trials. Building out a bridge across the "messy middle" of manufacturing is not just an engineering team decision, but a critical issue that will help decide the product's eventual success or failure.