4.5 Concept Exploration & Testing

The Miraclefeet Brace: Prototyping Approach

Craig Milroy, co-director of Stanford’s Product Realization Laboratory, interviews student Ian Connolly about his team’s approach to prototyping to address the need for a more effective, affordable solution for club foot.

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IDEO: Medtech Prototyping

David and Tom Kelley of IDEO share their approach to medtech prototyping.

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Prototyping versus Development

Mark Deem, a seasoned medtech engineer and serial entrepreneur, discusses how concept exploration and prototyping on the way to final concept selection is different than full-fledged R&D.

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Getting Started

In conjunction with the steps below, the guidelines described in the chapter can be used to help initiate an effective concept exploration effort. Just remember that the iterative nature of process may require innovators to circle back through these steps multiple times.

Identify the Questions or Issues to be Addressed through Concept Exploration

What to Cover

Before translating a design for a solution concept into a working model, clarify the purpose of the concept exploration activity to be certain that the goals can be achieved through techniques such as prototyping and testing modalities, including user, bench, simulated use, and tissue testing. Define specific questions that must be answered through the creation of the prototype (e.g., will this specific functionality work?) to guide test development. Keep in mind the environment in which the device will be used (e.g., hospital, home use, portable, fixed). This will help define the questions. The answers to these questions should prove a specific element of the design and, in so doing, reduce risk along the development cycle. Resist the temptation to raise questions that are not on the critical path. Remember that these questions can (and should) evolve over time as the invention progresses from idea to product. Each time a prototype is developed, the questions it is designed to answer must be revisited and revised to maximize the benefit of the effort. The answers to these questions should be translated into increasingly specific design requirements.

Where to Look

Go to trade shows in the therapeutic area and look at competitive products. Generate ideas for questions by looking at competitive devices as well as those entirely outside the therapeutic space, and use this as input to help define prototyping goals. Also, study the company’s own designs carefully to isolate the most critical questions to resolve at each stage of prototype development. Interact extensively with the engineering team to define prototyping goals and allow this team to drive the process.

Design the Minimal Model Needed to Answer Those Questions

What to Cover

For the top priority functional block(s), determine the best category of prototype to develop in order to answer the first question that has been defined. Strip out anything and everything from the model that does not explicitly need to be tested. Focus only on the critical path in defining the model. Look at what other companies have done and how they have designed their prototypes and products. For example, well-known companies have developed highly effective prototypes using nothing more than foam core and paper clips or two syringes and a woodworking clamp. A model does not have to be expensive, complex, or made from specialized materials to be effective. Custom prototyping is costly and time-consuming when certain concepts can be proven with ready-made, easily available, and inexpensive materials.

Where to Look

Interact extensively with the engineering team (if one exists) and/or seek input from others who have experience in designing and developing prototypes.

Identify and Prioritize Functional Blocks

What to Cover

Identify the functional blocks associated with the solution being studied. Each block should represent one aspect of the concept and will likely be tied to a distinct engineering discipline based on its characteristics (e.g., mechanical engineering, biomaterials science, electrical engineering, and computer science/software engineering). Prioritize which functional blocks to start with, based on what is known about each one and where the greatest risk/uncertainty exists.

Where to Look

Use the original need criteria, along with more specific functional design requirements that may have emerged through previous analysis (see chapters 4.1, 4.2, 4.3, and 4.4) to establish the boundaries for each block and to prioritize them.

Build the Model

What to Cover

Create the prototype focusing only on those elements necessary to address the key question that has been defined (e.g., functionality, interaction of parts, whether the clinical problem can be solved with the design). Prove the concept, retire the most significant risks, and iterate the design along the way. When considering materials, start with basic, inexpensive materials and then gradually progress to more complex, expensive alternatives (e.g., for a mechanical prototype, an inventor might advance from paper and wood to plastics and metals). Similarly, use purchased parts and other off-the-shelf materials whenever possible, reserving the need for specialty or manufactured parts until the later stages of prototype development. As the complexity of models progresses, consider what can realistically be accomplished in-house and what services might require specialized third-party assistance. Given the fact that multiple engineering disciplines may be involved in creating a single prototype, coordination of the efforts across multiple shops may be required.

Where to Look

  • See the following online appendices for more information about special considerations in building different types of prototypes:
  • Medical Device Register – Database that can be used to identify manufacturers of medical devices and see what companies are working in specific areas of interest.
  • Qmed Supplier Directory – Online information source that includes a database of suppliers.
  • Medical Design and Manufacturing Shows – The best place to talk to suppliers and review latest prototyping technology. Shows are held annually in Southern California, the East Coast, and Minneapolis.
  • Mechanical Engineering Resources
    • GlobalSpec A search engine and information source designed especially to serve the engineering, manufacturing, and related scientific and technical market segments.
    • McMaster-Carr A supply company with more than 550,000 products.
    • Local Machine Shops
    • Richard G. Budynas and J. Keith Nisbett, Shigley’s Mechanical Engineering Design (McGraw Hill, 2010) – A respected textbook and reference for mechanical prototyping and engineering.
    • Warren C. Young and Richard G. Budynas, Roark’s Formulas for Stress and Strain (McGraw Hill Professional, 2001) – A useful reference for more detailed mechanical engineering and design.
    • Tom Kelley, Jonathan Littman, and Tom Peters, The Art of Innovation (Crown Business, 2001) – See chapter 6 for valuable information on prototyping.
    • Tim Brown, Change by Design (Harper Business, 2009) – See chapter 4 for valuable information on prototyping).
    • 3D Printing”, Wikipedia.org – While sometimes the information on Wikipedia should be questioned, the entry on 3D Printing is recommended by engineers as being comprehensive and up-to-date.
  • Biomaterials Science Resources
    • ASM International Website– A searchable database of modules on materials commonly used for medical device development. Some content may require a license. Has clinically approved devices, including FDA information and literature reviews.
    • MatWeb– Database of materials. Does not tell which devices use what materials, but it can be used to check the grade of materials.
    •  Society for Biomaterials
    • Materials Research Society
    • ASTM International
    • International Organization for Standards (ISO)
    • Buddy D. Ratner, Allan S. Hoffman, Frederick J. Schoen, and Jack Lemons, Biomaterials Science: An Introduction to Materials in Medicine, Third Edition (Elsevier, 2013).
    • Anthony Atala, Robert Lanza, James A. Thomson, and Robert Nerem, Principles of Regenerative Medicine, Second Edition (Elsevier, 2010).
    • Robert Lanza, Robert Langer, and Joseph Vacanti, Principles of Tissue Engineering, Fourth Edition (Elsevier, 2014).
    • J. Brandrup, E.H. Immergut, and E.A. Grulke, The Polymer Handbook, Fourth Edition (Wiley-Interscience, 2003).
    • L.H. Sperling, Introduction to Physical Polymer Science, Fourth Edition (Wiley-Interscience, 2006).
    • J.R. Davis, Handbook of Materials for Medical Devices (ASM International, 2003).
    • M. N. Helmus, Biomaterials in the Design and Reliability of Medical Devices (Springer, 2003).
  • Electrical Engineering Resources
    • PIC Microcontroller Website
    • LabView Website
    • The MathWorks Website – For information about MatLab and Simulink.
    • Sparkfun.com– An online marketplace for electronics designed specifically for prototyping, which also includes tutorials, references, a blog, and other resources.
    • Electronics.stackexchange.com– A question and answer site for electronics and electrical engineering professionals, students, and enthusiasts.
    • Darren Ashby, Electrical Engineering 101, Third Edition (Newnes, 2011).
    • Paul Horowitz and Winfield Hill, The Art of Electronics, Second Edition (Cambridge University Press, 1989) – An authoritative text and reference on electronic circuit design.
    • Michael Margolis, The Arduino Cookbook, Second Edition (O’Reilly Media, 2011) – A guidebooks for experimenting with the Arduino microcontroller and programming environment.
  • Application and Software Development
    • Jonathan Anderson, John McRee, Robb Wilson, Effective UI: The Art of Building Great User Experience in Software (O’Reilly Media, 2010) – A good introduction to project management for software design.
    • Bill Scott, Theresa Neil, Designing Web Interfaces: Principles and Patterns for Rich Interactions (O’Reilly Media, 2009) – Important insights on developing consistent, effective user interfaces for the web.
    • Jonathan Rasmussion, The Agile Samurai: How Agile Masters Deliver Great Software (Pragmatic Bookshelf, 2010) – An easy-to-read introduction to various aspects of agile software development.

Test/Refine Prototype to Develop Design Requirements and Technical Specifications

What to Cover

Use appropriate user, bench, simulated use, and/or tissue tests to prove the concept being studied. Define a test requirement (this is often a guess, but grounded in good sense) and develop baseline results. This can determine whether redesign is necessary or redundancy is required. Document the test method and procedures and record results, including technical specification related to fatigue, tensile strength, and other important issues. Remember that virtually no bench, tissue, or animal model replicates the human model, so be thoughtful and vigorous in trying to establish a model that is tougher than any probable clinical use. Based on test results, modify the prototype to address clinical, mechanical, and electrical needs. Build a new prototype. Test again. As this process progresses, identify, document, and prioritize increasingly refined technical specifications and design requirements based upon design, user input, and other standards for the device. For more advanced prototypes, use experienced practitioners (doctors, nurses, technicians) to handle the device in the clinical environment and diligently collect their feedback.

Where to Look

  • Tool Shops and Outside Suppliers – To design simple test fixtures and models.
  • Vasodyn – Glass anatomical models.
  • Limbs and Things, USA – Medical simulation models.
  • FDA Human Factors Considerations – Increasing emphasis on human factors, the study of how people use technology, should be considered throughout the prototyping process, but not at the expense of rapid development if human factors can be built into later designs. These issues are particularly important in developing feels-like/looks-like/is-like models toward the end of product development.
  • Kano Model Analysis – For assistance in systematically understanding and prioritizing technical specifications and product features.