The Pitfalls of Medical Device Design: Late-Stage Design Changes

A close-up image of a technician’s hand as they place a processor in CPU socket on the motherboard of a computer or piece of tech


Creating medical devices that are safe and reliable is the primary responsibility of a medical device designer. They must assess technology, customer wants and needs, and the completeness of the execution of designs and processes.


Numerous challenges can arise if usability is not considered throughout the process from early conception to final validation. One common issue that might arise in the production of a medical device is late-stage design changes.


Changes to a device’s design after production begins is another of the most common pitfalls of medical device design. In the first installment of this blog series, we discussed the lack of design follow-through. In this second look, we will take a moment to discuss the late-stage design changes, potential delays and added costs that might develop.

Roadblocks in medical device design: late-stage design changes

When developing a new medical device and preparing to bring it to market, companies may not consider users at the beginning of the project. They may find themselves beginning the production with one path in mind, only to attempt to adapt the design in the later phases when alpha or beta prototypes are tested by users.

This can be one of the most difficult pitfalls to prevent in a design process. Engineering teams often insist early on that they know what users want, only to be proven wrong by user feedback later in the process.

Increasing expenses as the project progresses
Identifying a need that requires a design change early in the development process is all but free to the developer and the client. As the project begins, there is no incremental NRE cost because identifying changes and alterations is what those phases are designed to accomplish.

Identifying that same need later in the project requires re-working elements that have already been established. This represents going backwards, re-spending money and extending the end of the project, which eats into the ROI and the NPV of the overall program.

Backfilling usability data
Another issue in identifying potential issues early on is the idea of backfilling usability data. To meet technical standard requirements, companies may try to backfill usability efforts at the end of a project. These last-minute additions are done only to pass product standards and there is no time or intent to make meaningful changes if issues are discovered.

Sometimes, these efforts are even conducted after the release of the product, when real-world issues have already been identified and have taken place. To prevent late-stage changes and unhelpful backfilling, proper diligence must be adhered to throughout the design and production of a medical device. User research, application analysis, and further testing must continually take place.

The Minnetronix approach to medical product design

Minnetronix has developed a robust approach to the integration of usability. At each stage in the design life cycle, a focus on usability is a key component of the evolution of product design. This helps our design team identify adjustments early on and prevent changes later in the development of the product.

  1. User Research: Define our user groups – how, where, and when they will use the device, what tasks they perform, and what their core needs are. Information is gathered from stakeholder knowledge, research into predicate devices, and field observations of users working with similar systems.
  2. Application Specification: User research is compiled into an Application Specification. This includes a description of the users, user environment, and basic workflow. It is also where user needs are defined.
  3. Task Analysis: A Task Analysis document includes a breakdown of user tasks and associated risks which feed into every element of the user interface design and evaluation process.
  4. UFMEA: User needs and task-associated risks from the Application Specification inform the writing of a Use Error FMECA.
  5. Design Concepts and Prototypes: Concepts for the device design are vetted against the knowledge summarized in the application specification. Prototypes of the system are generated to be evaluated by representative users.
  6. Formative Testing: The task analysis is used to generate formative test procedures. Formative testing is performed with representative users on early prototypes or alpha versions of the devices.
  7. Concept Finalization and Design Specifications: As the design is finalized, knowledge gained from formative testing is used to refine the device. Gathered feedback, user needs, task analysis, and the Use Error FMECA inform the writing of usability requirements and a User Interface Design Document.
  8. Summative (Usability Validation) Testing: When finalized devices become available, the last step is summative testing. A protocol is written based on tasks defined in the Task Analysis. The risk associated with various tasks in the use error FMECA determines pass/fail criteria. A submission quality Summative report is generated which describes the entire usability process and the final evaluation.

During the entire design process, we seek to find opportunities to save steps and take leaps. This helps us prevent issues further down the road, preventing delayed launches and costly setbacks. Our strategic foresight and the proactive approach we apply to each project come from decades of experience in medical device design.

We can help your company uncover inefficiencies, discover new and bigger potential, and increase the impact of your technology. Contact Minnetronix Medical to learn more.

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