Credit: National Cancer Institute
Despite the fact that the medical device design process varies from country to country, there is a tremendous amount of overlap. At its core, the process is about optimizing safety and efficacy. Teams of software, biomedical, electrical and mechanical engineers tread congruent pathways the world over in the development of medical devices.
In this article, we look at the product design lifecycle according to the framework established by the American Food and Drug Administration (FDA). We also look at some international standards regarding medical device development as laid out by the International Organization for Standardization (ISO).
Design Control Guidance for Medical Device Manufacturers
In 1990, the FDA created the Safe Medical Device Act. This allowed for the addition of a new compliance category, known as design controls, to the current Good Manufacturing Practice (cGMP) requirements.
Then, in 1995, design controls were formally applied to medical devices. By 1997, the Quality System (QS) Regulation came into effect, usurping the cGMP. Design controls are now regulated under 21 CFR 820.30 and applicable to all Class III, Class II, and selected Class I devices.
The purpose of design control is to provide medical device companies with a standardized procedural framework. This helps ensure quality and accuracy in the product development lifecycle, while also reducing potential issues and risks.
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The 10 Stages of Medical Device Design Control
The product development process can be loosely generalized into design and production. For our purposes, we’ll focus on the former: Medical product design. Here are the 10 steps.
1. Device Concept, Risk Analysis, and Feasibility
This first step is all about cooperation. A medical product design company will work intimately alongside their client to understand the device’s desired functionality and how it will address a specific issue. Things like risks, benefits, and feasibility will all be considered.
2. Specification Development
Engineers now begin to formulate the mechanical, electrical, and software specifications necessary for the device. Some simple devices (like scalpels) merely have a mechanical component, while more complex devices (such as high frequency ventilators) require all three.
At this stage, precision is essential to avoid costly mistakes down the line. The design team must fully understand the relationship between the device’s structure and its function. This will help them choose the right materials and anticipate potential limitations.
3. Design Inputs – 21 CFR 820.30(c)
According to the FDA’s Code of Federal Regulations (CFR), design inputs relate to both the performance and physical characteristics of a medical device. These characteristics provide the basis for the device’s design. For instance, if a medical device needs to be portable, the design must make special considerations for both its weight and its size. Other characteristics include:
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4. Design Outputs – 21 CFR 820.30(d)
Design outputs are defined as, “the results of a design effort at each design phase and at the end of the total design effort.” Some examples include:
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Note that the relationship between design inputs and outputs is not strictly linear. As the above definition implies, certain outputs will become the basis for the next stage of inputs. At the completion of this iterative process, the design output is the device itself, as well as its unique labeling, packaging, and portions of the Device Master Record (DMR).
Credit: ThisisEngineering RAEng
5. Design Review – 21 CFR 820.30(e)
The manufacturing of medical devices is a meticulous and costly endeavor. By addressing issues during the pre-production process, a lot of time and money can be saved. That’s why the review stage is such a critical milestone in the design process: It allows engineers to pose the question, “Is this right?”
The team will conduct investigations (physical tests, simulations, etc.) against key criteria (usability, consistency, durability, etc.). If issues are discovered, designers will rework flaws, correct failures, discard redundancies, and add new features. After the corrections have been made, the device will undergo yet another review. This iterative process continues until it until review completes satisfactorily.
6. Design Verification – 21 CFR 820.30(f)
Once a medical device design passes review, it’s time to determine how well the design outputs stack up against the design inputs. Verification can take on many forms, from testing to inspections to analyses. The goal is to ensure that the device meets its internal criteria, such as regulatory compliance, product specifications, etc.
As per the FDA’s description, this stage represents a “confirmation by examination and provision of objective evidence that specified requirements have been fulfilled.” [FDA 21 CFR 820.30 F § 820.3 (z)]
7. Design Validation – 21 CFR 820.30(g)
According to the Project Management Body of Knowledge (PMBOK), design validation is defined as “the assurance that a product, service, or system meets the needs of the customer and other identified stakeholders.”
In contrast to verification, validation is an external process; emphasis is placed on end-users and the environment. Often, an independent third-party will be hired to validate the device. This is known as independent verification and validation (IV&V) and is widely considered the gold standard.
8. Medical Device Design Transfer – 21 CFR 820.30(h)
Once IV&V ends, the product and process designs are handed off to the production team. This process is known as the medical device design transfer. A design transfer checklist is created to ensure that the control standards are maintained during this transitional phase.
In the Waterfall model of project management, the transfer to manufacturing marks the end of the design process and the beginning of production; however, more complex medical machines are best approached with a concurrent model.
9. Design Changes – 21 CFR 820.30(i)
In contrast to the proactive design review phase, this stage is devoted to paperwork. Teams must certify that any changes made to the design have been identified, documented, validated, verified, reviewed, and approved before implementation.
10. Design History File (DHF) – 21 CFR 820.30(i)
Once the device design transfer is complete, the device is ready for the manufacturing team. At this point, it’s crucial to have all the relevant records of the device’s design history compiled into a Design History File (DHF).
Though it marks the last design control step before production, the DHF is actually expanded upon at each stage of the process. The insights contained in a DHF should be detailed, orderly, and accessible for future reference.
International Medical Device Design Standards
The International Organization for Standardization (ISO) is a globally recognized non-governmental organization (NGO), composed of representatives from 167 national standards organizations. Their purpose is to develop and publish a diverse array of commercial, industrial, and proprietary standards across nearly 100 industries—from jewelry to agriculture to medical devices.
The ISO plays an important role in facilitating worldwide trade by providing universally accepted standards. In regards to medical device design, there are two specific standards that facilitate entry into the global supply chain.
- ISO 14971 – Medical Device Risk Management
Established in 1998 and revised in 2019, ISO 14971 stipulates that medical device companies must minimize the risk associated with the normal use of their devices. ISO 14971 is applied risk management; it provides information on how to answer the question of whether the potential benefits outweigh the potential risks.
- ISO 13485 – Medical Device Quality Management Systems
First published in 1996 and updated in 2016, ISO 13485 standardizes the requirements for medical device quality management systems. In contrast to ISO 14971—a product-based standard—ISO 13485 is a process-based standard. It’s historically based on the ISO 9000 and ISO 9001, which represent the basis for quality management system guidelines.
Other pertinent international standards include ISO 10993 (biocompatibility), ISO 11607 (sterility), and IEC 50501 (electrical safety).
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