Regulatory Update: Design Control Considerations for Medical Device Components

      The development of a medical device is a complex and extensive process. Rigorous design planning and controls will mitigate risks that lead to failed verification testing or other delays in the project. Detailed and granular planning for the selection of materials and components may add time during the initial phases of the project but will likely reduce the problems and timeline of the project overall.

      The selection of materials and components for use in a medical device requires the assessment of numerous attributes, including but not limited to:

      • Dimensions or features of components
      • Materials of construction
      • Compatibility with manufacturing and sterilization processes
      • Intended use of components and the substances they will contact during intended use
      • Cleanliness and particulate requirements for components
        When developing a device, determining the design inputs requires assessment of its user's needs. As required by ISO 134851, design inputs must address both the requirements stated by the customer and those not stated by the customer but necessary for the intended use. While an initial user’s needs list may not identify attributes such as biocompatibility, sterilization compatibility or manufacturing requirements, such aspects must be considered as design inputs.

      Concurrently, risk management principles according to ISO 149712 and ISO/TR 249713 are employed to mitigate risks as solutions are identified to meet design inputs. Early incorporation of risk management processes during design to include component selection is recommended. Listed below in Table 1 is a simplified excerpt of an FMEA (Failure Mode and Effects Analysis) table for a medical device regarding component selection. This process requires identification of a risk and its effects, employing a solution to mitigate the risk, and then verifying that the mitigation is in fact adequate to reduce the risk.

      Representative FMEA Excerpt

      Risk Effect Mitigation Verification
      Improper component dimensions
      • Device loss of function
      • Leaks
      • Breach in system integrity, resulting in contamination of contained material
      • Selection of appropriate component
      • Purchasing controls (include component specification in purchase order)
      • Design verification testing (e.g., functional testing, leak testing) on representative finished device
      Unacceptable biocompatibility profile
      • Biocompatibility impact (e.g., irritation, sensitization, tissue damage)
      • Selection of components with known biocompatibility profiles
      • Minimize the materials and surfaces that directly or indirectly contact the patient
      • Biocompatibility testing on representative finished device
      Material incompatible with substances contacted during normal use
      • Adsorption of active ingredients from substances delivered to patient through device
      • Deterioration of device materials
      • Selection of substance-contacting components made of inert materials
      • Verification testing (substance interaction and material integrity) of representative finished device
      Material incompatible with assembly adhesives
      • Device loss of function
      • Leaks
      • Selection of components with materials that are compatible with commonly used adhesives
      • Use of components that do not require adhesives for assembly
      • Design verification testing (e.g., functional testing, leak testing) on representative finished device
      Material incompatible with assembly adhesives
      • Device loss of function
      • Leaks
      • Selection of components with materials that are compatible with commonly used adhesives
      • Use of components that do not require adhesives for assembly
      • Design verification testing (e.g., functional testing, leak testing) on representative finished device
      Material incompatible with sterilization process
      • Device loss of function
      • Biocompatibility risks due to sterilization process residuals
      • Selection of components with materials that are compatible with desired sterilization method or use of sterilization method appropriate for chosen device materials.
      • For example, use of materials that can withstand gamma irradiation or that do not have a high affinity for EO and ECN.
      • Design verification testing (e.g., functional testing) on representative, sterilized, finished device
      • Residual testing (for devices sterilized via EO)
      High bioburden or particulate contamination
      • Biocompatibility or other health risk (e.g., vessel occlusion) caused by particulate contamination
      • Sterility failure due to excessive bioburden
      • Selecting components manufactured and handled in a controlled environment
      • Purchasing controls for product cleanliness (include component specification in purchase order)
      • Sterilization validation
      • Bioburden monitoring
      • Biocompatibility and particulate testing

      Component Selection

      The use of risk management principles described above will enable a successful, efficient and holistic design and development process. An iterative design and risk management process is possible but helpful for devices assembled from varying components and materials. For example, a change to one component may impact design considerations that impact another requiring reevaluation of component selection. Qosina assists you in managing these aspects of the design process by:

      • Maintaining a resource center at qosina.com with detailed product information including drawings or CAD files with component dimensions
      • Sourcing components with a known and favorable biocompatibility profile
      • Sourcing components made of established materials that are compatible with materials and substances that contact the component in the finished device
      • Providing materials that conform to specified cleanliness or handling requirements and are compatible with your desired sterilization method
      • Proactively providing change notifications, enabling you to evaluate an impact on your finished product or system
      • Providing a second source for your components
      • Providing secondary components with the same dimensions and materials
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