Design Outputs: Turning Requirements into Useful Specifications

(Part 2 of a 5-Part Series)

When Design Inputs are defined, referenced, and justified, the next major step in the design control process is to generate Design Outputs. These outputs are the concrete specifications that bring the device into reality through testable products whether in preliminary bench tests, Design Verification, or Design Validation such as preclinical studies or approved clinical trials. Design Outputs enable the documentation of a design for ordering components and manufacturing those items into repeatable and reproducible products that can be design verified and design validated. Often teams skip the Design Output step—before Design Verification or Design Validation—in whole or part, which can lead to delays and increased cost. Let’s review the best implementation practices.

Design Outputs answer the question:

“How do we translate our documented Design Inputs into specific, verifiable deliverables?”

The project team creates controlled and traceable Production Specifications like component specifications, assembly drawings, manufacturing instructions, bills of materials, lot history records, and more—essentially all the tangible information needed to build and inspect the device.

?Design Outputs’ Regulations and Standards at a Glance

• 21 CFR 820.30(d): Requires manufacturers to document design outputs in terms that allow adequate evaluation of conformance to design input requirements.
• ISO 13485:2016 §7.3.4: States that design and development outputs must be in a form suitable for verification against the design and development inputs.?

Types of Design Outputs

Device Master Record (DMR) 21 CFR 820.181

• Record of all design output, the “what” and “how”
• Comprehensive set of specifications and procedures needed to manufacture a device.
• Best implemented as an Index of Design Output, at large, in Quality Management System (QMS)
• Tip: Include the Design-Input and Design-Output Matrix as a reference...Makes for easily referenced index for outside reviewers and required linkage back to inputs

Device History Record (DHR) 21 CFR 820.184

• Record of “when, who, and which lot or serial number”
• Demonstrate execution of DMR
• Exemplary embodiments:? Lot History Record (LHR), Traveler, Batch Record
• A record of each batch or unit of device(s) actually produced, proving it was manufactured product according to the DMR

Software Design Documentation

• Software code, version control logs, user interface specifications, etc.
• Aligns with IEC 62304 Clause 5 Medical device software life cycle processes
• Software Bill of Materials (SBOM)

Bill of Materials (BOM)

• Line by line accounting of each raw material or component
• Hierarchical BOMs may have components and subassemblies

Production Specifications & Drawings

• Components specifications
• Drawings with detailed dimensions, materials, tolerances: Component drawings, assembly diagrams, or exploded views

Manufacturing or Production Instructions

• Instructions for assembly
• Quality checks (in-process inspections) to ensure conformance
• Sterilization Instructions
• Distribution Instructions

Quality Inspections

• Receiving Inspections
• Component and subassembly inspections
• Final assembly inspections
• Sterilization documentation inspections
• Test Methods specific to Design Output

Labeling and Accompanying Documents

• Labels: Label text, symbols, and regulatory markings (e.g., CE, UDI).
• Labeling Instructions: General Labeling Instructions, Unique Device Identification (UDI)
• Instructions for Use (IFU)
• Maintenance Manuals
• Operation Manuals
• User Manuals

Packaging Documentation

• Drawings and written specifications
• Packaging Instructions

Equipment Specifications

• Tooling Documentation
• Fixture Documentation

Ensuring Traceability

Each Design Output should trace back to one or more Design Inputs. This link guarantees that every user needs & intended use and product requirement has a corresponding output that shows how it is being met.

• Unique Identifiers: Assign unique indelible IDs to each Product Requirement and Quality Management System (QMS) identification to each Design Output item.
• Design Input and Design Output Matrix: Maintain a table or database mapping each requirement to its outputs.
• Build a Device Master Record (DMR) of all Design Outputs and organize according to type

Design Verification & Design Validation Readiness

From an early-stage project perspective, Design Outputs form the basis for Design Verification and Design Validation readiness. Readiness is a relative state rather than an absolute state in most organizations. With significant downside if you are not absolutely ready. Here are a couple of principles and some advice.

Design Output Principle #1: The Design Outputs must be sufficiently documented to create a repeatable and reproducible product build in legitimate samples sizes for risk controlled testing.

• Clarity & Completeness: If a Design Output isn’t detailed enough (e.g., missing tolerances), Design Verification will stall, yield ambiguous results, or even worse…Necessary detail is built into the Design Verification protocol to execute it and subsequently lost after testing due to the rush of development.?
• Measurability: Design Outputs must reflect testable parameters (e.g., dimensions, performance limits). Conduct a Test Method Validation (TMV) and within the TMV do a measurement system capability analysis. This will address the veracity of your test’s repeatability, reproducibility, and capability through test-method and measurement system analysis.

Design Output Principle #2:? The Design Output does not account for DV&V Protocols’ acceptance criteria.

• The Design Input accounts for Acceptance Criteria; literally 1:1 when executed correctly.
• Hybridization of Design Inputs and undocumented Design Outputs into Acceptance Criteria are a pitfall covered in Part 3!

Design Output Principle #3:? The Design Output must be released into the Quality Management System (QMS) to be controlled and traceable.

• Design Outputs create a controlled basis—in the form of traceable and controlled product—from which to evaluate those DV&V acceptance criteria.
• Without traceable and controlled Design Outputs released into the QMS, the project's DV&V testing is under shifting sands, which simply equals repeated builds, for repeated testing, and more time and money to the finish line.

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Common Pitfalls

Insufficient Detail

• Problem: Omitting critical specifications leads to guesswork in manufacturing or inspection
• Solution: Provide explicit nominals and tolerances, material grades, and inspection criteria

No Link to Inputs

• Problem:? Free floating Design Outputs not clearly tied to user needs and intended uses or product requirements can miss functionality or create a product that exceeds cost and necessity
• Solution: Use an input-output matrix or equivalent software tool to track connections.

Revision Control & Change Management

• Problem: Failing to update and track changes can cause loss of traceability and lot control resulting in rebuilding or compliance issues.
• Solution: Follow regulations in 21 CFR 820.30(i), 820.40(b), 820.65, and 820.70 and standard instructions per ISO 13485:2016 §7.3.9 for changes…among others.

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Example: A Vascular Stent Project

Let’s say a Product Requirement is the following:

“The stent shall have an outside diameter of 2.00±0.05 mm with a wall thickness of 0.10±0.01 mm.”

Possible Design Outputs:

• Engineering Drawing: Stent geometry with annotated dimensions and tolerances highlighting critical inspection dimensions
• Manufacturing Process Instruction(s): Laser-cutting parameters, mandrel and collet loading, cleaning process, dimensional check procedure, pickling and electropolishing setup and parameters, final dimensional check, surface finish check
• Quality Inspection(s): Measurement equipment, directions for sample size, identifies measurement points, how to measure it, and where to document inspection results
• LHR to control and use all of the above bullet points

Why It Matters?

?? Converts Product Requirements to Manufacturable Reality: Design Outputs turn conceptual requirements into actionable documents and specifications.

?? Streamlines Manufacturing & Testing: Detailed outputs reduce confusion and rework, saving time and money. Locks down the design to be tested…no questions of "what was tested?"

?? Facilitates Design Verification and Design Validation: Well-defined outputs equal well-defined product, which is easier to verify and validate, fueling a smoother DV&V cycle.

?? Regulatory Compliance: Both 21 CFR 820 and ISO 13485 regulate and standardize, respectively, that outputs be controlled, traceable, and reviewable.

Core Considerations for Design Outputs

Specificity & Completeness

• Include all necessary details, materials, dimensions, software code documentation, packaging instructions. Avoid ambiguous language (e.g., “Tight tolerance” vs. “±0.02 mm”).

Consistency with Design Inputs

• Verify that each output corresponds to at least one input—no orphan outputs or stray requirements.

Documentation & Revision Control

• Maintain revision history and backward traceability to inputs. Any change in output should prompt a review of related inputs.

Regulatory Alignment

• Demonstrate how output traceability follows relevant standards and regulations (e.g., ISO 13485, 21 CFR 820.

Design Outputs are your bridge from written requirements to repeatable and reproducible devices. With solid outputs that are tied tightly to your inputs, you set the stage for effective design verification, design validation, and eventually, successful launch to the next step in product development.

-Mike

M. L. Reo Consulting LLC

This was Part 2 of a 5-Part series.

??Part 1: Design Inputs

??Part 2: Design Outputs

?Part 3: Design Verification and Design Validation

?Part 4: Risk Management in Design Control

?Part 5: Design Input and Output Matrix

#DesignControls #MedicalDevices #ProductDevelopment #QualitySystem

?References

• Quality System Regulation (21 CFR 820). Code of Federal Regulations, 2015.
• ISO 13485:2016. Medical Devices—Quality Management Systems—Requirements for Regulatory Purposes. ISO, 2016.
• Design Control Guidance for Medical Device Manufacturers. FDA, 1997.
• U.S. Food and Drug Administration. Cybersecurity in Medical Devices: Quality System Considerations and Content of Premarket Submissions (Draft Guidance). FDA, April 8, 2022.