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Summary

You must translate user needs into specific, testable technical requirements that define exactly what your medical device must do to meet user expectations. Product requirements establish the foundation for all design and development activities by creating measurable criteria that bridge the gap between user needs and technical implementation.

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Regulatory Context

Under 21 CFR Part 820.30 (Design Controls), you must implement:
  • Documented design inputs derived from user needs and regulatory requirements
  • Objective and testable requirements enabling design output verification
  • Traceability from user needs through system and subsystem requirements
  • Review and approval of all requirements before implementation
  • Change control procedures governing requirement modifications
Special attention required for:
  • Software medical devices per FDA Software as Medical Device guidance
  • Design input requirements must be unambiguous and verifiable
  • Risk control requirements derived from ISO 14971 risk management
  • Cybersecurity requirements per FDA cybersecurity guidance framework

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Overview

Product requirements form the critical bridge between user expectations and technical implementation by transforming high-level user needs into specific, measurable criteria that your development team can design against. This systematic translation process ensures that every aspect of your device’s functionality is deliberately planned, traceable, and verifiable through testing. Your System Requirements List establishes the foundation by defining what your device must do at the highest level of technical specification. These requirements translate user needs into objective, testable criteria that specify functional performance, safety characteristics, and operational constraints without prescribing implementation details. System requirements provide the strategic framework that guides all subsequent design decisions while maintaining flexibility for innovative solutions. Each requirement must trace directly back to user needs, ensuring that your development efforts address real user expectations rather than unnecessary features. Subsystem Requirements break down system-level specifications into detailed, implementable requirements for each component or functional area of your device. These granular requirements provide the technical specifications that individual development teams need to design, build, and verify specific subsystems. The subsystem level ensures comprehensive coverage by addressing hardware components, software modules, user interfaces, and system integrations with sufficient detail for implementation while maintaining clear traceability to system requirements. Risk control requirements represent a critical subset that transforms your risk assessment findings into specific safety features and protective measures. These requirements ensure that identified hazards are controlled through design rather than relying solely on user training or protective equipment. Risk control requirements must be seamlessly integrated with functional requirements to create cohesive designs that are both effective and safe. The hierarchical relationship between requirements levels creates a comprehensive specification framework that scales from user needs through system implementation. User needs inform system requirements, which drive subsystem requirements, which guide detailed design specifications. This structured approach ensures nothing falls through the cracks while maintaining clear decision-making criteria at each development level. Requirement quality directly impacts development success and regulatory approval. Well-written requirements use active voice, specific measurable criteria, and unambiguous language that eliminates interpretation differences between team members. Poor requirements lead to design inconsistencies, verification failures, and regulatory compliance issues that require costly rework and delay market approval. Your requirements must address complete device functionality including normal operation, edge cases, error conditions, and environmental variations. Consider performance under stress, degraded conditions, and reasonably foreseeable misuse scenarios. Requirements should specify not only what the device does, but how well it performs, under what conditions, and with what reliability. Traceability maintenance throughout the requirements hierarchy enables impact assessment for changes, comprehensive verification planning, and regulatory compliance demonstration. Each requirement must clearly link to its source (user needs or regulatory requirements) and its implementation (design outputs and verification methods). This traceability becomes essential during design changes, post-market surveillance, and regulatory inspections. The quality and completeness of your product requirements directly determine development efficiency, verification success, and regulatory approval outcomes. Well-structured requirements enable focused development, comprehensive testing, and confident regulatory submissions while reducing development costs and time-to-market.