Designing Medical Software

Developing embedded software for medical devices is no longer just about performance, size, or even innovation. It is more about compliance, safety, and trust. Regulatory bodies across the world tighten standards for software used in healthcare. So developers working on medical devices are expected to align not only with the best engineering practices but also with globally recognized compliance frameworks.

Today we explore the essential regulatory standards every embedded medical developer should understand IEC 60601, ISO 14971, and IEC 62304 and explore how these standards impact design, coding, testing, traceability, and documentation. We will briefly touch up on safety classifications, how clinical risk maps to technical implementation, and why traceability is a development discipline.

Designing Medical Software

Regulatory Frameworks

Regulatory framework oversees the entire lifecycle of a device or software from design and development to testing, manufacturing, deployment, and post-market investigation. Its primary goals are to:

• Protect patient health and safety
• Ensure product reliability and effectiveness
• Support compliance with national and international laws

IEC 60601 – Electrical Safety of Medical Equipment

This focuses on electrical, mechanical, thermal, and functional safety. Even though it applies broadly to the entire device (including hardware), software developers must know particularly

• IEC 60601-1 is the international standard for electrical safety and essential performance of medical electrical equipment and systems. It ensures all devices are single fault safe, meaning a single failure must not result in unacceptable risk during normal use or abnormal conditions. The standard covers electrical, mechanical, thermal, and functional safety, and introduces risk management aligned with ISO-14971, emphasizing essential performance metrics

Software must not only perform correctly but must not introduce any hazardous situations due to faults or unintended behavior.

ISO 14971 – Risk Management for Medical Devices

It is the international standard for risk management of medical devices, prescribing a systematic process to identify, evaluate, control, and monitor hazards throughout the product’s lifecycle. It defines risk as the combination of harm severity and probability of occurrence, emphasizing continuous risk reduction to acceptable levels.

Key concepts for developers:

• Every software module can introduce risk if it can impact patient safety.
• Risk must be quantified in terms of severity and probability.
• Risk controls can be implemented in software and must be verified.

IEC 62304 – Medical Device Software Lifecycle Processes

This is the most critical standard for embedded software developers. It mandates a structured software development lifecycle and requires that:

• The entire software process, from requirements to maintenance, is documented.
• Developers perform risk analysis and implement mitigations.
• Testing is thorough and traced back to requirements and risk controls.

It classifies software into three safety classes (Class A, B, C) based on the potential to cause injury:

• Class A: No injury or damage to health is possible
• Class B: Non-serious injury is possible
• Class C: Death or serious injury is possible

Each class comes with increasingly stringent requirements.

Safety Classifications and Their Impact on Development

Understanding the classification of your software is crucial to determining how much care must go into design, testing, and documentation.

Class	Injury Potential	Design/Test Expectations
A	No injury possible	Basic documentation, unit tests
B	Non-serious injury	Comprehensive unit/integration testing, code reviews
C	Serious injury or death	Formal methods, independent verification, exhaustive testing

As the class increases, design robustness and testing accuracy must scale. For instance:

• Class A software may allow for simple code-level unit tests.
• Class B software typically requires traceability from requirements → code → tests.
• Class C software demands independent reviews, formal testing, and often redundant safety checks in code.

A developer working on low-level firmware for a Class C infusion pump must be extremely careful. Even small bugs can lead to dangerous, life-threatening problems.

Mapping Clinical Risks to Technical Implementation

Bridging Clinical Risk and Embedded Design

One of the biggest challenges for embedded developers is translating clinical risks (typically identified by product managers, clinicians, or regulatory teams) into technical requirements.

Example scenario:

• Clinical risk: “Over-infusion of medication may cause overdose.”
• Software translation:
• Implement upper limit logic for infusion rate
• Include a watchdog timer for control loop anomalies
• Build in redundancy to confirm flow rate data from multiple sensors

Key responsibilities for developers:

• Translate each identified risk into a detectable hazard scenario.
• Implement mitigations (e.g., error detection, alarms, fallback modes).
• Log and test all fail-safe operations.

Failure Modes and Effects Analysis (FMEA)

A useful tool in this translation is Software FMEA, which asks:

• What if this function fails?
• What happens downstream?
• Can the fault propagate to a clinical hazard?
• How can the fault be detected, contained, or corrected?

Traceability and Documentation: The Developer’s Daily Discipline

For embedded developers in regulated industries, everything we build must be traceable. This traceability spans:

• Requirements: Every function in code must trace to a user, system, or safety requirement.
• Design: Each module or architecture decision should have rationale and linkage to requirements.
• Code: Comments, architecture documents, and software unit descriptions must map to risks and requirements.
• Tests: Unit tests, integration tests, and system tests must link to their associated requirement(s).
• Bugs: Every defect found must trace back to the code, the requirement it violated, and ideally the associated test case.

Traceability Tools and Artifacts

• Software Requirements Specification (SRS)
• Software Design Specification (SDS)
• Traceability Matrix (often automated via ALM tools like Polarion, Jama, or Codebeamer)
• Change Control Records
• Verification and Validation (V&V) Plans
• Release Notes and Maintenance Logs

Neglecting traceability not only leads to audit failure but also makes maintenance and updates nearly impossible without regression risks.

Testing is a Compliance Strategy

In IEC 62304, testing is not just about proving that software works — it’s about proving that risk controls are effective.

Different testing levels include:

• Unit Testing: Ensure individual functions operate correctly.
• Integration Testing: Confirm interfaces and modules interact safely.
• System Testing: Validate end-to-end behavior.
• Verification vs Validation:
• Verification:“Did we build the software right?”
• Validation:“Did we build the right software?”

For Class C devices, code coverage analysis, static analysis, and formal proofing may be expected. Automated testing frameworks such as Ceedling (for C), GoogleTest (for C++), or Python’s unittest (for Python modules) are often customized to generate test evidence.

Conclusion

Medical embedded software development is about trust, safety, and responsibility. The standards — IEC 60601, ISO 14971, and IEC 62304 — provide a roadmap to building safe and effective devices, but the real success lies in how developers internalize these standards into their daily practices.

Understanding safety classifications, mapping clinical risks to technical features, maintaining full traceability, and testing rigorously are the backbone of regulatory compliance.

At Embien Technologies, we bring deep domain expertise in developing embedded software for Class B and Class C medical devices. From architecting safe software systems to building comprehensive traceability pipelines and implementing robust risk controls, our team supports clients through every phase of compliant product development. By embedding compliance into our design DNA, we help ensure that the software not only meets regulatory requirements but ultimately contributes to improving patient outcomes.