Essential Work Sample Exercises for Hiring Top Medical Device Software Engineers

Medical device software engineering represents a unique intersection of cutting-edge technology and stringent regulatory requirements. Unlike conventional software development, engineers in this field must balance innovation with patient safety, creating solutions that not only function effectively but also comply with complex regulatory frameworks like IEC 62304 and FDA guidelines.

When hiring for these specialized positions, traditional interviews often fall short in revealing a candidate's true capabilities. Technical knowledge can be memorized, and past experiences can be embellished. However, well-designed work samples provide undeniable evidence of a candidate's skills in action, particularly their ability to write clean code, design robust architectures, troubleshoot effectively, and maintain comprehensive documentation—all while adhering to regulatory standards.

The stakes in medical device software are exceptionally high. A single bug or oversight can potentially impact patient safety and trigger costly recalls. This reality makes it crucial to identify engineers who demonstrate meticulous attention to detail, strong problem-solving abilities, and a deep understanding of both technical and regulatory aspects of the field.

The following work sample exercises are specifically designed to evaluate candidates for medical device software engineering roles. They simulate real-world challenges these professionals face daily, from implementing critical algorithms to designing system architectures that meet regulatory requirements. By incorporating these exercises into your hiring process, you'll gain valuable insights into how candidates approach complex problems, handle feedback, and balance technical excellence with compliance demands.

Activity #1: Critical Algorithm Implementation

This exercise evaluates a candidate's ability to write clean, efficient, and reliable code for a safety-critical medical device function. Medical devices often rely on precise algorithms to process sensor data, control actuators, or analyze patient information. This exercise simulates the implementation of such an algorithm, allowing you to assess the candidate's programming skills, attention to detail, and understanding of safety-critical software requirements.

Directions for the Company:

• Prepare a coding exercise that involves implementing a specific algorithm relevant to medical devices (e.g., a signal processing algorithm, a control system, or a data analysis function).
• Provide a clear specification document that outlines the requirements, expected inputs/outputs, and any constraints or edge cases that must be handled.
• Include relevant test cases that the candidate's implementation should pass.
• Allow candidates to use C, C++, or Python, depending on your company's technology stack.
• Set a reasonable time limit (60-90 minutes) and provide access to necessary documentation.
• Prepare a code review checklist that includes: code correctness, error handling, edge case management, code readability, and adherence to safety-critical software principles.

Directions for the Candidate:

• Implement a heart rate monitoring algorithm that processes raw ECG signal data to detect QRS complexes and calculate heart rate.
• Your implementation should handle various signal qualities, including noisy data, and identify potential arrhythmias.
• Write clean, well-documented code with appropriate error handling and boundary condition checks.
• Include unit tests that verify your implementation works correctly for the provided test cases.
• Be prepared to explain your implementation choices, particularly regarding reliability and safety considerations.
• You may use standard libraries for basic operations, but the core algorithm should be your own implementation.

Feedback Mechanism:

• After submission, the interviewer should review the code with the candidate, highlighting one strength (e.g., "Your error handling for noisy signals was particularly robust") and one area for improvement (e.g., "The algorithm might benefit from additional validation checks for extreme heart rates").
• Give the candidate 15 minutes to refine their implementation based on the feedback.
• Observe how receptive the candidate is to feedback and how effectively they incorporate it into their solution.
• Evaluate both the initial implementation and the improvements made after feedback.

Activity #2: Medical Device System Architecture Design

This exercise assesses a candidate's ability to design robust software architectures for medical devices that balance technical requirements with regulatory compliance. System architecture is a critical skill for medical device software engineers, as it establishes the foundation for safe, reliable, and maintainable software that can pass regulatory scrutiny.

Directions for the Company:

• Create a realistic medical device scenario with specific requirements (e.g., an insulin pump, patient monitoring system, or diagnostic device).
• Provide a document outlining the device's purpose, key functions, hardware constraints, and regulatory requirements.
• Include any relevant standards that must be considered (e.g., IEC 62304, FDA guidance documents).
• Prepare evaluation criteria focusing on: modularity, error handling, risk management, testability, and regulatory compliance.
• Allow 60-90 minutes for this exercise.
• Provide whiteboard space, diagramming tools, or paper for the candidate to create their design.

Directions for the Candidate:

• Design a software architecture for a continuous glucose monitoring system that interfaces with a smartphone app.
• Your design should address:
• Data acquisition from the glucose sensor
• Signal processing and glucose level calculation
• Alert generation for dangerous glucose levels
• Secure data storage and transmission to the smartphone
• User interface requirements
• Create a system architecture diagram showing major components, interfaces, and data flows.
• Identify potential failure modes and describe how your architecture mitigates these risks.
• Explain how your design supports IEC 62304 compliance, particularly regarding software safety classification and risk management.
• Be prepared to discuss how your architecture supports verification and validation activities.

Feedback Mechanism:

• After the candidate presents their design, provide specific feedback on one strong aspect (e.g., "Your approach to data validation at multiple levels creates excellent fault tolerance") and one area for improvement (e.g., "The error handling strategy could be more comprehensive for network communication failures").
• Give the candidate 15-20 minutes to revise their design based on the feedback.
• Ask them to explain how their revisions address the feedback and improve the overall architecture.
• Evaluate both their initial design and their ability to incorporate feedback effectively.

Activity #3: Bug Investigation and Resolution

This exercise evaluates a candidate's troubleshooting abilities, analytical thinking, and approach to resolving software issues in a medical device context. Effective debugging is essential in medical device software, where unresolved issues can have serious consequences for patient safety and regulatory compliance.

Directions for the Company:

• Prepare a code sample with deliberately introduced bugs that might occur in a medical device application.
• Include a mix of obvious syntax errors, subtle logic bugs, and potential safety issues.
• Provide a bug report describing the symptoms observed (e.g., "Device occasionally reports incorrect values when sensor readings change rapidly").
• Include relevant logs, test data, or other diagnostic information that would typically be available.
• Prepare a document explaining the expected behavior of the software.
• Allow 45-60 minutes for this exercise.

Directions for the Candidate:

• Review the provided code for a patient temperature monitoring module that is exhibiting intermittent inaccurate readings.
• Analyze the bug report, logs, and test data to identify potential causes of the issue.
• Document your troubleshooting process, including:
• Your hypothesis about the root cause(s)
• Evidence supporting your hypothesis
• Potential fixes for each identified issue
• Implement fixes for the bugs you identify, explaining your reasoning for each change.
• Suggest additional tests or validation steps to verify your fixes and prevent similar issues in the future.
• Consider and document any potential regulatory implications of the bugs and your proposed solutions.

Feedback Mechanism:

• After the candidate completes their analysis and fixes, review their approach, highlighting one strength (e.g., "Your systematic approach to isolating the temperature conversion error was excellent") and one area for improvement (e.g., "Consider how boundary conditions might be more thoroughly tested").
• Give the candidate 10-15 minutes to refine their solution or testing approach based on the feedback.
• Discuss how they would document this issue and its resolution for regulatory purposes.
• Evaluate their analytical process, technical solution, and understanding of the regulatory implications.

Activity #4: Risk Analysis and Documentation Exercise

This exercise assesses a candidate's ability to identify potential risks in medical device software and create appropriate documentation that would satisfy regulatory requirements. Documentation and risk management are critical aspects of medical device software development, often distinguishing it from other software engineering disciplines.

Directions for the Company:

• Prepare a simplified software requirements specification for a medical device feature (e.g., an automated medication delivery function).
• Include enough detail for the candidate to understand the feature's purpose and operation.
• Provide templates for risk analysis documentation that align with your company's practices and regulatory requirements.
• Allow 60 minutes for this exercise.
• Prepare evaluation criteria focusing on: thoroughness of risk identification, appropriate risk classification, effectiveness of proposed mitigations, and quality of documentation.

Directions for the Candidate:

• Review the requirements for an automated external defibrillator (AED) shock delivery subsystem.
• Conduct a preliminary hazard analysis by:
• Identifying potential failure modes in the software
• Assessing the severity and probability of each failure
• Determining potential causes of each failure
• Proposing software mitigations for each identified risk
• Complete the provided risk analysis documentation, ensuring it meets IEC 62304 requirements.
• Draft a verification and validation plan that would adequately test the risk mitigations you've proposed.
• Write a section of the software design specification that addresses how your design mitigates the identified risks.
• Be prepared to explain how your documentation would support regulatory submissions.

Feedback Mechanism:

• After reviewing the candidate's documentation, provide specific feedback on one strength (e.g., "Your identification of timing-related failure modes was particularly thorough") and one area for improvement (e.g., "The risk assessment could better quantify the probability of user interface misinterpretation").
• Give the candidate 15 minutes to enhance their documentation based on the feedback.
• Discuss how they would incorporate this risk analysis into the broader development process.
• Evaluate both the quality of their initial documentation and their ability to improve it based on feedback.

Frequently Asked Questions

How long should we allocate for these work sample exercises?

Each exercise is designed to take 45-90 minutes, depending on the complexity. For remote candidates, consider spreading the exercises across multiple interview sessions. For on-site interviews, select 1-2 exercises that best align with your priorities for the role.

Should we provide these exercises before the interview or during it?

For coding and bug fixing exercises, conducting them during the interview allows you to observe the candidate's problem-solving process in real-time. For architecture and documentation exercises, consider providing the requirements 24 hours in advance to allow for more thoughtful responses, similar to real-world scenarios.

How should we evaluate candidates who have limited experience with medical device regulations?

Focus on their technical skills and ability to understand and apply new regulatory concepts. During the feedback portion, provide brief guidance on regulatory considerations and evaluate how quickly they incorporate this perspective. Strong candidates without medical device experience will demonstrate an appreciation for safety-critical systems and rigorous documentation.

Can these exercises be adapted for different levels of seniority?

Yes. For junior roles, simplify the requirements and provide more guidance. For senior roles, increase the complexity and expect more comprehensive risk analysis and architectural considerations. For leadership positions, add questions about how they would guide a team through implementing their solutions.

How do we ensure these exercises don't disadvantage candidates from diverse backgrounds?

Review the exercises to ensure they don't require specialized domain knowledge that isn't essential to the role. Provide clear instructions and be open to different approaches that achieve the same goals. Focus evaluation on problem-solving methodology and core skills rather than familiarity with specific tools or terminology.

Should we compensate candidates for completing these exercises?

For exercises completed outside the interview process that require significant time (over 2 hours), consider offering compensation, especially for senior roles. This demonstrates respect for the candidate's time and expertise while ensuring you receive thoughtful submissions.

The medical device software industry demands engineers who can navigate complex technical challenges while maintaining unwavering commitment to quality, safety, and regulatory compliance. By incorporating these targeted work samples into your hiring process, you'll gain deeper insights into candidates' capabilities than traditional interviews alone can provide.

Remember that the best candidates will not only demonstrate technical proficiency but also show an understanding of the unique constraints and responsibilities that come with developing software for medical devices. Their approach to these exercises will reveal how they balance innovation with patient safety—a critical mindset for success in this field.

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