Medical Device Design Considerations

Understanding the Medical Device Development Landscape in Canada

The medical device industry represents one of the most challenging and rewarding sectors for engineering professionals. With Health Canada's stringent regulatory framework and the growing demand for innovative healthcare solutions across Atlantic Canada, engineering firms must navigate a complex intersection of technical excellence, patient safety, and regulatory compliance. In Nova Scotia, the healthcare technology sector continues to expand, with institutions like the QEII Health Sciences Centre and regional hospitals increasingly seeking locally developed medical solutions.

Medical device design encompasses everything from simple diagnostic tools to complex implantable devices, each requiring meticulous attention to detail throughout the entire product lifecycle. For engineering firms serving the Maritime provinces, understanding these considerations is essential for delivering devices that meet both clinical needs and regulatory requirements while supporting the region's growing life sciences sector.

Regulatory Framework and Health Canada Requirements

Before any medical device can reach Canadian patients, it must satisfy Health Canada's Medical Devices Regulations under the Food and Drugs Act. These regulations classify devices into four categories based on risk level, with Class I representing the lowest risk and Class IV the highest. Understanding this classification system is fundamental to the design process, as it determines the regulatory pathway and documentation requirements.

Device Classification Considerations

Class I devices, such as tongue depressors and elastic bandages, require only establishment licensing. Class II devices, including powered wheelchairs and pregnancy test kits, necessitate both establishment licensing and device licensing. Class III and IV devices, which include implantable devices and life-supporting equipment, demand the most rigorous pre-market review processes, often requiring clinical evidence and detailed risk analyses.

• Class I: Lowest risk, minimal regulatory burden, establishment licence required

• Class II: Low to moderate risk, device licence and quality system required

• Class III: Moderate to high risk, detailed safety and effectiveness data required

• Class IV: Highest risk, most stringent pre-market scrutiny and ongoing surveillance

Quality Management System Requirements

Health Canada mandates that manufacturers implement quality management systems compliant with ISO 13485:2016. This standard specifies requirements for demonstrating the ability to provide medical devices and related services that consistently meet customer and regulatory requirements. For engineering teams in Nova Scotia and throughout Atlantic Canada, establishing robust quality management protocols early in the design process prevents costly remediation efforts and regulatory delays.

The quality management system must address design controls, risk management, supplier management, production processes, and post-market surveillance. Documentation requirements are substantial, with design history files often comprising thousands of pages for complex devices. Engineering firms must maintain meticulous records of design inputs, outputs, reviews, verification, validation, and transfer activities.

Human Factors Engineering and Usability

Medical devices ultimately serve human users—whether healthcare professionals, patients, or caregivers. Human factors engineering, also known as usability engineering, ensures that devices can be used safely and effectively by their intended users in their intended use environments. This discipline has gained significant regulatory attention following numerous incidents attributed to use errors rather than device failures.

User-Centred Design Process

Implementing a user-centred design process involves extensive user research, including contextual inquiries at healthcare facilities, interviews with clinicians, and observation of existing workflows. For projects serving Maritime healthcare institutions, understanding the unique operational characteristics of regional hospitals, community health centres, and long-term care facilities provides invaluable design insights.

Key human factors considerations include:

• Physical ergonomics: Device dimensions, weight distribution, grip surfaces, and manipulation requirements

• Cognitive ergonomics: Information display, alarm management, workflow integration, and mental workload

• Environmental factors: Lighting conditions, noise levels, space constraints, and infection control requirements

• User population characteristics: Training levels, experience, physical abilities, and potential impairments

• Use scenarios: Normal use, emergency situations, maintenance procedures, and cleaning protocols

Usability Testing and Validation

Formative usability testing throughout the design process identifies potential use errors and informs iterative design improvements. Summative usability testing, conducted with the final device design, provides evidence that the device can be used safely and effectively. Test protocols must simulate realistic use conditions and include representative user populations. For devices intended for home use, testing should account for the diverse capabilities of Nova Scotia's aging population and the challenges of rural healthcare delivery common throughout the Maritimes.

Materials Selection and Biocompatibility

Material selection for medical devices requires balancing mechanical properties, manufacturing considerations, cost factors, and biological compatibility. For devices contacting patients, biocompatibility evaluation following ISO 10993 standards is mandatory. This evaluation framework considers the nature, duration, and frequency of patient contact.

Biocompatibility Testing Categories

The ISO 10993 series outlines biological evaluation requirements based on device contact type:

• Surface contacting devices: Skin, mucosal membrane, or breached surface contact

• Externally communicating devices: Blood path indirect, tissue/bone/dentin contact, or circulating blood contact

• Implant devices: Tissue/bone contact or blood contact

Contact duration classifications include limited exposure (less than 24 hours), prolonged exposure (24 hours to 30 days), and permanent contact (greater than 30 days). Each combination of contact type and duration determines the required biological evaluation endpoints, which may include cytotoxicity testing, sensitisation testing, irritation studies, systemic toxicity evaluation, and implantation studies.

Common Medical Device Materials

Engineering teams must carefully evaluate material options against application requirements. Stainless steel alloys, particularly 316L and 316LVM, offer excellent corrosion resistance and mechanical properties for surgical instruments and implants. Titanium and titanium alloys provide superior biocompatibility and strength-to-weight ratios for orthopaedic applications. Medical-grade polymers, including PEEK, UHMWPE, and various silicones, enable innovative device designs while maintaining biological safety.

For electronic medical devices, material selection must also address electromagnetic compatibility, thermal management, and chemical resistance to cleaning and sterilisation agents. The harsh environments found in Nova Scotia's coastal healthcare facilities, where salt air and humidity can accelerate material degradation, may warrant additional consideration for devices deployed regionally.

Design for Manufacturing and Sterilisation

Successful medical device design requires early and ongoing consideration of manufacturing processes and sterilisation requirements. Design decisions made during concept development can significantly impact production costs, quality consistency, and time-to-market.

Manufacturing Process Selection

The choice of manufacturing processes depends on device geometry, material requirements, production volumes, and cost targets. Common processes for medical devices include:

• CNC machining: Ideal for precision metal components, prototype development, and low-volume production

• Injection moulding: Cost-effective for high-volume polymer components with complex geometries

• Additive manufacturing: Enables patient-specific devices, complex internal structures, and rapid prototyping

• Sheet metal fabrication: Suitable for enclosures, brackets, and structural components

• Extrusion: Efficient production of tubing, catheters, and constant cross-section profiles

Design for manufacturing principles help ensure that devices can be produced consistently, economically, and at the required quality levels. These principles include minimising part count, standardising hardware, designing for assembly efficiency, and specifying appropriate tolerances based on functional requirements rather than arbitrary precision.

Sterilisation Compatibility

Devices requiring sterile presentation must be designed for compatibility with appropriate sterilisation methods. Common sterilisation processes include ethylene oxide (EtO) gas sterilisation, gamma irradiation, electron beam irradiation, and steam sterilisation (autoclaving). Each method presents unique material compatibility challenges and validation requirements.

For reusable devices requiring repeated sterilisation, material degradation over multiple cycles must be characterised and documented. Packaging design must maintain sterile barrier integrity throughout distribution and storage while facilitating aseptic presentation during clinical use. Sterilisation validation studies, including bioburden testing, sterility assurance level determination, and accelerated aging studies, require significant time and resources that must be planned into development schedules.

Risk Management Throughout the Design Lifecycle

ISO 14971 establishes the risk management framework for medical devices, requiring systematic identification, evaluation, control, and monitoring of risks throughout the entire product lifecycle. Effective risk management is not merely a regulatory requirement but a fundamental engineering discipline that protects patients and improves device quality.

Risk Analysis Methodologies

Several complementary risk analysis techniques support comprehensive hazard identification:

• Preliminary Hazard Analysis (PHA): Early-stage identification of potential hazards and hazardous situations

• Failure Mode and Effects Analysis (FMEA): Systematic evaluation of potential failure modes and their consequences

• Fault Tree Analysis (FTA): Top-down analysis of events that could lead to identified hazards

• Hazard and Operability Study (HAZOP): Structured examination of process deviations and their effects

Risk evaluation involves estimating the probability of harm occurrence and the severity of potential harm. Risk acceptability criteria must be established based on regulatory requirements, industry standards, and stakeholder expectations. Risks deemed unacceptable require mitigation through design changes, protective measures, or safety information.

Risk Control and Residual Risk

The risk control hierarchy prioritises inherently safe design over protective measures and protective measures over safety information. Engineering controls built into the device design provide more reliable protection than warnings or instructions that depend on user compliance. When residual risks remain after all practical risk control measures are implemented, these must be documented and communicated appropriately to users and patients.

Post-market surveillance activities monitor device performance in clinical use, identifying potential risks not apparent during pre-market development. Complaint handling, adverse event reporting, and periodic safety update reports contribute to ongoing risk management throughout the device lifecycle.

Verification, Validation, and Design Transfer

Design controls require objective evidence that devices meet their intended specifications (verification) and satisfy user needs and intended uses (validation). These activities must be planned, executed, and documented systematically to support regulatory submissions and demonstrate due diligence.

Verification Testing

Verification testing confirms that design outputs meet design input requirements. Testing protocols must specify acceptance criteria derived from requirements, test methods, sample sizes, and statistical analyses. Common verification activities include dimensional inspection, material testing, functional testing, environmental testing, and electromagnetic compatibility testing.

For devices intended for deployment across Atlantic Canada's diverse environments—from urban hospital settings to remote nursing stations—verification testing should encompass relevant environmental extremes including temperature variations, humidity levels, and transportation stresses encountered during distribution throughout the region.

Validation and Clinical Evidence

Validation demonstrates that devices satisfy user needs and intended uses under actual or simulated use conditions. For higher-risk devices, clinical investigations may be necessary to generate evidence of safety and effectiveness. Clinical study design, ethics approval, and regulatory submissions require specialised expertise and significant resources.

Design transfer activities ensure that the validated design can be manufactured consistently in the production environment. Process validation, including installation qualification, operational qualification, and performance qualification, confirms that manufacturing processes reliably produce devices meeting specifications.

Partner with Experienced Medical Device Engineering Professionals

Medical device development demands expertise across multiple engineering disciplines, regulatory frameworks, and quality systems. From initial concept development through regulatory approval and into production, each phase presents unique challenges requiring careful navigation. The consequences of design deficiencies—whether patient safety incidents, regulatory delays, or costly recalls—underscore the importance of getting medical device design right from the start.

At Sangster Engineering Ltd., our team brings comprehensive engineering expertise to medical device development projects throughout Nova Scotia and Atlantic Canada. We understand the regulatory requirements, technical challenges, and quality expectations that define successful medical device programmes. Whether you're developing a novel diagnostic device, improving an existing therapeutic system, or adapting proven technology for new clinical applications, our engineering professionals can help translate your vision into safe, effective, and regulatory-compliant medical devices.

Contact Sangster Engineering Ltd. today to discuss your medical device design project. Our Amherst, Nova Scotia office serves clients throughout the Maritime provinces and beyond, providing the technical excellence and regulatory expertise your project demands. Let us help you bring innovative healthcare solutions to the patients who need them.

Partner with Sangster Engineering

At Sangster Engineering Ltd. in Amherst, Nova Scotia, we bring decades of engineering experience to every project. Serving clients across Atlantic Canada and beyond.

Contact us today to discuss your engineering needs.