A Systems Engineering Guide to Point of Care Testing Devices

Developing point of care testing (POCT) devices means engineering for the moment of impact—where a rapid result can alter a patient outcome. Ignoring the systems-level complexity isn't just a project risk; it's a direct threat to patient safety, regulatory approval, and time-to-market. A failure to connect architecture, firmware, and manufacturing readiness guarantees costly rework, delays, and a product that's dead on arrival.

This guide is for the VPs of Engineering, program managers, and lead systems engineers accountable for delivering these complex medical devices. It’s not a market overview or a deep dive into assay chemistry. It is an operational playbook for navigating the critical hardware and firmware tradeoffs and, crucially, for designing for testability and manufacturability from day one.

You will learn how to:

• Frame the core architectural tradeoffs that define your product's cost, reliability, and regulatory path.
• Implement reliability patterns in hardware and firmware to mitigate field failures.
• Build a robust verification and manufacturing strategy to transition from prototype to production with control.

Architecting for Clinical Needs and Regulatory Compliance

The success or failure of a point-of-care testing device is often sealed in the architecture—the foundational blueprint balancing clinical needs, engineering feasibility, and regulatory constraints. This phase translates real-world scenarios into hard engineering specifications. A paramedic needing a blood gas reading in a moving ambulance becomes a set of concrete targets in your System Requirements Document (SRD): time-to-result under 90 seconds, diagnostic sensitivity of 99.5%, and defined shock/vibration tolerance per IEC 60601-1-12. Getting this translation wrong is a primary cause of late-stage rework and outright project failure.

From Risk Map to System Requirements

One of your first tasks is building a comprehensive risk map. This is not a box-checking exercise; it’s an active search for every potential failure mode, from assay chemistry to the user interface. Consider a device designed for an elderly patient's at-home use. The risk map must address real-world challenges:

• Human Factors: Can a user with poor eyesight or limited dexterity operate the device without error? This informs requirements for button size, screen contrast, and audible feedback cues.
• Environmental Factors: Will temperature swings in a drafty house affect assay reaction time? Does humidity degrade sensor accuracy? This drives decisions on thermal management and component sealing.
• Connectivity: If the device syncs data via Bluetooth, what happens if the connection drops mid-transfer? This demands fault-tolerant firmware and robust data validation protocols to prevent corruption.

This systems-thinking approach, central to how high-performing teams operate, forces engineering leaders to consider design for testability (DFT) and design for manufacturability (DFM) from the very first architecture meeting, not as an afterthought. You must also ensure that all chemicals used in R&D and manufacturing meet safety standards, including a thorough understanding of OSHA's MSDS requirements.

Making Defensible Architectural Tradeoffs

Every architectural decision is a tradeoff with a direct line to your budget, timeline, and regulatory strategy. These choices must be deliberate, documented in an Architecture Decision Log (ADL), and defensible to leadership and bodies like the FDA.

The goal of early-stage architecture is to make the least-bad decisions with incomplete information. You're not aiming for perfection; you're building a resilient framework that can adapt as you learn through prototyping and testing.

These tradeoffs are more critical than ever. The global POCT market was valued at USD 44.48 billion in 2023 and is projected to hit USD 125.33 billion by 2032. Capturing a share of this market requires designing systems that are testable, manufacturable, and compliant from day one. You can read the full research on the POCT market to grasp the scale.

The table below breaks down common, high-stakes decisions.

Critical POCT System Requirement Tradeoffs

These are not just technical choices; they shape your entire regulatory strategy. Aligning them with standards like ISO 13485 and a Secure Software Development Life Cycle (SDLC) paves a smoother path through verification and validation. For a deeper look, see our guide on the FDA approval process for medical devices.

Designing Reliable Embedded Hardware and Firmware

At the core of every POCT device is an intricate dance between hardware and firmware. Get it wrong, and you're left with a product that fails in the field, produces erroneous data, and will never be cleared by regulators.

For hardware engineers, the battle is won or lost at the analog front-end. Pristine signal integrity is paramount. Noise, drift, or interference between the sensor and the ADC can corrupt the measurement, rendering even the most sophisticated algorithm useless. This requires meticulous PCB layout, proper grounding, and careful component selection to minimize thermal noise and ensure power supply stability.

Hardware Design for Testability (DFT)

High-performing teams design for testability (DFT) from the first schematic. This is not an optional add-on; it's a core requirement for manufacturing at scale. A DFT-aware design strategically places test points, enables boundary scan (JTAG) for automated testing, and includes programming interfaces that are easily accessible by factory fixtures. Ignoring DFT creates a production bottleneck, forcing manual, error-prone testing that inflates your cost per unit. Building in these test hooks early empowers your contract manufacturer to develop automated test fixtures, resulting in higher yields and lower manufacturing costs.

Firmware Reliability Patterns for Field Operations

On the firmware side, the mission is deterministic and resilient operation. POCT devices operate in unpredictable environments, and the firmware must handle unexpected events gracefully without compromising patient safety. These reliability patterns are non-negotiable:

• Watchdog Timers: This fundamental safety net resets the system if the main application freezes, preventing the device from failing in an unsafe state.
• Brownout Detection: This circuit monitors the system voltage and forces a controlled reset if power sags below a safe operating threshold, preventing memory corruption or erratic CPU behavior.
• Fault Containment: Good firmware architecture is modular. A failure in a non-critical component (like a UI element) must not bring down the entire system, especially the core measurement loop.

Real-Time Constraints and IEC 62304

For many POCT devices, certain operations are time-critical. A device measuring a chemical reaction over a precise 60-second window has a hard real-time requirement. The firmware must guarantee that sensor readings occur at exact intervals, regardless of other tasks. A Real-Time Operating System (RTOS) is often the solution, allowing developers to assign priorities to ensure critical tasks execute on schedule.

This deterministic behavior is a key requirement for complying with software safety standards like IEC 62304, which governs the medical device software lifecycle. Failing to meet a real-time deadline is a significant risk that must be mitigated and documented. Our overview of embedded firmware development services provides more context on building these safety-critical systems.

A key takeaway for program leaders: hardware and firmware are not sequential activities. They are parallel and intertwined. The choice of a microcontroller (hardware) dictates firmware capabilities, while firmware's real-time requirements may demand a more powerful—and expensive—MCU. The best teams resolve these dependencies early.

Nailing Your Verification and Manufacturing Strategy

A POCT device that works on the lab bench but fails verification or cannot be built at scale is a commercial disaster. The bridge between a prototype and a successful product is a disciplined verification and manufacturing strategy where early design choices are tied to late-stage success.

The process begins with a verification plan where every test case traces directly back to a requirement in your System Requirements Document (SRD). This traceability is non-negotiable for any submission to the FDA or other regulatory bodies. Without it, you cannot prove your device is safe and effective.

Staged Verification: EVT, DVT, PVT

The journey from prototype to mass production is managed through formal gates: Engineering Validation Testing (EVT), Design Validation Testing (DVT), and Production Validation Testing (PVT). Each gate has clear entry and exit criteria. Rushing these stages is a recipe for schedule and budget overruns.

• EVT (Engineering Validation Testing): Focuses on core functionality. Does the device work as designed? You're testing subsystems and verifying basic specifications on units hand-built by the engineering team.
• DVT (Design Validation Testing): Tests the final "looks-like, works-like" product against the entire list of system requirements. This includes environmental testing (temperature, humidity, shock, vibration), EMC/EMI testing, and formal software validation on units built with production-intent tooling.
• PVT (Production Validation Testing): Validates the manufacturing line itself. The goal is to prove you can build the device repeatedly at volume while hitting all quality and yield targets.

A Real-World Scenario: The DVT Failure

Consider a team developing a handheld glucose meter. During EVT, the device performed flawlessly. But in DVT, 15% of units failed electrostatic discharge (ESD) testing. The root cause? A late-stage change to a cheaper plastic enclosure that lacked adequate shielding. The team had skipped a formal Engineering Change Order (ECO) process to save time.

The Fallout:

• Outcome: A two-month delay for a complete redesign and re-tooling of the enclosure.
• Cost: Over $100,000 in unplanned tooling costs and engineering hours.
• Lesson: Bypassing process controls creates massive downstream risk. A robust change control system and early engagement with manufacturing partners could have caught this issue during the design phase.

Building Your Manufacturing Test Plan

A comprehensive manufacturing test plan is the backbone of your quality system. It uses automated fixtures to verify critical functions on every unit before it leaves the factory, catching failures when they are cheap to fix. The plan should ensure every unit is stamped with a unique, serialized ID, tying its test results to a central database. This unit-level traceability is invaluable for failure analysis. If a batch of devices starts failing in the field, you can trace the problem to a specific lot of components or a production line event.

Investing in DFM and DFT isn't an expense; it's an insurance policy. The time spent upfront designing a test fixture or selecting a more reliable connector is nothing compared to the cost of a production line halt or a product recall. The best teams treat manufacturability as a core design requirement.

Navigating the Transition from Prototype to Production

Getting a prototype to work on your bench is one thing. Building thousands of them reliably is another. The transition to a scalable, high-yield product is where many devices stumble. It requires a shift from innovation to process, control, and supply chain orchestration.

This is where elegant designs meet the unforgiving reality of mass production.

From Design Freeze to Controlled Change

The transition from EVT to DVT hinges on the design freeze—a formal declaration that the core design is locked. This stops the endless cycle of "one more tweak" and focuses the team on verification and manufacturing readiness. After the freeze, any change must go through a formal Engineering Change Order (ECO) process. This isn't bureaucracy; it's discipline. An ECO forces a structured review of a change's impact on cost, schedule, and regulatory filings.

Orchestrating Your Supply Chain

Your Contract Manufacturer (CM) is your partner in scaling. Success depends on how well you enable them with an immaculate documentation package. This includes:

• Detailed Assembly Instructions: Visual, step-by-step guides that leave zero ambiguity.
• A Comprehensive Test Plan: Specifies every test, the required fixtures, and clear pass/fail criteria.
• Quality Control Metrics: Defines acceptable yield rates, cosmetic standards, and incoming material inspection protocols.

High-performing teams don't just "throw the design over the wall." They embed an engineer at the CM's facility during initial production runs. This creates single-threaded ownership, enabling rapid problem-solving and ensuring nothing is lost in translation.

Your Manufacturing Readiness Checklist

Before mass production, a final, comprehensive check is essential to minimize costly surprises.

Only when every item is marked "Complete" are you truly ready to scale.

Closing the Loop with Failure Analysis (FRACAS)

Even with perfect planning, failures will occur. Long-term success is determined by how quickly you find, fix, and learn from them. A Failure Reporting, Analysis, and Corrective Action System (FRACAS) is your most valuable tool.

1. Report: A failure is identified on the line and documented.
2. Analyze: Engineering performs a root cause analysis (RCA) to understand why it failed.
3. Correct: A corrective action is implemented—a design change (ECO), a process tweak, or a supplier quality alert.

This closed loop turns every production issue into an opportunity to make your product and process more robust. For a deeper dive, our guide on the transition from prototype to product provides a more granular roadmap.

Your POCT Development Action Plan

We've covered a framework for developing reliable point of care testing devices. The central theme is this: critical disciplines like rigorous requirements definition, designing for testability, and proactive manufacturing planning must be embedded from day one. Success is not about a single heroic effort; it's about the consistent application of engineering fundamentals.

Your immediate next step is to benchmark your current program against this framework. Ask the hard questions that separate devices that scale from those stuck in the lab.

Common Failure Modes and How to Detect Them Early

• Requirements Gaps: Signal: Constant feature creep and arguments during DVT. Detection: Can you trace every verification test case directly back to a requirement in the SRD? Gaps are a red flag for regulators and signal a disconnect between what you're building and what the market needs.
• Poor Testability: Signal: Manual, time-consuming testing during pilot runs; low first-pass yield. Detection: Review your current schematic. Does it include test points, programming headers, and JTAG access for automated manufacturing tests? If not, you are signing up for higher production costs and increased field failures.
• Late-Stage Integration Issues: Signal: Unexplained noise in sensor readings; firmware crashes on production hardware. Detection: Are hardware, firmware, and systems engineers collaborating from the start? A siloed approach where hardware is designed and then "thrown over the wall" to firmware is a recipe for disaster.

High-performing teams tackle these issues head-on, not after a demoralizing failure during DVT. They treat manufacturability as a core design requirement, on par with clinical performance.

Adopting an Integrated Approach

At Sheridan Technologies, our single-threaded ownership model ensures hardware, firmware, and manufacturing considerations are harmonized from the first architecture meeting. This integrated approach eliminates the costly handoffs and communication gaps that plague complex product development. We see the device as a complete system where a small PCB decision directly impacts the manufacturing test fixture and firmware reliability.

By designing for testability from day one, we help teams de-risk the crucial transition from prototype to mass-produced product. Whether you're architecting a new device or need to get a program back on track, a targeted assessment can mitigate risks before they become critical failures.

Frequently Asked Questions

When you're deep in the trenches of developing a point-of-care device, certain questions always seem to pop up. These aren't just academic—getting the answers right can be the difference between a project that sails through to production and one that gets bogged down by costly, late-stage surprises.

We’ve seen these challenges firsthand. Here’s a look at some of the most common technical and operational hurdles engineering leaders face, along with some hard-won insights.

What Are the Biggest Firmware Risks in POCT Device Development?

The top three firmware risks are missed real-time deadlines, inadequate fault tolerance, and security vulnerabilities. Missing a hard real-time deadline for acquiring sensor data—even by milliseconds—can produce inaccurate results, which is a clinical failure. You must also build in robust fault handling. A simple watchdog timer can be the difference between a graceful recovery from a software freeze and a device that fails unsafely. For connected devices, insecure data transmission is a non-starter; patient data privacy and device integrity are scrutinized during any regulatory review.

How Early Should We Involve a Contract Manufacturer?

Involve your contract manufacturer (CM) much earlier than you think—ideally during the architecture phase. Waiting until your design is "frozen" is a classic and expensive mistake. Bringing in a CM early allows their Design for Manufacturability (DFM) experts to provide input on component selection, PCB layout, and enclosure design from a high-volume production perspective. This early collaboration is your best defense against major redesigns, helping to optimize for yield, reduce production costs, and de-risk your supply chain.

What Is the Difference Between Verification and Validation?

This distinction is critical for regulatory compliance. They answer two very different questions:

• Verification asks, “Did we build the device right?” This internal process tests the device against your technical specifications. Does it meet the power budget? Does the sensor have the required sensitivity?

• Validation asks, “Did we build the right device?” This external process confirms the device meets the user's needs in a real clinical setting. Can a nurse use it correctly under pressure? Does it fit the workflow?

Both are mandatory for regulatory frameworks like ISO 13485. You can't have one without the other. Nailing both requires a deep understanding of the clinical workflow from the project's inception.

At Sheridan Technologies, we specialize in de-risking the journey from concept to a market-ready medical device. If you're architecting a new POCT system or need to get a program back on schedule, a manufacturing readiness assessment can identify potential risks before they become critical problems.