Challenge

To design highly compact electronics for a Point-of-Care (PoC) diagnostics device in parallel with the client’s assay development work.

Approach

We took an iterative approach to hardware design to ensure we supported our client’s need for rapid development and launch.

Outcome

We produced several prototype batches at different phases to facilitate hardware and software development. This allowed the client to progress with clinical trials and assay development before the final production device was available.

At a glance

Client
Confidential

Sector
Diagnostics

Services
Electronics

Team staff on project
6

Hardware development for PoC diagnostics

The device had to be compact, include measurement and control functions (including multiple optical measurement techniques), and be able to measure absorbance at different wavelengths. We also needed to add wireless connectivity, low power consumption and ensure the device was compliant with the in vitro diagnostics (IVD) safety standards. In parallel to this work, our client was continuing their assay development and needed prototype hardware.

Designing modular electronics

Because of the complexity of the device, we took a modular approach to limit the impact of requirement changes on the design; we designed nine different custom printed circuit boards (PCBs), some of these going through many design iterations as our client’s requirements evolved.

Understanding the science of the requirements allowed us to design and implement an innovative yet robust circuit. We configured off-the-shelf components to meet the required performance parameters without relying on long lead-time specialist parts.

By distributing the final design on to different interconnecting PCBs, we were able to meet competing design constraints such as high-speed memory routing on one board, high current traces on a second board and low noise analogue circuits on a third board. We were also able to ensure that high voltage and safety-critical circuits remained physically isolated from the end user, despite the need to minimise interior product volume.

Chris Ferris, Senior Consultant

Complex electronics into a portable device

We worked closely with the client’s design engineers to integrate the electronics around the mechanical and optical sub-assemblies. To make the best use of the available space, we used various technologies from a high-density ten-layer PCB to complex flexi-rigid designs.

Exchanging PCB design data in both 2D and 3D formats allowed us to meet the challenging electrical performance requirements whilst simultaneously ensuring the overall board shape and component profiles fitted the ever-evolving device shape.

Early EMC testing

The instrument had many functions that needed to be operated or monitored during Electro Magnetic Compatibility (EMC) tests. Because of the 2.3GHz radio and RFID modules, the device had to comply with multiple EMC standards, which required a significant number of tests.

For efficiency, we wrote dedicated test scripts to continuously check device functions, reducing the number of test runs required.

Peter Money, Engineering Consultant

Hardware verification

We developed approximately 180 verification tests to demonstrate that the hardware met the project’s requirements. For subsequent design variants and to reduce the re-test time, we used impact analysis to determine the subset of tests to be performed.

A dedicated project team of test engineers allowed us to push the final verification activities through in the fastest possible time.

Hardware standard compliance

Passing formal compliance testing on production representative samples was critical to avoid delays in product launch.

Early in the design process, we analysed the IVD standards and generated design-specific requirements. This enabled us to pass formal compliance testing at the Notified Body without any design modifications.

Chris Daily, Engineering Consultant

Transfer to manufacture

Our client was keen to be ready-to-go for full production as soon as the device’s design was complete and validated.  To facilitate this, we engaged early with our manufacturing partners and produced draft test specifications. We then supported manufacturers throughout the project by working with them to design their automatic test equipment.

To ensure that pre-production devices were available to the client for functional testing, assay development and clinical trials, we designed and built custom PCB test jigs so that batches of devices could be built and tested by the contract manufacturer, long before main production.

The combination of flexible modular design and early commencement of many pre-production activities, coupled with our close working relationship with partners and suppliers, supported our client’s need for rapid development and subsequent quick transition to market.

Chris Daily, Engineering Consultant

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