5 things every electrical medical device start-up should know

1. Produce a first issue of the product requirements at the beginning of your detailed design phase

As part of a successful medical device start-up, you need to know what you are trying to design before you design it.

Once you get past the proof-of-concept phase, it is no longer adequate to design against a rough draft of the requirements document, which is typically supplemented with notes from a myriad of emails and meeting minutes.

This could lead to wasted time and effort working on undefined or non-essential functions. It’s therefore important not to wait until the end of the project before issuing your requirements. Instead, agree and define them at the beginning of your detailed design phase. You can then revise and re-issue them as the project progresses, helping you identify where your design needs to adapt and evolve, on a rolling basis. When defining your requirements, focus on what is essential for the product and make sure they are succinct, unambiguous and testable.

TBDs (to be determined) are acceptable at this stage and even if you only get 90% of the final requirements right, that should still be adequate to progress forwards with.

From your product requirements, you’ll be able to generate the more detailed sub-system requirements for the electronics, software, system and mechanical sub-systems as appropriate. These will help to ensure that you are focusing design efforts on the product going to market.

2. Perform a detailed assessment of the required standards and generate specific design requirements

To comply with international regulations, you will need to have your product assessed for compliance with the relevant standards for your intended markets. Typically, for electrical medical equipment, these will include the IEC 60601 series, or for in vitro diagnostics (IVDs) the IEC 61010 series.

These standards will directly impact product developments such as your physical design, including materials specifications, component selection,and certifications, electrical isolation requirements, safety functions, enclosure design, indicators and alarms. They will also significantly impact your risk analysis, requirements for labelling and your instructions for use.

It’s important for medical technology companies to go through each standard and assess the clauses that are relevant to your design, then generate design-specific requirements against them.

These requirements should help to ensure your device is designed to comply from the start and minimise the risks of failing certification just before product launch.

When you have a near-final design, it is worthwhile to have a preliminary design review with the same assessment laboratory that you will be using for a formal standards compliance assessment. This will give you additional feedback on potential issues before issuing your design for pilot production and certification.

3. Electromagnetic compatibility: pre-compliance test your prototype

The first step in electromagnetic compatibility (EMC) compliance is always good EMC design practice. There is a lot you can do to help reduce emissions and improve immunity through careful layout, screening, filtering, component selection and electronics design techniques. For EMC, the proof of the design is in the testing, so it can be helpful to take your prototype to an EMC test house for some preliminary ‘first look’ testing.

• Top tip: if you don’t want to perform the whole suite of EMC tests on your prototype, consider testing at least the radiated and conducted emissions and possibly electrostatic discharge (ESD) if the enclosure design is likely to be similar to the final product.

Subsequent design changes will impact your device’s EMC performance, however, resolving some of these issues early will reduce the risk of time-consuming design changes later that could impact your mechanical design as well as updates to PCBs. Even just one day at the test house should produce some useful data for your design team.

As the design begins to mature, make sure to then return to the test house to conduct the full suite of EMC tests and modify your design as necessary. This will give your final ‘production representative’ device the best chance of passing formal testing.

4. Engage with your contract manufacturer during the design phase

If you’re hoping to start manufacturing as soon as your final design has been issued and want the process to be reliable, efficient and cost-effective, you should start to engage with your manufacturer early in the design phase.

Your design team should be able to address most of the Design for Manufacture (DFM) and Design of Test (DFT) issues. However, your selected manufacturing partner will be able to provide additional feedback and actionable insights on your proposed design in relation to their specific manufacturing, test and procurement capabilities.

Discussions and questions with your manufacturing partner should include:

• is the PCB layout optimised for their soldering and assembly processes?
• will the manufacturer be able to source the specified components and materials in production quantities, or do you need to re-design using alternatives?
• how will the device be assembled and can this be simplified by changing the design?
• are there any manually intensive processes that should be avoided?
• what are the lead times on tooling?

You will also need to discuss how your device is to be tested.

There are a wide array of test technologies and strategies available, including: bare board, Automated Optical Inspection (AOI), boundary scan and functional and system tests. The most appropriate solution for you will depend on your specific design, safety criticality, production quantities, market value and the manufacturer’s capabilities.

Discussions on testing should include:

•  what level of testing is required on components, sub-systems and the final assembly to ensure appropriate test coverage and detect defects?
• how will manufacturing test specifications be produced?
• is there a need for additional test pads or test connectors?
• does the manufacturer need to design and build custom test rigs?
• is a special version of the firmware required for the manufacturing tests?

Engaging your manufacturer early should allow time to prepare for production and avoid re-designs for test or manufacture. It could also lower your production costs and improve production yield and reliability.

5. Dry-run your design verification protocols before issuing them

The verification phase of a project is a significant activity that will include:

• generating a verification plan
• detailed test protocols
• preparing dedicated test set-ups
• training test personnel
• formal testing and documenting the results
• producing a verification report
• a traceability matrix

To minimise potential issues during formal testing, your draft verification test protocols should go through a ‘dry run’ before they are issued.

While this adds time to the project plan, it will reduce the overall time to perform verification.

Dry running your tests also has several advantages. It will allow you to check the steps of the protocol and make updates to the draft before it has been issued.

You will also be able to confirm if you have all the required equipment to perform the tests, gain valuable feedback from the test technician performing the tests and give an informal head’s up on design issues before you enter formal verification. Overall, your dry run is your opportunity to resolve design, protocol or test set-up issues efficiently, before they become formally controlled.

Following this, the formal verification testing should focus on providing evidence that the design meets your requirements, rather than fixing issues with the protocol or the design.