Author: Chris Sam Soon
Developing electronics for the highest-risk medical devices.
At Hydrix, one of my responsibilities is leading the development of Class III medical devices, products that are considered to have the highest risk, often used in supporting or sustaining human life, or more broadly, implanted devices. Examples of some of the Class III products we work on range from closed-loop drug injectors to control systems for artificial hearts.
In recent experience, sourcing electronic components for these devices has required increased rigour due to the high level of risk associated with the devices use cases, and ongoing supply challenges, resulting in a reduced pool of components available for selection. In this article, I’d like to share some of the fundamental approaches Hydrix undertakes during component selection for Class III products, with the aim of minimising the risk of late-stage component fit-for-purpose and/or supply surprises.
Start with the end in mind
A key consideration in Class III device electronic component selection is to assess the effects of that component failing against the performance of the safety function of the medical device. Typically, this assessment is done using standard risk management tools such as Hazard Analysis, Failure Modes Effects Analysis and Failure Modes Effects and Diagnostic Analysis (FMEA/FMEDA) that is undertaken during the development process. Part of this exercise is to apply a “likelihood” ranking to each hazard or failure mode and a “severity” ranking if failure was to occur. For failures that generate unacceptable risk, mitigation strategies (or Risk Control Measures) are implemented to reduce the risk to a tolerable level. Those components that have been identified as critical to the performance of the safety function of the device will need to meet stringent requirements to ensure safety, reliability, and effectiveness of the product.
Some semiconductor manufacturers do produce a range of high-reliability grade (Hi-Rel) products that cater to these requirements. These undergo a similar qualification process to automotive or MIL-Spec components, with an aim to:
- reduce latent failures
- improve processes
- bin components based on performance
- remove outliers
- provide tighter specifications
- increase data retention time of memory products.
Reliability data generated during these qualification tests can also be used to support arguments for product safety as part of the risk management activities. Additionally, topics on legal liability waiver will come into play in case of a component malfunction. This is important as some semiconductor manufacturers may refuse to supply parts to Class III products as it potentially opens them to significant liability risks due to the nature of the application.
Collaborate with your component supplier
It is therefore crucial during the early stages of the design process to make a proper component selection and to work together with the semiconductor manufacturer to ensure that the component meets the requirements for safety and reliability required in life-sustaining medical applications. If a focus is not placed on selecting appropriate components early on in the design phase, you may discover late in the development that some components are specifically excluded for life-sustaining medical applications. There are also circumstances where a supplier may require you to demonstrate suitability or take responsibility for the suitability of the part for use in the proposed application. The suitability of a component for use in a Class III product can be assessed by considering:
- A supplier’s adherence to applicable quality standards such as ISO13485/ISO9001.
- Control of the design and development changes, including process changes.
- Identification and traceability component/lot.
- Proper record keeping of materials, manufacturing processes and any changes to the product development lifecycle.
- Component up-screening.
- Guarantee of supply longevity.
Class III Medical devices by nature, have a long development life cycle and may be expected to remain on the market for an extended period of time. Due to the previously outlined qualification requirements, it can be difficult or even impossible to find suitable replacement components. Therefore, it is important that the selected components can continue to be purchased. Component lifecycle and longevity must be discussed during the engagement with authorised distributors to ensure availability and the manufacturer should subscribe to any End-of-Life component reports that the component manufacturers provide.
At Hydrix we routinely apply these considerations to the selection of the components used in our Class III designs. By approaching component selection in this manner, the risk of design rework or commercial issues down the track is minimised.
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About the author
Christopher Sam Soon | Principal Electronics Engineer
Christopher is a Principal Electronics Engineer at Hydrix, with over 15 years of product development experience across diverse medical, industrial, and automation sectors. His expertise shines particularly in safety-critical applications, where he has honed his skills in functional safety (SIL2/SIL3) and medical devices (Class II/III). Certified as a Functional Safety Expert by EXIDA and holding registration as a Professional Engineer with BLA, Christopher brings a wealth of knowledge to any project requiring meticulous attention to safety standards. He holds a Bachelor’s degree in Electrical Engineering from the National University of Singapore.
