Medical devices are becoming more powerful

07/25/2020 By Joe Aubin, Laird Performance Materials

Medical devices are increasingly being mentioned in the same breath as buzzy terms like artificial intelligence, machine learning and the internet of things. As devices become more connected and collect more data, patients, health care professionals and medical device manufacturers all stand to benefit.

However, these innovations present new challenges in the design process. To improve capabilities and performance, design teams are increasing devices’ processing power – and the signals emanating from them – which results in more electromagnetic interference and rising heat loads. Unfortunately, the current design process for medical devices will be inadequate as design engineers seek to address these challenges.
It’s not an overstatement to say that medical device design engineering has life or death implications. Patients rely on these complex devices to work flawlessly to maintain their health and, in some cases, stay alive. So, design flaws are unacceptable, and precision is crucial to ensure patient safety and regulatory compliance.

To properly manage risk in this increasingly challenging design environment, engineers must adopt a holistic, system-based approach to designing medical devices. If they assess various components of a device within the context of the larger system early in the design process – before the board is fully laid out – design engineers can optimize the limited and valuable real estate within a device. In the end, this approach will help them address EMI, thermal and structural challenges in a way that ensures long-term product reliability and performance.

Unify the design process

Traditionally, many different teams are involved in the medical device design process at various stages. Broad input is necessary, but too often these different teams interact with the product separately. As a result, teams address problems and add components in a piecemeal fashion that doesn’t make optimal use of the space within the product. This approach can also sometimes produce unintended performance consequences, cause delays or force rushed redesigns late in the process.

For example, electrical engineers may work to mitigate EMI separately from the mechanical teams that tackle thermal issues. Since EMI and heat are interrelated, these efforts can clash. For example, a heat sink can help lower thermal loads. However, it can exacerbate EMI. Addressing these two significant challenges together can ensure the manufacturer deals with both EMI and heat in a way that maximizes product performance.

A system-based approach is an alternative to the current, piecemeal model. A system-based approach can provide medical device manufacturers more design options earlier in the process and enable them to preempt potentially crippling thermal and EMI challenges – as well as structural defects. Before fully designing the product, a team should consider everything that will impact heat, EMI and the sensitive structural pieces of the device. For instance, is there a CPU within the device with an abnormally high thermal load? Is there a radio within the device operating at a high frequency, which would limit the effectiveness of a board-level shield? Is the board flexing too much?

This holistic approach can offer many benefits beyond device performance. By looking at EMI and thermal challenges at once, design engineers may find one solution to solve multiple problems. Designing at a system level can cut down the amount of assembly required and reduce the total cost of ownership of the various components within the device. Additionally, the team will be able to identify any flaws early on, potentially allowing the manufacturer to bring the device to market faster.

A trio of simulations

Using three types of simulation tools – electromagnetic modeling, computational fluid dynamics and mechanical simulations – design engineers can gain a comprehensive understanding of how various elements within the device interact and impact EMI, heat loads, as well as the device’s structure.

An electromagnetic simulation allows engineers to see where energy radiates throughout the system – and how that changes as the team adds and removes components. Computational fluid dynamics shows how fluid in a system (air is treated as a fluid for these simulations) flows in various directions based on temperature differentials. A mechanical simulation assesses the working of springs and other hardware, with an emphasis on how these parts impact board flexing or sensitive components like screens.

While design engineers often use simulation tools to validate design decisions, they can also use them to evaluate multiple concepts at a high level – before making final design decisions. This use of simulation tools allows the engineering team to determine the optimal architecture before committing to prototypes and tooling, and while they still have time to make large-scale changes.

De-risk the design process

To maintain a high level of precision within medical devices and minimize risk (from both safety and regulatory perspectives), design engineers must embrace this system-based approach to product development. By accounting for all elements in a device – from springs to EMI-reducing absorbers to thermal interface materials – holistically and early, design engineers can accommodate fast-moving medical technology innovations and improve their products.

Joe Aubin is a Systems Architect at Laird Performance Materials. He specializes in helping medical device manufacturers solve structural, EMI and thermal challenges.