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Medical Wearables – Ask an Expert Q&A

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Last updated May 20, 2024 | Published on Jul 22, 2022

Medical Wearables is a rapidly growing industry, so we had one of our experts answer a few frequently asked questions.

For our latest Ask an Expert blog, we invited people to submit any questions they had about Medical Wearables. We received questions spanning a breadth of topics, so we had one of our wearable device experts, Steve Baker, answer them.

What components typically make up a medical wearable?

The components in a medical wearable depend on the type, but transmitting wearables with on-board electronics usually include a cover film, thermoformed foam cover, printed flex electrode, printed circuit board assembly (or a printed assembly circuit with a battery), a stick-to-skin adhesive, conductive hydrogels, and a delivery/release liner. For wearables without on-board electronics, they can use a snap connector (or printed flexible electrode with connector), adhesive layer, stick-to-skin foam layer, conductive hydrogels, and a delivery/release liner.

We recently made a video that explains these different medical wearable components in detail.

What are some challenges unique to medical wearable design?

The biggest challenge to medical wearable design is usually deciding how long the adhesive needs to stick to the patient's skin. What we see from the industry right now is typically seven to twelve days, but there are a few adhesives out there that can be worn for up to twenty. The release factor then becomes a concern; does it irritate the skin based on the aggressiveness of the adhesive? We're always working with adhesive manufacturers to source new, highly engineered options that enable longer adhesion and more patient comfort.

The other unique wearable challenge is the flexibility and breathability of all the materials in the stack-up. Does the device flex well? Is it comfortable for the patient? Factoring in both challenges into cost structure is always important.

What is something people tend to overlook when designing medical wearables?

Simplicity. It's counterintuitive, but wearable designers can overestimate their needs with adhesives and layers. Thinking that you need extremely tight tolerances, additional spacers, or the longest-lasting stick-to-skin adhesive sounds great, but it can increase cost and isn't always necessary. Boyd relies on our years of knowledge and history creating wearable devices to say, that layer isn't really necessary, this spacer will give you enough of a gap for the hydrogel this adhesive is less expensive and will hold up to the outdoor environment. And if there is a unique use case for a wearable that requires highly engineered materials, we can help work those in, too.

How do you decide on a stick-to-skin adhesive?

Adhesion is the critical factor, which comes down to how long it needs to be worn and the wear conditions. If you go too aggressive with the adhesive, it may cause skin irritation. If you don't go with an aggressive enough adhesive, it may not stick based on the wear condition. We work with most medical adhesive manufacturers and compounders to meet different requirements. It's best to reach out to Boyd's team with your specific project requirements so we can suggest the right adhesive.

What is the tightest tolerance you can achieve on a wearable?

We frequently work with medical wearables that require extremely tight tolerances. It ranges a lot depending on the component, material, complexity, and geometry, but it can get down to +/- 0,05mm for complex, multilayered parts. We're always happy to look at specific designs and suggest suitable fabrication methods for tolerance requirements.

How can you make wearables more durable?

It's often moisture ingress that shortens life and decreases performance of a wearable, so the biggest factor is ensuring that you have the right adhesives that seal properly. Adhesives that not only stick to skin, but also between the different layers of the device. This all depends on the use of the wearable and the materials used in the different layers in the stack-up.

What is one of the most exciting medical wearable applications that you have worked on?

We recently worked on a continuous glucose monitor that had unique challenges. It required a very small footprint and included electronics for constant monitoring, so it had to be comfortable and long-lasting, even with all the design parameters involved. It's always exciting to use our expertise to push the envelope on a solution like this.

That said, I don't want to downplay simpler wearables, like ECG or EKG sensors. They're high-volume and cost sensitive, but still have multiple layers and interesting design aspects. It's also exciting to bring a high-volume, competitive, disposable device to the marketplace.

What do you think is the future of medical wearables?

Wearables are already a multi-billion-dollar market, and it's growing rapidly. Improvements in battery life technology, stretchable conductive inks, and enhancements to near-field communication (NFC) and Bluetooth are coming. It'll make the wearable industry much stronger, offering continuous remote patient monitoring outside of doctor's' offices and hospitals. It'll be fully remote, and that'll really change the medical wearable industry.

We’d like to thank everyone who submitted questions! To learn more about our Medical Wearable capabilities or inquire about your specific requirements, visit our Medical Wearables page or schedule a consultation with our experts.

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