Jennifer Green, senior global technical business development manager at Lubrizol explores importance of device design, as diabetes management is rapidly advancing, and the choice of materials is what helps distinguish good design.
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If you have ever participated in the design of a diabetes management device, you understand that it all starts with a simple question: What will someone actually live with, day after day? And not in a lab or as part of a design review, but out in the real world, on a real person’s skin.
This is the reason that advanced medical materials are not merely components listed on a specification sheet; they serve as the interface connecting the device to the individual using it. They determine if a patch remains secure during an intense workout, if a sensor continues to feel comfortable after ten days or if a parent can rely on it for their child. Prior to the development of a prototype, before the creation of packaging or the compilation of feature lists, the process starts with material selection, the element that determines the tactile experience of a device—its durability, usability and ability to seamlessly integrate into an individual's daily lifestyle.
This is an opportune moment to explore the reasons for its significance, as diabetes management is rapidly advancing, and the choice of materials is what helps distinguish good design from great care.
Finger pricks to fully connected care
with automated insulin delivery (AID) pumps that essentially act like an artificial pancreas outside the body, continuously reading glucose levels and dosing accordingly.
Additionally, there exists a wide range of options: single-use injector pens, digital monitoring devices, and hybrid systems that allow you to select either the CGM or the pump. The result is a diverse set of device architectures, each with different needs for coatings, membranes, tubing and adhesive films.
However, there is a shared theme: they are all transitioning into the wearable technology sector, meaning we’ve suddenly opened an entire world of opportunity (and responsibility) for the materials that make these devices work.
Why TPU keeps showing up
Medical material engineering teams dedicate significant time to examining the various applications of thermoplastic polyurethanes (TPUs) that are utilized in nearly every aspect of devices intended for diabetes management.
The application that is arguably the most technically intricate is found within the CGM sensor itself. Imagine a tiny electrochemical sensor, inserted just under the skin, coated in multiple polymer layers that act as semipermeable membranes.
Their role is to permit the appropriate substances to pass (such as oxygen and sufficient glucose) while obstructing or adjusting other analytes that may disrupt the measurement. Certain layers even enclose the enzyme responsible for glucose processing. The coatings have a thickness of merely a few microns, and it is this exceptionally thin interface that allows the sensor to function.
This is exactly where TPU shines. It’s highly tunable and bonds beautifully to itself, making it possible to build precise, layer-on-layer functionality. And because it can be customized at a very small scale, it’s a match for CGM sensors, which require only tiny amounts of polymer despite being produced in massive unit volumes.
Materials manufacturers have made significant investments in small-batch customization capabilities specifically to address this type of demand: ultra-consistent, highly specified polymers that deliver predictable performance consistently, as OEMs cannot tolerate variability in layer thickness or diffusion rate. Custom grades typically start as individual lot samples and may take years to achieve commercial volume; therefore, manufacturers must plan to prevent delays when demand increases.
Pumps, cannulas and comfort
Pump systems provide TPU with another opportunity to showcase its worth, particularly in tubing that must remain flexible and endure repeated bending and flexing without deteriorating. TPU is often used in conjunction with another material to improve its chemical resistance, since insulin solutions can be corrosive to plastics. This combination creates a tubing set capable of withstanding several days of use while maintaining its performance.
The most fascinating opportunity, however, is associated with the cannula, which is the small tube or needle that can remain beneath the skin for several days, providing rapid-acting insulin. Most cannulas are constructed using fluorinated chemistries such as PTFE or FEP. Although they fulfill their intended function, these materials often retain a rigid quality at body temperature, and OEMs have recognized micro-irritations and localized inflammation as common issues for patients.
This is where TPU sets itself apart. At body temperature, it becomes softer and conforms more easily to the surrounding tissue, leading to diminished micro-movements and a decreased likelihood of irritation, which translates to fewer premature site changes. In various fields of medicine, including peripheral IVs, polyurethanes have demonstrated a reduction in phlebitis (inflammation of the veins) when compared to fluorinated catheters. Extending these benefits to diabetes care could significantly enhance patient compatibility and reshape the therapeutic landscape.
There is an additional advantage in processing: PTFE necessitates high-temperature RAM extrusion. In contrast, TPU can be micro-molded or precision extruded at lower temperatures, which may lead to shorter cycle times and simplified supply chain processes for OEMs.
Adhesives and patient experience
There is also the adhesive-backed film that keeps all of this on the skin. It might seem like the least glamorous part of the device, but ask any patient what drives them crazy, and they’ll tell you it’s adhesives that don’t breathe, that irritate the skin, or that peel off at the wrong time.
As a backing layer for adhesives, TPU offers breathability, conformability and toughness in thin gauges for wearables that need to stay securely attached for multiday intervals. That performance is only half the story, though, because patients don’t want the device to call attention to itself. They want something that sits close to their skin, moves with them and disappears under their clothing. The process of creating devices that are more discreet begins with the selection of thinner, softer materials, which can ultimately determine whether the experience is perceived as clinical and intrusive or natural and effortless.
What OEMs are asking for
Over the last year, I’ve conversed with several of OEMs in this space, and their questions fall into a few consistent themes:
- Analyte selectivity (error-proofing). Manufacturers want to eliminate inaccurate readings by filtering out interfering substances (such as acetaminophen) and to enhance selectivity, allowing sensors to monitor additional analytes without experiencing crosstalk.
- New analytes. Many are also seeking to measure a wider range of analytes and biomarkers as part of a larger shift toward holistic wellness monitoring, beyond diabetes management.
- Extended wear time. Everyone wants to get to longer wear intervals, though this is often limited by biological factors like enzyme activity and wound healing response.
- Manufacturing efficiency. They want highly consistent materials that coat or extrude the same way every time, batch to batch.
- TPU cannot solve all these challenges on its own, of course, but it is one of the few materials versatile enough to be fine-tuned for permeability, polarity, mechanical softness and biocompatibility. And because it’s customizable in small volumes, it’s feasible to iterate quickly as device requirements evolve.
Three rules of thumb for OEMs
Distilling all this down into a few guiding principles for device developers:
- Start with the material, not the CAD file. Your design space opens up (or closes down) based on what your material can do.
- Think beyond performance specs. Comfort, conformability, and skin interaction are just as critical as mechanical strength or diffusion rate.
- Keep scalability in sight. Select materials that are both biocompatible and capable of being processed at the volumes and speeds that your market will ultimately require.
This is the new normal for diabetes technology. Expanded reimbursement, including Medicare coverage for Type 2, is pushing growth and raising the stakes. As a result, there is no margin for error in the design and development of these devices.
Materials are not merely components of the bill of materials; they serve as the cornerstone of the overall user experience. Choosing the right materials at an initial phase facilitates increased precision, better comfort and higher acceptance, while postponing this choice results in a heightened risk of facing constraints during the launch process.
The devices that will influence the next decade of care are being crafted right now, and they all start with the same question: What should this be made of?