Founded in 2010, Metronom Health (Metronom) is a Belgium-based, early-stage medical device company focusing on developing an opto-enzymatic continuous blood glucose monitoring technology for people living with diabetes. Metronom’s proprietary technology is believed to provide significant improvements over traditional electrochemical continuous glucose monitoring (CGM) technology in terms of accuracy in the hypo-glycemic range, reliability and user-friendliness, with lower pricing to encourage broader adoption and easier insurance coverage.
Metronom recognised the importance of using the right metrology tools in both R&D and production quality control for its CGM technology. The company invested in a NewView 9000 3D optical surface profiler from US-based ZYGO, since traditional measuring microscopes could not deliver quality images at the necessary scale. The NewView 9000 provided the clarity required, affording features such as 3D height mapping and more quantitative and deterministic resolution capabilities than traditional measuring microscopes. It also proved a key enabling tool in terms of helping to drive product innovation by providing valuable process and component information using data collection that was easily configurable and flexible.
The Metronom Health opto-enzymatic continuous glucose monitoring (CGM) device.
Manufacturing and metrology challenges
At the heart of the opto-enzymatic CGM device is a sensor that consists of an oxygen sensitive polymer at the end of an embossed fibre-optic waveguide. The oxygen sensitive polymer changes in fluorescence lifetime as the glucose oxidase enzyme consumes glucose and oxygen in a microscopic reaction chamber.
This approach has allowed Metronom to deliver a device that affords several advantages over electrochemical CGM devices, namely:
- a built-in quality system right at the sensing site;
- improved accuracy through a higher signal-to-noise ratio in the tissue;
- additional safety as a result of device-prompted calibration derived from a differential oxygen measurement, and
- non-interference with common medications such as acetaminophen.
In addition, Metronom’s technology is well suited for high-speed, high-volume manufacturing, which presents opportunities for significant cost advantages compared with electrochemical CGM devices.
Daniel Bartholomeusz, director of process engineering at Metronom, commented: “Despite, or perhaps because of, the obvious advantages of our CGM technology, there are some manufacturing challenges, and also some challenges specific to metrology. In terms of manufacturing per se, we had a difficult time measuring the high aspect ratio and surface roughness of the embossed optical microstructures. It was difficult to measure the depth of laser-cut blind hole features in clear polymers, and fill heights of clear chemistries in clear polymers. We needed to use metrology tools that combined high functionality with ease-of-use and cost-effectiveness, and that were speedy and scalable. We found that in all respects, ZYGO tools gave us what we needed.”
The Zygo NewView 9000 3D optical surface profiler.
Chosen metrology solutions
The NewView 9000 is based on ZYGO’s coherence scanning interferometry (CSI) technology, which delivers sub-nanometre precision at all magnifications and measures a wide range of surfaces, including smooth, rough, flat, sloped and stepped. All NewView 9000 measurements require no sample preparation and are non-destructive and fast (therefore improving productivity and process control).
Bartholomeusz continued: “The selection criteria when choosing the metrology solution that best matched our application requirements were quite stringent. It was important that X, Y resolution was ≤5 microns, pixel resolution was ≤2 microns and surface topography repeatability was ≤1 micron. In addition, it was important that the solution that we selected had two surface measurement capability and could measure transparent materials. We also required 50 x 150 mm X, Y travel and Z travel of ≥ 5 mm.
“In terms of ease of use, it was important that the system provided plane leveling, programmable movement control, feature recognition, pass/fail output capability, cross-section tools and auto-step height measurement tools, and was capable of image stitching. Finally, we needed a system that could be delivered quickly, was as close to a turnkey solution as possible, with local service support, and required minimal training time. And as for scalability, we needed fast scan rates. NewView 9000 provided all of this.”
Metronom identified some significant advantages that the NewView 9000 has over alternative technologies. The broad range of capabilities of the NewView 9000 allowed the company to characterise surface roughness on optical elements, depth of features and cross-sectional characteristics on laser cut elements, and film thickness for measuring excess waveguide resin fill.
The resin fill application proved truly impressive, enabling the NewView 9000 to dramatically outshine competing solutions and surpass expectations both in the lab and production development. The company also used CSI to measure chemistry fills, microdeposits of chemistries and blind-hole laser cut features.
The system also allowed for the comparison of 3D measurement data with 3D CAD data. For production, Metronom was able to 3D scan map, which allows for X, Y measurements at specific depths with much greater accuracy than focusing with a light measuring microscope. Also, automated and simple python scripts enabled fast reliable scans over a large surface. Critically, the company could measure heights of clear surfaces and perform valuable program automated data collection with electronic reports for quality records.
Bartholomeusz concluded: “The selection of the right metrology tools for our exacting CGM technology has been fundamentally important and key to our success. ZYGO’s NewView 9000 has enabled so much in our product development programme and has led to the creation of optimised and innovative product features. The NewView 9000 ended up being scalable, and it is a comprehensive and robust system that can be used in production environments. It has truly been a pivotal technology for Metronom.”
Metronom Health
Zygo