The critical role of metrology in product development

Founded in 2010, Metronom Health is an early-stage medical device company focused on developing innovative, opto-enzymatic continuous blood glucose monitoring technology for people with diabetes. Metronom’s proprietary technology is believed to provide very significant improvements over available Continuous Glucose Monitoring (CGM) technologies, in terms of accuracy in the hypoglycemic range, reliability, user-friendliness, with lower prices to encourage a wider adoption and easier insurance coverage. The company is now at a crossroads in its short history, relying on a strong focus on engineering and R&D to develop a CGM product that meets the needs of users, as well as the people who live with it. occupy.

During the development process, Metronom recognized the critical role of metrology in R&D and production quality control for its CGM. When working at a scale that was difficult to image with traditional microscopes, Metronom found that 3D optical metrology specialist ZYGO was able to deliver the clarity he was looking for, with features like 3D height mapping and more quantitative and deterministic resolution capabilities. than traditional microscopes. Metronom also found ZYGO’s metrology tools to be a key enabling technology that helped drive their product innovation by providing valuable process and component insights using easily configurable data collection and flexible.

Manufacturing and metrology challenges

Metronom Health’s Continuous Glucose Monitor (CGM) is based on opto-enzymatic technology instead of typical electrochemical CGMs. At the heart of the technology is a sensor made of an oxygen-sensitive polymer at the end of an embossed fiber optic waveguide. The oxygen-sensitive polymer changes its fluorescence lifetime when the glucose oxidase enzyme consumes glucose and oxygen in a microscopic reaction chamber. This approach enables Metronom to offer improved accuracy with a higher signal-to-noise ratio in tissue, an integrated quality system directly at the detection site, as well as additional security and calibration assisted by the derived device. a differential oxygen measurement and a CGM solution that does not interfere with common medications such as acetaminophen that can challenge electrochemical methods.

Additionally, Metronom’s technology is well suited for high-speed, high-volume manufacturing, which presents opportunities for significant cost advantages over existing CGM technology.

Daniel Bartholomeusz, Director of Process Engineering at Metronom, says: “Despite — or perhaps because of — the clear advantages of our CGM technology, there are manufacturing challenges, as well as challenges specific to metrology. In terms of manufacturing itself. We had difficulty measuring the high aspect ratio and surface roughness of the raised optical microstructures. It was difficult to measure the depth of laser cut blind holes in clear polymers and the infill heights of clear chemistries in clear polymers. We had to use metrology tools that combine high functionality, ease of use, cost-effectiveness, speed and scalability. We found that in every way, the ZYGO tools gave us what we needed.

Selected metrology solutions

The specific metrology tool used by Metronom was the ZYGO NewView 9000 3D Optical Surface Profiler, which enables quick and easy measurement of a wide range of surface types including smooth, rough, flat, sloped and stepped. All measurements using the NewView 9000 are non-destructive, fast (improving productivity and process control) and require no sample preparation. At the heart of the system is ZYGO’s Coherence Scanning Interferometry (CSI) technology which provides sub-nanometer accuracy at all magnifications and measures a wide range of surfaces.

Bartholomeusz continues: “The selection criteria when choosing the metrology solution that best matched the requirements of our application were quite strict. It was important that the XY resolution was ≤ 5 microns, the pixel resolution was ≤ 2 microns, and the surface topography repeatability was ≤ 1 micron. Additionally, it was important that the solution we selected had 2 surface measurement capabilities and could measure transparent materials. We also required an XY travel of 50 x 150 mm and a Z travel ≥ 5 mm. In terms of ease of use, it was important that the system provided plane leveling, programmable motion control, feature recognition, pass/fail output capability, cross section tools, auto measurement tools height and be able to stitch pictures together. Finally, we needed a system that could be delivered quickly, came as close as possible to a turnkey solution with local helpdesk, and required minimal training time. And when it came to scalability, we needed fast slew rates. NewView 9000 provided all of this.

Whether used in the laboratory or in process, Metronom has identified some significant advantages of the NewView 9000 over alternative technologies. The wide range of capabilities of the NewView 9000 enabled the company to characterize surface roughness on optical elements, feature depth and cross-sectional characteristics for laser-cut elements, and film thickness to measure excess waveguide resin filling. The resin filler application has proven to be truly impressive by significantly outperforming competing solutions and exceeding expectations both in the lab and production development. The company has also used interferometer scans to evaluate chemical fillings and to measure blind hole laser cutting characteristics.

The system also enabled the comparison of 3D measurement data to 3D CAD data and the measurement of chemical microdeposits. For production, Metronom was able to digitize a 3D map, which allows XY measurements at specific depths with far greater accuracy than focusing with an optical microscope measurement system. In addition, automated and simple python scripts enabled fast and reliable analyzes over a large area. Critically, the company could also measure the heights of unobstructed surfaces and produce valuable program automated data collection with electronic reporting for quality records.

Bartholomeusz concludes: “Selecting the right metrology tools for our demanding CGM technology has been of fundamental importance and has been key to our success. ZYGO’s NewView 9000 has contributed a lot to our product development program and led to the creation of optimized and innovative product features. The NewView 9000 ended up being scalable and it is a complete and robust system that can be used in production environments. This has really been a pivotal technology for Metronom.

Eric Felkel, Product Manager (Optical Profilers), Zygo Corporation.

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Gary C. Lisi