CGM Sensor Manufacturing: From Finger Sticks to ABB

CGM sensor manufacturing has to turn out, by the tens of millions, a device that sits in a person's skin for about two weeks: a thin sensing filament under the skin and electronics that send readings to a phone by Bluetooth. Someone on a 14-day sensor needs a new one every two weeks. This post follows glucose testing from the first enzyme electrode and finger-stick meters to the first continuous glucose monitor, approved in the United States in 1999, and on to the sensor plants in Ireland. It ends with where ABB robots could fit and what still makes these lines hard to run.

An Abbott FreeStyle Libre 3 box and sensor applicator, 2022. Photo: Raimond Spekking / Wikimedia Commons (CC BY-SA 4.0)

From enzyme electrodes and finger sticks to the first CGM

Glucose sensing began in the lab. Leland Clark presented his oxygen electrode on 15 April 1956, and in 1962 he and Ann Lyons of Cincinnati Children's Hospital built the first glucose enzyme electrode, a thin layer of glucose oxidase on an oxygen electrode. That work earned Clark the name "father of biosensors". Machines for reading blood glucose came next. The Ames Reflectance Meter, developed by Anton H. Clemens, was used in American hospitals in the 1970s, and a moving needle showed the result after about a minute.

Four blood glucose meters, including a 1991 Reflolux S reflectance meter by Boehringer Mannheim and a 1987 MediSense ExacTech Card. Photo: Christidy / Wikimedia Commons (public domain)

Testing then moved into homes. In the late 1970s studies showed that home monitoring improved control of type 1 diabetes, and the first meters for home use went on sale around 1981, led in North America by the Glucometer, launched in November 1981, and Roche's Accu-Chek. Hospitals resisted meter readings for more than a decade because laboratories argued their own measurements were more accurate. A finger-stick test measures blood glucose at a single moment, so people with diabetes pricked their fingers several times a day.

The lancing device from a GlucoCheck XL blood glucose meter kit, used for finger-stick tests, 2025. Photo: Roy Zuo / Wikimedia Commons (CC BY-SA 4.0)

Continuous monitoring arrived when the FDA approved the first CGM system in 1999. The first Medtronic MiniMed took a glucose reading every ten seconds, reported an average every five minutes, and its sensor could be worn for up to 72 hours. Dexcom's first system followed in 2006, also for 72 hours, and Abbott's FreeStyle Navigator in 2008 for five days. In September 2017 the FDA approved the FreeStyle Libre, the first CGM that needed no finger-stick calibration, worn for up to ten days. The Libre 2, approved in Europe in October 2018, lasted 14 days.

Close view of the insertion needle of a Medtronic Guardian 4 glucose sensor, 2023. Photo: Marius Vassnes / Wikimedia Commons (CC BY-SA 4.0)

Sensor plants in Ireland and lines built for volume

Most CGMs today are electrochemical. A filament inserted under the skin carries an enzyme that reacts with glucose in the fluid between the cells, producing a current of a few nanoamperes that rises with the glucose level, and the sensor usually lasts 14 to 16 days. Optical designs exist too, such as the Eversense, a sensor implanted by a doctor. Abbott's chief executive Robert Ford said in 2024 that the market had about 10 million users, while about 100 million people in the developed world have diabetes and about five times as many worldwide.

The circuit board and sensing filament inside a FreeStyle Libre 2 sensor, opened up in 2024. Photo: Krzeto / Wikimedia Commons (CC0)

Abbott opened its plant in Kilkenny, Ireland, in November 2024 to make FreeStyle Libre 3 sensors. The 30,000 square metre site has a 1,200 square metre ISO Class 8 cleanroom, runs on six air-to-water heat pumps and nearly 600 solar panels, and is part of a €440 million investment that also expanded Abbott's Donegal plant. Abbott said it would employ more than 800 people there and make more Libre sensors than at any of its other plants. Dexcom chose Athenry in County Galway for its first European plant, a 40,000 square metre, €300 million site that RTÉ reported would have capacity for tens of millions of glucose monitors a year.

A Dexcom G6 transmitter from a continuous glucose monitor, 2022. Photo: Geo Swan / Wikimedia Commons (CC0)

Abbott and Dexcom publish little about their assembly lines. A Dexcom job advert for its global engineering team describes developing product assembly equipment, robotics concepts and vision systems for automated inspection, all validated for a high-volume, highly regulated Class II medical device. In September 2026 FiberSense filled sensor fibres for the first time on a new automated filling line in Großostheim, Germany. We found no ABB robot on a CGM line. ABB's IRB 1300 does come in a version protected for clean-room applications, and ABB says one of the global leaders in medical devices uses its robots, through an Italian integrator, to make biomedical disposables.

An ABB IRB 1300 Clean Room robot. Photo: ABB

Quality control, new sensors and where ABB could fit

At these volumes, one faulty line touches millions of sensors. In November 2025 Abbott issued a correction for about three million FreeStyle Libre 3 and Libre 3 Plus sensors that could give incorrectly low glucose readings, and said it had traced the fault to one of its three sensor production lines and fixed it. In 2024 a smaller Libre 3 recall over incorrectly high readings had been given the FDA's most serious classification. Cameras that check every part, as the Dexcom advert describes, and a record of each step could help catch such faults earlier.

The filament housing of a FreeStyle Libre 2 sensor, taken apart in 2024. Photo: Krzeto / Wikimedia Commons (CC0)

ABB's small robots are a possible fit, though we found no CGM project yet. At GE Healthcare's prototype line in Helsinki, a single-arm YuMi IRB 14050, which ABB designed for small-parts assembly close to people, picks a matchbox-sized sensor battery part from a jig, lays glue beads along its shape and sets it back down; our post on medical device assembly covers that line. An IRB 360 FlexPicker, which ABB calls the fastest industrial delta robot in the world and builds for payloads from 1 to 8 kg, could pack finished sensor kits. Such cells are usually laid out and tested first in RobotStudio.

Engineers beside the single-arm YuMi cell at GE Healthcare's prototype line in Helsinki. Photo: ABB

More sensor types are coming. Abbott has begun rolling out its Libre Duo glucose and ketone sensor in Europe, and FiberSense won a CE mark in June 2026 for an optical sensor worn for up to 28 days, with first deliveries planned for late 2026. CGMs are also spreading to athletes and health-conscious consumers, and some Libre sensors already sell for as little as $75 cash. Price, validation and skills remain the open problems: every new line must pass formal qualification, and makers need engineers who understand robots, vision and medical regulation at once. Cobots such as ABB's GoFa, which ABB says can work alongside people without fencing, could help with kitting next to technicians, but that is still a possibility.

An ABB GoFa CRB 15000 cobot at a work table. Photo: ABB

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