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The ultimate guide to Unique Device Identification (UDI) directives for medical devices (and how to comply!)

This month, we’re talking about the print you see on medical devices and in-vitro products used for the traceability and serialisation of the product – called the UDI or Unique Device Identification mark. In the ever-evolving world of healthcare, new niche manufacturers and big medical device industrial corporations find themselves at a crossroads. Change has arrived within the Medical Device Regulation, and many large and small companies have yet to strike the right chord, grappling with the choices and steps essential to orchestrate compliance to the latest specifications. Automated vision systems are required at every stage of the production and packaging stages to confirm compliance and adherence to the standards for UDI. Vision systems ensure quality and tracking and provide a visible record (through photo save) of every product stage during production, safeguarding medical devices, orthopaedic and in-vitro product producers.

What is UDI?

The UDI system identifies medical devices uniformly and consistently throughout their distribution and use by healthcare providers and consumers. Most medical devices are required to have a UDI on their label and packaging, as well as on the product itself for select devices.

Each medical device must have an identification code: the UDI is a one-of-a-kind code that serves as the “access key” to the product information stored on EUDAMED. The UDI code can be numeric or alphanumeric and is divided into two parts:

DI (Device Identifier): A unique, fixed code (maximum of 25 digits) that identifies a device’s version or model and its maker.

Production Identifier (PI): It is a variable code associated with the device’s production data, such as batch number, expiry date, manufacturing date, etc. UDI-DI codes are supplied by authorised agencies such as GS1, HIBCC, ICCBBA, or IFA and can be freely selected by the MD maker.

UDIs have been phased in over time, beginning with the most dangerous equipment, such as heart valves and pacemakers. So, what’s the latest directive on this?

Navigating the Terrain of MDR and IVDR: Anticipating Challenges

The significant challenges presented by the European Medical Devices Regulation (MDR) 2017/745 have come to the fore since its enactment on May 26th, 2021. This regulatory overhaul supersedes the older EU directives, namely MDD and AIMDD. A pivotal aspect of the MDR is its stringent oversight of medical device manufacturing, compelling the display of a unique code for traceability throughout the supply chain – this allows full traceability through the process from the manufacture of the medical device to the final consumer use.

Adding to the regulatory landscape, the In-Vitro Diagnostic Regulation (IVDR) 2017/746 debuted on May 26th, 2022. This regulation seamlessly replaced the previous In-Vitro Diagnostic Medical Devices (IVDMD) regulation, further shaping the intricate framework governing in-vitro diagnostics. The concurrent implementation of MDR and IVDR ushers in a new era of compliance and adaptability for medical devices and diagnostics stakeholders.

What are the different classes of UDI?

Risk Profile Notify or Self-Assessment Medical Devices In-Vitro Diagnostic Medical Devices
High Risk to Low Risk Notified Body Approval Required Pacemakers, Heart Valves, Implanted cerebral simulators Class III Class D Hepatitis B blood-donor screening, ABO blood grouping
Condoms, Lung ventilators, Bone fixation plate Class IIb Class C Blood glucose self-testing, PSA screening, HLA typing
Dental fillings, Surgical clamps, Tracheomotoy Tubes Class IIa Class B Pregnancy self-testing, urine test strips, cholesterol self-testing
Self-Assessment Wheelchairs, spectacles, stethoscopes Class I Class A Clinical chemical analysers, specimen receptacles, prepared selective culture media

Deadlines for the classification to come into force

Implementing the new laws substantially influences many medical devices and in-vitro device companies, which is why the specified compliance dates have been prioritised based on the risk class to which the devices belong. Medical device manufacturers must adopt automated inspection into their processes to track and confirm that the codes are on their products in time for the impending deadlines.

The Act recognises four types of medical devices and four categories of in-vitro devices, which are classified in ascending order based on the degree of risk they provide to public health or the patient.

2023 2025 2027
UDI marking on DM Class III Class I
Direct UDI marking on reusable DM Class III Class II Class I
UDI marking on in-vitro devices (IVD) Class D Class C & B Class A

The term “unique” does not imply that each medical device must be serialised individually but must display a reference to the product placed on the market. In fact, unlike in the pharmaceutical industry, serialisation of devices in the EU is only required for active implantable devices such as pacemakers and defibrillators.

EUDAMED is the European Commission’s IT system for implementing Regulation (EU) 2017/745 on medical devices (MDR) and Regulation (EU) 2017/746 on in-vitro diagnostic medical devices (IVDR). The EUDAMED system contains a central database for medical and in-vitro devices, which is made up of six modules.

EUDAMED is currently used on a voluntary basis for modules that have been made available. The connection to EUDAMED must take place within six months of the release of all platform modules that are fully functioning.

Data can be exchanged with EUDAMED in three methods, depending on the amount of data to be loaded and the required level of automation.

The “visible” format of the UDI is the UDI Carrier, which must contain legible characters in both HRI and AIDC formats. The UDI must be displayed on the device’s label, primary packaging, and all upper packaging layers representing a sealable unit.

These rules mean medical device manufacturers need reliable, traceable automated vision inspection to provide the track and trace capability for automatic aggregation and confirmation of the UDI process.

The UDI is a critical element of the medical device manufacturing process, and therefore, applying vision systems with automated Optical Character Recognition (OCR) and Optical Character Verification (OCV) in conjunction with Print Quality Inspection (PQI) is required for manufacturers to guarantee that they comply with the legislation.

But what are the differences between Optical Character Recognition (OCR) vs Optical Character Verification (OCV) vs Print Quality Inspection (PQI)?
We get asked this often, and how you apply the vision system technology is critical for traceability. To comply with UDI legislation, medical device manufacturers must check that their products comply with the requirements and track them through the production process. Whether you use OCR, OCV, or PQI depends on the manufacturer stage and where you are in the manufacturing process.

Optical Character Recognition (OCR)

Optical character recognition is based on the need to identify a character from the image presented, effectively recognise the character, and output a string based on the characters “read”. The vision system has no prior knowledge of the string. It therefore mimics the human behaviour of reading from left to right (or any other orientation) the sequence it sees.
You can find more information on OCR here.

Optical Character Verification (OCV)
Optical character verification differs from recognition as the vision system has been told in advance what string it should expect to “read”, and usually, with a class of characters it should expect in a given location. Most UDI vision systems will utilise OCV, as opposed to OCR, as the master database, line PLC (Programmable Logic Controller), cell PLC and laser/label printer should all know what will be marked. Therefore, the UDI vision system checks that the characters marked are verified and readable in that correct location (and have been marked). This then allows for the traceability through the process through nodes of OCV systems throughout the production line.
You can find more information on OCV here.

Print Quality Inspection (PQI)

Print quality inspection methods differ considerably from the identification methods discussed so far. The idea is straightforward: an ideal template of the print to be verified is stored; this template does not necessarily have to be taken from a physically existing ‘‘masterpiece’’, it could also be computer-generated. Next, an image containing all the differences between the ideal template and the current test piece is created. Simply, this can be done by subtracting the reference image from the current image. But applying this method directly in a real-world context will show very quickly that it will always detect considerable deviations between the reference template and test piece, regardless of the actual print quality. This is a consequence of inevitable position variations and image capture and transfer inaccuracies. A change in position by a single pixel will result in conspicuous print defects along every edge of the image. So, print quality inspection is looking for the difference between the print trained and the print found. Therefore, PQI will pick up missing parts of characters, breaks in characters, streaks, lines across the pack and general gross defects of the print.

You can find more information on PQI here.

What about Artificial Intelligence (AI) with OCR/OCV for UDI?

Where we’ve been discussing OCR and OCV, we’ve assumed that the training class is based either on a standard OCR font (a unique sans-serif font created in the early days of vision inspection to provide a consistent font, recognisable by humans and vision systems), or a trainable, repeatable fixed font. OCR with AI is a comprehensive deep-learning-based OCR (or OCV) method. This innovative technology advances machine vision towards human reading. AI OCR can localise characters far more robustly than conventional algorithms, regardless of orientation, font type, or polarity. The capacity to automatically arrange characters enables the recognition of entire words. This significantly improves recognition performance because misinterpreting characters with similar appearances is avoided. Large images can be handled more robustly with this technique, and the AI OCR result offers a list of character candidates with matching confidence ratings, which can be utilised to improve the recognition results further. Users benefit from enhanced overall stability and the opportunity to address a broader range of potential applications due to expanded character support. Sometimes, this approach can be used. However, it should be noted that it can make validation difficult due to the need for a data set prior to learning, compared to a traditional setup.

Do all my UDI vision inspection systems require validation?

Yes, all the vision systems for UDI inspection must be validated to GAMP/ISPE levels. Having the systems in place is one thing, but the formal testing and validation paperwork is needed to comply fully with the legislation. You can find more information on validation in one of our blog articles here.

Industrial vision systems allow for the 100% inspection of medical devices at high production speeds, providing a final gatekeeper to prevent any rogue product from exiting the factory gates. These systems, in combination with factory information communication and track & trace capability, allow the complete tracking of products to UDI standards through the factory process.


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