UDI Requirements & Common Questions for Manufacturers

Starting on September 24, 2022, all reusable and reprocessed medical devices sold in the United States must have a UDI direct mark in accordance with FDA regulations. This requirement will now extend to class I products, such as surgical instruments, dental probes, and medical drills, in addition to classes III and II.

With the deadline approaching, Laser Marking Technologies is offering assistance in implementing industrial and medical laser marking to ensure compliance. The UDI code must be directly marked to meet quality standards for readability after multiple reprocessing cycles. The marking process must be validated, and the UDI must be registered in the GUDID database.

Manufacturers who have already taken steps to comply with UDI requirements in the U.S. will be better prepared for the new MDR regulations in Europe. However, many still face challenges with validation and EUDAMED registration. The pressure of time is mounting, and there are still uncertainties surrounding the proper implementation of direct labeling.

Our team has gathered a list of common questions and answers from webinars and collaborations with medical technology companies to address these concerns.

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UDI Commonly Asked Questions


What is a Unique Device Identifier (UDI)?

The Unique Device Identifier (UDI) is comprised of two primary elements:

  • The DI, which stands for Device Identification (such as GTIN), represents a product category that is globally and uniquely identified.
  • The PI (Production Identification) is attached to uniquely distinguish each individual product.


Is it necessary to include the expiration date of a medical device in the Unique Device Identification (UDI) system?

It is necessary to always include the expiration date in the Product Identifier – Unique Device Identifier (PI-UDI). In cases where the expiration date is not known, the manufacturing date should be indicated instead.

Furthermore, the PI-UDI comprises the subsequent essential elements:

  • Batch number (batch or lot number)
  • Serial number (if available; if possible, batch and serial number)
  • Software identification, if applicable


What are the requirements for the quality standards of a laser-marked UDI?

As per the FDA guidelines, the code verification process should meet a minimum quality grade of C, with better options being B or A. This level of quality assurance must be maintained throughout the entire lifespan of the product, even after undergoing multiple reprocessing cycles. One way to enhance the readability of the code is by using a lightened background. This process, known as frosting, involves using a laser to lighten the background. When the spaces and background of a data matrix code are highlighted in white alongside the black components, it is referred to as black-and-white marking. These techniques are commonly employed to improve the contrast and clarity of the code.


Is it required to directly mark a UDI on extremely small products, such as reprocessed rotary dental FG drills with a 1.6 mm diameter?

Direct marking is a requirement for all reprocessed class I products. This means that the Unique Device Identifier (UDI) on the product must meet the standard format, displayed in both plain text and as a machine-readable code. Nevertheless, there are instances where this does not apply:

  • If marking has an impact on the device’s safety or functionality
    If the implementation is not technically viable


When is it not possible to implement UDI marking from a technical perspective?

In cases where there is limited space to display the entire code in a format that is readable by both humans and machines, it is necessary to at least use the AIDC (Automatic Identification and Data Capture) format.

If the area available on the product surface is too small to accommodate the minimum size required for the machine-readable UDI code, it may not be technically possible to mark it. In such instances, it is important to provide an explanation in the technical documentation stating that the available space is insufficient.

Furthermore, the full UDI should be displayed on the packaging as well as the outer packaging of the product.

What is the smallest allowable size for a UDI code to be marked?

The machine-readable Unique Device Identifier (UDI) can be displayed either in the form of a data matrix or a linear barcode. Data matrix codes are more efficient in terms of space usage compared to barcodes, which require more space to convey the same amount of information. In order to ensure that the Automatic Identification and Data Capture (AIDC) code can be easily read by a code verifier, there are specific minimum module sizes for data matrix codes.

For laser marked GS1-standardized codes, the smallest module size is set at 0.1 mm (0.0039 inches). The overall width and height of the Data Matrix Code (DMC) are calculated based on the encoded data size along with the addition of a bright zone surrounding the code on all four sides, each with a width equal to one module.

When it comes to ink-based code marking, GS1 requires a minimum X-module size of 0.254 mm (0.1 inches) due to the lower contrast sharpness achieved compared to laser marking.

What dimensions are optimal for a data matrix code?

It is advised by LMT to use a DMC area size of around 2.5 x 2.5 mm (0.0984 x 0.0984 inches) or larger. This size guarantees that most verifiers can effectively scan the code.

By doing so, quality control can be implemented in dental practices using simpler readers compared to those used in industrial settings.

What is the deadline for medical devices to be registered in the EUDAMED database?

Following the enforcement of the Medical Device Regulation (MDR) on May 26, 2021, the launch of the EUDAMED database and the mandate for registration were delayed until May 26, 2022, due to the impact of the Coronavirus pandemic and constraints faced by the Notified Bodies. From this specified date onwards, all newly introduced products into the market are required to obtain a Unique Device Identifier (UDI) and register on the database.

For products that have been existing in the market for an extended period, a transition period is granted until May 26, 2024. This extension allows for the continued presence of these “legacy products” in the market, on the condition that a declaration of conformity has been prepared for Class I products with the support of a notified body before May 26, 2021. Similarly, devices with valid certificates in line with the stipulations of MDD 93/42/EEC are permitted to remain in circulation.

However, it is essential for existing products to be included in the EUDAMED database, even though a UDI is not yet mandatory at this stage. To facilitate their registration in compliance with the system, these products are provided with distinct identification numbers by EUDAMED.

When is the ideal time to begin executing direct marking strategies?

As per the regulations of the Medical Device Regulation (MDR), the direct marking of Unique Device Identification (UDI) on Class III devices is not required until May 2023. Nonetheless, it is crucial to consider that the complete implementation of an optimal marking solution can be a time-consuming process, lasting several months. The validation of machinery and processes typically consumes the most time in this process. Therefore, thorough preparation and planning of responsibilities in advance are essential to ensure a timely execution and validation of the marking solution.

Is it possible for LMT to offer validation for the marking process in conjunction with the marking system?

Laser Marking Technologies provides assistance to customers with IQ-OQ-PQ-MQ, however, they are unable to provide validation of the process itself. This responsibility falls on the production site where it should be conducted directly. Engaging an experienced external validation partner can offer reliable support, and LMT is willing to facilitate connections with experts in the field. It is important to emphasize that validation should be conducted every three years to ensure accuracy. In certain circumstances, such as machine relocation, additional validation may be necessary to account for potential changes in lighting or other variables.