UDI Marking

UDI is an abbreviation of Unique Device Identification, a system used to identify medical devices. Learn about basic knowledge associated with UDI, advantages of adoption, and the corresponding marking methods.

Identifying medical devices helps improve safety in the medical field, including in the distribution stage. This operational system was designed to make providing the optimal treatment even easier.

In December 2013, the International Medical Device Regulators Forum (IMDRF) published guidance for the international adoption of UDI. Currently UDI is only mandatory within the USA, but other countries are also pursuing compliance.

UDI requirements in the US

Put into effect in the US in September 2013, the UDI system gradually became mandatory a year later in September 2014. Adoption of the UDI system began on the following dates in other countries where production of US-bound medical devices exists.

Classification Incidental conditions Label display
database registration
Main unit display
Class III and
PHA (Public Health Act)
licensed products
Life-support/extension equipment 09/24/2014 09/24/2015
Equipment not for life support/extension 09/24/2016
Class II, Class I,
Embedded devices 09/24/2015 Non-operating
Life-support/extension equipment 09/24/2015
Class II Other than the above 09/24/2016 09/24/2018
Class I, unclassified 09/24/2020 09/24/2022

Refer to: GS1 Healthcare Japan conference “Operational guide to direct marking on to medical devices”

Typical products made with laser marking

[Class I]
Components related to the following equipment, small steel objects
[Class II]
Endoscopes, X-ray diagnostic equipment, ultrasonic image diagnosis equipment

Need for direct marking

Steel medical instruments, such as endoscopes, are generally compact and precise. Repeated use after washing and sterilizing is common, so paper and film display labels are problematic due to limited space for affixing and lack of long-term durability.

There are also unacceptable risks in terms of medical practices, such as a label coming off during surgery and becoming residual foreign particles within a patient’s body.

These concerns have resulted in a growing need to use a system that incorporates a direct marking method.

Need for direct marking


Managing medical equipment through direct marking offers the following advantages:

  • Quality control by monitoring how frequently tools are used
  • Optimized part replacement and ordering
  • Improved efficiency and standardization of instrument sets
  • In-process instrument tracking (location management)
  • Excess stock control
  • Loss and theft analysis
Cleaning / Disinfection / Inspection / Packaging Sterilisation / Transportation / Storage / Use / Transportation

What kind of marking is necessary?

The following GS1 code is used for direct marking on medical instruments.

  • GS1-128
  • GS1 Data Matrix (if surface area for GS1-128 cannot be ensured)

The following information must be provided for use as a display item.

  • 01: GTIN (product code) / 10: Lot no. / 17: Expiration date
  • 21: Serial no. / 11: Manufacturing date

These two-digit numbers are called AI (application identifiers). If the numbers are meant to be expressed as visible characters, they must be surrounded by parentheses ( ).

Code display example
GTIN: 4569951110016
Serial number: 42345A-2
(01)04569951110016 (21)42345A-2

The display size of direct marking on medical instruments and other healthcare products as specified in the GS1 standard is as noted in the following table.

GS1 Data Matrix specifications
Marking method* Module width (x)
Unit: mm (inch)
Quiet zone
Minimum Objective Maximum
Ink 0.254
1×, all 4 sides
Method A:
Laser marking, etc.
1×, all 4 sides
Method B:
Dot pin marking, etc.
1×, all 4 sides

Excerpt from GS1 system symbol specification table 7 in the GS1 General Specifications

Advantages of cold marking

Laser marks on medical devices typically fall into the following categories:

This method involves using the heat of the laser to color the surface of a target black.
This method involves increasing the laser irradiation density to remove the surface of a target.
Cold marking
This method involves coloring the surface of a target black without removing the oxidized film.
Cold marking

Many medical components have a chromium exterior, which turns into chromium carbide when heat is applied (thus reducing its corrosion-resistance). Conventional near-IR lasers use heat to create black contrast, which risks causing corrosion over time. UV lasers - thanks to photolytic processing - can mark parts without damaging the surface material.

Oxidized marking
Oxidized marking
Cold Marking
Cold Marking
Salt water spray test results
Oxidized marking
Oxidized marking
Cold Marking
Cold Marking

Ability to mark extremely small codes

Controlling the laser beam size makes it possible to create minute markings as small as 0.5 mm × 0.5 mm (0.02" x 0.02") even when marking a 26-digit (18 × 18 cells) GTIN or serial number in a GS1 data matrix.

2.0 mm × 2.0 mm (0.08" x 0.08")
2.0 mm × 2.0 mm
(0.08" x 0.08")
1.0 mm × 1.0 mm (0.04" x 0.04")
1.0 mm × 1.0 mm
(0.04" x 0.04")
0.5 mm × 0.5 mm (0.02" x 0.02")
0.5 mm × 0.5 mm
(0.02" x 0.02")