8 potential UDI code readability issues and the critical role of vision : Page 2 of 2

Kasey Tipping in Unique Device Identification on September 15, 2016

8 Potential UDI code readability issues

UDIs are typically marked as a bar code, a QR code, or a DataMatrix code. Reading 1-D and 2-D UDI codes and text can be challenging in real-world applications because of the wide range of surfaces on which the codes may be marked, variations in the size, shape, position and orientation of the code, the potential for degradation in printing and marking of the codes, and variations in ambient lighting.

The task is even harder for medical devices that don’t have much room for a code, such as scalpels or syringes. Laser etching onto metals is the typical approach, but it’s not easy. The laser must be calibrated correctly, and the code must be marked clearly enough to be read.

Following are 8 potential UDI code readability issues:

1.       Low resolution. Many times parts or codes on one line can change in size, which means that a standard resolution bar code reader can read some codes, but not others. Look for readers that offer subpixel processing and reading capabilities.
2.       Missing perimeter features. Sometimes, codes are printed too close to an edge, causing the code to be missing key finder patterns. Look for readers that employ algorithms that can accommodate codes without a quiet zone or clocking or finder pattern.   
3.       Specularity. Specular reflection occurs often when codes are printed on glossy materials. These can be very hard for laser scanners because glare could occur through the laser line. Image-based readers just need a small sliver of the code in order to decode. 
4.       Warped. Warped codes can sometimes seem as though they are missing part of the code. Look for systems with algorithms that can read codes that do not have quiet zones or clocking or finder patterns. 
5.       Poorly marked. Poorly marked codes could be due to a printer being low on ink and having poor contrast for example. Powerful algorithms can read the most damaged codes.
6.       Small modules. For very small codes, a variety of lensing options can compensate and read the code.
7.       Scratched. Look for systems that only need a small portion of a 1-D code to read it, so if a code is marked with a marker or scratched it can still be read.
8.       Extreme perspective. Part or code placement can be difficult, and the code can sometimes be presented to the reader at an extreme angle. Look for systems that can accommodate such angles.   

Recent technology advancements are benefitting medical device manufacturers and other supply chain contributors rushing to comply with UDI regulations. For example, in the vision-based ID reader space, software algorithms have been developed that are able to find and decode even damaged and poorly marked 1-D or 2-D codes through a wide range of illumination, marking, and material variations. Another advancement involves application-specific solutions for vision systems that eliminate the need for programming and pre-built documentation that substantially reduces the time required for FDA validation.


While UDI offers potential advantages in securing and improving the efficiency of the medical device supply chain, medical device manufacturers are encountering serious challenges to compliance.

FDA may fine-tune the regulations in the future. In the meantime, milestones are occurring on a regular basis. For instance, the number of products for which direct marking is required has increased. So it’s incumbent upon device manufacturers to make plans and take action to ensure compliance.

Kasey Tipping (above) serves as Technical Marketing Specialist - ID Products for Cognex Corp. (Natick, MA).

For more information, contact Cognex at One Vision Drive, Natick, MA 01760-2059 USA. Tel (Toll Free): 1-877-COGNEX1 (1-877-264-6391), Fax: +1 508 650-3344, Email: [email protected], Web: http://www.cognex.com/  


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