UDI Barcode Verification: Most Common Problems
Whether you are using 1D barcodes such as GS1-128 or 2D symbols such as Data Matrix codes for UDI compliance marking, UDI barcode verification is of paramount importance for assuring barcode quality. Our test lab has seen a lot of UDI barcodes and there are some recurring problems to be avoided. Here are some of the most common.
- Overprinting, whatever the print method, is a frequent quality problem. Print head temperatures are too high in thermal, thermal transfer; inkjet settings or ink viscosity are incorrect for the substrate. Visually compare the black dots or squares in a Data Matrix code with their white equivalents: are they dimensionally equivalent?
- Substrate itself can be problematic. Some of the infusion bags we’ve seen do not produce the high reflectance values one might expect—in fact they often produce low reflectance rather than high reflectance, appropriate for reverse printing the barcode. Other substrate problems include patterned surfaces which cause reflectance variations that can confuse a scanner.
- Background noise such as printing or graphics behind a barcode on a clear pouch can virtually destroy the scanability of an otherwise high quality barcode. This can be minimized by printing the barcode over a white patch.
- Quiet zone encroachment is a frequent problem, and often on 2D symbols. People seem to be generally aware of quiet zones on 1D barcodes such as GS1-128, but oblivious to quiet zone requirements for 2D symbols such as Data Matrix code. Printing a data-rich 1D barcode on a small label can be a problem, requiring the barcode to be very accurately and consistently positioned so that neither of the quiet zones is infringed.
- Using a 1D barcode to encode a large amount of data can lead to problems such as described above. Frequently when the 1D symbol gets very long, and often-seen solution is to decrease the size of the X dimension to fit symbol to a narrow label. This makes it more difficult to print the barcode accurately and to scan it easily. A better solution s to replace the 1D symbol with a Data Matrix code.
- Distortion is increasingly a problem as the printing technology makes it possible to print the barcode on uneven surfaces. 1D barcodes are sensitive to distortion on one axis, but 2D symbols are sensitive on both the X and Y axis. When printing a barcode on bottles or other 3D objects, tapered or curved areas should be avoided.
- Data structure in a UDI barcode is very specific. Data must be properly prefixed, some fields are fixed length, and others are variable. It can be complicated and this is an area where mistakes are often made. Using a well known, current version of label design software is a good insurance against incorrectly structuring a UDI barcode, and UDI barcode verification is the last line of defense against a devastating error.