At Ziath, we think two-dimensional barcodes are pretty neat! Not only can they store more data than linear barcodes, but because they’re located at the bottom of the tube, they can be quickly scanned without taking samples out of the rack. Their 2D design also means they’re inherently more resistant to scanning problems. But while they offer excellent all-round performance, from time to time scanning issues do happen. Here we highlight some of the most commonly encountered scanning issues – and how to avoid them.
Poor barcode contrast
Whether we’re talking about bar service or barcode scanning, to get the results you want quickly it’s a good idea to stand out from the crowd. White on black (or black on white) gives the optimal colour contrast for 2D barcodes, and it’s a combination that is in common use. However, we have seen some pretty unusual variations! Light grey on dark grey, grey on silver, or even black barcodes printed directly onto a clear tube with no contrasting background at all – these combinations aren’t as effective at achieving a quick and easy scan. Although the algorithms we use in our software will help in these situations, if you are about to purchase some 2D-coded tubes it is worth checking that your scanner can read them!
Barcodes covered in ice
When you take a sample straight out of a minus 80 °C freezer, there is a good chance that it’s going to be covered in a fair amount of ice. This can often obstruct the 2D barcode and prevent it from scanning properly. But rather than changing your tubes to a costly alternative there’s a simple solution, which we’ve blogged about previously. To remove the ice, just use our cheap ‘sponge and alcohol’ technique – it works really well!
Tubes placed in incompatible racks
Laboratory 2D-coded sample tubes come in all sorts of shapes and sizes – with more models entering the market every month. However, this can be a problem if the manufacturer does not provide a suitable rack for the tubes. If tubes are placed in racks that aren’t designed to hold them, barcodes can be obscured or held too high up in the rack. So if you are experimenting with a range of tubes from one manufacturer and racks from another, just check that the rack holes are wide enough for the scanner to read the whole of the barcode and that the barcode is not too far from the scanning window.
Wrong barcode type
Historically, all 2D rack barcode scanners were designed to read Data Matrix barcodes. However, some manufacturers print QR codes on their tubes, which cannot be read by these scanners. Whilst these barcodes may look similar, it’s important to recognise the subtle differences. Unlike Data Matrix barcodes, QR codes are usually larger and contain three distinct squares in the corners (check out our handy spotter’s guide below).
Barcode printed too close to tube edge
Sometimes we all need a bit of space to work effectively, and this is certainly true of barcodes. In order to scan properly, all barcodes (be they linear or 2D Data Matrix barcodes) require a small amount of surrounding blank space so that the scanner knows where the code begins and ends. This ‘quiet zone’ also ensures scanners don’t mistake text or other markings on the tube or label for information. For Data Matrix barcodes, this white space should be at least the size of two ‘modules’ (the black and white pixels that make up the 2D grid). Barcodes that are printed too near the edge of the tube can impinge on this white space, and just like putting too many eggs in a basket, the results aren’t pretty.
Despite the impressively reliable performance of 2D barcodes, scanning issues can and do happen. Thankfully, through good laboratory practice, the use of appropriate equipment and consumables, and the occasional crafty trick, these challenges can be overcome.
If you’re interested in learning how to optimise your 2D barcode scanning and enhance your lab’s sample management, then download our new tips and tricks eBook today.