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Barcode Labelling: The Basics

Variety of barcode labels

The introduction of barcoding and automatic identification and data capture (AIDC) has revolutionised the way we identify, track and trace inventory in every environment – and the clinical laboratory is no exception. Barcode labels can be applied to virtually any surface exponentially increasing the speed and reliability of cataloguing chemicals, specimens, samples and patients.


A barcode is simply a computer-readable pattern that contains data about the item it’s attached to. It may be a linear barcode, where information is formatted in a series of parallel lines, or a 2D code that uses a grid of squares, rectangles, dots or hexagons. In either case, when that information is required, the markings - and the gaps between them – can be “read” by a scanner or imager and the data relayed back to your computer system, decoded.

Clinical trial booklets with 2D data matrix codes


Automating your processes with barcode labels exponentially increases productivity; speeding up your data-logging and greatly reducing the risk of error caused by poor handwriting or mis-reading data.

Unlike handwriting, barcodes printed on the correctly selected label won’t fade or smudge during challenging laboratory processes – water baths, handling and rubbing, alcohol wipes and solvent exposure. A durable label material will also keep data securely attached to microslides, blood tubes, microvials etc. through long-term freezer storage and cold transit (where most labels typically fall off).


The first step is considering the amount of space you have for a label, and how much data it’s critical to include. If your media is particularly small (such as a microvial or centrifuge tube), you may want to consider a “cap and tube” label pair. A 2D code on the lid allows quick scanning (the tube doesn’t need to leave its rack), with additional information stuck to the side of the vessel on a larger label.

The most popular symbology for linear laboratory barcodes is Code 128, as its high-density format can store a lot of alphanumeric data in a relatively small space. Code 128 is also specified in ISO/IEC 15417:2007 for laboratories adhering to those standards.

A linear barcode - Code 128 symbology


2D barcodes are ideal for when space is really at a premium, and the data matrix or QR code format is often chosen – a data matrix symbol can hold up to 2,335 alphanumeric characters. These do require a more sophisticated scanner to read, however.

A 2D code - QR code symbology


If you already have access to label design software and a quality thermal transfer printer (highly recommended for barcode durability) then printing in-house may be an economical option. However, outsourcing your label printing can save a lot of time (and frustration), and saves the investment in a printing system if you don’t already have one in place. That, combined with the convenience of receiving quality-tested, ready-to-use durable labels, makes it an option worth considering.

Microvials with cap and tube labels


Remember, clarity is the key to a scanner reading a barcode quickly so if you choose to print your labels in-house, keep the following in mind:

  • Thermal transfer printing may offer greater durability than laser printing – as long at the label material and printer ribbon are correctly matched.
  • Printing at 300dpi or greater will ensure sharp barcodes, particularly at small sizes.
  • Low-contrast printing, or voids in the print may impair the readability of your barcode. 
  • Consider including a human-readable element as a back-up in case scanning fails.

Linear barcodes on microslides

Barcode labels are a hugely beneficial tool for sample identification, improving the the efficiency of your processes, protecting your valuable data and reducing the risk of human mistakes.

To find out how easy it is to switch to barcoding, or how to improve the barcode labeling system you already have in place, contact the CILS Label Technology Centre on 01903 219000, via email or fill out a contact form. Their labeling experts will be happy to help with any queries about durable labels, pre-printed labels, software or thermal transfer printing.

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