Using barcodes in sample and inventory management

Barcodes are used in laboratories all around the world for accurate inventory management.

Invented in the early 1950s, barcodes are a graphical, machine-readable representation of data, originally based on morse code.

With the typical error rate for manual data entry being “one error for every 300 keystrokes”, it’s easy to see why barcodes have been used in laboratories and inventory management for decades as “barcodes reduce the error rate to between 1 error in 15,000 or 1 error in 36 trillion characters depending upon the barcode type”. (Page 114, Purchase Order Management Best Practices: Process, Technology, and Change Management, Sabri et al., 2006)

Used alongside a software solution for the tracking of samples and storage, barcodes allow scientists easy access to data about the sample, plate, vial or container being used in a process. This enables them to easily identify the correct samples they need and allows tracking, including the movement and storage, of the precious samples.

Barcoded Tube

Some scientists swear by the use of barcodes, while others still debate whether human readable labels are more important.

Barcoding and Human Readable Labels

The use of human readables vs barcoded labels isn’t as clear cut as one option being better than the other, there are use case examples for combined labels being needed.

In the case of human biologicals: if it’s a human sample, you can’t just leave it lying around, you have to be able to see that it’s a human sample and this is where the human readable label is needed, possibly with the hazard codes displayed clearly.

However, even if a human readable label is needed, a barcode is still used in addition as the barcode guarantees its uniqueness and makes the sample easier to track.

Rather than thinking of barcodes and human readable labels as a black and white choice, scientists can make use of both to ensure the right information is available at the right time in the process.

It’s a bit like picking an item up in the supermarket, all of the ingredients and information is readable on the packet, but there is also a barcode on the product, which is the unique identifier. You know it’s a packet of cheese and onion crisps. The barcode allows stock tracking of this flavour and pricing does not rely on a till operator finding a human readable price sticker that may fall off.

Pre-barcoded vs. Labels

When considering whether to invest in pre-barcoded labware or printing your own labels, the answer will depend on your process requirements. If you need a huge amount of labware items, it might be best to buy it in pre-barcoded as you can be assured they’re always the same quality, always in the same position and that nobody applied it in the wrong way.

If you’re working with much smaller numbers of samples and labware, then you might choose to print your own labels as it doesn’t take long to assign the sample and print a barcode label.

When printing your own labels, there is always the risk of applying the barcode in the wrong position so that it cannot be read properly by instrumentation that you use daily for preparing samples or quantifying results.

Another potential issue with printing and applying your own labels is that the weight of the label must also be taken into account when weighing samples. Practices vary, but it’s important that the label weight is not mistakenly included as being part of the weight of the sample. This isn't the case for pre-barcoded labware.

In the long run, pre-barcoded labware can also be cheaper as while the upfront cost of buying thousands of tubes might be expensive, the time saved by not having to precisely apply a barcode to each tube might be worth a lot more!

Benefits of barcodes

As a solution that has been around for decades and used across multiple industries, the technology needed to use barcodes is relatively cheap, especially when compared to alternatives such as Radio-frequency identification (RFID).

It’s also a tried and tested method that has been improved over time. Barcodes have gotten smaller and the reliability of reading them has greatly improved. Technologies such as 2D codes have also been developed that can hold a large amount of data in a very small space.

When combined with automation, barcodes can be a very powerful way to track, find and search for samples while creating a comprehensive audit trail.

Newer label types are also becoming impervious to the conditions they’re put in, whether it be a -80°C freezer, or solvents being spilt over them, they not only stay in place on the tube more often, some 2D codes can actually be partially destroyed and the code can still be read. 

Issues with barcodes

While some types of barcodes can take the freezing temperature of a lab freezer, it’s not unknown for barcode labels to fall off the tubes as the glue fails under the harsh conditions.
This obviously causes issues with the tracking and identification of a sample. Although, this issue is not exclusive to barcode labels as it can happen with all types of labels.

Another potential issue with barcodes is the availability of barcode scanners in the lab. If the scientist doesn’t have the right equipment to hand, they’re more likely to just write on the tube instead so it’s identifiable to anyone who comes across it. However, with web based software applications and barcode readers available from as little as $5, this is easily resolved.

With multiple sources of barcodes, there is a very small chance that a barcode supplied from one CRO could be the same as one supplied by another CRO. This risk of duplication of the barcode, while generally unlikely can be prevented by inventory management software, such as Mosaic, which can warn when duplicate labware barcodes are received and allowing tracked remedial fixes to be applied. 

Evolution of technologies to cope with external environment

One of the major issues with barcodes and freezing samples is that frost can cover the barcodes. 2D codes are less prone to this due to inherent replication of the identifier within the barcode, but novel ways of getting around this issue have been created to make scanning less error prone.

Rack scanners have been developed that blow warm air over the base of 2D rack tubes and heaters and special glass have also been developed to avoid condensation on the top of the rack scanners.

An interesting approach to this problem is the p-chip® systems by Brooks and PharmaSeq. This uses an ice penetrating laser light to excite a chip in the base of the tube and power a radio signal allowing tubes to be identified. Due to the precision of the laser, the position of the tube within a rack can be also identified.

RFID can also be used, although has issues with positioning as the signal within a rack can be too broad to detect where in a rack the tube is. However, for ease of tracking, for instance on samples being picked up from a lab, An RFID can give a simple pickup signal when the labware has been removed from the sample management laboratory.

These technologies are more expensive than traditional barcodes, but work well with information systems as they are again, just a labware unique identifier.

The future of barcodes

For many, the benefits of barcodes in sample management outweigh the issues, and with future technologies being developed, some of the issues mentioned may soon be a thing of the past.

While barcodes are unlikely to drastically change in the future, the way we use them and interact with them in the lab will change.

In terms of mobility, there’s always the possibility that we might see mobile devices being used in the future to scan labware, again, without the need to go back to a workstation to check what a sample is.

Other future trends might see more labware using non label printing such as the TubeWriter™360, to reduce the risk of the labels falling off due to freezing and thawing or damage from solvents as discussed earlier.

Barcodes are here to stay

Barcodes are not going away and the technology used with barcodes will continue to develop. Barcodes in conjunction with software will continue to guide users and equipment with more information to streamline processes.

With the right technology and systems in place, barcodes can make laboratory inventory management and sample tracking seamless. Titian’s Mosaic software helps to make this possible. By integrating with laboratory automation, liquid handling and printers, Mosaic makes it easy to track, search and find samples and also allows you to assign barcodes and print the appropriate labels for the labware.

Learn more about why barcodes and labelling matters in sample management in our whitepaper: The Essential Guide to Managing Laboratory Samples. Download it here.

Tags: inventory management