When implementing a new laboratory information management system (LIMS) or any other digital management system, assessing how samples and inventory will be tracked and traced is important. Barcode labels are frequently used for such purposes, as they can be scanned at each step of a given workflow and accounted for much faster and reliably than handwritten labels. However, with so many types available, it’s essential to apply the right barcode to ensure the requisite information can be tracked efficiently.
Consider the data to be encoded
Typically, sample information for research laboratories contains a variety of data, including the name, date, previous processing, and location of each tube or vial. For this reason, using 2D barcodes for most assays and experiments is often recommended. 2D barcodes such as the QR code, Data Matrix, JAB code, Aztec code, and PDF417 all allow encoding of numeric, alphanumeric, and special characters, all of which allow storage of crucial sample information. Data Matrix, Aztec code, and PDF417 even allow byte/binary code storage, if needed.
In contrast, when processing samples whose identity must remain unknown (i.e. patient specimens), 2D barcodes may not be necessary. If 1D barcodes are to be used, note that UPC, EAN, and Interleaved 2 of 5 only record numeric data. For recording of alphanumeric text using 1D barcodes, GS1 Databar Expanded or Code 39 are required.
Data capacity requirements
For applications requiring 2D barcodes, it’s worth noting that the QR code has a higher general storage capacity than either PDF417 or Data Matrix. The QR code can store up to 7,089 characters, with an alphanumeric capacity of 4296. This is far superior to Data Matrix, which stores up to 3,116 characters (2,335 alphanumeric characters), or PDF417, which stores up to 2,710 characters (1,850 alphanumeric characters).
Though Data Matrix and PDF417 have lower storage capacities than the QR code, they are also able to encode byte/binary data, a feat the QR code is unable to perform. Here, Data Matrix outpoints PDF417, with a storage of 1,556 binary characters, versus PDF417’s capacity of 1,108 characters. Interestingly, while the Aztec code has a lower overall storage capacity compared to Data Matrix, it has a higher byte/binary capacity, able to store up to 1914 characters.
For 1D barcodes, storage is much more limited compared with 2D barcodes. UPC barcodes can store 6-12 characters, while EAN barcodes store 8-13. For alphanumeric 1D barcodes, Code 39 stores up to 43 characters, and GS1 Databar Expanded encodes up to 75 numeric or 41 alphanumeric characters.
Each barcode has its own specific size recommendations, which are crucial to crosscheck against the size and shape of each label. Certain types of barcodes may be better suited for specific containers; for instance, 2D barcodes are optimal for use on the tops of microtubes and vials, while 1D barcodes are generally used vertically along larger tubes. If you’re using your phone as a scanner, it’s recommended to ensure that the barcode is large enough for the phone’s camera to adequately focus on it.
When selecting a barcode, always ensure its orientation aligns with the scanner’s reading ability. Placing a 1D barcode along the circumference of a test tube is counterproductive, as the scanner can only read a portion of the barcode since it cannot read around the tube. Instead, ensure that the barcode runs horizontally and flat along the length of the tube, where the scanner can visualize the entire code.
Harsh laboratory conditions, such as cryogenic storage, high-heat sterilization, and chemical exposure, can affect the viability of the barcode printout, especially if a thermal-transfer printer is not being used. While thermal-transfer printing provides optimal resistance against these conditions, it is also worth selecting barcodes with correction capabilities, like QR code, Data Matrix, or PDF417, to ensure a lower chance of a failed scan in case fading or abrasion does occur.
Always verify if your barcodes are compatible with conventions within your lab and other departments. This is especially important for shipping samples, as the barcodes sent with the samples should always be compatible with those used by the receiving facility. In-house, it is often necessary to consult with other lab members to ensure that barcoding SOPs are met to help streamline workflows, including sample processing, data generation, inventory, and analysis.
LabTAG by GA International is a leading manufacturer of high-performance specialty labels and a supplier of identification solutions used in research and medical labs as well as healthcare institutions.