Radio-frequency identification (RFID) is transforming the way labs manage frozen biological samples, streamlining workflows, improving traceability, and minimizing the risks associated with frost-obscured codes and manual labeling. This article, originally published in ‘Biocompare, ebook Essential Guide to Best Practices in the Lab 13’, explores how RFID technology can overcome common challenges in frozen sample handling and protect the integrity of thermally sensitive materials.
Method overcomes challenges to streamline research workflows and protect thermally sensitive materials.
Biological samples are commonly stored in small, 2D-coded tubes, which in turn are held in racks within ultra-low-temperature (ULT) freezers or vapor-phase liquid nitrogen storage containers. However, 2D-codes can become obscured by a build-up of frost and ice, making sample identification a time-consuming and error-prone process. This article explains how radio-frequency tagging overcomes these challenges to streamline research workflows and better protect thermally sensitive materials.
Challenges for traditional frozen sample management
Traditionally, biological samples such as DNA, cell lysates, and tissue homogenates would be stored in small, plastic consumable tubes that were hand-labeled with a permanent marker. The tubes would then be placed in racks and transferred to a ULT freezer or liquid nitrogen dewar, with their locations being recorded on sheets of paper attached to the outside of the storage unit.
A main drawback of this approach is that it risks sample loss through lost or damaged labels. It also introduces the potential for error due to hand-written labels being deciphered incorrectly. In addition, the challenges of keeping paper records up to date limit audit traceability and throughput. As a result, tubes with laser-etched 2D-codes are now more commonly used. Because the codes are read with a handheld scanner, rather than by eye, this approach avoids any ambiguity and instead provides clear digital information that can be easily edited whenever a tube is moved.
Although laser-etched 2D-codes represent a significant improvement on hand-written labels, they can still present problems. Specifically, the codes may become covered in frost and ice, which can cause fog or condensation that prevents codes from linking to the “line of sight” of their reader. Ambient lighting, background image noise, variation in code lasering, and material quality are all known to exacerbate these issues.
An established work-around is to clear the 2D-codes using alcohol. However, this takes time and therefore exposes samples to harmful temperature excursions, which can compromise sample integrity.
Principles of radio-frequency tagging
Compared to light rays, radio waves are less affected by the physical phenomena just described. For this reason, radio waves have recently been utilized for frozen sample management by Azenta Life Sciences, a sample management and automation company that has developed a unique Radio-Frequency Identification (RFID) technology that allows for electronically tracking large collections of samples without the need to remove ice from the storage tubes.
The process begins with loading up to 96 2D-coded tubes into a standard SBS rack, to which an RFID tag is applied with an easy-to-use tool. The tag contains a microchip, which stores the identities and locations of the tubes as per the 2D-codes, and an antenna, which transmits the information to an RFID reader when within range. By combining RFID technology with optical reading, this approach verifies the identification of the sample and highlights if a tube is missing or has moved position in the rack, even if the 2D-codes are obscured.
Advantages of radio-frequency tagging for frozen sample management
A main advantage of radio-frequency tagging for frozen sample management is that it mitigates against the risk of samples thawing. Racks can quickly be read straight from frozen storage, rather than having to be transferred back to the lab, which both safeguards precious sample material and helps to ensure data accuracy.
Radio-frequency tagging can also improve operational efficiency through better tracking of samples as they are stored, moved, or processed. By removing doubt over which samples are tested, radio-frequency tagging reduces the need to repeat experiments, thus saving both time and resources.
A further benefit of radio-frequency tagging is that it can simplify regulatory compliance. Complying with regulatory requirements for laboratory storage conditions, maintaining a chain of custody, and ensuring data integrity through accurate record-keeping, all of which can be enhanced by more robust traceability.
Getting started with radio-frequency tagging
The RFID sample management solution from Azenta Life Sciences consists of ready-to-use RFID SBS racks, plus the RFID RITrack Mirage instrument to decode tubes and then write/re-write data onto tags.
Researchers can also download a complementary, free app from the App Store or Google Play to any compatible smartphone device with Near Field Communication (NFC). This allows the tag information to be read and the data displayed in either graphical or tabular format, and includes a pick list function for checking off tubes from several different racks right in front of the freezer.