Barcodes: a useful tool for the lab

Nov. 18, 2012

All you may hear is a beep, but it’s a welcome sound. It tells you that data has been collected quickly and accurately. Although barcodes are ubiquitous, an understanding of them in the clinical lab does not often run deep—and superficial knowledge may translate into uneven results. If the potential benefits of barcodes are not fully realized, labs cannot be as productive as they otherwise might be.

Barcodes 101

The basic principle behind barcodes is a straightforward one: different amounts of light are reflected by different colored surfaces. The black bars in a barcode symbol reflect less light than the white spaces. Regardless of the specific technology employed (handheld wand, moving-beam laser, or CCD), every barcode scanner contains a source of light and a method for receiving and reading the light reflected by a scan.

How long the light is reflected into the scanner depends on the width of the bar or space being scanned. Predefined width patterns (typically, just different arrangements of narrow and wide bars and spaces) are used to represent the data encoded. Linear barcodes have been thought of as a printed version of the Morse code; narrow bars and spaces represent dots while wide ones represent dashes. The set of rules followed by the scanner to determine what a specific series of wides and narrows (dots and dashes) means is called the decode algorithm. Most linear scanners are capable of decoding numerous barcode languages (called symbologies) without user intervention, so the operator need not know what type of barcode is being scanned.

Development of two-dimensional (2-D) symbologies was driven by the desire to encode more information in less space. These symbologies operate on a similar principle to that of standard barcodes but require more sophisticated reading devices called imagers. These scanners use vision-based technology to take a picture of the symbol and, regardless of orientation, decode it instantaneously. Some of these imagers will also decode linear symbols as well.

Implementation in the lab

As with all technologies, issues arise when implementing or enhancing a barcode system. However, obstacles can easily be overcome with careful planning and thorough training.

Message length: A common issue within a medical lab is figuring out where to put the label on the hardware. Tubes, vials, microwell plates, and slides all have limited real estate to accommodate a label. Therefore, it is critical to determine early on exactly how much information must be encoded. Resist the natural tendency to want to encode everything there is to be known about an item. Shorter messages are easier to decode than longer ones, and all else being equal, label costs are lower with smaller labels.

Symbol contrast: Barcode scanners need to easily differentiate between bars and spaces, so clarity and contrast are important. Because of this, black and white is the color scheme of choice. Barcode enthusiasts have been heard to say, “Black and white means ‘read’ all over.” That reference to an old joke about newspapers is a bit hokey, but it’s accurate. Pre-printed labels from an experienced vendor offer the best assurance of barcode image quality. If your lab’s barcode label production can be outsourced, that option should be rigorously explored.

Label production: Thermal transfer is the single best print technology for printing labels on-site. But all thermal transfer printers are not created equal. A 600 dpi model with very tight print tolerances may be especially useful in the lab, and matching the label stock with the right ribbon is absolutely critical to scanning success. A vendor with extensive laboratory expertise can help decide which equipment is best for you, thus avoiding common pitfalls.

Suitable scanners: The array of scanners available today can be overwhelming, but don’t let that allow you to lose sight of how scanning will take place in your lab. Consider all the real-life scenarios and select scanners accordingly. If you only use linear barcodes, there is no need for image readers. If you use a mix of linear and 2-D, there are scanners available—at a slightly higher cost—that will read both. Most laboratory equipment comes with scanners already installed, so the primary concern is where additional, human-based scanning will occur. Simple hands-free scanner holders, which allow the technician to easily present the item to the scanner, are available for some units. In situations where people will be interacting with technology, the “try before you buy” approach makes a lot of sense. Make sure you test your scanners with the same label(s) that will be routinely used in your application.

Training: One great feature of barcode technology is ease-of-use. There are three major types of scanning devices in use today:

  • Contact wands—Holding the scanner as you would a pen, draw an imaginary line through the linear barcode symbol, starting on the white margin (called the quiet zone) at one end of the symbol and ending on the white margin at the opposite end. Don’t allow the imaginary line to leave the symbol until the pass is complete. Barcodes are bi-directional, so they can be scanned left-to-right or right-to-left, and scanning speed can range anywhere from two to 20 inches per second.
  • Laser scanners—Pull the trigger and shoot. Based on the printing characteristics of the barcode, adjustments in the distance from the scanner to the symbol may be necessary to find the spot that produces the best results. Some lasers emit a spot of light so users can ensure they’ve located the symbol correctly before the actual scanning happens.
  • CCDs—These simple scanners take a flash photo of the entire symbol. The user touches the barcode with the scanner and a successful read occurs.


In most cases, when a job is done quickly, accuracy suffers. But barcodes have exploded in popularity because they don’t require that trade-off. With a high quality barcode label, a working scanner, and a trained operator, data collection can happen at lightening speeds with 100% data accuracy. There are few places where this is more important than in today’s clinical laboratory. Physicians, medical laboratory scientists, and patients all have a stake in the lab’s accuracy, and new regulatory pressures reward facilities that produce results effectively and efficiently.

There is probably no technology that provides a larger return on investment than barcode scanning. But the productivity improvements aren’t automatic, and developing a best-practices approach to using the technology can be a challenge. With the guidance offered above, however, pitfalls can be avoided, budgets can be adhered to, and data can be collected quickly, without error. But best of all, critical medical results that may drive life-and-death decisions will be based on data that is reliable and accurate. And that’s good for everyone.

Bruce R. Wray is a market manager for St. Paul, Minnesota-based Computype, Inc.