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Barcodes in drug discovery: The quiet revolution
October 2012
by Bruce R. Wray, Computype  |  Email the author

Your barcode awareness may begin and end with the "beep" you hear. Yet, you know that data has been collected quickly, quietly and accurately. From the grocery store to the microwell plate in your lab, barcodes are ever- present. But our knowledge of them is often superficial, and as a result, we don't fully enjoy their benefits. Their critical role in drug discovery suggests knowing how they work makes us more productive users of the technology.  
Our purpose here is to provide a technical overview of linear and two-dimensional (2D) symbologies (barcode languages), understand the print characteristics that impact scanability, offer training suggestions for new users and confirm how barcode scanning reduces errors and increases throughput in today's drug discovery lab.
How do barcodes work?  
The basic principle couldn't be simpler: Light is reflected in different amounts by different colored surfaces. The black barcode bars reflect less light than the white spaces. Regardless of the device employed (handheld wand, moving-beam laser, CCD), every barcode scanner contains a source of light and a method for receiving the light reflected from a scan.  
The width of each bar or space being scanned determines how long the light is reflected into the scanner. 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, with narrow bars and spaces representing dots, and wide ones representing dashes. The scanner then uses a decode algorithm to figure out what each specific series of bars means. Most linear scanners are capable of decoding numerous barcode languages or symbologies without user intervention, so the user need not know what type of barcode is being scanned.
What about 2D codes?
Driven by the desire to encode more information in less space, 2D symbologies were born. They operate on a similar principle to basic barcodes, but require more sophisticated reading devices, called imagers. These scanners use vision-based technology to take a picture of the symbol and instantaneously decode it, regardless of orientation. Some of these imagers will also decode basic barcodes as well.  
Making barcodes work for you  
Like all technologies, there are some common issues that may arise when implementing or enhancing a barcode system. These unforeseen problems can easily be overcome with careful planning and training.  
Message length
Plates, slides, tubes and vials all have limited real estate to accommodate a label, which is a common barcode constraint within a drug discovery facility. Before you try to design a label that encodes the date, technician ID, sample origin, study name, patient ID, medical record number, Social Security number and your favorite color, consider using a unique number that simply provides access to the database instead. Shorter messages are easier to decode and label costs will be lower.  
Symbol contrast
Barcode scanners need to be able to easily differentiate between bars and spaces, which is why black and white is the preferred color scheme. Some barcode enthusiasts have been heard to say, "Black and white means 'read' all over." Hokey, but accurate. If this is of concern, preprinted labels from an experienced vendor offer the best assurance of symbol contrast.
Label production  
If preprinted labels are not an option, the best technology for on-demand barcode production is thermal transfer printing. But all thermal transfer printers are not created equal. 600-dpi models with very tight print tolerances are especially useful in drug discovery, where plates, slides and tubes offer little space for labeling. Matching the label stock with the right ribbon is also critical to scanning success. It's important to work with a vendor with extensive laboratory expertise to avoid common printing pitfalls. An inexpensive label quickly becomes very costly when it has fallen off, or worse, is misread.  
Appropriate 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. Look at all the real-life scenarios and select scanners accordingly. If linear barcodes are the only type you use, there is no need for image readers. If you use a mix of linear and 2D barcodes, there are more advanced (and costly) scanners available that will read both. Most laboratory equipment comes with scanners already installed, so the primary concern should be where additional, human-based scanning will occur. In situations where people will directly interact with technology, the "try-before-you-buy" approach makes sense. Make sure you test the scanner with the same labels that will be routinely used in your application.
Robotic automation
The automated lab is quickly becoming the de-facto standard. In drug discovery labs, this often includes print-and-apply label applicators specifically designed to work in conjunction with automated plate handling equipment. On a more basic level, there are simple print-and-apply systems designed for cylindrical surfaces that can also apply labels to flat surfaces, so both microwell plates and tubes can be labeled with the same device.  
If all this makes your head spin, there's an even simpler solution: Outsource your labeling entirely. There are now firms that offer prelabeled labware on a service bureau basis. The user specifies a container and sequence, and the firm provides the labware—tubes, plates, slides—with those items already labeled and packaged sequentially. Permanent ID for especially harsh environments is even available via ceramic labels fired onto glassware.
One of the great features of barcode technology is its ease-of-use. There are three major types of scanning devices in use today, and training couldn't be simpler:  
  • 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 bidirectional, so they can be scanned left-to-right or right-to-left. Scanning speed can be anywhere from two to 20 inches per second.

  • Laser scanners: Simply pull the trigger and shoot. Based on the printing characteristics of the symbol, adjustments in the distance from the scanner to the barcode may need to be made to find the sweet spot that produces the best results.

  • CCDs: These simple scanners take a flash photo of the entire symbol. The user need only touch the barcode with the scanner and a successful read will occur.

What's next in automatic identification for the drug discovery lab?
No discussion of automatic identification and barcodes would be complete without a mention of radio frequency identification (RFID). The technology offers some compelling capabilities. RFID uses radio waves to communicate between a reader and a tagged item. The tag responds with a signal that is modulated with information stored within it.  
One attractive feature of RFID is that a line-of-sight is not required for reading. In other words, the object to be scanned does not need to be optically visible to the reader. The tag can be in an unopened carton or stored high on an inaccessible shelf. Another differentiating feature of RFID is its ability to change the information encoded in the chip from a distance. With read/write chips, information can be updated and changed remotely, so the identification of the item is accurate in real time.
The added expense of an RFID infrastructure has proven to be difficult for many lab environments to justify. While barcode scanning requires a relatively small investment in proven technology, RFID is still new enough that costs are high. But there is no question that as demand increases, competition will intensify and prices will fall. For today, it might be prudent to view RFID as a possible future enhancement to the barcode system, rather than an immediate replacement for it.  
How will barcodes improve my lab?
Generally speaking, when a job is done quickly, accuracy suffers. Barcodes have exploded in the lab 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 lightning speeds with 100-percent accuracy. There are few places where this is more important than in the area of pharmaceutical research and drug discovery. Researchers, doctors, medical professionals, clinicians and patients all have a vested interest in lab accuracy, and new regulatory pressures reward facilities that produce results effectively and efficiently.
There is no technology that represents a larger return on investment than barcodes. But the productivity improvements aren't automatic, and developing a best-practices approach to using the technology is certainly important. By following the guidance above and partnering with experienced vendors, pitfalls can be avoided, budgets can be adhered to and data can be collected quickly and without error. Most importantly, critical results affecting patient outcomes will be based on data that is reliable and accurate. And that's good for all of us.  
Bruce Wray is a market manager for St. Paul, Minn.-based Computype. He has more than 25 years of experience in automatic identification and labeling.     



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