Linear Barcodes

Most consumers will be familiar with linear barcodes. UPC codes, printed on consumer products we buy every day, are one of the most common linear barcodes around. As the name suggests, linear barcodes are created using lines. The pattern of the lines and the spaces between them encodes information that can be “read” by a scanner and used by an electronic system. One major benefit of linear barcodes is that all commonly used modern scanning equipment can decipher them and collect data.

Orientation – barcodes can be printed in two directions: Horizontal orientation, often called “picket fence” layout. Vertical orientation, usually referred to as “ladder” orientation.

Although no formal studies have been undertaken, many users report that it is easiest to scan a wristband with a vertically oriented barcode. The rationale for this preference is due to the barcode reader’s difficulty in accommodating a curvature in the band when scanning a horizontal barcode.

Common Symbologies – there are a number of common linear symbologies used in healthcare settings. Those most commonly used for wristbands include:

• PDF417 – this symbology has fast become the standard wristband barcode. The size of the barcode for the information being encoded tends to be much smaller than other symbologies, making scanning easier. PDF417 has other advantages including:

• Fully alphanumeric                  • Widely supported throughout the industry                  • High-density code does not waste space                  • Flexibility to go from one subset of the symbology to another, even within                     the same symbol                  • Data security that ensures that a printing defect cannot cause a character                     to be transposed into another valid character.

• Code 3 of 9 (sometimes called Code 39) – although this began as the most common symbology used on patient wristbands, the selection of this symbology had more to do with what Hospital Information Systems could support. Since the resulting barcode tends to be longer than many other symbologies, this barcode is falling out of favor for wristband use.

Two-Dimensional Barcodes (2D)

Two dimensional barcodes are widely used in some industries, such as express package services, and they are fast gaining in popularity for wristband use. These barcodes are made up of a block of cells which are filled or unfilled to represent data. Advantages of 2D barcodes include their large data capacity, error detection and correction features that improve scanability, and space efficiency. These features make 2D barcodes a good choice for forward-looking facilities. The major consideration hospitals should keep in mind when considering implementing a solution that involves 2D barcodes is the need for a barcode reading device that includes an “imager”.

Common Symbologies – several 2D symbologies have gained attention in the patient identification world. Those most commonly used for wristbands include:

• PDF 417 – this symbology is the most popular symbol of its type. It offers flexibility in choosing the error correction level, making it extremely robust and less likely to be damaged.
• MicroPDF417 – this is a highly space-efficient symbology that encodes information efficiently into a small area.
• Aztec – this code is the most space efficient of all symbologies recommended in the healthcare arena. One reason it has gained attention is that it is easily repeated and can form a continuous symbol, which is useful on a curved surface, such as a wristband. A unique characteristic of the Aztec code is that it doesn’t require any quiet zone.