Sandia LabNews

New barcode system uses spread-spectrum approach

Sandia team takes barcode to a new dimension

When a research team tackled inventing a new barcode approach for tags or security seals (under a Laboratory Directed Research and Development project initiated by Materials Chemistry Dept. 8722 Manager Bill Even), the group invented a novel way to distribute information in shades of gray.

The mottled design is as easy to scan as the ubiquitous Uniform Price Code’s row of lines and can be nearly as affordable in its simplest versions. Its added advantages include substantial robustness and economical security features. The code is readable even if 70 percent is missing or obscured; it contains embedded correction parameters and so doesn’t require registration fiducials; it can encrypt and limit access to various levels of information; and it can be reset during inventory, as well as potentially track elapsed time, temperature, or environmental conditions.

In fact, the code, which resembles the marbled cover of a composition notebook, doesn’t actually have to be seen as a distinct barcode. It can be colored and hidden in a logo, designed to expire after a period of time, or used as a seal to indicate suspicion of tampering.

"There are a large variety of alternatives that we would like people to get out there and run with," says Bill, who began this patent-pending research three years ago.

Unlike the UPC’s unique 1-dimensional sequence of bars and spaces that is read as dark and light intervals, this 2-dimensional pattern repeats like a speckled wallpaper print.

"Each bit of data is encoded pseudo-randomly across the entire barcode," says team member Eric Cummings (8358). "All of the encoded bits are then overlaid to form a grayscale, or analog, barcode image. Because each bit of data is spread redundantly across the barcode, you can recover all of the data even when some or most of the barcode is missing — providing you know the key to the pseudo-random code."

They call the invention, which is available for further development and commercialization, a "spread-spectrum" barcode.

Even if ripped or written over, the pattern still reveals its embedded information when scanned by a regular CCD camera. On the other hand, the average person can’t decode the encrypted data, or counterfeit a copy. Higher-end versions that are not just run off a desktop printer can include self-assembled, luminescent particle "fingerprints," temperature-sensitive gels or inks reset by changing temperature, and chemically sensitive inks to indicate spoilage, among other possibilities.

With guidance from Ivan Waddoups (5845), Bill and the group noticed a void in commercially available options between tags that might cost less than a dime and highly secure seals requiring thousands of dollars’ investment. This project targeted that gap with an affordable alternative that can be scaled to either provide economically robust information in a tag and/or confer security as a seal.

Applications, then, could range from basic retailing, warehousing, manufacturing, and industrial or mine safety to secure mail routing, private labeling, and ID badges. At the most secure end with a "rewritable" surface gel for authentication, federal agencies might appreciate the ability to automatically measure damage or tampering to protect currency or goods such as pharmaceuticals, precious resources, or nuclear material.

The distributed-fiducial, scan-correlation concept allows applications in aerospace, nondestructive evaluation, and optical targeting, by enabling global, rapid distortion detection and precision alignment and calibration. Additional team members include Paul Dentinger and Blake Simmons (both 8722), Tony Lajeunesse (8243), Cullen Lee (5907), Bill Cordwell (5931), and former postdoc Jennifer Irvin.