Researchers at the University of Aveiro in Portugal are developing DNA barcode tags that can be harmlessly applied to a wide variety of products, even foods or liquids. Each tag is a unique combination of DNA base pairs that attach to most surfaces, and can later be collected, amplified, and sequenced. The power of this technique lies in the uncountable micro-matings that take place in the DNA solution where the primary goal is to determine like from unlike. Every known sequencing method has some margin of error, and the chance of false positives or false negatives exists whenever the signal to noise ratio is too low.
The most imaginative use for DNA barcodes is to trace neurons, and their activities, within the brain. The original BRAIN Initiative, before its initial aspirations were chopped back, called for something even more dramatic — growing barcodes that stored vast amounts of information in real time. In other words, molecular ticker tapes built into every neuron. DNA sequencing pioneer George Church holds the patent for a so-called nucleic acid memory device. This concept uses a specially constructed DNA polymerase (an enzyme which copies DNA) to directly transmute voltages appearing across the membranes of cells into DNA base pair patterns. By using several ticker tapes to create a sufficient level of redundancy, an arbitrary degree of accuracy can be achieved, all within the existing energy budget of the cell.