UCSB researchers have created sensors using specific DNA sequences, combined with off-the-shelf components, that can detect cocaine in the blood and other substances.

The sensor consists of a gold electrode covered in specific strands of DNA. When the target molecule, in this case cocaine, binds to the DNA, it changes conformation. That change increases current flow through the electrode, creating a measurable electronic signal that can be read by the device. The magnitude of the change in current indicates the concentration of the substance — the fraction of DNA molecules that change conformation is proportional to the number of cocaine molecules in the sample.