Fish and DNA Chips

by Ben Coxworth

Salmon... they’re good to eat, provide a livelihood for fishermen, are an important part of their ecosystem, and now it seems that they can store data. More specifically, their DNA can.
Scientists from National Tsing Hua University in Taiwan and the Karlsruhe Institute of Technology in Germany have created a “write-once-read-many-times” (WORM) memory device, that combines electrodes, silver nanoparticles, and salmon DNA.

While the current device is simply a proof-of-concept model, the researchers have stated that DNA could turn out to be a less expensive alternative to traditional inorganic materials such as silicon.

The device is made up of a thin film of salmon DNA that has been impregnated with silver atoms, then sandwiched between two electrodes. When UV light is shone onto the system, the atoms cluster together into nanoparticles. Subsequently, when no or little voltage is applied to the electrodes, only a low electrical current is able to travel through the UV-irradiated DNA. This is the equivalent of the device’s “off” state.

Because the material is unable to hold a charge under a high electrical field, however, once the voltage exceeds a certain threshold, a higher current is able to travel through the DNA. This represents the “on” state.

These changes in conductivity were found to be irreversible—once the device has initially been set to either “on” or “off” it stays that way, regardless of what voltages are subsequently applied. Even after up to 30 hours, it retains its conductivity.

The scientists are now hoping that their discovery could lead to new techniques for the design of optical storage devices. This isn’t the first time that DNA has been suggested for such applications. Researchers at Imperial College London have created logic gates using DNA and bacteria, while American scientists have genetically engineered the bacterium E. coli to coax its DNA into computing the solution to a classic mathematical puzzle.