Your next data storage device could be a fish.
As revealed by a paper in the academic journal Applied Physics Letters, researchers from National Tsing Hua University in Taiwan and the Karlsruhe Institute of Technology in Germany recently used salmon DNA to build a write-once-read-many (WORM) data storage device. Data is written to the device with a laser and read electronically, and you can enjoy the thought that your data's sitting on a piece of sushi.
DNA is amazing stuff. Sure, it's the "blueprint of life", encoding the proteins that drive an organism's biochemical processes and shape an individual's characteristics. But there’s a lot more to it. These researchers are just the latest to make a biopolymer from DNA and use the material in a device of some sort.
In this case, the DNA came from the testes of Oncorhynchus keta -- aka chum salmon. Sperm DNA is cheap and biofriendly. It's "a widely used source of cheap DNA," said Yu-Chueh Hung, an electrical engineering professor at National Tsing Hua University. "Sperm in salmon is produced in huge amounts and it has a high content of DNA."
Composite materials that include DNA can be made in solution. It's relatively simple, inexpensive liquid chemistry. Compared to memory chips and disk drives, which are made of high-quality crystalline materials formed in expensive clean room facilities, the salmon sperm polymer makes for less expensive devices and is a biofriendly material available in large quantities, said Hung. It's also biodegradable.
The great thing about using DNA in electronics is it likes metal. DNA plays particularly well with metal nanoparticles. These ultra-small specks of metal are abundantly useful. When mixed into a material, they can change the material's optical and electrical properties. DNA also happens to be a good tool for forming metal nanoparticles.
Polymer-nanoparticle composite materials can be easily switched between two states: electrically conductive and electrically resistive. This means the materials can store data. The two states can represent the 1's and 0's of digital information.
DNA offers several advantages over ordinary polymers. Shine light on a blend of DNA and silver salts, and you get a polymer with silver nanoparticles embedded in it. DNA also readily forms thin films via spin coating. The layers in data storage devices and other electronics generally have to be very thin.
The researchers' prototype is a thin film of the DNA-nanoparticle mix partially sandwiched between metal electrodes. In the default state the nanoparticles trap electrons, making the material electrically resistant. Shine a laser on the film or send an electrical current through it, and tiny pathways open between the nanoparticles, making the material electrically conductive. So, shining a laser on a tiny patch of the film writes a bit of data. Send a current through a patch of the film to measure the conductivity, and you can read the data. Low conductivity = 0, high conductivity = 1.
The technology is of limited use because it’s not rewritable, though future research could change that. And fish-sperm-enabled storage is a long way from showing up in a DVD factory or data center. To be practical, it would have to hold onto data for years, something the researchers haven't figured out yet. Still, it's a great demonstration of the versatility and potential of DNA materials.
Of course, there's the "Eew!" factor. Will people willingly put something made from fish sperm in their computers?
Update: This article has been updated to include additional information from the researcher.
