Researchers from Germany and Taiwan have combined expertise to create a “write-once-read-many-times” (WORM) memory device made from embedding silver nanoparticles into a biopolymer film of salmon DNA.
The collaboration began a little over a year ago. Researchers from the DFG-Center for Functional Nanostructures (CFN) at the Karlsruhe Institute of Technology (KIT) in Germany, led by Dr. Ljiljana Fruk, had been working on producing nanoparticles through DNA templates, which has been a fertile area of research of late. Meanwhile, the team at the National Tsing Hua University, led by Dr. Yu-Chueh Hung, worked on optimizing the process and actually designed the memory device.
The device they came up with is a DNA-based biopolymer nanocomposite that is sandwiched between two electrodes. When UV light shines on it, the silver atoms group into nano-sized particles. By creating these particles, the researchers were able to encode data. This device is able to store data through the phenomenon known as bistability, in which a device exhibits two states of different conductivities at the same applied voltage.
The DNA-based biopolymer nanocomposite was used because of its affinity with metal ions and its effectiveness as a template for metal polymer nanoparticle systems.
The memory device is fully described in the journal Applied Physics Letters under the title “Photoinduced write-once read-many-times memory device based on DNA biopolymer nanocomposite”,.
In working with the device, the Taiwanese researchers soon discovered that once it had been turned on it would stay turned on, and that variations in voltage across the electrodes did not alter the device’s conductivity. In other words, once information is written onto the device it cannot be written over, and the information appears to persist indefinitely.
The researchers have indicated that the technique for making the device could provide new design techniques for making optical storage devices, as wall as having applications in plasmonics.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.