In separate but related research in Japan, Daisuke Takagi at NTT Basic Research Laboratories in Atsugi, Japan, decided to replace the metal nanoparticles (the seeds for growing carbon nanotubes) with a densely packed layer of diamonds, each around 5 nanometres across. Passing ethanol gas over these diamonds created a lush forest of nanotubes 1 to 2 nanometres wide. Carbon nanotubes grown from diamond nanoparticles can be grown closer together. This could eventually allow the carbon nanotube memory shuttle memory from Berkeley to be grown closer together.
We report on a simple electromechanical memory device in which an iron nanoparticle shuttle is controllably positioned within a hollow nanotube channel. The shuttle can be moved reversibly via an electrical write signal and can be positioned with nanoscale precision. The position of the shuttle can be read out directly via a blind resistance read measurement, allowing application as a nonvolatile memory element with potentially hundreds of memory states per device. The shuttle memory has application for archival storage, with information density as high as 10**12 bits/in2, and thermodynamic stability in excess of one billion years.
The reversibility of the nanoparticle motion allows a memory “bit” that can be rewritten. Here we show this property, moving the nanoparticle back and forth over the position threshold defining the state of the device. A nanoparticle of iron is moved with carbon nanotubes