Computing with carbon nanotubes: Optimization of threshold logic gates using disordered nanotube/polymer composites

Abstract

This paper explores the use of single-walled carbon nanotube (SWCNT)/poly(butyl methacrylate) composites as a material for use in unconventional computing. The mechanical and electrical properties of the materials are investigated. The resulting data reveal a correlation between the SWCNT concentration/viscosity/conductivity and the computational capability of the composite. The viscosity increases significantly with the addition of SWCNTs to the polymer, mechanically reinforcing the host material and changing the electrical properties of the composite. The electrical conduction is found to depend strongly on the nanotube concentration; Poole-Frenkel conduction appears to dominate the conductivity at very low concentrations (0.11% by weight). The viscosity and conductivity both show a threshold point around 1% SWCNT concentration; this value is shown to be related to the computational performance of the material. A simple optimization of threshold logic gates shows that satisfactory computation is only achieved above a SWCNT concentration of 1%. In addition, there is some evidence that further above this threshold the computational efficiency begins to decrease.

Data Classification Using Carbon-Nanotubes and Evolutionary Algorithms

“…Formation of percolation paths is variable and reconfigurable allowing the creation of complex electrical networks. This adds an extra dimension to the problem, compared to previous experiments where SWCNTs were mixed with a solid polymer [11,8].…”

“…Different organic and inorganic media have been used as materials, such as slime moulds [7], bacterial consortia [1], cells (neurons) [18], liquid crystals (LC) panels [6] and nano-particles [3]. Single walled carbon nanotubes (SWCNT) based materials have shown the potential to solve computational problems [8,11,22,14,15]. In [19] it is argued that inorganic materials make a better medium for unconventional computing exploration.…”

Training a Carbon-Nanotube/Liquid Crystal Data Classifier Using Evolutionary Algorithms

“…The purpose of the LC matrix is to provide a fluid medium in which the SWCNT can move in response to the applied electric field enabling the nanotubes to form reconfigurable and variable complex electrical networks. This adds an extra dimension to the problem compared to previous experiments, where SWCNT were mixed with a solid polymer [9], [7] and the resulting material system was in solid state, as opposed to the liquid state of the material used here.…”

“…In [5] and [4] liquid crystals (LC) panels were used for evolving logic gates, a tone discriminator and a robot controller. Single walled carbon nanotubes (SWCNT) based materials have shown the potential to solve variety of computational problems [7], [9], [23], [12], [13], [14] and [15].…”

Evolution in Nanomaterio: The NASCENCE Project

“…• Digital acquisition cards together with programmable switch arrays [8] • Mbed microcontrollers with digital to analogue converters [33] • Purpose built platforms [31,3] …”