Multilayer nanocomposites and devices

Multilayer nanocomposites and devices

zero poisson's ratio film

The mesoscale nano-sponge. As the multilayer film is compressed the incommensurate nanoparticle layers buckel the polymer layer leading to deformation at zero Poisson’s ratio. The deformation mode is similar to cork. As a result of no expansion in the lateral direction the film compresses at extremely low stress. As a result the modulus decreases as film thickness reduces.

penny_touch

Touch Sensitivity of Film. A bias can be aplied to CdS nanoparticle/gold nanoparticle/conductive polymer composite film such that current increases as pressure is exerted on the film. The electroluminesence from CdS is imaged after pressing a penny on the film. Importantly, the sensitivity in 35-90 kPa contact pressure and resolution are similar to human finger, the best tactile device made by nature.


Physical and chemical properties of materials (such as optical, electrical, magnetic, and catalytic) exhibit remarkable and sometimes surprising changes compared to bulk when their characteristic dimensions are reduced to the nanoscale regime. The synergistic effect of effect of nanoscale structure on large scale properties of thin film is leveraged to develop a tactile device on par with human touch. These ~200 nm thick films of polymer and nanoparticles have a modulus of over six orders of magnitude lower than its constituent. The film’s layer-by-layer fabricated deposition exhibits surprising electro-optical properties that can image texture by touch. The tactile image maps the texture at resolution and sensitivity on par with human finger. (Lab publications)

Relevent Publications

  • “Ultrasoft 100 nm Thick Zero Poisson’s Ratio Film with 60% Reversible Compressibility,” Nano Letters, 2012, 12, 2171-2175.
  • “High-Resolution Thin-Film Device to Sense Texture by Touch,” Science, 2006, 312, 1501-1504.
  • “Tactile Devices to Sense Touch at Par with Human Finger”, Angewandte Chemie Int. Ed., 2008, 47, 7808-7826;
  • "Tactile Imaging of an Imbedded Palpable Structure for Breast Cancer Screening", ACS Applied Material & Interface, 2014, 6, 14278-14285.