Nanocoining 

Overview

Nanocoining is a novel process that covers a metal surface with 3D sub-wavelength features more than 500x faster than e-beam lithography. These nano-features can seamlessly cover the surface of a cylindrical drum mold that is in turn used to replicate features via roll-to-roll manufacturing. The resulting nanostructured surfaces are invisible to the eye and can manipulate light or repel water, giving the surface desirable properties including:

  • Anti-reflective and anti-glare
  • Increased optical transmission
  • Structural (pigment-free) color
  • Anti-fogging
  • Self-cleaning
  Demonstration of increased transmission (left) and self-cleaning (right)  

Demonstration of increased transmission (left) and self-cleaning (right) 

Nanofabrication is traditionally time-consuming and expensive. Nanocoining overcomes these limitations by rapidly stamping nanostructures into a metal surface, leaving behind about 100 million nano-features per second. This process is achieved by nano-patterning a diamond die using traditional nanofabrication techniques like focused ion beam milling. The die is then mounted on a novel ultrasonic actuator that indents the nanofeatures into a rotating metal drum 50,000 times per second. The motion of the actuator and the metal drum are precisely controlled to ensure registration of the indented nanostructures.

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Competitive Advantage

Nanocoining has a distinct competitive advantage for making robust metal molds with sub-wavelength features, particularly in its speed and scale. The advantage of nanocoining is enhanced by its ability to pattern seamless cylinders.

Interference lithography can pattern flat shims that can be wrapped around a base cylinder, but this method creates a seam. Further, even slight deviation in the flat will disrupt the entire interference pattern. Electron-beam lithography can produce high-resolution nanofeatures but is extremely limited by speed and scale. Nanocoining, on the other hand, can create seamless nanopatterned drum molds at high speed. Nanocoining is:

  • 500 times faster than electron-beam lithography
  • Free of vacuum and chemical processes
  • Able to seamlessly nanopattern cylindrical drum molds
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Current Results

Smart Material Solutions, Inc. has designed and built a pilot system capable of diamond turning cylinders with optical finishes and indenting nanostructures using nanocoining. Nanocoining has been used to create prototype molds; larger molds will be produced in the near future, since the pilot system is capable of making molds up to 6 inches long and 6 inches in diameter.

Smart Material Solutions has also begun fabricating new nanostructures in diamond for use in the nanocoining process. These include periodic, stochastic, and arbitrary features with a range of shapes (pillars, gratings) and sizes (100 nm to 2 µm pitch). We have also produced hierarchical features with nanofeatures on top of microfeatures.

 SEM images of micro and nanopatterns fabricated into diamond.

SEM images of micro and nanopatterns fabricated into diamond.

Applications in toDay's world

There are countless applications for structured structures.  Some, such as the "moth-eye," are multifunctional - simultaneously giving a surface anti-reflective and non-wetting properties.

Non/Enhanced Wetting Applications:

  • Anti-fogging windshields
  • Self-cleaning windows or solar cells
  • Anti-fouling and oleophobic surfaces

Optical Applications:

  • Brighter OLED displays and lighting
  • More efficient solar panels
  • Wire grid polarizers

 

Partnership Opportunities

Smart Material Solutions is actively seeking strategic partnerships and pilot projects with film/chemical companies that have expertise in roll-to-roll embossing of functional film products.