Scalable, Versatile Nanomaterial Separation
Density Gradient Ultracentrifugation (DGU)
NanoIntegris was founded to commercialize a technology for separating carbon nanotubes and other nanomaterials by their optical and electronic properties. This technology, developed by the Hersam Research Group at Northwestern University, employs a technique known as density gradient ultracentrifugation (DGU). How does DGU work?
Resolving the Polydispersity Problem
The widespread commercial use of carbon nanotubes has so far been precluded by limitations in CNT manufacturing. CNTs can be produced in large quantities using growth methods such as arc-discharge synthesis, chemical vapor deposition, and laser ablation. These manufacturing technologies, however, can only generate batches of tubes with mixed optical and electronic properties. This polydispersity is problematic for many applications. For example, to produce a nanotube transistor, one would need tubes that are uniformly semiconducting.
Consequently, in recent years, many companies and academic research groups have developed novel strategies for generating optoelectronically uniform CNTs. These strategies have included:
- Dielectrophoresis
- Chemical selection
- Controlled electrical breakdown
- Chromatography
- Selective growth
In comparison to DGU, however, each of these strategies falls short in terms of output purity, scalability, versatility, and/or cost effectiveness.
Advantages of DGU
Since 2006, DGU has received widespread praise from CNT researchers for its inventiveness and utility. What makes DGU so unique?
- Versatility: DGU is compatible with SWNTs of a wide range of diameters, produced by any means of synthesis (laser, arc, CVD). DGU can also be used to sort other nanomaterials, like double-walled nanotubes and graphene.
- Precision: DGU can be tuned to separate SWNTs by a number of properties, including electronic type, diameter, length, and chirality.
- Purity: Nanotubes sorted via DGU are not irreversibly modified in any way. An additional benefit of DGU is that it removes many of the carbonaceous and catalyst impurities that occur naturally in as-grown nanotubes. Our IsoNanotubeTM and PureTubeTM products are among the highest-purity SWNTs on the market today.
- Effectiveness: Using DGU, we can produce SWNTs that are up to 99% pure in their optoelectronic properties.
- Scalability: Just how scalable is DGU? Very. Since 2007, we have achieved over a thousand-fold increase in production capacity by optimizing our separation process, and our scale-up progress shows no signs of slowing down.
