Dielectrophoretic Length-Selective Separation of Single-Walled Carbon Nanotubes


Single-walled carbon nanotubes (SWNTs) possess unique physical, optical, and electrical properties with great potential for future nanoscale device applications. Common synthesis procedures yield SWNTs with large length polydispersity and varying chirality. Electrical and optical applications of SWNTs often require specific lengths, but preparation of SWNTs with desired length remains a challenge. 

Invention Description
Researchers at Arizona State University and Duke University have developed an insulator-based dielectrophoresis (iDEP) method for fractionating SWNTs by length. With iDEP, SWNTs are subject to a nonuniform electric field, resulting in induced dipole moments that cause the SWNTs to be attracted to or repelled from regions of high electric field strength. Semiconducting SWNTs of varying length suspended with sodium deoxycholate (NaDOC) show unique dielectrophoretic properties at low frequencies (<1 kHz) that were exploited using an iDEP-based microfluidic constriction sorter device for length-based sorting. Specific migration directions in the constriction sorter were induced for long SWNTs (≥1000 nm) with negative dielectrophoretic properties compared to short (≤300 nm) SWNTs with positive dielectrophoretic properties.

Potential Applications
•  Nanoscale electronics
•  Biosensors
•  Biological transporters

Benefits and Advantages
•  Over 90% sorting efficiencies for long (≥ 1000 nm) and short (≤ 300 nm) SWNTs
•  Capable of sorting SWNTs in continuous mode which is advantageous for applications with larger quantities of SWNTs
•  Confers known iDEP advantages including simple fabrication and low cost

Related Publication: Length-Selective Dielectrophoretic Manipulation of Single-Walled Carbon Nanotubes

Faculty Profile of Professor Alexandra Ros

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