# US 9,517,938 B2 · Applying spatial gradient magnetic field to metallic/semiconducting SWNTs in fluid > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,517,938 B2 - Document ID: US9517938B2 - Status: Granted - Kind: B2 - Application number: 14/791,650 - Filed: 2015-07-06 - Published: 2015-10-29 - Granted: 2016-12-13 - Earliest claimed: 2009-12-09 - Assignees: Texas Instruments Incorporated - Applicants: Texas Instruments Incorporated - Inventors: James Cooper Wainerdi; Robert Reid Doering; Luigi Colombo - Web page: https://patentgrep.com/patent/US9517938B2 ## CPC - B03C 1/035: Open gradient magnetic separators, i.e. separators in which the gap is unobstructed, characterised by the configuration of the gap - B03C 1/005: Pretreatment specially adapted for magnetic separation - B03C 1/0335: {using coils} - C01B 32/172: Sorting - B03C 2201/20: Magnetic separation of bulk or dry particles in mixtures - B03C 2201/22: characterised by the magnetic field, e.g. its shape or generation - B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites - B82Y 40/00: Manufacture or treatment of nanostructures - C01B 2202/02: Single-walled nanotubes - C01B 2202/22: Electronic properties - Y10S 977/751: with specified chirality and/or electrical conductivity - Y10S 977/845: Purification or separation of fullerenes or nanotubes - B03C: MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS (separating isotopes B01D59/00; combinations of magnetic or electrostatic separation with separation of solids by other means B03B, B07B) - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A process of sorting metallic single wall carbon nanotubes (SWNTs) from semiconducting types by disposing the SWNTs in a dilute fluid, exposing the SWNTs to a dipole-inducing magnetic field which induces magnetic dipoles in the SWNTs so that a strength of a dipole depends on a conductivity of the SWNT containing the dipole, orienting the metallic SWNTs, and exposing the SWNTs to a magnetic field with a spatial gradient so that the oriented metallic SWNTs drift in the magnetic field gradient and thereby becomes spatially separated from the semiconducting SWNTs. An apparatus for the process of sorting SWNTs is disclosed. ## Claims ### Claim 1 A process of sorting metallic single wall carbon nanotubes (SWNTs) from semiconducting SWNTs, comprising: A. disposing the metallic SWNTs and the semiconducting SWNTs in a dilute fluid; B. applying a varying dipole-inducing magnetic field to the metallic SWNTs and the semiconducting SWNTs in the dilute fluid, including varying the dipole-inducing magnetic field with time so as alternately increase the dipole-inducing magnetic field with time and decrease the dipole-inducing magnetic field with time, and in which the applying a varying dipole-inducing magnetic field includes: i. providing an upper dipole-inducing electromagnetic coil and a lower dipole-inducing magnetic coil; ii. applying to the upper dipole-inducing electromagnetic coil a current with a sinusoidal profile waveform having a positive slope phase and a negative slope phase; and iii. applying to the lower dipole-inducing electromagnetic coil a current with a sinusoidal profile waveform that is synchronized with a triangular profile waveform of the current in the upper dipole-inducing electromagnetic coil; and C. applying a spatial gradient magnetic field to the metallic SWNTs and the semiconducting SWNTs in the dilute fluid, including: i. providing an upper gradient electromagnetic coil and a lower gradient magnetic coil; ii. applying to the upper gradient electromagnetic coil a current with a sinusoidal profile waveform; and iii. applying to the lower gradient electromagnetic coil a current with a sinusoidal profile waveform that is opposite the sinusoidal profile waveform of the current in the upper gradient electromagnetic coil. ### Claim 2 (depends on 1) The process of claim 1 in which the applying a varying dipole-inducing magnetic field includes orienting the metallic SWNTs in the dipole inducing magnetic field. ### Claim 3 (depends on 1) The process of claim 1 in which the applying a spatial gradient magnetic field includes spatially separating the metallic SWNTs from the semiconducting SWNTs. ### Claim 4 (depends on 1) The process of claim 1 in which said dilute fluid has a pressure less than 1 millitorr. ### Claim 5 (depends on 1) The process of claim 1 in which applying a varying dipole-inducing magnetic field includes applying rates of current through the upper dipole-inducing electromagnetic coil and the lower dipole-inducing electromagnetic coil sufficient to provide a dipole inducing magnetic field to the SWNT that has a field strength, varying in time at a rate of at least 1000 Tesla/second, that is sufficient to produce an orientation configuration of the metallic SWNTs within 45 degrees of an axis of the dipole-inducing magnetic field. ### Claim 6 (depends on 1) The process of claim 1 in which applying a varying dipole-inducing magnetic field includes applying an upper dipole-inducing magnet current sinusoidal waveform with a current that increases during the positive slope phase and decreases during the negative slope phase. ### Claim 7 (depends on 1) The process of claim 1 in which applying a spatial gradient magnetic field includes applying an upper gradient electromagnetic coil current sinusoidal profile waveform with current that is positive during the positive slope phase and is negative during the negative slope phase, and applying a lower gradient magnetic coil current sinusoidal profile waveform so that current is negative during the positive slope phase and is positive during the negative slope phase. ### Claim 8 (depends on 1) The process of claim 1 in which applying the upper gradient electromagnetic coil current waveform and the lower gradient electromagnetic coil current waveform includes applying a magnitude of the upper gradient electromagnetic coil current waveform that is substantially equal to a magnitude of the lower gradient electromagnetic coil current waveform.