Length-selective dielectrophoretic manipulation of single-walled carbon nanotubes
Systems & methods for sorting single-walled carbon nanotubes (SWNTs) using an iDEP-based sorting device. The device includes an inlet channel with a constriction and the inlet channel splits into multiple different channels after the constriction—the multiple channels includes a center channel and at least one side channel. A sample is introduced into the iDEP sorting device containing a plurality of SWNTs of different lengths suspended in a fluid. An electrical field is applied to the sample between a first electrode in the center channel and a second electrodes at a proximal end of the inlet channel. The applied electrical field causes longer SWNTs to move towards the side channels while the shorter SWNTs move towards the center channel. Accordingly, a first plurality of shorter SWNTs is then collected from the center channel and a second plurality of longer SWNTs is collected from the at least one side channel.
1 . A method of manufacturing a microfluidic device for sorting particles, the method comprising:
generating a chrome photomask;
applying the photomask to a silicon master wafer;
mixing polydimethylsiloxane (PDMS) elastomer base with a curing agent to form a mixture;
pouring the mixture over the master wafer;
curing the master wafer to form a PDMS cast;
removing the PDMS cast from the master wafer;
irreversibly bonding the PDMS cast with a glass slide to form the microfluidic device, the microfluidic device comprising:
an inlet channel including a constriction, wherein a cross-sectional area of the inlet channel reduces at the constriction;
a center channel;
at least one side channel, wherein the inlet channel splits into multiple channels after the constriction, the multiple channels including the center channel and the at least one side channel;
wherein the inlet channel diverges from the constriction into the center channel and the at least one side channel; and
positioning an electrode in the center channel where an electrical field source is configured to apply an electrical field between the electrode and a proximal end of the inlet channel.
2 . The method of manufacturing of claim 1 , wherein the particles are single-walled carbon nanotubes.
3 . The method of manufacturing of claim 1 , further comprising generating a plurality of reservoirs in the PDMS cast.
4 . The method of manufacturing of claim 3 , wherein a first set of the plurality of reservoirs includes a diameter of about 1.5 mm, and wherein a second set of the plurality of reservoirs includes a diameter of about 3.0 mm.
5 . The method of manufacturing of claim 1 , further comprising treating the PDMS cast with oxygen plasma in a plasma cleaner oven.
6 . The method of manufacturing of claim 1 , wherein applying the photomask to a silicon master wafer includes using SU-8 negative photoresist.
7 . The method of manufacturing of claim 1 , wherein the PDMS elastomer base is mixed with the curing agent at a 10:1 ratio (w/w) to form the mixture.
8 . The method of manufacturing of claim 1 , further comprising degassing the master wafer after pouring the mixture over the master wafer, and wherein the master wafer was degassed for about 30 minutes.
9 . The method of manufacturing of claim 1 , wherein the master wafer was cured for about four hours at about 80° C. to form the PDMS cast.
10 . The method of manufacturing of claim 1 , further comprising cleaning the PDMS cast.
11 . The method of manufacturing of claim 10 , wherein the PDMS cast is cleaned with 2-propanol and distilled water in an ultrasonic bath for about two minutes, dried with nitrogen, and baked on a hot plate for about 30 seconds at 90° C.
12 . The method of manufacturing of claim 1 , further comprising treating the PDMS cast with oxygen plasma in a plasma cleaner oven for about 30 seconds.
13 . The method of manufacturing of claim 1 , wherein the inlet channel is about 100 μm in width.
14 . The method of manufacturing of claim 1 , wherein the at least one side channel is about 20 μm in width.
15 . The method of manufacturing of claim 1 , wherein the inlet channel and the at least one side channel are about 20 μm in height.