Source: http://www.freshpatents.com/-dt20110707ptan20110165337.php
Timestamp: 2013-05-25 15:12:53
Document Index: 136385553

Matched Legal Cases: ['Application No. 60', 'art 300', 'art 300', 'art 300', 'art 300', 'art 300', 'art 300', 'art 3500', 'art 4400', 'art 4400', 'art 4900']

Method And System For Printing Aligned Nanowires And Other Electrical Devices 1 views for this patent on FreshPatents.comupdated 05/24/13
Patents sorted by company.	07/07/11 | Class 427 Monitor | RSS | Browse: Prev - Next Method and system for printing aligned nanowires and other electrical devices Abstract: Methods and systems for applying nanowires and electrical devices to surfaces are described. In a first aspect, at least one nanowire is provided proximate to an electrode pair. An electric field is generated by electrodes of the electrode pair to associate the at least one nanowire with the electrodes. The electrode pair is aligned with a region of the destination surface. The at least one nanowire is deposited from the electrode pair to the region. In another aspect, a plurality of electrical devices is provided proximate to an electrode pair. An electric field is generated by electrodes of the electrode pair to associate an electrical device of the plurality of electrical devices with the electrodes. The electrode pair is aligned with a region of the destination surface. The electrical device is deposited from the electrode pair to the region. ...
Agent: Nanosys, Inc. - Palo Alto, CA, USInventors: J. Wallace Parce, James M. Hamilton, Samuel Martin, Erik FreerUSPTO Applicaton #: #20110165337 - Class: 427466 (USPTO) - 07/07/11 - Class 427 Related Terms: Electrical Device The Patent Description & Claims data below is from USPTO Patent Application 20110165337, Method and system for printing aligned nanowires and other electrical devices.
This application is a divisional of allowed U.S. application Ser. No. 12/114,446, filed on May 2, 2008, which claims the benefit of U.S. Provisional Application No. 60/916,337, filed on May 7, 2007, both of which are incorporated by reference herein in their entireties.
Methods and systems for applying nanowires to surfaces are described. In an example aspect, nanowires are provided proximate to an electrode pair. An electric field is generated by electrodes of the electrode pair to associate the nanowires with the electrodes. The electrode pair is aligned with a region of the destination surface. The nanowires are deposited from the electrode pair to the region.
In aspects, the printing station may be configured to perform the transfer of the nanostructures as a “wet” transfer or a “dry” transfer.
As used herein, the term “nanowire” generally refers to any elongated conductive or semiconductive material (or other material described herein) that includes at least one cross-sectional dimension that is less than 500 nm, and preferably, equal to or less than less than about 100 nm, and has an aspect ratio (length:width) of greater than 10, preferably greater than 50, and more preferably, greater than 100. Exemplary nanowires for use in the practice of the methods and systems of the present invention are on the order of 10\'s of microns long (e.g., about 10, 20, 30, 40, 50 microns, etc.) and about 100 nm in diameter.
A wide range of types of materials for nanowires, nanorods, nanotubes and nanoribbons can be used, including semiconductor material selected from, e.g., Si, Ge, Sn, Se, Te, B, C (including diamond), P, B—C, B—P(BP6), B—Si, Si—C, Si—Ge, Si—Sn and Ge—Sn, SiC, BN, BP, BAs, MN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, Cul, AgF, AgCl, AgBr, Agl, BeSiN2, CaCN2, ZnGeP2, CdSnAs2, ZnSnSb2, CuGeP3, CuSi2P3, (Cu, Ag)(Al, Ga, In, Tl, Fe)(S, Se, Te)2, Si3N4, Ge3N4, Al2O3, (Al, Ga, In)2 (S, Se, Te)3, Al2CO, and an appropriate combination of two or more such semiconductors.
The term “positioning” as used throughout refers to the alignment and association, as well as the deposition or coupling, of nanowires onto a surface, for example, an electrode pair. Positioning includes nanowires that are both aligned and non-aligned. The term “aligned” nanowires as used throughout refers to nanowires that are substantially parallel or oriented in the same or substantially same direction of one another (i.e. the nanowires are aligned in the same direction, or within about 45° of one another). The nanowires of the present invention are aligned such that they are all substantially parallel to one another and substantially perpendicular to each electrode of an electrode pair (e.g., aligned parallel to an axis through both electrodes) (though in additional embodiments, they can be aligned parallel to an electrode). Positioning of nanowires onto an electrode pair includes positioning the nanowires such that the nanowires span the electrode pair. In embodiments in which the nanowires are longer than the distance separating two electrodes of an electrode pair, the nanowires may extend beyond the electrodes.
As used herein the phrase “proximate to an electrode pair” as it relates to providing the nanowires means that the nanowires are provided or positioned such that they can be acted upon by an electric field generated at the electrode pair. This is a distance from the electrode pair such that they can be associated with the electrodes. In example embodiments, the nanowires are provided such that they are at distance of less than about 10 mm from the electrode pairs. For example, the nanowires may be provided such that they are less than about 100 μm, less than about 50 μm, or less than about 1 μm from the electrode pair.
In embodiments, the present invention provides a system or apparatus for nanostructure alignment and deposition. For example, FIG. 2 shows a nanostructure transfer system 200, according to an example embodiment of the present invention. As shown in FIG. 2, transfer system 200 includes a nanostructure print head 202, nanostructure(s) 204, and a destination substrate 212. Nanostructure print head 202 is a body configured to receive nanostructure(s) 204, and to transfer nanostructure(s) 204 to substrate 212. As shown in FIG. 2, nanostructure print head 202 has a transfer surface 206 and includes an electrode pair 208. Substrate 212 has a surface 210, referred to as a “destination surface” for receiving nanostructure(s) 204. Electrode pair 208 is located on transfer surface 206. Nanostructure(s) 204 are received by electrode pair 208 of transfer surface 206, for transfer to destination surface 210. Nanostructure(s) 204 can include any of the nanostructure types mentioned elsewhere herein, including one or more nanowires. Further description of the components of transfer system 200 is provided further below.
Nanowires may be provided proximate to first and second electrodes 704 and 706 in a variety of ways according to step 302 of flowchart 300. For example, FIG. 8 shows a portion of a nanowire transfer system 800, according to an embodiment of the present invention. As shown in FIG. 8, transfer system 800 includes print head 702 and a solution container 802. Container 802 contains a solution 804 that includes a plurality of nanowires 806, which may be referred to as a “nanowire suspension.” In the embodiment of FIG. 8, transfer surface 206 of print head 702 is temporarily moved (e.g., “dipped”) into solution 804 to enable nanowires 806 to become proximate to electrode pair 208, according to step 302 of flowchart 300.
Thus, in the embodiments described above, one or more nanowires 806 are provided by providing a suspension of nanowires (e.g., a nanowire “ink”) to electrode pair 208. As represented in FIG. 10, a nanowire suspension is provided by flowing a solution containing nanowires against an electrode pair on a transfer surface. As nanowires 806 are provided, the suspension flow helps to align the nanowires in the direction of the flow.
In an embodiment, container 802 can be stirred, vibrated, or otherwise moved to maintain a homogeneous suspension of nanowires 806. In another embodiment, where a stratified suspension of nanowires is desired, gravity, electric fields and/or an overflow by a nanowire-free solvent of similar or lower density can be used to create stratification. A stratified suspension of nanowires may be used in a variety of ways. For example, print head 702 may be positioned in a high nanowire-density region of the stratified suspension for deposition of nanowires, and subsequently positioned in a lower density, “clean solvent” region for removal of excess nanowires.
According to step 304 of flowchart 300 (FIG. 3), an electric field is generated by electrodes of an electrode pair to associate nanostructures with the electrodes. FIG. 13 shows a nanowire transfer system 1300 that can be used to perform step 304 of flowchart 300 (FIG. 3), according to an example embodiment of the present invention. As shown in FIG. 13, system 1300 includes a voltage source 1302. Voltage source 1302 is a signal/waveform generator coupled to electrode pair 208 by electrical signal 1304. Voltage source 1302 generates electrical signal 1304 as a direct current (DC) and/or alternating current (AC) signal to cause electrode pair 208 to generate an electric field. For example, FIG. 14 shows transfer system 800 of FIG. 8, where an electric field, represented between first and second electrodes 704 and 706 by arrow 1402, is generated by application of a voltage to electrode pair 208. Electric field 1402 is generated between electrodes 704 and 706 of electrode pair 208 by energizing electrode pair with electrical signal 1304 to associate at least some of nanowires 806 with electrode pair 208. It should be noted that electric field 1402 can be generated before, after, or during the period of nanowire producing/introduction into container 802. As used herein, the terms “electric field” and “electromagnetic field” are used interchangeably and refer to the force exerted on charged objects in the vicinity of an electric charge. As used herein, “energizing the electrode pair” refers to any suitable mechanism or system for providing an electric current to the electrodes such that an electric field is generated between electrodes of an electrode pair.
The energizing of electrode pair 208 to create electric field 1402 can also be caused by supplying an electromagnetic wave to electrode pair 208. As is well known in the art, waveguides of various dimensions and configurations (e.g., cylindrical, rectangular) can be used to direct and supply an electromagnetic wave (see e.g., Guru, B. S. et al., “Electromagnetic Field Theory Fundamentals,” Chapter 10, PWS Publishing Company, Boston, Mass. (1998)). Operation frequencies of waveguides for use in the practice of the present invention are readily determined by those of skill in the art, and may be in the range of about 100 MHz to 10 GHz, about 1 GHz-5 GHz, about 2-3 GHz, about 2.5 GHz, or about 2.45 GHz, for example.
As is further described below, as nanowires 806 encounter an AC electric field 1402 generated between electrodes 704 and 706, a field gradient results. A net dipole moment is produced in proximate nanowires 806 (e.g., nanowire 806a in FIG. 14), and the AC field exerts a torque on the dipole, such that proximate nanowires align parallel to the direction of the electric field. For example, FIG. 15 shows nanowire 806a having been aligned by electric field 1402 parallel to electric field 1402 in association with electrode pair 208.
In embodiments, first and second electrodes 704 and 706 are separated by a distance that is less than, equal to, or greater than a long axis length of nanowires 806. Nanowires 806 of any length can be aligned and positioned using the methods of the present invention. In an embodiment, the distance between electrodes of an electrode pair is such that the nanowires extend just beyond the first edge of the electrode. In an embodiment, nanowires 806 extend just beyond a first edge and into a middle of each electrode, with tens of nanometers to several microns overlapping the electrode material at the end of a nanowire 806. Nanowires 806 that are shorter than the distance between electrodes 704 and 706 may be able to couple to only one electrode in a pair (if they couple at all), and thus may be removed during subsequent removing phases if desired. Similarly, nanowires 806 that are substantially longer than the distance between electrodes 704 and 706 hang over one or more of electrodes 704 and 706, and may be removed during subsequent removing phases (larger exposed surface area). Thus, this embodiment additionally provides a way to preferentially select nanowires 806 of a particular length from a suspension of a range of nanowire sizes, and align and deposit them onto an electrode pair 208. Embodiments may also associate and couple nanowires 806 that are “straight” rather than bent or crooked. Hence, such embodiments provide an added benefit of depositing preferably straight nanowires 806, rather than less preferred bent or crooked nanowires 806.
In addition to aligning the nanowires parallel to an AC electric field, the field gradient exerts a dielectrophoretic force on proximate nanowires 806, attracting them toward electrode pair 208. FIG. 16 shows a force 1602 attracting nanowire 806a towards electrode pair 208 of print head 702. In an embodiment, force 1602 is a dielectrophoretic force. The gradient is highest at electrode pair 208, exerting an increasing attraction toward the electrodes. An electric double-layer is produced at the surface of each electrode of electrode pair 208, such that oppositely charged ions are present at each electrode. In the presence of electric field 1402, the ions migrate away from each electrode and initially toward nanowire 806a hovering proximately nearby (e.g., above or below). As ions approach oppositely charged nanowire 806a, the ions are repulsed by the like charge and then directed back toward the respective electrode resulting in a circulating pattern of ions. Liquid that is present (i.e., the nanowire suspension) is also circulated, generating an electro-osmotic force that opposes the dielectrophoretic force attracting nanowire 806a to the electrodes. Thus, in an embodiment, a force 1606 shown in FIG. 16 may be an osmotic force. As forces 1602 and 1606 reach an equilibrium (or relative equilibrium), nanowire 806a is held in place such that it becomes associated with electrode pair 208. As used herein the terms “associated” and “pinned” are used to indicate that nanowires (such as nanowire 806a) are in such a state that the electro-osmotic force and the dielectrophoretic force are at equilibrium, such that there is no or little net movement of the nanowires away from electrode pair 208 (i.e., normal or substantially normal to transfer surface 206 and electrode pair 208). This is also called the “association phase” throughout.
Furthermore, in an embodiment, charge values of nanowires 806 and transfer surface 206 affect association or pinning of nanowires to electrode pair 208. For example, FIG. 16 shows print head 702 having associated nanowire 806a (additional nanowires not shown may also be associated). As shown in FIG. 16, transfer surface 206 may have a layer 1604 that provides a surface charge to transfer surface 206, such as an oxide layer. The charge polarity of layer 1604 can be selected to attract or repel nanowire 806a, as desired. For example, layer 1604 can provide a negative surface charge to transfer surface 206 that results in a repulsive force on nanowire 806a, which may also have a negative surface charge (e.g., in isopropyl alcohol). Thus, force 1606 repelling nanowire 806a in FIG. 16 may include an electrostatic repulsive force that results from a same charge polarity of nanowire 806a and layer 1604.
For further example description regarding the association of nanowires with electrode pairs, various nanowire densities, alternating current frequencies, modulating of the electric field, “locking” nanowires to an electrode pair, etc., refer to co-pending U.S. Appl. No. 60/857,765, filed Nov. 9, 2006, titled “Methods for Nanowire Alignment and Deposition,” which is incorporated by reference herein in its entirety.
Following the associating of nanowires 1702 with electrodes 704 and 706, uncoupled nanowires can then be removed from electrode pair 208 so as to substantially eliminate nanowires that are not fully aligned, not fully coupled, overlapped, crossing, or otherwise not ideally coupled to electrode pair 208. Nanowires that are to be removed following the coupling phase are described herein as “uncoupled nanowires.” Any suitable method for removing uncoupled nanowires can be used. For example, the uncoupled nanowires can be removed using tweezers (e.g., optical tweezers, see, e.g., U.S. Pat. Nos. 6,941,033, 6,897,950 and 6,846,084, the disclosures of each of which are incorporated herein by reference in their entireties) or similar instrument, or by shaking or physically dislodging the uncoupled nanowires. Suitably, uncoupled nanowires are removed by flushing away the nanowires. As used herein, the term “flushing away” includes processes where a fluid (either gaseous or liquid phase) is flowed over or around the nanowires so as to remove them from the electrode pairs. Nanowires that are crossed can be uncrossed using a suitably modulated electric field, and a third electrode can be used to remove “uncoupled nanowires,” such as dielectrophoretically or electroosmotically. Uncoupled nanowires can also be removed inertially, and by other techniques.
FIG. 27 shows an example plan view of transfer surface 206, according to an example embodiment of the present invention. As shown in FIG. 27, transfer surface 206 includes first and second electrodes 704 and 706, and a plurality of vacuum ports 2604a-2604c. In the example of FIG. 27, three vacuum ports 2604a-2604c are shown. First vacuum port 2604a is positioned on transfer surface 206 adjacent to first electrode 704. Second vacuum port 2604b is positioned on transfer surface 206 between first and second electrodes 704 and 706. Third vacuum port 2604c is positioned on transfer surface 206 adjacent to second electrode 706. Any number of vacuum ports 2604 may be present, and may be distributed on transfer surface 206 as desired. In the example of FIG. 27, vacuum ports 2604a-2604c are rectangular shaped. In other embodiments, vacuum ports 2604 may have other shapes, including round, square, etc.
As shown in FIG. 30, at a first plot region 3006 representing a first potential minimum on plot line 3002 for transfer surface 210, nanowires 1702 are associated (pinned) with electrode pair 208. The pinned nanowires remain relatively rigid/aligned without being in contact with a transfer surface. In the current example, first plot region (first potential minimum) 3006 occurs when transfer surface 206 and destination surface 210 are approximately 1 μm-4 μm apart. At a second plot region (second potential minimum) 3008 representing a potential minimum on plot line 3004 for destination surface 210, nanowires 1702 are attracted to destination surface 210 due to the electrostatic attraction by the nitride layer. Nanowires 1702 may be “locked” on destination surface 210 in this manner. Second plot region 3008 occurs when nanowires and destination surface 210 are spaced approximately 0.1 μm-0.4 μm apart.
The transfer of nanowires 1702 from transfer surface 206 onto destination surface 210 is achieved by first “weakly” pinning nanowires 1702 on transfer surface 206 at low electric fields and low frequencies, “strongly” pinning nanowires 1702 on transfer surface 206 using low electric fields and high frequencies, moving transfer surface 206 to close proximity with destination surface 210, and finally releasing nanowires 1702 from potential minimum 3006 of transfer surface 206 by reducing the AC field on electrodes 704 and 706 of transfer surface 206. Due to the electrostatic repulsion represented by a potential maximum 3010 between nanowires 1702 and transfer surface 206 (e.g. layer 2902 on transfer surface 206) nanowires 1702 move away from transfer surface 206 after reduction of the AC attractive field. Within the rotational diffusion time (i.e. time required for nanowires to be rotated by an angle θ from a pre-aligned direction while subjected to gravity and Brownian motion) nanowires 1702 maintain the desired alignment determined by the AC field across electrodes 704 and 706 on transfer surface 206. The close proximity (e.g., ˜1 μm) of the pre-aligned nanowires 1702 in solution to destination surface 210 enables a transfer onto destination surface 210 due to the electrostatic attraction represented by potential minimum 3008 (e.g. layer 2904 on destination surface 210). An efficient transfer of nanowires 1702 is enabled when the rotational diffusion time is large compared to the translational diffusion time for motion of nanowires from potential minimum 3006 to potential minimum 3008. Functional layers on nanowires 1702 and on destination surface 210 can be used to minimize the translational diffusion time without affecting the rotational diffusion time.
Furthermore, flowchart 300 is adaptable to using multiple electrode pairs on a single transfer surface to deposit groups of nanowires on substrates in parallel. For example, FIG. 34 shows a nanowire transfer system 3400 that includes a print head 3402 having two electrode pairs, according to an embodiment of the present invention. As shown in FIG. 34, print head 3402 has a transfer surface 3404 having a first electrode pair 208a and a second electrode pair 208b. First electrode pair 208a is shown having associated nanowires 1702a, and second electrode pair 208b is shown having associated nanowires 1702b. Nanowires 1702a are designated for deposit on first region 1904a of destination surface 210, and nanowires 1702b are designated for deposit on second region 1904b of destination surface 210.
Thus, in an embodiment, each step of flowchart 300 shown in FIG. 3 may be performed for both of first and second electrode pairs 208a and 208b in parallel. In step 302, in parallel with providing nanowires 1702a proximate to first electrode pair 208a, nanowires 1702b can be provided proximate to second electrode pair 208b. In step 304, in parallel with generating a first electric field (e.g., electric field 1402 in FIG. 14) using first electrode pair 208a, a second electric field can be generated using second electrode pair 208b to associate nanowires 1702b with second electrode pair 208b. In embodiments, a same electrical signal (e.g., electrical signal 1304) can be provided to both of first and second electrode pairs 208a and 208b, or different electrical signals can be generated and provided.
In step 306, in parallel with aligning first electrode pair 208a with first region 1904a, second electrode pair 208b can be aligned with second region 1904b. In step 308, in parallel with depositing nanowires 1702a from first electrode pair 208a to first region 1904a, nanowires 1702b can be deposited from second electrode pair 208b to second region 1904b. In step 310, first and second electrode pairs 208a and 208b can be removed from alignment with their respective regions in parallel, by withdrawing print head 3402 from destination surface 210.
In step 3504, an electric field is generated by electrodes of the electrode pair to associate an electrical device with the electrodes. For instance, an electrical potential may be coupled to electrode pair 208 to generate the electric field. The electric field generated by electrode pair 208 may be used to associate one of electrical devices 3602 with electrode pair 208 that is proximately located to electrode pair 208. As shown in FIG. 37, electrical device 3602a is associated with electrode pair 208. In an embodiment, associated electrical device 3602a is held suspended at a distance from transfer surface 206 by the electric field.
The example embodiments described above for generating an electric field by an electrode pair to associate nanostructures are adaptable to associating electrical devices. For example, as described with respect to FIG. 14, an electric field 1402 is generated between electrodes 704 and 706 of electrode pair 208. Electric field 1402 can be used to align electrical device electrical device 3602a, and to position electrical device 3602a between electrodes 704 and 706. When electrical device 3602a encounters an AC electric field generated between electrodes 704 and 706, a field gradient results. A net dipole moment is produced in proximate electrical devices 3602, and the AC field exerts a torque on the dipole, such that proximate electrical device 3602a aligns parallel to the direction of the electric field.
Furthermore, in an embodiment, the field gradient exerts a dielectrophoretic force on proximate electrical device 3602a, attracting it toward electrode pair 208, as described above for nanowires with respect to FIG. 16. An electro-osmotic force may also be generated, as described above, that opposes the dielectrophoretic force attracting electrical device 3602a to the electrodes. As these forces reach an equilibrium (or relative equilibrium), electrical device 3602a is held in place such that it becomes associated, or “pinned,” with electrode pair 208.
As mentioned above, electrical devices 3602 in FIG. 36 may all be the same type of electrical device or may include different electrical device types. When different electrical device types are present, electrodes 704 and 706 may be sized and/or positioned to generate the electric field in a manner to only attract a designated type of electrical device. In an embodiment, electrical device 3602a may have a metal (or other material) patterned thereon to enhance the attraction of electrical device 3602a to electrodes 208.
In step 3506, the electrode pair is aligned with a region of the destination surface. For example, as shown in FIG. 38, electrode pair 208 is aligned with destination surface 210, by print head 702, which is moved towards destination surface 210. In an embodiment, electrode pair 208 is aligned in contact with destination surface 210. In another embodiment, electrode pair 208 is aligned adjacent to destination surface 210, a short distance away from destination surface 210. Electrode pair 208 may be aligned with any region of surface 210, including a generally open region (i.e., no contacts on surface 210 are required), a region having electrical contacts corresponding to electrode pair 208, or other region. Electrode pair 208 is aligned with a region of surface 210 on which electrical device 3602a is to be positioned.
In step 3508, the electrical device is deposited from the electrode pair to the region. Electrical device 3602a may be deposited on destination surface 210 in a variety of ways. Various example embodiments for depositing nanostructures on a surface are described in detail above. For example, the embodiments described above with respect to FIGS. 28-33 for depositing nanostructures may be used to deposit electrical device 3602a. For example, in FIG. 28, a force 2802 is present (which may include one or more forces) that attracted nanowires 1702 from print head 702 to destination surface 210 and/or repelled nanowires 1702 from print head 702. Force 2802 may also be used to deposit electrical device 3602a to destination surface 210 from print head 702. Example forces that may be present in force 2802 include an electric field (AC and/or DC), a vacuum force, an electrostatic force, gravity, ultrasonic excitation, and/or other forces. These and other passive and active forces may be used to attract/repel electrical device 3602a, as would be known to persons skilled in the relevant art(s). Furthermore, ultrasonic vibration may be used, as described above with respect to FIGS. 31A-31C, to aid in freeing electrical device 3602a from print head 702, to transfer to destination surface 210 (e.g., via a force such as gravity, an electrostatic force, etc.).
In step 3510, the electrode pair is removed from alignment with the region of the surface. For example, as shown in FIG. 39, print head 702 is moved away from destination surface 210. Electrical device 3602a remains deposited on surface 210. Print head 702 can subsequently be used to repeat performing flowchart 3500 for the same region of surface 210, a different region of surface 210, and/or a surface of a structure other than substrate 212, to deposit further electrical devices. Furthermore, in an embodiment, print head 702 may be used to simultaneously transfer nanostructures and electrical devices.
Further embodiments are described in this section for applying nanostructures to surfaces using print heads. Print heads used to “print” nanowires onto a substrate in the presence of a fluid, as described above, may cause a shear force that is orthogonal to the motion of the print head as the print head approaches the substrate. As a result, the fluid is forced out of the region between the print head and the substrate due. This fluid shear can displace the nanowires laterally, causing the nanowires to be misplaced in the printing process.
In embodiments, drain holes are formed in a print head to remove fluid from the region between the print head and the destination surface as the print head approaches the destination surface. The drain holes reduce a shear force on the nanowires, to enable the nanowires to be more reliably transferred from the print head to the destination surface. For example FIG. 42 shows a nanostructure transfer system 4200, according to an example embodiment of the present invention. As shown in FIG. 42, system 4200 includes a print head 4202 and substrate 212. FIG. 43 shows a view of transfer surface 206 of print head 4202. As shown in FIGS. 42 and 43, transfer surface 206 includes first and second openings 4204a and 4204b (also referred to as “drain holes”). First and second openings 4204a and 4204b receive solution 4004 from the region between transfer surface 206 and destination surface 210 when print head 4202 is moved toward substrate 210. Removal of solution 4004 due to first and second openings 4204a and 4204b reduces a shear force on nanowire 1702 while being deposited from transfer surface 206 to destination surface 210.
In step 4406, a fluid is received through at least one opening in the transfer surface from between the transfer surface and the destination surface during step 4404. As indicated by arrows 4206 in FIGS. 42 and 43, solution 4004 between transfer surface 206 and destination surface 210 flows outward from a central region of transfer surface 2006 due to transfer surface 206 moving toward destination surface 210. Furthermore, as indicated by arrows 4210 shown in FIG. 42, solution 4004 flows into openings 4204a and 4204b in transfer surface 206. Openings 4204a and 4204b relieve at least a portion of the shear force received by nanowire 1702 by receiving solution 4004.
Although two openings 4204 (openings 4204a and 4204b) are shown in FIGS. 42 and 43, any number of openings 4204 may be present in transfer surface 206. For example, instead of a pair of openings 4204 (as shown in FIGS. 42 and 43), an array of openings 4204 of any number may be present at the locations of openings 4204a and 4204b. Such openings may have any shape, including being round, rectangular, or any other shape.
Furthermore, openings 4204 may have any distribution/geometry relative to electrodes 704 and 706 to further reduce the shear force. For example, as shown in FIG. 43, openings 4204a and 4204b may be located relative to electrodes 704 and 706 so that nanowire 1702 is located midway between openings 4204a and 4204b. In this manner, a “dead zone” for flow of solution 4004 at the location of nanowire 1702 is created (e.g., a flow stream is parted at nanowire 1702), so that the shear force experienced by nanowire 1702 may be brought close to none. In the embodiment of FIG. 43, openings 4204 can be holes and/or slots that are positioned symmetrically along either side of the long axis of nanowire 1702.
Furthermore, as shown in FIG. 43, openings 4202 may have lengths that are longer than a long axis length of nanowire 1702. Alternatively, openings 4202 may have a length that is the same or less than a long axis length of nanowire 1702. A width of openings 4204a and 4204b may be selected so that a substantial amount of solution 4004 between openings 4204a and 4204b on either side of nanowire 1702 may exit through openings 4204a and 4204b. Although openings 4204 are shown in FIG. 42 as being located along the length of nanowire 1702, alternatively or additionally, openings 4204 may be located on transfer surface 206 adjacent to one or both ends of nanowire 1702. Furthermore, although openings 4204a and 4204b are shown in FIG. 42 as penetrating all the way through print head 4202, alternatively, openings 4204 may penetrate partially through print head 4204 (e.g., may be recessed areas in transfer surface 206, of any suitable depth).
In the example of FIGS. 42 and 43, solution 4004 is enabled to passively flow into openings 4204. In another embodiment, solution 4004 may be actively drawn into openings 4204. For instance, a piston/cylinder arrangement, a corkscrew, vacuum suction, and/or further mechanisms may be used to actively draw solution 4004 into openings 4204. For example, FIG. 46 shows a nanostructure transfer system 4600, according to an embodiment of the present invention. System 4600 is generally similar to system 4200 shown in FIG. 42, with the addition of first and second pistons 4602a and 4602b. Pistons 4602a and 4602b are located in openings 4204a and 4204b, respectively. First piston 4602a and opening 4204a form a first piston/cylinder arrangement, and second piston 4602b and opening 4204b form a second piston/cylinder arrangement. First and second pistons 4602a and 4602b may be configured to move in the directions of arrows 4604 during step 4404 of flowchart 4400, to enable solution 4004 to be drawn into openings 4204a and 4204b according to step 4406 of flowchart 4400.
For example, FIG. 51 illustrates nanostructures being associated with transfer surfaces of print head 4810 in solution (e.g., in a liquid environment) at association station 4802. In an embodiment, print head 4810 is one of a plurality of print heads received at association station 4802. In another embodiment, a single print head 4810 is received. In the example of FIG. 51, print head 4810 has six transfer surfaces 206a-206f. In other embodiments, print head 4810 may have other numbers of transfer surfaces 206, including a two-dimensional array of transfer surfaces 206. Transfer surfaces 206a-206f are submerged in a nanowire solution 5106 (e.g., a nanowire ink) contained by a reservoir 5104. As shown in FIG. 51, print head 4810 has five through-holes or openings 5108a-5108e, with each opening 5108 being positioned between a corresponding adjacent pair of transfer surfaces 206. Openings 5108 may be configured similarly to openings 4204 described above with respect to FIG. 42. In embodiments, print head 4810 may include any number and configuration of openings 5108.
Although not shown in FIG. 51, in the current example, each transfer surface 206a-206f includes a respective pair of electrodes (e.g., electrode pair 208 of FIG. 2, which may include electrodes 704 and 706 shown in FIG. 7). The electrodes generate an electric field (e.g., electric field 1402 shown in FIG. 14) to associate one or more nanowires 5110 in nanowire solution 5106 with the respective transfer surface 206. For example, FIG. 51 shows a first nanowire 5110a in solution 5106 that is not associated with any of transfer surfaces 206a-206b. A second nanowire 5110b is shown associated with second transfer surface 206b. A third nanowire 5110c is nearby but not associated with first transfer surface 206a. During or after step 4902, print head 4810 of FIG. 48 may optionally be configured to flush excess nanostructures from transfer surfaces 206 of plurality of print heads 4818 at association station 4802. For example, FIG. 52 shows excess nanowires being flushed from transfer surfaces 206a-206f of print head 4810. In the example of FIG. 51, a fluid (e.g., solution 5106) is shown being flowed through openings 5108a-5108e (as indicated by arrows 5202) to flush excess nanowires 5110 from transfer surface 206a-206f. A fluid source (not shown in FIG. 52) configured to produce a suitable fluid pressure may be coupled to an inlet 5102 of print head 4810, or may be otherwise coupled to print head 4810, to provide the fluid to flow through openings 5108a-5108e. A fluid velocity and flush time provided by the fluid source may be determined for a particular application. For example, fluid velocities in the range of 1-100 μm/s may be used, during a flush time of 60 minutes or less (e.g., 1 minute or less), in embodiments.
Excess nanowires 5110, such as nanowire 5110c, which may be desired to be flushed from transfer surfaces 206, are nanowires that may be weakly associated with a transfer surface 206, that may have become entangled with other nanowires 5110 that are associated, and/or that may have become otherwise attached to (but not associated with) a surface of print head 4810. For example, nanowire 5110c is shown in FIG. 52 as having been flushed from transfer surface 206a. Referring back to flowchart 4900, in step 4904, an inspection of the print heads is performed. For example, as shown in FIG. 48, inspection station 4804 receives plurality of print heads and associated nanostructures 4820. Inspection station 4804 is configured to perform an inspection of transfer surfaces 206 of the received plurality of print heads, and to select at least one print head of received plurality of print heads based on the inspection. As shown in FIG. 48, inspection station 4804 outputs at least one selected print head and associated nanostructures 4822.
For instance, FIG. 53 shows an example of inspection station 4804, according to an embodiment of the present invention. As shown in FIG. 53, inspection station 4804 has received a plurality of print heads 4810a-4810c. Each of print heads 4810a-4810c has a respective plurality of transfer surfaces 206a-206f. An inspection device 5302 is present that is configured to inspect arrangements of nanowires 5110 associated with transfer surfaces 206 of print heads 4810a-4810c. Inspection device 5302 may be an optical inspection device (e.g., a microscope, a camera, and/or other optical inspection device), an electrical inspection device, a mechanical inspection device, and/or further type of inspection device. Inspection device 5302 may be configured to determine whether a sufficient number of nanostructures is present at each transfer surface 206, to determine whether an unsuitable arrangement of nanostructures is present at a transfer surface 206 (e.g., determine whether sufficient contact between electrodes is made by the present nanostructures), and/or to otherwise determine the suitability and/or unsuitability of an arrangement of nanostructures at transfer surfaces 206 of print heads 4810a-4810c. For example, in FIG. 53, inspection device 5302 may determine that an insufficient number of nanowires 5110 (e.g., no nanowires) is present at transfer surface 206c of print head 4810a, while all transfer surfaces of print heads 4810b and 4810c have sufficient numbers and arrangements of nanowires 5110. Because inspection device 5302 determined that transfer surface 206c of print head 4810 does not have a sufficient number of associated nanowires 5110, print head 4810a may be indicated as having failed inspection, while print heads 4810b and 4810c may be indicated as having passed inspection.
In step 4906, one or more print heads are selected based on the inspection. One or more print heads that passed inspection in step 4904 may be selected. In the current example, because inspection device 5302 determined that print heads 4810b and 4810c passed inspection, while print head 4810a failed inspection, print heads 4810b and 4810c may be selected for further processing in system 4800. Note that in an embodiment, an arrangement of nanowires 5110 at a print head 4810 that failed inspection may be repaired. For example, in the current example, after transfer surface 206c was determined (in step 4904) to be lacking a sufficient number of nanowires, one or more additional nanowires 5110 may be associated with transfer surface 206c. Subsequently, print head 4810a may be re-inspected (repeat step 4904). If print head 4810a passes the re-inspection, print head 4810a may be selected in step 4906. Example embodiments for repairing arrangements of nanostructures on surfaces (e.g., transfer surfaces, destination surfaces) are described in detail further below.
In step 4908, the nanostructures are transferred from the selected print head(s) to a destination surface. For example, as shown in FIG. 48, printing station 4806 receives at least one selected print head and associated nanostructures 4822. In the current example, at least one selected print head and associated nanostructures 4822 includes print heads 4810b and 4810c. Printing station 4806 also receives a panel 4816, which is an example of destination substrate 212 shown in FIG. 2. Printing station 4806 is configured to transfer the nanostructures from the received at least one of the plurality of print heads to a plurality of regions of a surface of panel 4816. As shown in FIG. 48, printing station 4806 outputs a plurality of print heads 4824 and a panel with deposited nanostructures 4828.
FIG. 54 shows print head 4810b and panel 4816 in solution 5106. In FIG. 54, one or more nanowires 5110 are associated with each of transfer surfaces 206a-206f of print head 4810b. In FIG. 55, print head 4810b is moved adjacent to panel 4816, so that each of transfer surfaces 206a-206f is aligned with a corresponding one of regions 1902a-1902f of panel 4816. In FIG. 56, print head 4810b has deposited nanowires 5110 on panel 4816, and has withdrawn from panel 4816. For instance, as shown in FIG. 56, nanowire 5110b is deposited from transfer surface 206b to region 1904b of destination surface 210 of panel 4816.
In step 4910, the print heads are cleaned. For example, as shown in FIG. 48, cleaning station 4808 receives plurality of print heads 4824. In the current example, plurality of print heads 4824 includes print heads 4810a-4810c. Cleaning station 4808 is configured to clean the received plurality of print heads 4824. Cleaning station 4808 may be configured to clean print heads 4824 in any manner, to remove any remaining nanostructures (e.g., nanostructures that were not deposited from a print head at printing station 4806) and/or to remove any further contaminants.
For instance, FIG. 57 shows an example of cleaning station 4808, according to an embodiment of the present invention. In FIG. 57, a fluid source 5702 may be present that outputs and/or directs a fluid to transfer surfaces 206a-206f, as indicated by arrows 5704, to remove/dislodge contaminants from transfer surfaces 206a-206f. Fluid source 5702 may be any mechanism for providing a fluid flow of a suitable pressure. The fluid output/directed by fluid source 5702 may be solution 5106 and/or other fluid, such a fluid configured to clean transfer surfaces 206a-206f. As shown in FIG. 48, cleaning station 4808 outputs plurality of print heads 4818. Plurality of print heads 4818 may be received by association station 4802 for a next cycle of nanostructure printing to be performed by system 4800. In an embodiment, a single set of print heads may proceed from station to station in system 4800, such that at any particular time, all print heads are at the same station. In another embodiment, at any particular time, each station may be operating on a corresponding set of print heads, which shift to a next station at predetermined time intervals.
For example, in FIG. 58, inspection device 5802 may determine that an insufficient number of nanowires 5110 (e.g., no nanowires) is present at region 1904c of panel 4816. Because inspection device 5802 determined that region 1904c does not have a sufficient number of nanowires 5110, region 1904c may be indicated for repair.
FIG. 59 shows a repair of the arrangement of nanostructures at region 1904c being performed. In the example of FIG. 59, a print head 5902 is shown repairing region 1904c, by depositing one or more nanostructures, including a nanowire 5110c, on region 1904c. Thus, in an embodiment, print head 5902 may be configured to add one or more nanostructures to a region 1904 in need of repair. Alternatively or additionally, if nanostructures are present in a region 1904 in need of repair, print head 5902 may be configured to rearrange the present nanostructures (e.g., move nanostructures into contact with desired electrical conductors of the region 1904), and/or to remove one or more present nanostructures, to create a sufficient nanostructure arrangement.
As shown in FIG. 48, panel repair station 4812 outputs a panel with deposited nano structures 4830.
Nanostructure printing system 4800 includes printing station 4806, which in the example of FIGS. 54-56, performs a “wet” nanostructure transfer process (e.g., nanowires 5110 are transferred in FIGS. 54-56 in reservoir 5104 containing solution 5106) (also referred to as “wet stamping”). In an alternative embodiment, a nanostructure printing system may perform a “dry” nanostructure transfer process. For example, FIG. 61 shows a nanostructure printing system 6100, according to an example embodiment of the present invention. Nanostructure printing system 6100 includes an association station 6102, a drying station 6104, a print head repair station 6106, a printing station 6108, a cleaning station 6110, and a panel repair station 6114. Printing station 6108 of system 6100 is configured to perform a dry nanostructure transfer process. Association station 6102, drying station 6104, print head repair station 6106, printing station 6108, and cleaning station 6110 form a print head pipeline portion of system 6100, and printing station 6108 and panel repair station 6114 form a panel pipeline portion of system 6100.
Download full PDF for full patent description/claims.You can also Monitor Keywords and Search for tracking patents relating to this Method and system for printing aligned nanowires and other electrical devices patent application.
Other recent patent applications listed under the agent Nanosys, Inc.:
20090317044 - Nanocomposites	How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method and system for printing aligned nanowires and other electrical devices or other areas of interest.###
Previous Patent Application:Electrostatic composition based on a polyamide matrixNext Patent Application:Apparatus for forming solder damIndustry Class:Coating processes###Design/code © 2013 FreshContext LLC/Freshpatents.com.Patent data source: patents published by the United States Patent and Trademark Office (USPTO)Information published here is for research/educational purposes only (and in conjunction with our Keyword Monitor) and is not meant to be used in place of the full USPTO patent document/images or a comprehensive patent archive search. Complete official applications are on file at the USPTO and may contain additional data/images. FreshPatents.com is not affiliated with or endorsed by the USPTO or firms/individuals or products/designs/ideas related to listed patents and there may be applicable trademarks or servicemarks within the documents.FreshPatents.com Support - Terms & ConditionsThank you for viewing the Method and system for printing aligned nanowires and other electrical devices patent info.- - - AAPL - Apple, BA - Boeing, GOOG - Google, IBM, JBL - Jabil, KO - Coca Cola, MOT - Motorla
Results in 1.30614 seconds Other interesting Freshpatents.com categories: