Patents by Inventor David A. Walker
David A. Walker has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 12350880Abstract: Methods and apparatus comprising a dewetting phase and a polymerization liquid that are immiscible, and can be used for the formation of three-dimensional objects, wherein the method does not require a dead zone. Additionally, methods and apparatus that employ an optically transparent cooling apparatus to mitigate heat generated during the fabrication process, and the use of a mobile phase to provide a shearing interface to reduce interfacial adhesive forces.Type: GrantFiled: September 6, 2022Date of Patent: July 8, 2025Assignee: NORTHWESTERN UNIVERSITYInventors: Chad A. Mirkin, David A. Walker, James L. Hedrick, III
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Patent number: 12214546Abstract: Methods and apparatus comprising a dewetting material and a polymerization liquid that are immiscible and dewetting, and can be used for the formation of three-dimensional objects, wherein the method does not require a dead zone. Additionally, methods and apparatus that employ the use of a flowing dewetting material to provide a shearing interface to reduce interfacial adhesive forces.Type: GrantFiled: March 9, 2020Date of Patent: February 4, 2025Assignee: NORTHWESTERN UNIVERSITYInventors: David A. Walker, James L. Hedrick, III, Chad A. Mirkin
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Publication number: 20240368392Abstract: A method of making a polyimide (PI)-based material. In one embodiment, the method begins by dispersing a polyamic acid (PAA) oligomer and photo-initiator into a photo-reactive monomer to form a liquid resin. In contrast to the above-described prior art, the liquid resin is substantially devoid of any non-reactive solvents. Electromagnetic radiation is then applied (e.g., in a 3D printing operation) to solidify the liquid resin and to substantially form a interpenetrating polymer network (IPN) in which the PAA oligomer is entangled within the network formed by the photo-reactive monomer but remains substantially independent and un-crosslinked from the PAA oligomer. Thereafter, the PAA-based IPN is thermally cycled to form a polyimide-based IPN.Type: ApplicationFiled: May 2, 2024Publication date: November 7, 2024Inventors: David A. Walker, Matthew N. Pearlson
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Publication number: 20230040818Abstract: Methods and apparatus comprising a dewetting phase and a polymerization liquid that are immiscible, and can be used for the formation of three-dimensional objects, wherein the method does not require a dead zone. Additionally, methods and apparatus that employ an optically transparent cooling apparatus to mitigate heat generated during the fabrication process, and the use of a mobile phase to provide a shearing interface to reduce interfacial adhesive forces.Type: ApplicationFiled: September 6, 2022Publication date: February 9, 2023Inventors: Chad A. Mirkin, David A. Walker, James L. Hedrick, III
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Patent number: 11465339Abstract: Methods and apparatus comprising a dewetting phase and a polymerization liquid that are immiscible, and can be used for the formation of three-dimensional objects, wherein the method does not require a dead zone. Additionally, methods and apparatus that employ an optically transparent cooling apparatus to mitigate heat generated during the fabrication process, and the use of a mobile phase to provide a shearing interface to reduce interfacial adhesive forces.Type: GrantFiled: May 31, 2017Date of Patent: October 11, 2022Assignee: NORTHWESTERN UNIVERSITYInventors: Chad A. Mirkin, David A. Walker, James L. Hedrick, III
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Patent number: 11415877Abstract: Disclosed herein are methods of using a fluoro oil mask to prepare a beam pen lithography pen array.Type: GrantFiled: December 7, 2017Date of Patent: August 16, 2022Assignee: NORTHWESTERN UNIVERSITYInventors: Chad A. Mirkin, David A. Walker, James L. Hedrick, III
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Publication number: 20220193988Abstract: Methods and apparatus comprising a dewetting material and a polymerization liquid that are immiscible and dewetting, and can be used for the formation of three-dimensional objects, wherein the method does not require a dead zone. Additionally, methods and apparatus that employ the use of a flowing dewetting material to provide a shearing interface to reduce interfacial adhesive forces.Type: ApplicationFiled: March 9, 2020Publication date: June 23, 2022Inventors: David A. Walker, James L. Hedrick, III, Chad A. Mirkin
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Patent number: 11292187Abstract: Methods and apparatus comprising a dewetting phase and a polymerization liquid that are immiscible, and can be used for the formation of three-dimensional objects, wherein the method does not require a dead zone. Additionally, methods and apparatus that employ an optically transparent cooling apparatus to mitigate heat generated during the fabrication process, and the use of a mobile phase to provide a shearing interface to reduce interfacial adhesive forces.Type: GrantFiled: October 30, 2020Date of Patent: April 5, 2022Assignee: NORTHWESTERN UNIVERSITYInventors: Chad A. Mirkin, David A. Walker, James L. Hedrick, III
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Publication number: 20210114288Abstract: Methods and apparatus comprising a dewetting phase and a polymerization liquid that are immiscible, and can be used for the formation of three-dimensional objects, wherein the method does not require a dead zone. Additionally, methods and apparatus that employ an optically transparent cooling apparatus to mitigate heat generated during the fabrication process, and the use of a mobile phase to provide a shearing interface to reduce interfacial adhesive forces.Type: ApplicationFiled: October 30, 2020Publication date: April 22, 2021Inventors: Chad A. Mirkin, David A. Walker, James L. Hedrick, III
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Publication number: 20190384161Abstract: Disclosed herein are methods of using a fluoro oil mask to prepare a beam pen lithography pen array.Type: ApplicationFiled: December 7, 2017Publication date: December 19, 2019Inventors: Chad A. Mirkin, David A. Walker, James L. Hedrick, III
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Publication number: 20190160733Abstract: Methods and apparatus comprising a dewetting phase and a polymerization liquid that are immiscible, and can be used for the formation of three-dimensional objects, wherein the method does not require a dead zone. Additionally, methods and apparatus that employ an optically transparent cooling apparatus to mitigate heat generated during the fabrication process, and the use of a mobile phase to provide a shearing interface to reduce interfacial adhesive forces.Type: ApplicationFiled: May 31, 2017Publication date: May 30, 2019Inventors: Chad A. Mirkin, David A. Walker, James L. Hedrick, III
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Patent number: 8473351Abstract: Authorization verification systems and methods are described that store a record of an authorization determination performed at a point of sale or other point of control. The system receives authorization information for an individual indicative of the individual's authorization to purchase a product or service, to enter a location, to attend an event, or to otherwise participate in an encounter whose access is limited to authorized individuals. In one embodiment, the authorization verification system receives information relating to the individual's age via an electronic scanning of a driver's license or other identification card, or by other methods, and uses the birth date information to calculate the customer's current age. The current age can be displayed on an existing display of a point-of-sale device or other display.Type: GrantFiled: March 11, 2003Date of Patent: June 25, 2013Assignee: First Data CorporationInventors: Cassandra Mollett, Alan Jay Bethscheider, Susan Diane Brauckman, David A. Walker, David Wayne Smith
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Patent number: 7769638Abstract: Authorization verification systems and methods are described that determine whether an authorization check is to be performed in conjunction with an online purchase or other electronic commerce transaction, and, if the authorization check is to be performed, that check the authorization of an individual wishing to participate in the online transaction and that store a retrievable record of the authorization check. The system receives authorization information for the individual that is indicative of the individual's authorization to purchase a product or service online, or to otherwise participate in an electronic commerce encounter whose access is limited to authorized individuals.Type: GrantFiled: March 11, 2003Date of Patent: August 3, 2010Assignee: First Data CorporationInventors: Cassandra Mollett, Alan Jay Bethscheider, Susan Diane Brauckman, David A. Walker, David Wayne Smith
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Patent number: 7191941Abstract: Authorization verification systems and methods are described that determine whether an authorization check is to be performed at a point of sale or other point of control, and, if the authorization check is to be performed, that check the authorization and that store a retrievable record of the authorization check. The system receives authorization information for an individual that is indicative of the individual's authorization to purchase a product or service, to enter a location, to attend an event, or to otherwise participate in an encounter whose access is limited to authorized individuals. In one embodiment, authorization for making a purchase is limited to individuals above an age threshold, and the authorization verification system receives information relating to the individual's age via an electronic scanning of a driver's license or other identification card, or by other methods, and uses the birth date information to calculate the customer's current age.Type: GrantFiled: March 11, 2003Date of Patent: March 20, 2007Assignee: First Data CorporationInventors: Cassandra Mollett, Alan Jay Bethscheider, Susan Diane Brauckman, David A. Walker, David Wayne Smith
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Patent number: 7182255Abstract: Systems and methods are described that determine a threshold value for an authorization check, such as an age verification, that is performed at a point of sale or other point of access control where access to a product, service, location, event, or the like, is restricted to individuals who meet an authorization threshold. In embodiments associated with purchases that comprise a variety of items for purchase and a variety of associated age-related authorization thresholds, systems and methods are described for determining an age-related authorization threshold for the purchase as a whole that will authorize the purchase of the items. In embodiments in which a purchaser's authorization is checked with respect to a determined threshold value, a record of the authorization check can be stored and can subsequently be retrieved to verify that an authorization check for the encounter was carried out using the determined threshold value.Type: GrantFiled: August 24, 2005Date of Patent: February 27, 2007Assignee: First Data CorporationInventors: Cassandra Mollett, Alan Jay Bethscheider, Susan Diane Brauckman, David A. Walker, David Wayne Smith
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Patent number: 6935559Abstract: Systems and methods are described that determine a threshold value for an authorization check, such as an age verification, that is performed at a point of sale or other point of access control where access to a product, service, location, event, or the like, is restricted to individuals who meet an authorization threshold. In embodiments associated with purchases that comprise a variety of items for purchase and a variety of associated age-related authorization thresholds, systems and methods are described for determining an age-related authorization threshold for the purchase as a whole that will authorize the purchase of the items. In embodiments in which a purchaser's authorization is checked with respect to a determined threshold value, a record of the authorization check can be stored and can subsequently be retrieved to verify that an authorization check for the encounter was carried out using the determined threshold value.Type: GrantFiled: June 25, 2004Date of Patent: August 30, 2005Assignee: First Data CorporationInventors: Cassandra Mollett, Alan Jay Bethscheider, Susan Diane Brauckman, David A. Walker, David Wayne Smith
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Publication number: 20040238630Abstract: Systems and methods are described that determine a threshold value for an authorization check, such as an age verification, that is performed at a point of sale or other point of access control where access to a product, service, location, event, or the like, is restricted to individuals who meet an authorization threshold. In embodiments associated with purchases that comprise a variety of items for purchase and a variety of associated age-related authorization thresholds, systems and methods are described for determining an age-related authorization threshold for the purchase as a whole that will authorize the purchase of the items. In embodiments in which a purchaser's authorization is checked with respect to a determined threshold value, a record of the authorization check can be stored and can subsequently be retrieved to verify that an authorization check for the encounter was carried out using the determined threshold value.Type: ApplicationFiled: June 25, 2004Publication date: December 2, 2004Inventors: Cassandra Mollett, Alan Jay Bethscheider, Susan Diane Brauckman, David A. Walker, David Wayne Smith
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Patent number: 6755344Abstract: Systems and methods are described that determine a threshold value for an authorization check, such as an age verification, that is performed at a point of sale or other point of access control where access to a product, service, location, event, or the like, is restricted to individuals who meet an authorization threshold. In embodiments associated with purchases that comprise a variety of items for purchase and a variety of associated age-related authorization thresholds, systems and methods are described for determining an age-related authorization threshold for the purchase as a whole that will authorize the purchase of the items. In embodiments in which a purchaser's authorization is checked with respect to a determined threshold value, a record of the authorization check can be stored and can subsequently be retrieved to verify that an authorization check for the encounter was carried out using the determined threshold value.Type: GrantFiled: March 11, 2003Date of Patent: June 29, 2004Assignee: First Data CorporationInventors: Cassandra Mollett, Alan Jay Bethscheider, Susan Diane Brauckman, David A. Walker, David Wayne Smith
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Patent number: 6722352Abstract: An internal combustion engine having an integrally connected pressure swing adsorption (PSA) system to provide oxygen-enriched air or oxygen-deficient air, in situ, to the mixing chamber of a spark-ignition or compression-ignition engine.Type: GrantFiled: November 6, 2001Date of Patent: April 20, 2004Assignee: Praxair Technology, Inc.Inventors: James Smolarek, David A. Walker, Bernard T. Neu
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Patent number: D779513Type: GrantFiled: July 7, 2014Date of Patent: February 21, 2017Assignee: Microsoft CorporationInventors: Oscar E. Murillo, Kristoffer S. Schultz, Cheryl Nicole Platz, Addison K. Linville, Kelly Rose McArthur, David A. Walker, Tyrone Samson, Vikram Bapat, John Henson, Jason Ryan Farmer, Craig Fox, Stefanie Lyn Tomko, Lisa Stifelman, Shane Jeremy Landry