Switchable surfaces

• US 20030142901A1
• Filed: 10/31/2002
• Published: 07/31/2003
• Est. Priority Date: 11/02/2001
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Langer, Robert S., Lahann, Joerg, Mitragotri, Samir S.
• Granted Patent: US 7,020,355 B2
• Time in Patent Office: Days
• US Class Current: 385/18
• CPC Class Codes: B01D 15/20 relating to the conditioning of the sorbent material
• CPC Class Codes: B01D 15/3861 using an external stimulus
• CPC Class Codes: B01J 20/286 Phases chemically bonded to a substrate, e.g. to silica or to polymers
• CPC Class Codes: B01J 20/3204 Inorganic carriers, supports or substrates
• CPC Class Codes: B01J 20/3208 Polymeric carriers, supports or substrates
• CPC Class Codes: B01J 20/3225 involving a post-treatment of the coated or impregnated product
• CPC Class Codes: B01J 20/3251 comprising at least two different types of heteroatoms selected from nitrogen, oxygen or sulphur
• CPC Class Codes: B01J 20/3285 Coating or impregnation layers comprising different type of functional groups or interactions, e.g. different ligands in various parts of the sorbent, mixed mode, dual zone, bimodal, multimodal, ionic or hydrophobic, cationic or anionic, hydrophilic or hydrophobic
• CPC Class Codes: B01J 2219/00432 Photolithographic masks
• CPC Class Codes: B01L 2300/0822 Slides
• CPC Class Codes: B01L 2300/089 Virtual walls for guiding liquids
• CPC Class Codes: B01L 2400/0688 surface tension valves, capillary stop, capillary break
• CPC Class Codes: B01L 3/5027 by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B01L 3/502707 characterised by the manufacture of the container or its components by shaping or joining plastic parts B29C59/00, B29C65/00; by laminating B32B37/00; manufacture of microstructural devices in general B81C
• CPC Class Codes: B01L 3/502792 for moving individual droplets on a plate, e.g. by locally altering surface tension
• CPC Class Codes: B01L 3/5088 confining liquids at a location by surface tension, e.g. virtual wells on plates, wires B01L3/50857 takes precedence
• CPC Class Codes: B05D 1/185 applying monomolecular layers B05D1/204 takes precedence
• CPC Class Codes: B05D 5/04 to obtain a surface receptive to ink or other liquid B05D5/02, B41M5/52 take precedence
• CPC Class Codes: B05D 5/08 to obtain an anti-friction or anti-adhesive surface rendering particulate materials free-flowing in general, e.g. making them hydrophobic B01J2/30
• CPC Class Codes: B29C 59/16 by wave energy or particle radiation , e.g. infrared heating B29C59/007 takes precedence
• CPC Class Codes: B41C 1/1041 : by modification of the lithographic properties without removal or addition of material, e.g. by the mere generation of a lithographic pattern
• CPC Class Codes: B82Y 10/00 : Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 30/00 : Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C40B 60/14 : for creating libraries
• CPC Class Codes: F16K 2099/0074 : using photolithography, e.g. etching
• CPC Class Codes: F16K 2099/0084 : Chemistry or biology, e.g. "lab-on-a-chip" technology
• CPC Class Codes: F16K 2099/0086 : Medical applications
• CPC Class Codes: F16K 99/0001 : Microvalves microdevices B81B1/00; manufacture or treatment of devices or systems in or on a substrate B81C1/00; microfluidic structures B01L3/5027; micropumps F04B19/006
• CPC Class Codes: F16K 99/0017 : Capillary or surface tension valves, e.g. using electro-wetting or electro-capillarity effects
• CPC Class Codes: F16K 99/0034 : Operating means specially adapted for microvalves
• CPC Class Codes: F16K 99/0036 : operated by temperature variations
• CPC Class Codes: F16K 99/004 : using radiation
• CPC Class Codes: F16K 99/0042 : Electric operating means therefor
• CPC Class Codes: F16K 99/0046 : using magnets
• CPC Class Codes: F16K 99/0051 : using electrostatic means
• CPC Class Codes: G01N 30/00 : Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation G01N3/00, G01N5/00, G01N7/00, G01N9/00, G01N11/00, G01N13/00, G01N15/00, G01N17/00, G01N19/00, G01N21/00, G01N22/00, G01N23/00, G01N24/00, G01N25/00, G01N27/00, G01N29/00 take precedence
• CPC Class Codes: G02B 6/3522 : the optical element enabling or impairing total internal reflection using evanescent coupling G02B6/3536
• CPC Class Codes: G02B 6/3538 : based on displacement or deformation of a liquid controlling the intensity of light by displacement or deformation of a fluid in general G02B26/004; fluid-filled lens of variable focal length G02B3/14
• CPC Class Codes: G02B 6/355 : 1x2 switch, i.e. one input and a selectable single output of two possible outputs
• CPC Class Codes: G02B 6/3568 : characterised by the actuating force
• CPC Class Codes: G02B 6/357 : Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G11B 7/0045 : Recording G11B7/006, G11B7/0065 take precedence
• CPC Class Codes: G11C 13/0014 : comprising cells based on organic memory material
• CPC Class Codes: G11C 13/0019 : comprising bio-molecules
• CPC Class Codes: G11C 2213/14 : Use of different molecule structures as storage states, e.g. part of molecule being rotated
• CPC Class Codes: H01M 8/04119 : with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
• CPC Class Codes: H01M 8/04291 : Arrangements for managing water in solid electrolyte fuel cell systems H01M8/04119 takes precedence
• CPC Class Codes: H01M 8/0662 : Treatment of gaseous reactants or gaseous residues, e.g. cleaning
• CPC Class Codes: Y02E 60/50 : Fuel cells

Abstract

A substrate having a surface with reversibly switchable properties. The surface comprises a nanolayer of a material that switches from a first conformation state to a second conformation state when an external stimulus is applied. When the nanolayer is in the first conformation state, the surface is characterized by a first property, and when the nanolayer is in the second conformation state, the surface is characterized by a second property.

Claims

1. A method of reversibly modifying a property of a surface, comprising:

depositing a nanolayer of a material on a substrate; and

applying an external stimulus to the nanolayer, wherein;

when the stimulus is applied, the nanolayer shifts from a first conformation state to a second conformation state.

2. The method of claim 1, wherein, when the nanolayer is in the first conformation state, the surface is characterized by a first property, and, when the nanolayer is in the second conformation state, the surface is characterized by a second property.

3. The method of claim 1, wherein the change in conformation state comprises a member of a change from a cis to a trans configured double bond, rotating a molecular group about an axis, opening a hinged molecular group, bending a molecular chain, and unbending a molecular chain.

4. The method of claim 1, wherein the external stimulus is selected from the group consisting of application of a voltage, a change in an applied voltage, a change in temperature, a change in pH, exposure to UV light, exposure to electromagnetic radiation, application of a magnetic field, removal of a magnetic field, a change in capacitance, application of an electrostatic charge, removal of an electrostatic charge, and any combination of the above.

5. The method of claim 1, wherein the external stimulus is selected from the group consisting of exposure to a ligand, exposure to a biomolecule, exposure to a small molecule, exposure to a bioactive agent, exposure to an ion, and any combination of the above.

6. The method of claim 1, wherein the property is selected from the group consisting of degree of hydrophilicity, degree of hydrophobicity, electrical charge, chemical composition, polarizability, transparancy, conductivity, light absorption, affinity for a biomolecule, affinity for a small molecule, affinity for a bioactive agent, osmotic potential, zeta potential, surface energy, coefficient of friction, tackiness, and any combination of the above.

7. The method of claim 1, wherein the substrate comprises a member of the group consisting of metal, ceramic, glass, non-crystalline solid, semiconductor, polymer, composite, and any combination thereof.

8. The method of claim 7, further comprising pretreating a surface of the substrate before the step of depositing.

9. The method of claim 8, wherein pretreating comprises a member of depositing a material on at least a portion of the surface, oxidizing at least a portion of the surface, etching at least a portion of the surface, and any combination thereof.

10. The method of claim 1, wherein the step of depositing comprises using at least one technique selected from chemical vapor deposition, metal oxide chemical vapor deposition, sputtering, sol-gel techniques, evaporation, pulsed laser deposition, and ion beam assisted deposition, molecular self assembly, soft lithography, layer by layer deposition and Langmuir Blodgett techniques.

11. The method of claim 10, wherein the nanolayer comprises a self-assembled monolayer comprising a plurality of molecular assemblies each having a cleavable endgroup, and wherein the method further comprises removing the endgroup, wherein the change in conformation state comprises causing a terminal group of the molecular assembly to bend towards the substrate.

12. The method of claim 1, wherein the nanolayer comprises a plurality of molecular assemblies each comprising at least first and second information carriers, wherein:

the molecular assembly includes at least one active group that interacts with the external stimulus,

the molecular assembly includes at least one tether, wherein, when the active group interacts with the external stimulus, the tether shifts from a first conformation to a second conformation,

when the tether has the first conformation, the properties of the surface are substantially determined by the first information carrier,

when the tether has the second conformation, the properties of the surface are substantially determined by the second information carrier, and

a member of the first information carrier, the second information carrier, and both information carriers may also be a member of the at least one tether, the at least one active group, and both of the above.

13. The method of claim 12, wherein the nanolayer comprises molecular assemblies having a plurality of compositions.

14. The method of claim 13, wherein the molecular assemblies are disposed substantially randomly within the nanolayer.

15. The method of claim 13, wherein:

the nanolayer comprises first and second molecular assemblies having first and second compositions,

the first and second molecular assemblies are deposited in separate regions, and

the external stimulus may be separately applied to the individual regions.

16. The method of claim 12, wherein the molecular assembly comprises two tethers.

17. The method of claim 16, wherein the first and second conformations of the molecular assembly are related by a 180°

rotation.

18. The method of claim 12, wherein the molecular assemblies comprise a hinged amphiphile, wherein, in the first conformation, the amphiphile is folded closed to define an interior and an exterior, and, in the second, the amphiphile is at least partially open.

19. The method of claim 12, wherein the molecular assemblies comprise paired hinged amphiphiles each having first and second arms, wherein, in the first conformation, the amphiphiles are folded closed, and, in the second conformation, the second arms of the paired amphiphiles unfold from the first arms, wherein the first arms of the paired amphiphiles are bonded to each other through non-covalent interactions in both the first and second conformations.

20. The method of claim 12, wherein the active group comprises a member of a charged molecular group, a polar molecular group, a dipolar molecular group, an aromatic group, a non-polar molecular group, a magnetic particle, a magnetic atom, a magnetic ion, and any combination of the above.

21. The method of claim 20, wherein the magnetic particle is coated with a surfactant comprising one of the information carriers.

22. The method of claim 1, further comprising:

adsorbing a member of a small molecule, a bioactive agent, and a biomolecule onto the nanolayer; and

releasing the member from at least a portion of the nanolayer by the step of applying.

23. The method of claim 22, wherein the step of adsorbing comprises applying a second external stimulus to the nanolayer, wherein the second external stimulus causes the nanolayer to change from the second conformation state to the first conformation state, wherein, in the first conformation state, the member is retained substantially within the nanolayer.

24. The method of claim 1, wherein the method further comprises adapting the substrate such that the external stimulus may be applied to a portion of the nanolayer.

25. The method of claim 1, wherein the external stimulus is applied to a portion of the nanolayer, and wherein the portion of the nanolayer to which the external stimulus is applied shifts from the first to the second conformation state.

26. The method of claim 1, further comprising depositing a liquid crystal over the nanolayer, wherein a change in the conformation state of the nanolayer causes a change in orientation of the liquid crystal.

27. A surface with reversibly switchable properties, comprising:

a nanolayer of a material characterized in that, when an external stimulus is applied, the nanolayer switches from a first conformation state to a second conformation state, wherein,

when the nanolayer is in the first conformation state, the surface is characterized by a first property, and

when the nanolayer is in the second conformation state, the surface is characterized by a second property.

28. The surface of claim 27, wherein the change in conformation state comprises a member of a change from a cis to a trans double bond, rotating a molecular group about an axis, unfolding a folded molecular group, and bending a molecular chain.

29. The surface of claim 27, wherein the stimulus is selected from application of a voltage, a change in an applied voltage, a change in temperature, a change in pH, exposure to UV light, application of a magnetic field, removal of a magnetic field, a change in capacitance, application of an electrostatic charge, removal of an electrostatic charge, and any combination of the above.

30. The surface of claim 27, wherein the stimulus is selected from exposure to a ligand, exposure to a biomolecule, exposure to a small molecule, exposure to a bioactive agent, exposure to an ion, and any combination of the above.

31. The surface of claim 27, wherein the property is selected from degree of hydrophilicity, degree of hydrophobicity, electrical charge, chemical composition, polarizability, transparency, conductivity, light absorption, osmotic potential, zeta potential, surface energy, coefficient of friction, tackiness, and any combination of the above.

32. The surface of claim 27, wherein the nanolayer is disposed on a substrate selected from metal, ceramic, glass, non-crystalline solid, semiconductor, polymer, composite, and any combination thereof.

33. The surface of claim 32, wherein at least a portion of the substrate is a member of etched, oxidized, coated with a material, or any combination of the above.

34. The surface of claim 32, wherein the substrate is adapted and constructed to permit the external stimulus to be applied to a portion of the nanolayer, which portion switches from the first conformation state to the second conformation state.

35. The surface of claim 32, wherein the nanolayer comprises a self-assembled monolayer comprising a plurality of molecular assemblies from which an endgroup has been removed after the molecular assemblies were disposed on the substrate, wherein the change in conformation comprises bending a terminal portion of the molecular assembly towards the substrate.

36. The surface of claim 27, wherein the nanolayer comprises a plurality of molecular assemblies each comprising at least first and second information carriers, wherein:

the molecular assembly includes at least one active group that interacts with the external stimulus,

the molecular assembly includes at least one tether, wherein, when the active group interacts with the external stimulus, the tether shifts from a first conformation to a second conformation,

when the tether has the first conformation, the properties of the surface are substantially determined by the first information carrier,

when the tether has the second conformation, the properties of the surface are substantially determined by the second information carrier, and

a member of the first information carrier, the second information carrier, and both information carriers may also be a member of the at least one tether, the at least one active group, and both of the above.

37. The surface of claim 36, wherein the nanolayer comprises molecular assemblies having a plurality of compositions.

38. The surface of claim 37, wherein the molecular assemblies are disposed substantially randomly within the nanolayer.

39. The surface of claim 37, wherein:

the nanolayer comprises first and second molecular assemblies having first and second compositions,

the first and second molecular assemblies are deposited in separate regions, and

the external stimulus may be separately applied to the individual regions.

40. The surface of claim 36, wherein the molecular assembly comprises two tethers.

41. The surface of claim 40, wherein the two conformations are related by a 180°

rotation.

42. The surface of claim 36, wherein the molecular assemblies comprise a hinged amphiphile, wherein, in the first conformation, the amphiphile is folded closed to define an interior and an exterior, and, in the second, the amphiphile is at least partially open.

43. The surface of claim 42, wherein the molecular assemblies comprise paired hinged amphiphiles each having first and second arms, wherein, in the first conformation, the amphiphiles are folded closed, and, in the second conformation, the second arms of the paired amphiphiles unfold from the first arms, wherein the first arms of the paired amphiphiles are bonded to each other through non-convalent interactions in both the first and second conformations.

44. The surface of claim 42, wherein the nanolayer retains a member of a small molecule, a bioactive agent, and a biomolecule within the amphiphile in the first conformation.

45. The surface of claim 36, wherein the active group comprises a member of a charged molecular group, a polar molecular group, a dipolar molecular group, an aromatic group, a non-polar molecular group, a magnetic particle, a magnetic atom, a magnetic ion, and any combination of the above.

46. The surface of claim 45, wherein the magnetic particle is coated with a surfactant comprising one of the information carriers.

47. The surface of claim 27, wherein, when the nanolayer is in the first conformation, a member of a small molecule, a bioactive agent, and a biomolecule is adsorbed onto the nanolayer, and when the nanolayer is in the second conformation, the member is released by the nanolayer.

48. The surface of claim 27, wherein the external stimulus may be applied to a portion of the nanolayer.

49. The surface of claim 27, further comprising a liquid crystal disposed over the nanolayer, wherein a change in the conformation state of the nanolayer causes a change in orientation of the liquid crystal.

50. A plate for offset printing comprising the surface of claim 27.

51. A data storage medium comprising the surface of claim 27.

52. A polymer electrolyte membrane fuel cell, comprising

a polymer electrolyte membrane;

a cathode;

an anode;

a humidity control system; and

at least one surface according to claim 27 disposed proximal to the cathode, the anode, or both, wherein the surface is hydrophilic when the nanolayer is in the first conformation state and hydrophobic when the nanolayer is in the second conformation state, and wherein the humidity control system adjusts the conformation of at least a portion of the surface in response to a measured humidity within the fuel cell.

53. A polymer electrolyte membrane fuel cell, comprising

a polymer electrolyte membrane;

a cathode;

an anode; and

at least one surface according to claim 27 disposed between a fuel source and the cathode, the anode, or both, wherein the surface retains sulfur, SO_x, or both when the nanolayer is in the first conformation state and has a low affinity for sulfur and SO_x when the nanolayer is in the second conformation state.

54. The polymer electrolyte membrane of claim 53, further comprising a material having a high affinity for sulfur, SO_x, or both, wherein the material is retained by the surface when the nanolayer is in the first conformation state and released by the surface when the nanolayer is in the second conformation state.

55. A method of operating a microfluidic system, comprising:

providing a surface according to claim 27;

adjusting the conformation state of portions of the surface to create a predetermined pattern of channels defined by hydrophilic and hydrophobic regions of the surface.

56. The method of claim 55, further comprising changing the conformation of a portion of a nanolayer to control the flow of fluid along one of the channels.

57. A method of operating a microfluidic system, comprising:

providing a surface according to claim 27;

adjusting the conformation state of portions of the surface to transport a drop of a fluid across the surface.

58. A switch for a waveguide disposed at a junction between an incoming waveguide and first and second outgoing waveguides, the switch comprising:

a chamber having a surface and containing a liquid and a gas and an interface between them, wherein;

the surface comprises a nanolayer of a material characterized in that, when an external stimulus is applied, the nanolayer shifts from a first conformation state to a second conformation state,

when the nanolayer has one of the first or second conformation state, light can pass through the liquid from the incoming waveguide to the first outgoing waveguide, and

when the material has the other of the first or second conformation state, light from the incoming waveguide is reflected off the liquid-gas interface and directed into the second outgoing waveguide.

59. A substrate having a surface having at least first and second properties, wherein:

the first property is defined by a surface property of the substrate,

the second property is defined by a surface property of a nanolayer deposited on the substrate, and

the surface density of the nanolayer is adapted and constructed such that the interaction with the surface of a chemical entity having a size less than a predetermined size is defined by the first property and the interaction with the surface of a chemical entity having a size greater than the predetermined size is defined by the second property.

60. A method of reversibly modifying a property of a surface, comprising:

depositing a nanolayer of a material on at least a first portion of a substrate; and

applying an external stimulus to the nanolayer, wherein;

when the stimulus is applied, the nanolayer shifts from a first adsorption affinity to a second adsorption affinity, wherein the affinity is for an entity that adsorbs onto the surface.

61. The method of claim 60, further comprising causing the nanolayer to shift from the second adsorption affinity to the first adsorption affinity.

62. The method of claim 60, wherein the affinity is for adsorption of a member of a surfactant, water, a predetermined analyte, a biomolecule, a small molecule, and a bioactive agent.

63. The method of claim 60, further comprising depositing a second nanolayer on a second portion of the substrate.

64. A substrate having a surface with reversibly switchable properties, the surface comprising:

a nanolayer of a material characterized in that, when an external stimulus is applied, the nanolayer switches from a first adsorption affinity to a second adsorption affinity, wherein the affinity is for an entity that adsorbs onto the surface.

65. The substrate of claim 64, wherein the affinity is for adsorption of a member of a surfactant, water, a predetermined analyte, a biomolecule, a small molecule, and a bioactive agent.

66. The substrate of claim 64, wherein the external stimulus causes a redistribution of the electron density within the nanolayer.

67. A biosensor comprising the substrate of claim 64.

68. A medium for chromatographic separation comprising the substrate of claim 64.

69. A self assembled monolayer comprising an area-per-molecule of 6.756 nm².

70. The self assembled monolayer of claim 69, wherein the monolayer comprises 16-mercaptohexadecanoic acid.