Systems and methods for fabricating water-responsive actuators

{
  "publication_number": "US11603827B1",
  "country": "US",
  "kind": "B1",
  "title": "Systems and methods for fabricating water-responsive actuators",
  "abstract": "Water-responsive actuators and methods for creating water responsive actuators are disclosed. In some embodiments, the disclosed subject matter includes a first layer, for example a plastic tape, and a second layer, for example bacterial spores and cured adhesive. The second layer can be created in a pattern. The pattern can include joints, which can contract when exposed to dry air and can thereby bend the actuator, and can expand when exposed to humid air and thereby return the actuator its original position.",
  "claims": [
    "1. A water-responsive actuator comprising: a substantially planar first layer comprising a flexible material that substantially maintains its shape in the presence of water; and a second layer positioned on a surface of the first layer; wherein the second layer comprises a cured solution including a bacterial spore and a cured adhesive, the second layer being water-responsive to permit repeatable actuation in the presence of water, wherein the cured solution comprises the cured adhesive in a ratio of 0.1% to 5% by volume to the solution.",
    "2. The actuator of claim 1, wherein the bacterial spore comprises a Bacillus subtilis spore.",
    "3. The actuator of claim 1, wherein the second layer comprises a patterned layer.",
    "4. The actuator of claim 1, wherein the water responsive actuator further comprises an electrical heater adapted to affect local humidity.",
    "5. The actuator of claim 1, wherein the second layer is adapted to be electrically conductive.",
    "6. The actuator of claim 1, wherein the cured adhesive comprises an adhesive having a Young's Modulus of between 1 GPa to 2 GPa.",
    "7. The actuator of claim 1, wherein the second layer is adapted for actuation by contact with liquid water.",
    "8. The actuator of claim 1, wherein the second layer is adapted for actuation by contact with liquid water and to return to an initial shape by cessation of such contact with liquid water.",
    "9. The actuator of claim 1, wherein the second layer is adapted for actuation by contact with air having a relative humidity of at least 30%.",
    "10. The actuator of claim 1, wherein the second layer is adapted for actuation by contact with air having a first relative humidity and to return to an initial shape by contact with air having a second relative humidity, wherein said second relative humidity is at least 10% less than said first relative humidity."
  ],
  "description_excerpt": "Humidity responsive actuators can be a versatile technology for various applications from power generation to soft robotics. Actuation can be maintained by fluctuating ambient humidity externally or within the limits of natural fluctuations.\n\nMaterials such as graphene oxide, polymers, liquid crystals, paper, and biologically based materials can be used to create humidity responsive actuators. Certain polymer based actuators can exhibit limited work density due to their low Young's Modulus. Graphene oxide, in contrast, can enable stiffer devices but can present challenges when attempting to pattern complicated geometries in a scalable way. Printing based techniques can be used to achieve programmable humidity responsive actuators, but such actuators can require long process times to fabricate complicated geometries.\n\nThe spatial gradients of relative humidity near evaporating surfaces can provide a source for humidity responsive actuators, especially for power generation applications. However, certain actuators exhibit limited resistance to direct liquid water contact. For example, certain polymer based and paper based actuators can be prone to taking up excessive amount of water when soaked inside water, resulting in an irreversible expansion in their size. Their function, shapes and characteristics can be substantially affected by the water uptake and subsequent drying. This can make them prone to failure when operated very close to water surfaces, which bars their usage nearby the aqueous environments.",
  "cpc": [
    "C12N 1/20",
    "B05D 2401/20",
    "B05D 3/067",
    "B05D 7/24",
    "B29C 65/4845",
    "C12N 1/02",
    "C12N 1/125",
    "C12N 1/205",
    "C12R 2001/075",
    "C12R 2001/125",
    "F03G 7/06",
    "F03G 7/0612"
  ],
  "ipc": [
    "C08K 11/00",
    "C09J 11/00",
    "C09J 5/00",
    "F03G 7/06",
    "B05D 3/06",
    "B05D 7/24",
    "B29C 65/48",
    "C12N 1/02",
    "C12N 1/12",
    "C12N 1/20"
  ],
  "assignees": [
    "Columbia University in the City of New York"
  ],
  "inventors": [
    "Ozgur Sahin",
    "Onur CAKMAK",
    "Xi Chen"
  ],
  "filing_date": "2019-05-10",
  "publication_date": "2023-03-14",
  "grant_date": "2023-03-14",
  "priority_date": "2016-11-11",
  "application_number": "US-201916408659-A",
  "family_id": "62110052",
  "cited_by_count": 2,
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}