Liquid flow induced power generation using nanoscale metal layers
Energy harvesting devices and methods for converting the mechanical energy of a flowing ionic solution, such as rainwater or seawater, into electric energy are provided. The energy harvesting devices include an electric current generating device that includes a metal layer and an amphoteric metal oxide film disposed over a surface of the metal layer. By moving an electric double layer across the surface of the amphoteric metal oxide film, an electric current is generated in the metal layer.
1. A method of harvesting energy using a liquid flow-based device comprising:
a metal layer comprising a metal;
an amphoteric metal oxide film adjacent to the metal layer at an interface, the amphoteric metal oxide film having a surface disposed opposite the interface, wherein the metal layer has a thickness that facilitates charge carrier motion parallel to the interface; and
at least one of: an electronic device that consumes electrical power connected laterally across the metal layer and configured to be powered by a current running parallel to the interface; and an energy storage device connected laterally across the metal layer and configured to be charged by a current running parallel to the interface, the method comprising:
exposing the surface of the amphoteric metal oxide film to a flow of an ionic solution having a temporally varying flow rate, or a temporally varying flow direction, wherein the temporally varying flow rate or the temporally varying flow direction generates a current in the metal layer and the flow of the ionic solution does not have a temporally varying ionic conductivity; and
powering the electronic device or charging the energy storage device with the generated current.
2. The method of claim 1 , wherein the ionic solution is an aqueous salt solution.
3. The method of claim 2 , wherein the ionic solution comprises salinized water from a natural body of water.
4. The method of claim 1 , wherein the ionic solution comprises blood.
5. The method of claim 4 , wherein the liquid flow-based device is implanted in a vein or an artery.
6. The method of claim 1 , wherein the metal oxide is a redox active metal oxide comprising metal atoms in at least two different oxidation states.
7. The method of claim 6 , wherein the metal is iron, nickel, copper, vanadium, or a mixture or alloy thereof.
8. The method of claim 1 , wherein the metal oxide is extrinsically doped with an n-type or a p-type dopant.
9. The method of claim 1 , wherein the metal layer has a thickness of up to 500 nm.
10. The method of claim 1 , wherein the ionic solution comprises multivalent ions.