Tear-activated micro-battery for use on smart contact lenses
A body-mountable device includes an electrochemical battery configured to provide power when exposed to an aqueous fluid. The aqueous fluid could be blood, sweat, tears, or some other bodily fluid. The electrochemical battery includes an anode that includes zinc metal and is configured to provide an electrical potential relative to a cathode when the anode and cathode are exposed to oxygen and an aqueous fluid. The electrochemical battery could provide power to electronics configured to measure a physiological parameter at a plurality of points in time, to record such measured parameters, to transmit such measured parameters to an external system, or to perform some other functions. Components of the body-mountable device could be embedded in a polymeric material configured for mounting to a surface of an eye. Components of the body-mountable device could be disposed on a flexible substrate configured for mounting to a skin surface.
1. A body-mountable device comprising:
a shaped polymeric material;
a substrate at least partially embedded within the shaped polymeric material;
an electrochemical battery disposed on the substrate and comprising:
a cathode; and
an anode, wherein the anode comprises zinc metal, wherein the electrochemical battery provides an electrochemical potential between the anode and the cathode when the anode and cathode are exposed to an aqueous fluid from an environment of the body-mountable device, and wherein the anode and the cathode comprise interdigitated electrodes; and
one or more electronic components electrically connected to the cathode and the anode, wherein the one or more electronic components are configured to receive power from the electrochemical battery when the electrochemical battery is exposed to the aqueous fluid.
2. The body-mountable device of claim 1 , wherein the aqueous fluid is a tear fluid of an eye, wherein the shaped polymeric material has a concave surface and a convex surface, wherein the concave surface is configured to be removably mounted over a corneal surface of the eye and the convex surface is configured to be compatible with eyelid motion when the concave surface is so mounted.
3. The body-mountable device of claim 1 , further comprising:
an antenna disposed on the substrate, wherein the one or more electronic components are disposed on the substrate and electrically connected to the antenna; and
a sensor disposed on the substrate, wherein the one or more electronic components are electrically connected to the antenna, wherein the one or more electronic components are configured to: (i) operate the sensor to measure a physiological parameter of a body when the body-mountable device is mounted to the body and in contact with an aqueous fluid of the body; and (ii) use the antenna to indicate the measured physiological parameter.
4. The body-mountable device of claim 1 , wherein the electrochemical battery further comprises a protective layer, wherein the protective layer is permeable to water and to oxygen.
5. The body-mountable device of claim 4 , wherein the protective layer comprises a hydrogel that comprises units of hydroxyethyl methacrylate.
6. The body-mountable device of claim 4 , wherein the shaped polymeric material comprises the protective layer.
7. The body-mountable device of claim 1 , wherein the cathode comprises platinum.
8. The body-mountable device of claim 1 , wherein the anode comprises a layer of zinc metal disposed on a layer of a different metal that is disposed on the substrate.
9. A method comprising:
operating a body-mountable device at a body location where a bodily fluid is at least intermittently present, wherein the body-mountable device comprises:
a shaped polymeric material;
a substrate at least partially embedded within the shaped polymeric material;
an electrochemical battery disposed on the substrate and comprising:
a cathode; and
an anode, wherein the anode comprises zinc metal, wherein the electrochemical battery provides an electrochemical potential between the anode and the cathode when the anode and cathode are exposed to the bodily fluid, and wherein the anode and the cathode comprise interdigitated electrodes; and
one or more electronic components electrically connected to the cathode and the anode, wherein the operating comprises:
exposing the electrochemical battery to the bodily fluid such that the electrochemical battery provides an electrochemical potential between the anode and the cathode to power the one or more electronic components.
10. The method of claim 9 , wherein the bodily fluid is a tear fluid of an eye, wherein the shaped polymeric material has a concave surface and a convex surface, wherein the concave surface is configured to be removably mounted over a corneal surface of the eye and the convex surface is configured to be compatible with eyelid motion when the concave surface is so mounted.
11. The method of claim 9 , wherein the electrochemical battery further comprises a protective layer, wherein the protective layer is permeable to water and to oxygen.
12. The method of claim 11 , wherein the protective layer comprises a hydrogel that comprises units of hydroxyethyl methacrylate.
13. The method of claim 11 , wherein the shaped polymeric material comprises the protective layer.
14. The method of claim 9 , wherein the body-mountable device further comprises:
an antenna disposed on the substrate, wherein the one or more electronic components are disposed on the substrate and electrically connected to the antenna; and
a sensor disposed on the substrate, wherein the one or more electronic components are electrically connected to the antenna, wherein the operating further comprises:
measuring, by the one or more electronic components using the sensor, a physiological parameter of the body; and
indicating, by the one or more electronic components using the antenna, the measured physiological parameter.
15. The method of claim 9 , wherein the cathode comprises platinum.
16. The method of claim 9 , wherein the anode comprises a metal trace disposed on the substrate.