Fluid regulating microvalve assembly for fluid consuming cells
A fluid regulating microvalve assembly for use to control fluid flow to a fluid consuming electrode, such as an oxygen reduction electrode, in an electrochemical cell. The microvalve assembly includes a stationary valve body having an aperture and a microactuator movable from a first position where the microvalve body aperture is closed to fluid flow to at least a second position where fluid is able to pass through the microvalve body aperture. The fluid regulating microvalve assembly can utilize cell potential or a separate source to open and close the microvalve. The fluid regulating microvalve assembly can be located outside the cell housing or inside the cell housing, for example between one or more fluid inlet apertures and the fluid consuming electrode. The invention includes a method of making a multilayer microvalve assembly, particularly one for use in a fluid depolarized battery, using a printing process to deposit at least one of the layers.
1. An electrochemical cell, comprising:
a housing comprising one or more fluid inlet apertures, a negative electrode, a fluid consuming positive electrode, and a microvalve assembly operatively connected to the one or more fluid inlet apertures for controlling passage of fluid to the fluid consuming positive electrode, wherein the microvalve assembly comprises;
(a) a stationary microvalve body comprising a polymer, elastomer or rubber and an aperture located between a first surface and a second surface;
(b) a movable microactuator connected to the microvalve body and capable of moving between a first position where fluid cannot pass through the microvalve body aperture and a second position which allows fluid to pass through the microvalve body aperture; and
(c) a segment of a circuit extending from a first lead located on the microvalve body to a resistive material layer of the movable microactuator to a second lead of the microvalve body.
2. The electrochemical cell according to claim 1 , wherein the microactuator moves away from the microvalve body in moving from the first to the second position, and the microactuator moves toward the microvalve body in moving from the second to the first position.
3. The electrochemical cell according to claim 1 , wherein at least one of the microvalve body and the microactuator comprises a printed layer.
4. The electrochemical cell according to claim 1 , wherein the microvalve assembly includes a control unit that is adapted to monitor a fluid level within the housing and is able to apply a potential across the microvalve assembly.
5. The electrochemical cell according to claim 1 , wherein the microvalve assembly is operatively connected between the one or more fluid entry apertures and the fluid consuming positive electrode.
6. The electrochemical cell according to claim 1 , wherein the cell is an air depolarized cell, an air-assisted cell, or a fuel cell.
7. The electrochemical cell according to claim 1 , wherein the cell is a button cell, a cylindrical cell, or a prismatic cell.
8. The electrochemical cell according to claim 1 , wherein the microvalve body includes a substrate and an insulating layer printed on at least a portion of the substrate.
9. The electrochemical cell according to claim 1 , wherein the microactuator comprises a resistive material layer.
10. The electrochemical cell according to claim 9 , wherein the resistive material layer comprises metal or a polymer containing conductive particles.
11. The electrochemical cell according to claim 1 , wherein the resistive material layer heats and distorts away from the microvalve body aperture to the second position when a potential is applied between the first lead and the second lead.
12. The electrochemical cell according to claim 1 , wherein the microvalve assembly includes a latch operatively connected to the microvalve body.
13. The electrochemical cell according to claim 1 , wherein the microvalve assembly includes an integrated control unit capable of controlling the movement of the microactuator between the first position and the second position.
14. The electrochemical cell according to claim 1 , wherein the movable microactuator is operatively connected to the microvalve body through one or more printed supports, and wherein the movable microactuator comprises a membrane sheet and a resistive material layer printed on the membrane sheet.
15. The electrochemical cell according to claim 14 , wherein the microactuator includes a boss connected to a bottom side of the membrane sheet that seals the microvalve body aperture in the first position to prevent fluid flow through the microvalve body aperture.
16. The electrochemical cell according to claim 14 , wherein the movable microactuator includes a segment of a circuit extending from a first lead to the resistive material layer to a second lead, and wherein a potential applied between the first lead and the second lead causes distortion of the microactuator and movement from the first position to the second position.