Electrochemical sensor with barrier isolating the electrodes from each other and method of forming thereof
Electrochemical sensors ( 100 ) include at least two electrodes ( 110 A, HOB), over which an electrolyte ( 114 ) is formed. The electrodes are isolated from one another in order for reduction/oxidation reactions to occur at the electrodes and for an electric current to flow therebetween. The present disclosure describes the use of a barrier ( 121 ) in the electrochemical sensor that is configured to isolate electrodes from one another for the purpose of preventing electrode shorting. Additionally, the physical structure of the barrier can also act as a stencil for shaping the electrodes.
1. An electrochemical sensor, comprising:
a substrate having one or more gas transmission openings formed therein, the openings arranged to allow gases to pass through the substrate;
a first electrode having a first height, wherein the first height and other dimensions of the first electrode define a first boundary;
a second electrode having a second height, wherein the second height and other dimensions of the second electrode define a second boundary;
a first barrier surrounding the first boundary, wherein the first barrier has a first barrier height;
a second barrier surrounding the second boundary, wherein the second barrier has a second barrier height, and wherein the first barrier is different from the second barrier; and
an electrolyte formed over the first and second barriers and the first and second electrodes, wherein the first barrier and the second barrier are configured to isolate at least part of the first electrode from part of the second electrode.
2. An electrochemical sensor according to claim 1 , wherein a maximum height of the first barrier height and the second barrier height is at least equal to a maximum height of the first height of the first electrode and the second height of the second electrode.
3. An electrochemical sensor according to claim 1 , wherein the first barrier height is at least 10 μm in height.
4. An electrochemical sensor according to claim 1 , wherein a wall of the first barrier is well-shaped and has two peaks enclosing a dip.
5. An electrochemical sensor according to claim 4 , wherein a lowest height of the dip is at least equal to a maximum height of the first and second electrodes.
6. An electrochemical sensor according to claim 1 , wherein the electrochemical sensor further comprises an upper insulating layer having one or more openings configured to receive the first and second electrodes.
7. An electrochemical sensor according to claim 6 , wherein one of the first barrier and the second barrier is arranged over the upper insulating layer.
8. An electrochemical sensor according to claim 6 , wherein the upper insulating layer is a passivation layer.
9. An electrochemical sensor according to claim 6 , wherein the first barrier is configured to also receive the first electrode, such that first electrode is at least partly defined by the first barrier.
10. An electrochemical sensor according to claim 1 , wherein the first barrier acts as a stencil for forming the first electrode.
11. An electrochemical sensor according to claim 1 , wherein the electrochemical sensor further comprises a passivation layer and the first barrier is formed over the passivation layer.
12. An electrochemical sensor, comprising:
a substrate having one or more gas transmission openings formed therein, the openings arranged to allow gases to pass through the substrate;
a first electrode having a first height, wherein the first height and other dimensions of the first electrode define a first boundary, the first electrode formed in a first pattern over an upper surface of the electrochemical sensor;
a second electrode having a second height, wherein the second height and other dimensions of the second electrode define a second boundary formed in a second pattern over the upper surface of the electrochemical sensor;
first and second protrusions formed over the upper surface of the electrochemical sensor and formed at least between the first and second electrodes, wherein the first protrusion surrounds the first boundary and the second protrusion surrounds the second boundary, and wherein the first protrusion is different from the second protrusion; and
an electrolyte formed over the first and second protrusions and the first and second electrodes, wherein the first and second protrusions are configured to prevent the first and second electrodes from contacting one another.
13. A method of forming an electrochemical sensor, the method comprising:
providing a substrate having one or more gas transmission openings, the openings arranged to allow gases to pass through the substrate;
forming a first barrier for a first electrode;
forming a second barrier for a second electrode, wherein the first barrier is different from the second barrier;
forming a first electrode within a first boundary defined by the first barrier, wherein the first boundary surrounds the first electrode;
forming a second electrode within a second boundary defined by the second barrier, wherein the second boundary surrounds the second electrode; and
forming an electrolyte over the first and second barriers and the first and second electrodes, wherein the first and second barriers are configured to isolate at least part of one electrode from part of another electrode.
14. A method according to claim 13 , wherein forming the first barrier comprises forming the first barrier using photolithography, lamination or deposition in an additive process.
15. A method according to claim 13 , wherein forming the first barrier comprises forming the first barrier using etching in a removal process.
16. A method according to claim 13 , wherein the method further comprises forming an upper insulating layer having one or more openings configured to receive the first and second electrodes.
17. A method according to claim 16 , wherein forming the first barrier comprises arranging the first barrier over the upper insulating layer.
18. A method according to claim 16 , wherein forming the first barrier comprises configuring the first barrier to also receive the first electrode, such that the first electrode is at least partly defined by the first barrier.