Reference electrode of electrochemical sensor

Abstract

A reference electrode for an electrochemical sensor includes a substrate having a well, a channel, and a conductive element therein. The well extends from a first surface of the substrate toward a second surface of the substrate. The channel is located in the substrate. The longitudinal axis of the channel may be substantially perpendicular to the longitudinal axis of the well. The channel has a first end connected to the well, and the conductive element is exposed to a second end of the channel. The channel and the well form a flow path for the conductive medium. A valve is coupled to the flow path and configured to control the conductive medium to flow through the flow path to the conductive element.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 322,400, filed on March 22, 2022, entitled “Reference Electrode for Electrochemical Sensor,” which is assigned to the assignee of the present application and is incorporated herein by reference. Technical Field

[0003] The present invention relates generally to electrochemical sensors and, more particularly, to reference electrodes for electrochemical sensors. Background Art

[0004] Electrochemical sensors are a class of chemical sensors in which electrodes act as transducer elements in the presence of an analyte. Electrochemical sensors can convert information related to an electrochemical reaction (e.g., a reaction between an electrode and an analyte) into a useful qualitative or quantitative signal. Electrochemical sensors can generate an electronic output of a digital signal for further analysis. Summary of the invention

[0005] A simplified summary of one or more aspects is presented below in order to provide a basic understanding of these aspects. This summary is not an extensive overview of all contemplated aspects, and is neither intended to identify key or important elements of all aspects, nor to describe the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description presented later.

[0006] The technology described herein relates in some aspects to a reference electrode in an electrochemical sensor, the reference electrode comprising: a substrate including an inner wall defining a flow path for a conductive medium; a conductive element in the substrate, wherein the conductive element is exposed at an end of the flow path; and a valve coupled to the flow path and configured to control the flow of the conductive medium through the flow path to the conductive element.

[0007] In some aspects, the technology described herein relates to a reference electrode and also includes: an additional flow path for the conductive medium, the additional flow path being arranged in the substrate; an additional conductive element in the substrate, wherein the additional conductive element is exposed at an end of the additional flow path; and an additional valve coupled to the additional flow path and configured to control an additional flow of the conductive medium through the additional flow path to the additional conductive element.

[0008] In some aspects, the technology described herein relates to a reference electrode wherein a portion of the flow path overlaps a portion of the additional flow path.

[0009] In some aspects, the technology described herein relates to a reference electrode, wherein the valve includes an electroactive polymer configured to impede the flow of a conductive medium in response to an electrical stimulus.

[0010] In some aspects, the technology described herein relates to a reference electrode, wherein the flow path includes: a well in the substrate, the well extending from a first surface of the substrate toward a second surface of the substrate, wherein the first surface is opposite to the second surface; and a channel arranged in the substrate and located between the first surface and the second surface, wherein a first end of the channel is connected to the well, the conductive element is exposed at a second end of the channel, and the first end is opposite to the second end.

[0011] In some aspects, the technology described herein involves a reference electrode wherein the valve is disposed along a wall of the channel.

[0012] In some aspects, the technology described herein relates to a reference electrode and further includes: an additional conductive element in the substrate; an additional channel in the substrate connected to the well, wherein the additional conductive element is exposed to the additional channel; and an additional valve arranged along the additional channel.

[0013] In some aspects, the technology described herein relates to a reference electrode, wherein the flow path includes: a first well in the substrate, the first well extending from a first surface of the substrate toward a second surface of the substrate, wherein the first surface is opposite to the second surface; a second well in the substrate, the second well extending from the first surface toward the second surface, wherein the conductive element is exposed to the second well; and a channel arranged between the first surface and the second surface, wherein a first end of the channel is connected to the first well, a second end of the channel is connected to the second well, and the first end is opposite to the second end.

[0014] In some aspects, the technology described herein involves a reference electrode wherein the valve is disposed in the channel.

[0015] In some aspects, the technology described herein relates to a reference electrode and also includes: a third well in the substrate; an additional conductive element in the substrate, wherein the additional conductive element is exposed to the third well; an additional channel connected to the first well and the third well; and an additional valve arranged along the additional channel.

[0016] In some aspects, the technology described herein relates to an electrochemical sensor, comprising: one or more working electrodes in the substrate; and a reference electrode electrically coupled to the one or more working electrodes, the reference electrode comprising: a substrate including an inner wall defining a flow path for a conductive medium, a conductive element in the substrate, wherein the conductive element is exposed at an end of the flow path, and a valve coupled to the flow path and configured to control the flow of the conductive medium through the flow path to the conductive element.

[0017] In some aspects, the technology described herein relates to an electrochemical sensor, further comprising: an additional flow path for the conductive medium, the additional flow path being disposed in the substrate; an additional conductive element in the substrate, wherein the additional conductive element is exposed at an end of the additional flow path; and an additional valve coupled to the additional flow path and configured to control an additional flow of the conductive medium through the additional flow path to the additional conductive element.

[0018] In some aspects, the technology described herein relates to an electrochemical sensor wherein the valve comprises an electroactive polymer configured to obstruct the flow of a conductive medium in response to an electrical stimulus.

[0019] In some aspects, the technology described herein relates to an electrochemical sensor further comprising one or more counter electrodes.

[0020] In some aspects, the technology described herein relates to an electrochemical sensor, wherein the flow path includes: a first well in the substrate, the first well extending from a first surface of the substrate toward a second surface of the substrate, wherein the first surface is opposite to the second surface; a second well in the substrate, the second well extending from the first surface toward the second surface, wherein the conductive element is exposed to the second well; and a channel arranged between the first surface and the second surface, wherein a first end of the channel is connected to the first well, a second end of the channel is connected to the second well, the first end is opposite to the second end, and the valve is arranged on the channel.

[0021] The technology described herein relates in some aspects to a reference electrode in an electrochemical sensor, the reference electrode comprising: a first layer comprising: a first flow path configured to facilitate a first flow of a conductive medium in the first layer, a first conductive element exposed to the first flow path, and a first valve coupled to the first flow path and configured to control the first flow of the conductive medium in the first layer; and a second layer located above the first layer, the second layer comprising: a second flow path configured to facilitate a second flow of the conductive medium in the second layer, a second conductive element exposed to the second flow path, and a second valve coupled to the second flow path and configured to control the second flow of the conductive medium in the second layer.

[0022] In some aspects, the technology described herein relates to a reference electrode further comprising a third layer located between the first layer and the second layer, wherein the third layer comprises a third flow path connected to the first flow path and the second flow path.

[0023] In some aspects, the technology described herein relates to a reference electrode, wherein the third layer further comprises one or more third valves coupled to the third flow path, and the one or more third valves are configured to control the flow of the conductive medium from the first layer to the third layer.

[0024] In some aspects, the technology described herein relates to a reference electrode, wherein the first flow path includes: a well extending from a first surface of the first layer toward a second surface of the first layer, wherein the first surface is opposite to the second surface; and a channel arranged between the first surface and the second surface, wherein a first end of the channel is connected to the well, a first conductive element is exposed to a second end of the channel, the first end is opposite to the second end, and the first valve is arranged along the channel.

[0025] In some aspects, the technology described herein relates to a reference electrode, wherein the first flow path includes: a first well extending from a first surface of the first layer toward a second surface of the first layer, wherein the first surface is opposite to the second surface; a second well extending from the first surface toward the second surface, wherein the first conductive element is exposed to the second well; and a channel arranged between the first surface and the second surface, wherein a first end of the channel is connected to the first well, a second end of the channel is connected to the second well, and the first end is opposite to the second end, and the first valve is arranged along the channel.

[0026] To accomplish the above and related ends, one or more aspects include the features hereinafter fully described and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of one or more aspects. However, these features are indicative of only a few of the various ways in which the principles of the various aspects may be employed, and this description is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] For a more complete understanding of the present disclosure and its features and advantages, reference may be made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like components, and in which:

[0028] FIG. (FIG.) 1 shows an example electrochemical sensor according to some embodiments of the present disclosure;

[0029] Figure 2A and 2Bshows an example working electrode according to some embodiments of the present disclosure;

[0030] Figure 3A and 3B shows an example reference electrode according to some embodiments of the present disclosure;

[0031] Figures 4A-4D Another example reference electrode according to some embodiments of the present disclosure is shown;

[0032] Figure 5 An example electrochemical sensor including a plurality of reference electrodes according to some embodiments of the present disclosure is shown;

[0033] Figure 6 Another example electrochemical sensor according to some embodiments of the present disclosure is shown;

[0034] Figure 7 Yet another example electrochemical sensor according to some embodiments of the present disclosure is shown;

[0035] Fig. 8A and 8B An example system including an electrochemical sensor including a cover according to some embodiments of the present disclosure is shown;

[0036] Fig. 9 Another example system including an electrochemical sensor according to some embodiments of the present disclosure is shown, the electrochemical sensor including a cover;

[0037] Fig.10 An example electrochemical sensor including a reference electrode having multiple channels according to some embodiments of the present disclosure is shown;

[0038] Fig.11 Another example electrochemical sensor including a reference electrode having multiple channels according to some embodiments of the present disclosure is shown;

[0039] Fig.12 shows an example reference electrode having a channel coupled to a valve according to some embodiments of the present disclosure;

[0040] Fig.13 shows an example reference electrode including a stirring element according to some embodiments of the present disclosure;

[0041] Fig.14 shows an example interface between a stirring element and a wall according to some embodiments of the present disclosure;

[0042] Figures 15A-15C shows example stirring elements having different shapes according to some embodiments of the present disclosure;

[0043] Fig.16 shows an example reference electrode including a heating element according to some embodiments of the present disclosure;

[0044] Fig.17 shows an example interface between a heating element and a wall according to some embodiments of the present disclosure;

[0045] Figures 18A-18C Example heating elements having different shapes are shown according to some embodiments of the present disclosure;

[0046] Fig.19 shows an example electrochemical sensor including a reference electrode on a sample channel according to some embodiments of the present disclosure;

[0047] Fig. 20A and 20B shows a reference electrode including multiple layers according to some embodiments of the present disclosure; and

[0048] Fig.21 Valves controlling the inlet and outlet of a reference electrode are shown according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0049] Electrochemical sensors have advantages such as simple measurement process, short response time, sufficient sensitivity and selectivity. Electrochemical sensors are widely used in many applications. Biosensors are examples of such sensors. Biosensors are analytical devices that convert biological reactions into electrical signals.

[0050] Electrochemical sensors typically include multiple types of electrodes in contact with an electrolyte. These electrodes may include a working electrode (or sensing electrode), a reference electrode, and a counter electrode. The working electrode typically includes two main components: a recognition element and a sensor. The recognition element selectively reacts with the analyte. The reaction is then converted into an electrical signal by the sensor. The recognition element and the transducer form the sensing electrode of the electrochemical sensor. The electrochemical sensor may include multiple working electrodes. The reference electrode typically maintains a constant electrode potential relative to the working electrode. In a potentiometric sensor, the sensor response is the potential (voltage) difference measured between the sensing electrode (the electrode where the chemical phenomenon of interest occurs) and a reference electrode having a stable reference potential that is not affected by the analyte. The reference electrode is used as a stable reference voltage for measurement. In current measurement (or voltage measurement, etc.), the sensor response is the current measured between the sensing electrode and the counter electrode (where the counter reaction occurs). Typically in amperometric sensors (or voltammetric sensors, etc.), a bias voltage is applied to the sensing electrode to promote a chemical reaction or physical process. In the latter case, the bias voltage is applied to the reference electrode, so it is important again that the reference electrode potential is stable. In addition, the presence of species interacting with the working electrode / electrolyte interface can induce a current between the working electrode and the counter electrode due to reduction / oxidation (REDOX) reactions at the working electrode. In some cases, it can cause a change in electrode potential as a result of the interaction between the analyte and the working electrode. In other cases, this is a change in impedance or resistance that may be proportional to the concentration of the analyte.

[0051] High-quality reference electrodes are important in electrochemical sensors. Reference electrodes are the basic unit in many chemical sensors that rely on electrochemical measurements, including glucose sensors and fire alarms. The stability and robustness of the reference electrode affects the accuracy, sensitivity, and lifetime of the sensor.

[0052] The present invention relates to an electrochemical sensor including a reference electrode. An example electrochemical sensor includes one or more reference electrodes and one or more working electrodes in a substrate. The electrochemical sensor may also include one or more counter electrodes in the substrate. The reference electrode may include a well and a channel defined by an inner wall of the substrate and a conductive element. The well extends from a first surface of the substrate toward a second surface of the substrate. The channel is located in the substrate. The longitudinal axis of the channel may be substantially perpendicular to the longitudinal axis of the well. The channel has a first end connected to the well, and the conductive element is exposed at the second end of the channel. The reference electrode may include an additional well extending from the first surface toward the second surface. The additional well may be connected to the second end of the channel and may be in contact with the conductive element. The channel and the well form a flow path for a conductive medium. For example, the conductive medium may be a solid or semi-solid film, or may be a liquid. The flow path may be connected to a stirring element or a heating element that facilitates the flow of the conductive medium. The stirring or heating element may help alleviate any accumulation of blockages or deposits, or may improve the efficiency of the analytical process in certain applications.

[0053] Compared with conventional reference electrodes, the reference electrode in the present invention has lower drift and is more stable. The use of one or more channels limits the diffusion of ions between the test solution (or sample) and the reference electrode, thereby providing a more stable reference electrode potential and thus providing more accurate sensor measurements. Miniaturized reference electrodes can be produced. Miniaturized reference electrodes can be used in microfluidic applications or other applications requiring miniaturization.

[0054] The following detailed description presents various descriptions of certain specific embodiments. However, the innovations described herein may be embodied in a variety of different ways, for example, as defined and covered by the claims or selected examples. In the following description, reference may be made to the accompanying drawings in which the same reference numerals may represent identical or functionally similar elements. It should be understood that the elements shown in the accompanying drawings are not necessarily drawn to scale. In addition, it should be understood that some embodiments may include more elements than shown in the drawings or a subset of the elements shown in the drawings. In addition, some embodiments may combine any suitable combination of features from two or more drawings.

[0055] Other features and advantages of the disclosure will be apparent from the following description and from the claims.

[0056] As described herein, one aspect of the present technology may be the collection and use of data available from various sources to improve quality and experience. The present disclosure contemplates that, in some cases, the data collected may include personal information. The present disclosure contemplates that entities involving such personal information respect and value privacy policies and practices.

[0057] The following disclosure describes various illustrative embodiments and examples for implementing the features and functionality of the present disclosure. Although specific components, arrangements, or features are described below in conjunction with various example embodiments, these are merely examples for simplifying the present disclosure and are not intended to be limiting. Of course, it will be understood that in the development of any actual embodiment, many implementation-specific decisions must be made to achieve the developer's specific goals, including compliance with system, business, or legal constraints, which may vary from implementation to implementation. In addition, it will be understood that while such development work may be complex and time-consuming; however, it will be a routine task for a person of ordinary skill in the art who benefits from the present disclosure.

[0058] In this specification, reference may be made to the spatial relationship between the various components shown in the accompanying drawings and the spatial orientation of the various aspects of the components. However, as will be appreciated by those skilled in the art after a complete reading of this disclosure, the devices, components, members, devices, etc. described herein may be positioned in any desired direction. Therefore, the use of terms such as "above", "below", "above", "below", "top", "bottom" or other similar terms to describe the spatial relationship between the various components or to describe the spatial orientation of aspects of these components should be understood to describe the relative relationship between the components or the spatial orientation of various aspects of these components, respectively, because the components described herein may be oriented in any desired direction. When used to describe a series of dimensions or other characteristics (such as time, pressure, temperature, length, width, etc.) of an element, operation or condition, the phrase "between X and Y" indicates a range that may include X and Y.

[0059] Furthermore, the terms "comprising," "including," "including," "having," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, process, apparatus, or system that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to that method, process, or system. Furthermore, the word "or" refers to an inclusive or and not to an exclusive or.

[0060] The systems, methods, and devices of the present disclosure each have several innovative aspects, no single one of which is solely responsible for all of the desirable attributes disclosed herein. The details of one or more implementations of the subject matter described in this specification are set forth in the following description and drawings.

[0061] Figure 1An example electrochemical sensor 100 according to some embodiments of the present disclosure is shown. The electrochemical sensor 100 includes a substrate 110, a working electrode 120 (individually referred to as "working electrode 120"), and a reference electrode 130. In some embodiments, the electrochemical sensor 100 may include fewer, more, or different components. For example, the electrochemical sensor 100 may include one or more counter electrodes, for example, in embodiments where the electrochemical sensor 100 is a voltammetric or amperometric sensor.

[0062] The substrate 110 may include plastic materials, semiconductor materials (e.g., silicon, glass, etc.), ceramic materials, other types of materials, or some combination thereof. Depending on the specific requirements of the electrochemical sensor application, the substrate 110 may be manufactured using, for example, injection molding, lamination, flexible / assembly or additive manufacturing techniques or other suitable techniques.

[0063] The working electrode 120 includes a conductive contact (also referred to as a "conductive contact"). The conductive contact includes a conductive material, which can be a metal, such as gold (Au), etc. In some embodiments, the conductive contact is recessed in the substrate. For example, the working electrode 120 includes a working well and a conductive contact above (e.g., below) the end of the working well. In other embodiments, the conductive contact can be embedded or protruding. Figure 1 In the embodiment of the present invention, working electrodes 120 are aligned along a line 105 parallel to the Y axis. The center of each working electrode 120 is located on line 105. In other embodiments, the center of the working electrode can be slightly offset from line 105. Working electrodes 120 can be substantially aligned or not aligned.

[0064] Line 105 may indicate the sample channel of electrochemical sensor 100 ( Figure 1 105 may indicate the position of a portion of the sample channel, such as the centerline or edge of the sample channel. The sample channel may provide a test sample (or analyte) to the working hole of the working electrode 120. The test sample may be a fluid, such as blood, other types of biological fluids, etc. The sample channel may also be used to provide a working membrane for the working electrode 120.

[0065] The reference electrode 130 includes two wells 133 and 135 defined in the substrate 110 and a conductive contact exposed to the well 135. In some embodiments, the well 133 may be within the sample channel, but the well 135 may be outside the sample channel. The well 133 may be in direct contact with the test sample. For example, the test sample may be provided through the sample channel, the test sample may be in a container surrounding the electrochemical sensor 100, or the test sample may be dispensed or placed in the well 133. However, the well 135 may not be in direct contact with the test sample. Figure 1In some embodiments, the well 133 is aligned with the working electrode 120 along the Y axis, while the well 135 is not aligned with the working electrode 120. In other embodiments, the well 133 can be substantially aligned with the working electrode 120, aligned with a subset of the working electrode 120, or not aligned with the working electrode 120. The distance 137 from the well 133 to the well 135, for example, the distance 137 from the center of the well 133 to the center of the well 135 in the XY plane is in the range of 1 mm to 2.5 mm. In some embodiments, the working electrode 120 is coupled to a sample channel (or other source) that provides a test sample to the working well of the working electrode 120. The sample channel can also be used to provide a working film for the working electrode 120.

[0066] No conductive contacts are exposed to the well 133. The conductive contacts of the reference electrode 130 include a conductive material, which may be a metal (e.g., silver (Ag), gold (Au), platinum (Pt)), other conductive materials (e.g., carbon), etc. In some embodiments, the conductive contacts may include other materials. In one example, the conductive contact includes a mixture of a metal (e.g., Ag) and a non-metal (e.g., silver chloride (AgCl)). For example, a metal may be formed on a non-metal by plating, such as selective plating. The two wells 133 and 135 may be connected by a channel therebetween. The channel may be separate from the sampling channel. For example, the channel may be located between the first surface and the second surface of the substrate 110 and extend laterally between the well 133 and the well 135. The wells 133 and 135 and the channel may be at least partially filled with a reference medium, such as a reference electrode electrolyte. The reference medium may be solid, semi-solid, or liquid, and may be referred to as a reference film. The conductive contacts of the reference electrode 130 may be connected to a test solution / sample or a working electrode 120 via the well 133 or 135. In this way, diffusion of ions (e.g., Cl, etc.) to / from the conductive contact of reference electrode 130 is limited by lateral ion diffusion through wells 133 and 135 and the channel, rather than conventional bulk diffusion. Lateral ion diffusion is slower than conventional bulk diffusion.

[0067] Figure 2A and 2B An example working electrode 220 according to some embodiments of the present disclosure is shown. The working electrode 220 may be Figure 1 An embodiment of the working electrode 120 in FIG. Figure 2A As shown, the working electrode 220 is arranged in the substrate 210. The substrate 210 can be Figure 1 The substrate 210 has surfaces 213 and 215 that are opposite to each other along the Z-axis.

[0068] Working electrode 220 includes working well 223 and conductive element 225. Working well 223 extends from surface 213 toward surface 215. Working well 223 has opening 227 and end 229. Opening 227 is located on surface 213. End 229 is located between surface 213 and surface 215. Conductive element 225 is located below end 229.

[0069] like Figure 2B As shown, the working well 223 is partially filled with a working film 240. The working film 240 is in contact with the conductive element 225. In some embodiments, the working film 240 is an ion selective membrane (ISE) or other layer that imparts selectivity.

[0070] Figure 3A and 3B An example reference electrode 330 is shown according to some embodiments of the present disclosure. The reference electrode 330 may be Figure 1 The reference electrode 330 is arranged in the substrate 310. The substrate 310 can be Figure 1 An embodiment of the substrate 110 in FIG. Figure 3A As shown, the substrate 310 has surfaces 313 and 315 that are opposite to each other along the Z-axis.

[0071] Reference electrode 330 includes a well 333, a channel 335, and a conductive element 337. Well 333 extends from surface 313 toward surface 315. Well 333 has an opening 332 and an end 334. Opening 332 is located on surface 313. End 334 is located between surface 313 and surface 315. Channel 335 extends along the X-axis. One end of channel 335 is connected to end 334 of well 333. The other end of channel 335 is connected to conductive element 337. In some embodiments, the longitudinal axis of channel 335 can be perpendicular or substantially perpendicular to the longitudinal axis of well 333. For example, well 333 has a longitudinal axis along the Z-axis, and channel 335 has a longitudinal axis along the X-axis. Well 333 and channel 335 constitute a flow path. The flow path can allow the reference film to flow, for example, toward conductive element 337. In addition, well 333 and channel 335 constitute a "tortuous" path for ion diffusion, which is slower than bulk diffusion.

[0072] like Figure 3B As shown, a portion of the well 333 and the channel 335 are filled with the reference film 340. In some embodiments, the well 333 may be completely filled with the reference film 340. Figure 3BIn some embodiments, the channel 335 is completely filled with the reference film 340. In other embodiments, the channel 335 may not be completely filled with the reference film 340. The reference film 340 is in contact with the conductive element 337. In some embodiments, the reference film 340 is a viscous material (e.g., an electrolyte). The reference film 340 may become a solid material (e.g., a solid organic material) after the solvent evaporates. Although Figure 3A and 3B Although not shown, reference electrode 330 may include or be connected to a hole in substrate 310 through which air may be exhausted from substrate 310 when reference film 340 is introduced into reference electrode 320 .

[0073] Figures 4A-4D Another example reference electrode 430 according to some embodiments of the present disclosure is shown. The reference electrode 430 may be Figure 1 The reference electrode 430 is arranged in the substrate 410. The substrate 410 can be Figure 1 An embodiment of the substrate 110 in FIG. Figure 4A As shown, substrate 410 has surfaces 413 and 415 that are opposite to each other along the Z-axis.

[0074] Reference electrode 430 includes wells 433 and 439, channel 435, and conductive element 437. Well 433 extends along the Z axis from surface 413 toward surface 415. Well 433 has an opening 432 and an end 434. Opening 432 is located on surface 413. End 434 is located between surface 413 and surface 415. Well 439 also extends along the Z axis from surface 413 toward surface 415. Well 439 has an opening 436 and an end 438. Opening 436 is located on surface 413. End 438 is located between surface 413 and surface 415.

[0075] Channel 435 extends along the X-axis. One end of channel 435 is connected to end 434 of trap 433. The other end of channel 435 is connected to end 438 of trap 439. In some embodiments, end 434 may at least partially overlap with the end of channel 435. Similarly, end 438 may at least partially overlap with the other end of channel 435. In some embodiments, the longitudinal axis of channel 435 may be perpendicular or substantially perpendicular to the longitudinal axis of trap 433 or 439. For example, trap 433 or 439 has a longitudinal axis along the Z-axis, and channel 435 has a longitudinal axis along the X-axis. Traps 433 and 439 and channel 435 constitute a flow path. The flow path may allow the reference film to flow, for example, toward conductive element 437. In addition, traps 433 and 439 and channel 435 including membrane 440 constitute a "tortuous" path for ion diffusion, which is slower than bulk diffusion. For example, the well 439 may allow for a larger volume of the reference film 450 on the conductive element 437 (e.g., Figure 3BThis can provide a longer lifespan. Figure 4A and 4B Although not shown, reference electrode 430 may include or be connected to a hole in substrate 410 through which air may be exhausted from substrate 410 when reference film 440 is introduced into reference electrode 430 .

[0076] like Figure 4B As shown, a portion of well 433, channel 435, and a portion of well 439 are filled with reference film 440. In some embodiments, well 433 or 439 may be completely filled with reference film 440. Figure 4B In some embodiments, the channel 435 is completely filled with the reference film 440. In other embodiments, the channel 435 may not be completely filled with the reference film 440. The reference film 440 is in contact with the conductive element 437. In some embodiments, the reference film 440 is a viscous material (e.g., an electrolyte). The reference film 440 may become a solid material (e.g., a solid organic material) after the solvent evaporates.

[0077] like Figure 4C As shown, a portion of well 433 and a portion of channel 435 are filled with reference film 450, but another portion of channel 435 and a portion of well 439 are filled with a different reference film 460. In some embodiments, well 433 or 439 may be completely filled with reference film 450 or 460. Figure 4D In an embodiment, channel 435 is completely filled with reference membranes 450 and 460. In other embodiments, channel 435 may not be completely filled with reference membranes 450 and 460. Reference membrane 460 is in contact with conductive element 437. In some embodiments, reference membrane 450 may be a solid membrane (e.g., a solid organic material), and reference membrane 460 may be an aqueous membrane. Reference membrane 460 may include a gel, such as sodium chloride (NaCl) gel, potassium chloride (KCl) gel. Reference membrane 460 may include a polymer, such as Nafion (a brand name for sulfonated tetrafluoroethylene-based fluoropolymer copolymer). Reference membrane 460 may include other materials. An example of reference membrane 460 is 1% agarose containing NaCl.

[0078] Figure 3A , 3B , 4A and 4B have a rectangular shape in the XZ plane. In other embodiments, the channel 335 or 435 may have different shapes according to the specific requirements of the application. For example, the size of the channel 335 along the Z axis may increase or decrease in the direction from the well 333 to the conductive element 337 along the X axis. Similarly, the size of the channel 435 along the Z axis may increase or decrease in the direction from the end 434 to the end 438 along the X axis. In addition, the longitudinal axis of the channel 335 or 435 may not be perpendicular to the longitudinal axis of the well.

[0079] Figure 5 An example electrochemical sensor 500 including multiple reference electrodes 530 and 540 according to some embodiments of the present disclosure is shown. Reference electrodes 530 and 540 can have similar or different components. An embodiment of reference electrode 530 or 540 can be reference electrode 130, 330, or 430. Reference electrode 530 includes two wells 533 and 535. Well 535 is associated with a conductive conductor that can be located below the end of well 535. Reference electrode 530 can also include a channel ( Figure 5 540). Reference electrode 540 includes three wells 543, 545, and 547. Well 543 is located between well 545 and well 547. Each of wells 545 and 547 is associated with a conductive conductor, which may be located below the end of the well. Reference electrode 540 may also include a first channel ( Figure 5 543 and 547 to form a second channel for a second flow path. In some embodiments, the benefit of two wells 545 and 547 having conductive elements is redundancy, so that in the event of a failure of one of the conductive elements, the reference electrode 540 still has a working conductive element.

[0080] In other embodiments, the electrochemical sensor 500 may include more reference electrodes 530 or 540. The electrochemical sensor 500 also includes a substrate 510 and a working electrode 520 (individually referred to as a "working electrode 520"). In some embodiments, the reference electrodes 530 and 540 are electrically coupled to different working electrodes 520. In other embodiments, the reference electrodes 530 and 540 can be electrically coupled to the same working electrode 520. In addition, the reference electrodes 530 and 540 can be operated simultaneously or at different times. In some embodiments, each reference electrode includes, for example, a valve arranged at a channel between two wells of the reference electrode. The valve can control the flow of a reference film in the reference electrode and control the operation of the reference electrode. For example, the reference electrode can be closed by closing the valve, which prevents the flow of the reference film, and the reference electrode can be opened by opening the valve. These valves can be used to select which reference electrode to use.

[0081] Figure 6 Another example electrochemical sensor 600 according to some embodiments of the present disclosure is shown. The electrochemical sensor 600 includes a substrate 610, a working electrode 620 (individually referred to as "working electrode 620"), a reference electrode 630, and a sample channel 640. The reference electrode 630 has a single well located outside the sample channel 640. The well may not be in direct contact with the sample.

[0082] Figure 7 Yet another example electrochemical sensor 700 according to some embodiments of the present disclosure is shown. The electrochemical sensor 700 includes a substrate 710, a working electrode 720 (individually referred to as "working electrode 720"), and a reference electrode 730. In some embodiments, the electrochemical sensor 700 may include fewer, more, or different components. For example, the electrochemical sensor 700 may include one or more counter electrodes, for example, in embodiments where the electrochemical sensor 700 is a voltammetric or amperometric sensor. The reference electrode 730 includes an elongated well to be filled with a reference film. One end of the elongated well 733 is located between the working electrodes 720, and the other end is coupled to a conductive element 735. For example, the conductive element 735 may be located above the other end of the elongated well 733. In Figure 7 In some embodiments, the elongated well 733 extends along the X-axis and has a longitudinal axis along the X-axis. In some embodiments, the reference electrode 730 includes a polymer (e.g., PVC (polyvinyl chloride), LCP (liquid crystal polymer), etc.) covering part or all of the elongated well 733 to define the elongated well 733. In other cases, such as using Flex technology, a solder mask can be placed under the polymer to ensure that no copper is exposed.

[0083] exist Figure 7 In the embodiment of the present invention, the elongated well 733 has a racetrack shape in the XY plane. In other embodiments, the elongated well 733 can have different shapes in the XY plane, such as rectangular, elliptical, trapezoidal, etc. In addition, the length of the elongated well 533 along the X-axis can vary. The different shapes, depths and positions of the wells, channels and relative openings can be optimized according to the specific requirements of the application.

[0084] Fig. 8A and 8B An example electrochemical sensor 800 including a cover 810 is shown, according to some embodiments of the present disclosure. Figure 8B yes Fig. 8ACross section along line BB. The electrochemical sensor 800 also includes a working electrode 820 (individually referred to as "working electrode 820"), a reference electrode, and a sample channel 840. The interface between the electrode and the sample is within the sample channel 840. The cover 810 defines the sample channel 840, in which the working electrode 820 is disposed. In some embodiments, the cover 810 is located on a substrate, such as substrate 110, 210, 310, 410, 510, 610, or 710, in which the working electrode 820 and the reference electrode are disposed. The cover 810 may partially cover a surface of the substrate, for example, covering the entire surface except for the sample channel 840. The reference electrode may include a first well 833 having an opening inside the sample channel 840 and a second well 839 having an opening outside the sample channel 840. The cover 810 does not cover or seal the first well 833 of the reference electrode. The first well may receive a test sample provided to the electrochemical sensor 800, for example, through the sample channel 840. In Fig. 8A and 8B In an embodiment of the present invention, the membrane 830 is present in the first well 833. The membrane 830 can be one of the above-mentioned membranes. The cover 810 can cover (or seal) the opening of the second well 839 of the reference electrode. The second well 839 may not be in direct contact with the test sample. The conductive element 835 can be exposed to the second well 839. The cover 810 can include a rubber gasket, tape, epoxy resin, a cover, a box, a microfluidic substrate, etc. The cover 810 can be used with other electrochemical sensors, such as any other electrochemical sensor described herein.

[0085] Fig. 9 Another example electrochemical sensor 900 including a cover 910 is shown according to some embodiments of the present disclosure. The electrochemical sensor 900 also includes a working electrode 920 (individually referred to as "working electrode 920"), a reference electrode, and a sample channel 940. The cover 910 can be connected to Fig. 8A and 8B The cover 910 may be the same or similar to the cover 810 in the sample channel 940. The cover 910 defines a sample channel 940 in which the working electrode 920 is disposed. The reference electrode may include a well having an opening within the sample channel 940. The opening is not covered by the cover 910. The reference electrode may also include another well outside the sample channel 940, which may be covered or sealed by the cover 910. The membrane 930 is present in the well of the reference electrode within the sample channel 940.

[0086] Fig.10An example electrochemical sensor 1000 is shown according to some embodiments of the present disclosure, which includes a reference electrode 1030 having a plurality of channels 1035a-c. The electrochemical sensor 1000 also includes a substrate 1010 and a working electrode 1020 (individually referred to as "working electrode 1020"). In some embodiments, the electrochemical sensor 1000 may include fewer, more, or different components. For example, the electrochemical sensor 1000 may include one or more counter electrodes.

[0087] The reference electrode 1030 includes a well 1033, channels 1035a-c (collectively referred to as "channels 1035" or "channels 1036") and wells 1037a-c (collectively referred to as "wells 1037" or "wells 1037"). In some embodiments, the well 1033 is located within the sample channel and can be in direct contact with a sample provided through the sample channel. The well 1037 can be outside the sample channel and is not in direct contact with the sample. Each channel 1035 provides a flow path from the well 1033 to the well 1037. For example, the channel 1035 has a first end connected to one end of the well 1033 and a second end connected to the well 1037. The second end is opposite to the first end. A conductive element is coupled to each well 1037. For example, the conductive element can be located above the end of the well 1037 connected to the corresponding channel 1035. The conductive elements can be operated separately. In some embodiments, the conductive elements are insulated from each other, and different potentials can be applied to the conductive elements at the same time.

[0088] Well 1033, channel 1035, and well 1037 form a flow path for the reference membrane that the conductive element can contact. Since there are three channels 1035 and three wells 1037, the reference electrode 1030 can provide three flow paths, all of which start from the well 1033. In other embodiments, the reference electrode 1030 can include a different number of channels 1035 and a different number of wells 1037.

[0089] Fig.11 Another example electrochemical sensor 1100 is shown, according to some embodiments of the present disclosure, which includes a reference electrode 1130 having a plurality of channels 1135a-c. The electrochemical sensor 1100 also includes a substrate 1110 and a working electrode 1120 (individually referred to as "working electrode 1120"). In some embodiments, the electrochemical sensor 1100 may include fewer, more, or different components. For example, the electrochemical sensor 1100 may include one or more counter electrodes.

[0090] The reference electrode 1130 includes a well 1133, channels 1135a-c (collectively referred to as "channels 1135" or "channels 1135"), and another well 1137. Each channel 1135 provides a flow path from the well 1133 to the well 1137. For example, the channel 1135 has a first end connected to one end of the well 1133 and a second end connected to the well 1137. The second end is opposite to the first end. A conductive element coupled to the well 1137 can contact a reference film flowing to the well 1137 through some or all of the three channels 1135. For example, the conductive element can be located above the end of the well 1137 connected to the channel 1135. The well 1133, the channel 1135, and the well 1137 form a flow path for the reference film. The flow of the reference film can start from the well 1133, then be divided into the three channels 1135, and merge together in the well 1137. In some embodiments, the channel 1135 can be blocked, for example by closing a valve.

[0091] Fig.12 An example reference electrode 1230 having channels 1235a and 1235b connected to valves 1239a and 1239b according to some embodiments of the present disclosure is shown. The reference electrode 1230 also includes a well 1233 and wells 1237a and 1237b. Channel 1235a is connected to wells 1233 and 1237a. Channel 1235b is connected to wells 1233 and 1237b. Therefore, the reference electrode 1230 forms two flow paths. Valve 1239a is arranged along channel 1235a, and the flow of the conductive medium in channel 1235a can be controlled. For example, when valve 1239a is opened, the reference film can flow from well 1233 to well 1237a through channel 1235a, so that the reference film can reach the conductive element below well 1237a. When valve 1239a is closed, valve 1239a becomes a barrier that prevents the reference film from flowing through channel 1235a and reaching the conductive element. Similarly, valve 1239b is arranged along channel 1235b, and can control the flow in channel 1235b. Valves 1239a and 1239b can be used to select which conductive element to enable / access. In some embodiments, the conductive element (below trap 1237a) is configured for wireless communication, while the additional conductive element (below trap 1237b) is configured for wired communication. In some embodiments, valve 1239a or 1239b can be a hydrophobic valve. In other embodiments, valve 1239a or 1239b can be a barrier that can be broken by applying energy (e.g., voltage, current pulse, mechanical vibration). In some embodiments, the valve may include an electroactive polymer located on the wall of channel 1235a or 1235b. When a stimulus (e.g., an electric field) is applied to the valve, the electroactive polymer will hinder the flow of fluid in the channel. For example, the electroactive polymer can expand to close the valve. The material, shape, and structure of the valve can be optimized according to the specific requirements of the application.

[0092] Fig.13 An example reference electrode 1330 including stirring elements 1340a-d is shown according to some embodiments of the present disclosure. Reference electrode 1330 includes wells 1333 and 1339, a channel 1335 between wells 1333 and 1339, and a conductive element 1337 below well 1339 in substrate 1310. Wells 1333 and 1339 and channel 1335 form a flow path for the conductive medium. Stirring elements 1340a-d (collectively referred to as "stirring elements 1340" or "stirring elements 1340") are arranged on the walls of wells 1333 and channel 1335. Fig.13 As shown, stirring elements 1340a and 1340b are arranged on the outer surface of channel 1335, stirring element 1340c is arranged on the outer surface of channel 1331, and stirring element 1340 is arranged on another outer surface of channel 1.33. In other embodiments, reference electrode 1330 may include a different number of stirring elements 1340, stirring elements 1330 arranged at different positions (e.g., on the wall of well 1339), or stirring elements 1340 of different sizes or shapes. In addition, reference electrode 1330 may include different flow paths, for example, a flow path including one well and one channel.

[0093] The stirring element 1340 is configured to stir the flow of the reference membrane in the flow path. For example, the stirring element 1340 can generate motion to manipulate or move the fluid present in the flow path. The stirring element 1340 can, for example, apply mechanical stress to the flow path in response to an electrical signal (e.g., an electric field), a radio frequency signal, or other types of signals. The mechanical stress can change the size or shape of the flow path (e.g., the size or form of the well 1333 or the channel 1335), which can promote or reduce the flow of the reference membrane in the flow path. The stirring element 1340 may include an electroactive polymer or a piezoelectric material.

[0094] Fig.14 An example interface between a stirring element 1420 and a wall 1410 of a flow path in a reference electrode is shown in accordance with some embodiments of the present disclosure. The stirring element 1420 may be Fig.13 The wall 1410 may be a wall of the well 1333 or a wall of the channel 1335. Fig.14 As shown, the interface is not smooth. Instead, the stirring element 1420 has protrusions that correspond to the recesses in the wall 1410. This "rough" interface can improve the adhesion between the stirring element 1420 and the wall 1410. It can also affect how the structure moves, deflects, or bends to interact with the fluid in the flow path.

[0095] Figures 15A-15CExample stirring elements 1520a-c having different shapes are shown according to some embodiments of the present disclosure. The stirring elements 1520a-c are disposed on the walls 1510a-c, respectively. Fig.15A A stirring element 1520a is shown having a circular shape in the XY plane. Fig. 15B A stirring element 1520b is shown having a ring shape in the XY plane. Fig. 15C A stirring element 1520c is shown having a rectangular shape in the XY plane. In other embodiments, the stirring element may have a shape similar to Figures 15A-15C The shapes shown are different shapes. The stirring element can be patterned according to the needs of the application. The pattern or shape will affect the movement of the channel structure and the way the fluid is manipulated. The relative shape and interface between the stirring element and the wall can be modified to optimize the required movement, thereby optimizing the stirring level of the film or material applied to the channel. The stirring element can be a piezoelectric material (such as lead zirconate titanate (PZT), barium titanate, gallium nitride, zinc oxide, polyvinylidene fluoride, ferroelectric materials with perovskite structure, etc.) or an electroactive polymer (such as a ferroelectric polymer, such as polyvinylidene fluoride, ionic polymer-metal composites, stimulus-responsive gels, electrostrictive grafted polymers, etc.) or a conductive material, so that applying a stimulus (such as voltage, current, etc.) will cause the structure to deform or expand or contract or warp, thereby applying a stirring force to the medium / fluid / film in the channel. In some embodiments, the stimulus can be applied in a pulsed or intermittent manner, and a pulsed or intermittent stirring force is applied to manipulate the fluid / medium / film in the channel. The shape / size / thickness / interface between the stirring element and the adjacent layer can be modified and optimized according to the specific requirements of the application.

[0096] Fig.16 An example reference electrode 1630 including heating elements 1640A-D is shown according to some embodiments of the present disclosure. Reference electrode 1630 includes wells 1633 and 1639, a channel 1635 between wells 1633 and 1639, and a conductive element 1637 below well 1639 in substrate 1610. Wells 1633 and 1639 and channel 1635 form a flow path for the reference film. Heating elements 164a-d (collectively referred to as "heating elements 1640" or "heating elements 1640") are arranged on the walls of wells 1633 and channel 1635. Fig.16As shown, heating elements 1640a and 1640b are arranged on the outer surface of channel 1635, heating element 1640c is arranged on the outer surface of channel 1630, and heating element 1640d is arranged on another outer surface of channel 1630. In other embodiments, reference electrode 1630 may include a different number of heating elements 1640, heating elements 1640 arranged at different positions (e.g., on the wall of well 1639), or heating elements 1630 of different sizes or shapes. The heating element may be arranged on the inner surface of the flow path. In addition, reference electrode 1630 may include different flow paths, for example, a flow path including a well and a channel. Heating element 1640 is configured to increase the temperature of the fluid in the flow path. Heating element 1640 may, for example, provide heat to the fluid in response to an electrical signal (e.g., an electric field) or other types of signals. The shape, position, and number of the heating elements may be optimized according to the application and the convection or desired heat treatment stage. This also applies to piezoelectric elements that can be incorporated into the structure to manipulate or stir the fluid.

[0097] Fig.17 An example interface between a heating element 1720 and a wall 1710 of a flow path is shown according to some embodiments of the present disclosure. The heating element 1720 may be Fig.16 The wall 1710 may be a wall of the well 1333 or a wall of the channel 1335. Fig.17 As shown, the interface is not smooth. Instead, the heating element 1720 has protrusions that correspond to the recesses in the wall 1710. This "rough" interface can improve the adhesion between the heating element 1720 and the wall 1710. This principle can also be applied to add electroactive or piezoelectric layers. By the way that the layers of the bimetallic strip will bend or flex, defined portions of the channel can also be constructed to deflect / move and manipulate the fluid in a desired manner, which can be optimized depending on the specific application of the electrochemical sensor.

[0098] Figures 18A-18C Example heating elements 1820a-c having different shapes are shown according to some embodiments of the present disclosure. The heating elements 1820a-c are disposed on the walls 1810a-c, respectively. Fig.18A A heating element 1820a is shown having a circular shape in the XY plane. Fig.18B The heating element 1820b is shown having a ring shape in the XY plane. Fig.18C The heating element 1820c is shown as having a rectangular shape in the XY plane. In other embodiments, the heating element may have a Figures 18A-18CThe shapes shown in FIG. 4 are different shapes. The heating elements can be patterned as required by the application. The shape, position and number of elements can be optimized based on the specific thermal current or thermal treatment steps required for a specific application of the electrochemical sensor.

[0099] Fig.19 An example electrochemical sensor 1900 according to some embodiments of the present disclosure is shown, which includes a reference electrode on a sample channel 1940. In this example, the sample channel 1940 can represent any sample source, including a container into which the electrochemical sensor 1900 is immersed or a sample aliquot that is dispensed or applied to the electrochemical sensor 1900. The electrochemical sensor 1900 also includes a substrate 1010 and a working electrode ( Fig.19 ). The substrate 1910 may be Figure 1 In some embodiments, the electrochemical sensor 1900 may include fewer, more, or different components. For example, the electrochemical sensor 1900 may include one or more counter electrodes. The shape, position, and orientation of the stirring element may be modified and optimized according to the requirements of a specific application.

[0100] The sample channel 1940 can be used to provide the test sample and the working film to the working electrode. Fig.19 As shown, the reference electrode is located below the sample channel 1940. The reference electrode includes a well 1933, a channel 1935, a conductive element 1937, another well 1939, and a stirring element 1950 (individually referred to as "stirring element 1950"). In some embodiments, the conductive element 1937 is arranged on the surface of the channel 1935. The channel 1935 is connected to the well 1933, forming a flow path for the fluid to the conductive element 1937. The channel 1935 is also connected to the well 1939. The well 1939 can be used as a vent through which air (for example, air from the solidification of the fluid) can be discharged from the reference electrode.

[0101] like Fig.19 As shown, the stirring element 1950 is connected to the wells 1933 and 1939 and the channel 1935. The stirring element 1950 can change the fluid flow in the flow path. In some embodiments, the stirring element 1950 is a coil, which can be energized by a radio frequency signal. The coil can stir, for example, a pulsed fluid within a defined proximity in response to the radio frequency signal. The characteristics of the coil (e.g., shape, construction, material, stacking of adjacent materials, etc.) can be determined based on the specific application of the electrochemical sensor 1900. The stirring element 1950 can be integrated with the sample channel 1940 so that an external radio frequency signal can be applied to the stirring element 1950. Although Fig.19Not shown, the electrochemical sensor 1900 may include a heating element to heat the fluid in the flow path. The stirring element 1950 may include an electroactive polymer or a piezoelectric material. The size or shape of the stirring element 1950 may be optimized according to the specific application of the electrochemical sensor and the required fluid operation.

[0102] Fig. 20A and 20B A reference electrode 2000 including multiple layers 2010, 2020, and 2030 is shown according to some embodiments of the present disclosure. Fig. 20A is a perspective view of the reference electrode 2000. Fig. 20B is a side view of reference electrode 2000. Layers 2010, 2020, and 2030 are stacked together along the Z axis. Layer 2020 is between layer 2010 and layer 2030.

[0103] like Fig. 20A As shown, layer 2010 includes wells 2040a, 2050a and 2060a, channels 2055a and 2065a, and valves 2070a and 2080a. Channel 2055a is connected to wells 2040a and 2050a to form a first flow path. Channel 2065a is connected to wells 2040a and 2060a to form a second flow path. Valve 2070a is coupled to channel 2055a to control the first flow path. Valve 2080a is coupled to channel 2065a to control the second flow path.

[0104] Similarly, the third layer 2030 includes traps 2040b, 2050 and 2060, channels 2055b and 2065b, and valves 2070 and 2080b. As shown, the traps 2050 and valves 2070 in the third layer 2030 corresponding to the traps 2050a and valves 2070a are covered by the second layer 2020, not shown. Channel 2055b is connected to traps 2040b and 2050a to form a first flow path. Channel 2065b is connected to traps 2040b and 2060 to form a second flow path. Valve 2070 in the third layer corresponding to valve 2070a is coupled to channel 2055b to control the first flow path. Valve 2080b is coupled to channel 2065b to control the second flow path. In some embodiments, each trap in the third layer 2030 can be aligned with the trap in layer 2010. For example, well 2040b can be aligned with well 2040a, well 2050 (not shown) can be aligned with corresponding well 2050a, and well 2060b can be aligned with well 2060b. In addition, channel 2055b can be aligned with channel 2055b, channel 2065b can be aligned with channel 2065b, or each layer can be operated independently using different / unaligned paths or networks. Fluid can also flow from the well or channel in layer 2010 to the corresponding well or channel in layer 2030 through layer 2020. In other embodiments, some or all of layers 2010, 2020 and 2030 can be operated independently. The flow path or flow network in one layer may be different from that in another layer. A layer may have a flow path or flow network (e.g., well, channel or both) that is not aligned with another layer. A system can be constructed so that fluid can flow laterally within a layer and between layers. This may make it possible for a system in which materials can be processed / analyzed in parallel on multiple layers.

[0105] The second layer 2020 includes valves 2090 (individually referred to as "valve 2090"). The valve 2090 controls the flow of fluid from the layer 2010 to the layer 2030. In other embodiments, the second layer 2020 may include a different number of valves 2090, and the valves 2090 may have different positions in the second layer 202. In some embodiments, the number or position of valves in the layer 2020 may be determined to enable fluid to flow between the layers 2010, 2020, and 2030. The number or position of valves in the layer 2020 may be determined based on the positions of the channels 2055a, 2055b, 2065a and 2065b, the wells 2040a, 2040b, 2050a, 2050 (not shown), 2060a and 2060, or other components (such as ports) in the layers 2010 or 2030. The number or position of valves in the layer 2020 may also be determined based on the requirements or processing steps of the system using the reference electrode 2000. The reference electrode 2000 can be used in a vertically integrated system where fluids can flow laterally within a single layer and vertically between layers. The lateral and vertical flows can be controlled by using valves. The valves used in the system can be constructed using the materials / structures described above. The shape / size / material / structure of the valve can be modified and optimized based on the specific requirements of the application.

[0106] Fig.21 Valves 2110 and 2120 are shown controlling an inlet 2130 and an outlet 2140 of a reference electrode 2100 according to some embodiments of the present disclosure. Valve 2110 is coupled to inlet 2130. When valve 2110 is open, fluid can flow into reference electrode 2100 through inlet 2130. Valve 2120 is coupled to outlet 2140. When valve 2120 is open, fluid can flow out of reference electrode 2100 through outlet 2140. Dashed lines represent example flow paths 2150 within reference electrode 2100.

[0107] Numerous other aspects can be seen from the above detailed description and the accompanying drawings. These aspects are indicated by the following clauses.

[0108] Item 1. A reference electrode in an electrochemical sensor, the reference electrode comprising: a substrate including an inner wall defining a flow path for a conductive medium; a conductive element in the substrate, wherein the conductive element is exposed at an end of the flow path; and a valve coupled to the flow path and configured to control the flow of the conductive medium through the flow path to the conductive element.

[0109] Item 2. The reference electrode described in Item 1 also includes: an additional flow path for the conductive medium, the additional flow path being arranged in the substrate; an additional conductive element in the substrate, wherein the additional conductive element is exposed at an end of the additional flow path; and an additional valve coupled to the additional flow path and configured to control the additional flow of the conductive medium through the additional flow path to the additional conductive element.

[0110] Clause 3. The reference electrode of Clause 2, wherein a portion of the flow path overlaps a portion of the additional flow path.

[0111] Clause 4. The reference electrode of any of Clauses 1-3, wherein the valve comprises an electroactive polymer configured to impede flow of the conductive medium in response to an electrical stimulus.

[0112] Item 5. A reference electrode as described in any of Items 1-4, wherein the flow path comprises: a well in the substrate, the well extending from a first surface of the substrate toward a second surface of the substrate, wherein the first surface is opposite to the second surface; and a channel arranged in the substrate and located between the first surface and the second surface, wherein a first end of the channel is connected to the well, the conductive element is exposed to a second end of the channel, and the first end is opposite to the second end.

[0113] Clause 6. The reference electrode of Clause 5, wherein the valve is disposed along a wall of the channel.

[0114] Item 7. The reference electrode of Item 6, further comprising: an additional conductive element in the substrate; an additional channel in the substrate connected to the well, wherein the additional conductive element is exposed to the additional channel; and an additional valve arranged along the additional channel.

[0115] Item 8. A reference electrode as described in any of Items 1-7, wherein the flow path comprises: a first well in the substrate, the first well extending from the first surface of the substrate toward the second surface of the substrate, wherein the first surface is opposite to the second surface; a second well in the substrate, the second well extending from the first surface toward the second surface, wherein the conductive element is exposed to the second well; and a channel arranged between the first surface and the second surface, wherein a first end of the channel is connected to the first well, a second end of the channel is connected to the second well, and the first end is opposite to the second end.

[0116] Clause 9. The reference electrode of Clause 8, wherein the valve is disposed in the channel.

[0117] Item 10. The reference electrode described in Item 9 also includes: a third well in the substrate; an additional conductive element in the substrate, wherein the additional conductive element is exposed to the third well; an additional channel connected to the first well and the third well; and an additional valve arranged along the additional channel.

[0118] Item 11. An electrochemical sensor comprising: one or more working electrodes in the substrate; and a reference electrode electrically coupled to the one or more working electrodes, the reference electrode comprising: a substrate including an inner wall defining a flow path of a conductive medium, a conductive element in the substrate, wherein the conductive element is exposed at an end of the flow path, and a valve coupled to the flow path and configured to control the flow of the conductive medium through the flow path to the conductive element.

[0119] Item 12. The electrochemical sensor described in Item 11 also includes: an additional flow path for the conductive medium, the additional flow path being arranged in the substrate; an additional conductive element in the substrate, wherein the additional conductive element is exposed at an end of the additional flow path; and an additional valve coupled to the additional flow path and configured to control the additional flow of the conductive medium through the additional flow path to the additional conductive element.

[0120] Clause 13. The electrochemical sensor of Clause 11 or 12, wherein the valve comprises an electroactive polymer configured to impede flow of the conductive medium in response to an electrical stimulus.

[0121] Clause 14. The electrochemical sensor of any of Clauses 11-13, further comprising one or more counter electrodes.

[0122] Clause 15. An electrochemical sensor as described in any one of clauses 11-14, wherein the flow path comprises: a first well in the substrate, the first well extending from the first surface of the substrate toward the second surface of the substrate, wherein the first surface is opposite to the second surface; a second well in the substrate, the second well extending from the first surface toward the second surface, wherein the conductive element is exposed to the second well; and a channel arranged between the first surface and the second surface, wherein a first end of the channel is connected to the first well, a second end of the channel is connected to the second well, the first end is opposite to the second end, and the valve is arranged on the channel.

[0123] Item 16. A reference electrode in an electrochemical sensor, the reference electrode comprising: a first layer comprising: a first flow path configured to facilitate a first flow of a conductive medium in the first layer, a first conductive element exposed to the first flow path, and a first valve coupled to the first flow path and configured to control the first flow of the conductive medium in the first layer; and a second layer located above the first layer, the second layer comprising: a second flow path configured to facilitate a second flow of the conductive medium in the second layer, a second conductive element exposed to the second flow path, and a second valve coupled to the second flow path and configured to control the second flow of the conductive medium in the second layer.

[0124] Clause 17. The reference electrode of Clause 16, further comprising a third layer located between the first layer and the second layer, wherein the third layer comprises a third flow path connected to the first flow path and the second flow path.

[0125] Clause 18. The reference electrode of Clause 17, wherein the third layer further comprises one or more third valves coupled to the third flow path, and the one or more third valves are configured to control the flow of the conductive medium from the first layer to the third layer.

[0126] Item 19. A reference electrode as described in any of Items 16-18, wherein the first flow path comprises: a well extending from a first surface of the first layer toward a second surface of the first layer, wherein the first surface is opposite to the second surface; and a channel arranged between the first surface and the second surface, wherein a first end of the channel is connected to the well, a first conductive element is exposed to a second end of the channel, the first end is opposite to the second end, and the first valve is arranged along the channel.

[0127] Clause 20. A reference electrode as described in any of clauses 16-19, wherein the first flow path comprises: a first well extending from a first surface of the first layer toward a second surface of the first layer, wherein the first surface is opposite to the second surface; a second well extending from the first surface toward the second surface, wherein the first conductive element is exposed to the second well; and a channel arranged between the first surface and the second surface, wherein a first end of the channel is connected to the first well, a second end of the channel is connected to the second well, and the first end is opposite to the second end, and the first valve is arranged along the channel.

[0128] It is understood that not all objects or advantages may be achieved according to any particular embodiment described herein. Thus, for example, those skilled in the art will recognize that certain embodiments may be configured to operate in a manner that achieves or optimizes one or a group of advantages taught herein without necessarily achieving other objects or advantages taught or suggested herein.

[0129] It must also be noted that all specifications, dimensions, and relationships (e.g., number of reference electrodes, channels, holes, etc.) outlined herein are for exemplary and didactic purposes only. Such information may be changed significantly without departing from the spirit of the present disclosure or the scope of the appended claims. These specifications apply only to one non-limiting example, and therefore, they should be interpreted as such. In the foregoing description, example embodiments have been described with reference to a specific arrangement of components. Various modifications and changes may be made to these embodiments without departing from the scope of the appended claims. Therefore, the specification and drawings should be regarded as illustrative, not restrictive.

[0130] Note that, through the numerous examples provided herein, interactions may be described in terms of two, three, four or more components. However, this is done for clarity and example purposes only. It should be understood that the system may be integrated in any suitable manner. Along similar design alternatives, any of the components, modules and elements shown in the figures may be combined in a variety of possible configurations, all of which are clearly within the broad scope of this specification.

[0131] Note that in this specification, references to various features (e.g., elements, structures, modules, components, steps, operations, characteristics, etc.) included in "one embodiment," "an example embodiment," and "a specific embodiment," "another embodiment," "some embodiments," and "various embodiments," "other embodiments," or "alternative embodiments," etc., are intended to indicate that any such features are included in one or more embodiments of the present disclosure, but may or may not be combined in the same embodiment.

[0132] Numerous other changes, substitutions, variations, alterations, and modifications may be ascertained by those skilled in the art, and the present disclosure may be intended to include all such changes, substitutions, variations, alterations, and modifications that fall within the scope of the appended claims. Note that all optional features of the above-described systems and methods may also be implemented with respect to the methods or systems described herein, and that the details in the examples may be used anywhere in one or more embodiments.

[0133] To assist the United States Patent and Trademark Office (USPTO) and any reader of any patent that issues from this application in interpreting the claims appended hereto, applicants wish to note that applicants: (a) do not intend to invoke 35 U.S.C. 112(f) as it existed on the date of filing this application, unless the term “means” or “step” is specifically used in a particular claim; and (b) do not intend, by any statements in the specification, to limit the present disclosure in any manner that may not be reflected in the appended claims.

Claims

1. A reference electrode in an electrochemical sensor, the reference electrode comprising: a substrate including an inner wall defining a flow path for the conductive medium; a conductive element in the substrate, wherein the conductive element is exposed at an end of the flow path; and A valve is coupled to the flow path and configured to control the flow of the conductive medium through the flow path to the conductive element.

2. The reference electrode according to claim 1, further comprising: an additional flow path for the conductive medium, the additional flow path being arranged in the substrate; an additional conductive element in the substrate, wherein the additional conductive element is exposed at an end of the additional flow path; and An additional valve is coupled to the additional flow path and is configured to control an additional flow of the conductive medium through the additional flow path to the additional conductive element.

3. The reference electrode according to claim 2, wherein a portion of the flow path overlaps a portion of the additional flow path.

4. The reference electrode according to any of the preceding claims, wherein the valve comprises an electroactive polymer configured to impede the flow of the conductive medium in response to an electrical stimulus.

5. A reference electrode according to any preceding claim, wherein the flow path comprises: a well in the substrate, the well extending from a first surface of the substrate toward a second surface of the substrate, wherein the first surface is opposite to the second surface; and A channel is arranged in the substrate and located between the first surface and the second surface, wherein a first end of the channel is connected to the well, the conductive element is exposed at a second end of the channel, and the first end is opposite to the second end.

6. The reference electrode according to claim 5, wherein the valve is arranged along the wall of the channel.

7. The reference electrode according to claim 6, further comprising: additional conductive elements in the substrate; an additional channel in the substrate connected to the well, wherein the additional conductive element is exposed to the additional channel; and An additional valve is arranged along the additional passage.

8. A reference electrode according to any one of the preceding claims, wherein the flow path comprises: a first well in the substrate, the first well extending from a first surface of the substrate toward a second surface of the substrate, wherein the first surface is opposite to the second surface; a second well in the substrate, the second well extending from the first surface toward the second surface, wherein the conductive element is exposed to the second well; and A channel is disposed between the first surface and the second surface, wherein a first end of the channel is connected to the first well, a second end of the channel is connected to the second well, and the first end is opposite to the second end.

9. The reference electrode according to claim 8, wherein the valve is arranged in the channel.

10. The reference electrode according to claim 9, further comprising: a third well in the substrate; an additional conductive element in the substrate, wherein the additional conductive element is exposed to the third well; an additional channel connected to the first well and the third well; and An additional valve is arranged along the additional passage.

11. An electrochemical sensor comprising: one or more working electrodes in the substrate; and a reference electrode electrically coupled to the one or more working electrodes, the reference electrode comprising: a substrate including an inner wall defining a flow path of a conductive medium, a conductive element in the substrate, wherein the conductive element is exposed at an end of the flow path, and A valve is coupled to the flow path and configured to control the flow of the conductive medium through the flow path to the conductive element.

12. The electrochemical sensor according to claim 11, further comprising: an additional flow path for the conductive medium, the additional flow path being arranged in the substrate; an additional conductive element in the substrate, wherein the additional conductive element is exposed at an end of the additional flow path; and An additional valve is coupled to the additional flow path and is configured to control an additional flow of the conductive medium through the additional flow path to the additional conductive element.

13. The electrochemical sensor of claim 11 or 12, wherein the valve comprises an electroactive polymer configured to impede the flow of the conductive medium in response to an electrical stimulus.

14. The electrochemical sensor according to any one of claims 11 to 13, further comprising one or more counter electrodes.

15. The electrochemical sensor according to any one of claims 11 to 14, wherein the flow path comprises: a first well in the substrate, the first well extending from a first surface of the substrate toward a second surface of the substrate, wherein the first surface is opposite to the second surface; a second well in the substrate, the second well extending from the first surface toward the second surface, wherein the conductive element is exposed to the second well; and A channel is arranged between the first surface and the second surface, wherein a first end of the channel is connected to the first well, a second end of the channel is connected to the second well, the first end is opposite to the second end, and the valve is arranged on the channel.

16. A reference electrode in an electrochemical sensor, the reference electrode comprising: The first layer includes: a first flow path configured to facilitate a first flow of the conductive medium in the first layer, a first conductive element exposed to the first flow path, and a first valve coupled to the first flow path and configured to control a first flow of the conductive medium in the first layer; and The second layer is located above the first layer, and the second layer includes: a second flow path configured to facilitate a second flow of the conductive medium in the second layer, a second conductive element exposed to the second flow path, and A second valve is coupled to the second flow path and configured to control a second flow of the conductive medium in the second layer. 17 . The reference electrode according to claim 16 , further comprising a third layer located between the first layer and the second layer, wherein the third layer comprises a third flow path connected to the first flow path and the second flow path.

18. The reference electrode of claim 17, wherein the third layer further comprises one or more third valves coupled to the third flow path, and the one or more third valves are configured to control the flow of the conductive medium from the first layer to the third layer.

19. The reference electrode according to any one of claims 16 to 18, wherein the first flow path comprises: a well extending from a first surface of the first layer toward a second surface of the first layer, wherein the first surface is opposite to the second surface; and A channel is arranged between the first surface and the second surface, wherein a first end of the channel is connected to the well, a first conductive element is exposed at a second end of the channel, the first end is opposite to the second end, and the first valve is arranged along the channel.

20. The reference electrode according to any one of claims 16 to 19, wherein the first flow path comprises: a first well extending from a first surface of the first layer toward a second surface of the first layer, wherein the first surface is opposite to the second surface; a second well extending from the first surface toward the second surface, wherein the first conductive element is exposed to the second well; and A channel is arranged between the first surface and the second surface, wherein a first end of the channel is connected to the first well, a second end of the channel is connected to the second well, and the first end is opposite to the second end, and the first valve is arranged along the channel.

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