Electrode degradation mitigation methods and systems utilizing polarity switching electrostatics

Abstract

A method (100) for mitigating electrode degradation in saline conditions can include exposing (110) an electrolytic cell to a saline environment. The electrolytic cell can comprise a first electrode, a second electrode, and a polarity switching circuit. The first electrode and the second electrode can form a primary electrode gap oriented in a primary plane. The polarity switching circuit can be capable of alternatingly applying a positive charge or a negative charge to each of the first and second electrodes. A polarity switching mode (120) can be initiated using the polarity switching circuit to drive at least a portion of ions at least the Debye length from each of the first electrode and the second electrode within an ion repulsion zone. An electrolysis mode (130) can be initiated within a delay time of completing the polarity switching mode to perform an electrolysis stage.

Description

[0001] PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0002] ELECTRODE DEGRADATION MITIGATION METHODS AND SYSTEMS UTILIZING POLARITY SWITCHING ELECTROSTATICS

[0003] CROSS REFERENCE TO RELATED APPLICATIONS

[0004] This application claims priority to U.S. Provisional Application 63 / 746,421, filed January 17, 2025 and U.S. Provisional Application 63 / 794,592, filed April 25, 2025, which are each incorporated by reference.

[0005] STATEMENT REGA DING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0006] This invention was made with government support under DE-AR0001836 awarded by the U.S. Department of Energy / ARP A-e. The government has certain rights in the invention.

[0007] BACKGROUND

[0008] A carbon dioxide monitoring system incorporating an electrolytic bubble-based sensor can help to increase the ocean's potential as a carbon sink and help mitigate climate concerns. Although testing has shown the sensor's effectiveness across different environmental conditions, the presence of heightened sodium chloride in the ocean has posed significant challenges, as the electrolytic reaction at the anode produces toxic chlorine gas (CL). This not only poses an environmental risk but is also a primary factor in the degradation and shortened lifespan of electrolytic-based metal electrodes (~l-7 days) due to highly corrosive interaction of CI2 with most metals. Among common causes of electrode degradation in ocean-based electrolytic devices, including biofouling and ion particulate accumulation, the production of CI2 in the presence of sodium and chlorine ions, which constitute approximately 85% of the ocean’s ionic content, is particularly destructive, as CI2 can combine with other common oceanic ions, such as magnesium or potassium, to form other corrosive compounds that rapidly and severely damage electrodes.

[0009] Several technologies have been developed to enhance oxygen evolution reaction (OER) for seawater electrolysis, with the gold standard being the use of an electrostatic polyanion layer, semi-permeable membrane layer, or a pH buffer layer to prevent chlorinePATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0010] ions from reaching the primary electrolytic electrodes. However, this approach is unsuitable for some systems such as a bubble sensor system, because a typical dielectric-based polymer membrane significantly reduces the conductivity of the bubble-generating electrode, lowering bubble generation efficiency by several magnitudes.

[0011] SUMMARY

[0012] A method for mitigating electrode degradation in saline conditions can include exposing an electrolytic cell to a saline environment. The saline environment can include native ions and can have a Debye length. The electrolytic cell can comprise a first electrode, a second electrode, and a polarity switching circuit. The first electrode and the second electrode can be spaced apart from one another to form a primary electrode gap oriented in a primary plane (see FIG. 2 for one example). The polarity switching circuit can be electrically connected to each of the first electrode and the second electrode. Further, the polarity switching circuit can be capable of alternatingly applying a positive charge or a negative charge to each of the first electrode and second electrode.

[0013] The method can further include initiating a polarity switching mode using the polarity switching circuit, where at least one positive pulse and at least one negative pulse are alternately applied across the primary electrode gap to drive at least a portion of the ions at least the Debye length from each of the first electrode and the second electrode within an ion repulsion zone. The first electrode and the second electrode have opposite charges during the polarity switching mode. Further, at least one positive pulse has a positive pulse amplitude and a positive pulse duration, and the at least one negative pulse has a negative pulse amplitude and a negative pulse duration.

[0014] The method can further include initiating an electrolysis mode within a delay time of completing the polarity switching mode to perform an electrolysis stage.

[0015] In one specific example, an electrolytic cell for use in a saline environment can include a first electrode, a second electrode, a third electrode, and a polarity switching circuit. The first electrode and the second electrode can be spaced apart from one another to form a primary electrode gap oriented in a primary plane. The third electrode can be spaced apart from the first electrode and the second electrode to form a secondary electrode gap wherePATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0016] the third electrode is non-coplanar with the primary plane and electrically connected to the first electrode such that at least one voltage can be maintained across the first electrode gap and the second electrode gap. The polarity switching circuit can be electrically connected to each of the first electrode, the second electrode and the third electrode, and can be capable of alternatingly applying a positive charge or a negative charge to each of the first electrode, second electrode and third electrode. The conditions and device options described above in connection with the methods also apply to this section focusing on the device.

[0017] Further, an electrolytic system can include a plurality of the electrolytic cells oriented in a common substrate.

[0018] There has thus been outlined, rather broadly, the more important features of the invention so that the detailed description thereof that follows may be better understood, and so that the present contribution to the art may be better appreciated. Other features of the present invention will become clearer from the following detailed description of the invention, taken with the accompanying drawings and claims, or may be learned by the practice of the invention.

[0019] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process flow diagram of one example method consistent with examples of the present disclosure.

[0020] FIG. 2 is a schematic of a bubble sensor with integrated planar and elevated antidegradation units to reduce degradation overtime in sea water due to chlorine evolution reaction by repelling oceanic ions consistent with one example.

[0021] FIG. 3A-3H is a schematic illustration of the planar and elevated anti-degradation units acting as electrodes and utilize a polarity switching mechanism to repel unwanted ions away from the bubble producing electrode to prevent chlorine evolution reaction and longterm ion accumulation / degradation by taking advantage of the short Debye length where repelled ions will not be directly attracted back during electrolysis in accordance with another example.

[0022] FIG. 4A is schematic illustration of a copper mesh integrated on a common substrate, such that the fabrication can be done on a single wafer, providing a smaller gap distance toPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0023] the bubble producing electrode for high current density and improved ion repulsion in accordance with another example.

[0024] FIG. 4B is a side view of a section 401 of FIG. 4A.

[0025] FIGs. 5A-5I are schematic side views showing various steps for forming antidegradation units integrated with previously developed bubble sensor, in which a Pt planar unit was fabricated on the sensor die and the elevated unit was developed by integrating a copper mesh into the PDMS microchannel in accordance with still another example.

[0026] FIG. 6 is a picture of a bubble producing electrode set having two supply electrodes and a bubble generating electrode having a notched profile in accordance with one example.

[0027] FIG. 7 is a picture of a copper mesh integrated as an out-of-plane electrode as an elevated anti-degradation unit in accordance with the example of FIG. 6.

[0028] FIG. 8A is a schematic illustration of a macro-scale experiment showing the capability of the anti -degradation electrode to prevent chlorine production during electrolysis using Great Salt Lake water in accordance with another example.

[0029] FIG. 8B is a schematic illustration of a macro-scale experiment showing a standard electrolysis electrode using Great Salt Lake water in accordance with the prior art for comparison.

[0030] FIG. 9 is a graph of chlorine gas produced by the proposed sensor reduced the CI2 production by approximately 89% compared to the original bubble sensor verified using GCMS measurements in accordance with one example.

[0031] FIG. 10A is a graph of the capacitance measurement of one example bubble sensor over 5 days in the Great Salt Lake water, showing 5.85% deviation by the fifth day (7.9x improvement over original sensor).

[0032] FIG. 1 OB is a graph of the capacitance measurement of the original (non-invention) bubble sensor over 5 days in the Great Salt Lake water, showing 45.91% deviation by the fifth day. Note that degradation measurement is based on day-to-day capacitance change.

[0033] FIG. 11 A-l II is a process flow diagram for forming anti-degradation units integrated with previously developed bubble sensor having a mesh electrode in accordance with another example.PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0034] FIG. 12A-12C are SEM images showing the accumulation over time on a copper mesh surface at 30 minutes, 5 days, and 7 days utilizing an SEM image with EDS elemental spectral analysis in accordance with an example.

[0035] FIG. 13 is an illustration showing that by applying a voltage across the sensor where the cathode is on the copper mesh, the copper oxide on the mesh reduces and is etched away, peeling off any accumulated ions and biofouling that was on it. With the copper mesh, a voltage supply of 3 V (9 mW) over 10 s was sufficient in cleaning the electrode in this example.

[0036] FIG. 14 is a graph of the accumulated ions and biofouling overtime on the copper mesh and its relation to the >10% deviation point on previous bubble sensor results in this example.

[0037] FIG. 15 is a graph of the oxide thickness on copper mesh over time and the energy needed to etch the oxide off the copper surface in accordance with another example.

[0038] These drawings are provided to illustrate various aspects of the invention and are not intended to be limiting of the scope in terms of dimensions, materials, configurations, arrangements or proportions unless otherwise limited by the claims.

[0039] DETAILED DESCRIPTION

[0040] While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that various changes to the invention may be made without departing from the spirit and scope of the present invention. Thus, the following more detailed description of the embodiments of the present invention is not intended to limit the scope of the invention, as claimed, but is presented for purposes of illustration only and not limitation to describe the features and characteristics of the present invention, to set forth the best mode of operation of the invention, and to sufficiently enable one skilled in the art to practice the invention. Accordingly, the scope of the present invention is to be defined solely by the appended claims.

[0041] DefinitionsPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0042] In describing and claiming the present invention, the following terminology will be used.

[0043] The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “an ion” includes reference to one or more of such materials and reference to “the electrode” refers to one or more of such devices.

[0044] As used herein with respect to an identified property or circumstance, “substantially” refers to a degree of deviation that is sufficiently small so as to not measurably detract from the identified property or circumstance. The exact degree of deviation allowable may in some cases depend on the specific context.

[0045] As used herein, “adjacent” refers to the proximity of two structures or elements. Particularly, elements that are identified as being “adjacent” may be either abutting or connected. Such elements may also be near or close to each other without necessarily contacting each other. The exact degree of proximity may in some cases depend on the specific context.

[0046] As used herein, the term “about” is used to provide flexibility and imprecision associated with a given term, metric or value. The degree of flexibility for a particular variable can be readily determined by one skilled in the art. However, unless otherwise enunciated, the term “about” generally connotes flexibility of less than 2%, and most often less than 1%, and in some cases less than 0.01%.

[0047] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary.

[0048] As used herein, the term “at least one of’ is intended to be synonymous with “one or more of.” For example, “at least one of A, B and C” explicitly includes only A, only B, only C, or combinations of each.PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0049] Numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numerical range of about 1 to about 4.5 should be interpreted to include not only the explicitly recited limits of 1 to about 4.5, but also to include individual numerals such as 2, 3, 4, and sub-ranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges reciting only one numerical value, such as “less than about 4.5,” which should be interpreted to include all of the above-recited values and ranges. Further, such an interpretation should apply regardless of the breadth of the range or the characteristic being described.

[0050] Any steps recited in any method or process claims may be executed in any order and are not limited to the order presented in the claims. Means-plus-function or step-plus-function limitations will only be employed where for a specific claim limitation all of the following conditions are present in that limitation: a) “means for” or “step for” is expressly recited; and b) a corresponding function is expressly recited. The structure, material or acts that support the means-plus function are expressly recited in the description herein. Accordingly, the scope of the invention should be determined solely by the appended claims and their legal equivalents, rather than by the descriptions and examples given herein. Example Embodiments

[0051] A technology is described for the utilization of electrodes to facilitate oxygen evolution reaction (OER) with reduced or eliminated detrimental effects to a primary electrolytic process under saline environments. Through the use of polarity-switching electrostatics, ions that could degrade electrodes during the electrolytic process are repelled into an ion-repulsion zone where they largely remain trapped due to being outside the range of the electrostatic force, constrained by the Debye length within the oceanic conditions or other saline body. This technology takes advantage of the short Debye length in the ocean, such that ions are repelled from the primary electrolytic electrode and are not attracted back with the polarity switch as it is unaffected by the electrostatic force due to the ions repelling beyond the electric field Debye length. This design also reduces power consumption byPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0052] employing micro-scale integration such that the power consumption can be reduced when going through the process of repelling the oceanic ions.

[0053] Table 1 summarizes common technologies to facilitate OER or the reduction of chlorine evolution reaction (CER) and other previously mentioned parameters compared to one example of the invention (i.e. polarity switching electrostatics).

[0054] Table 1: Table of the State-of-the-Art Technology that facilitates oxygen evolution reaction in seawater electrolysis compared to polarity switching electrostatics.

[0055]

[0056] Most of the state-of-the-art technology show slightly superior ability in reducing the Ch production with no external power needed for activation in comparison to the proposed idea; however, all of the state-of-the-art technology appear to vastly reduce the electrolytic efficiency of the electrode when integrating the OER facilitation layer leading to heighted response time if integrated into the bubble sensor due to the interference with the electrolytic generation of the bubble.

[0057] Referring to FIG. 1, a method 100 for mitigating electrode degradation in saline conditions can include exposing an electrolytic cell to a saline environment 110. The method 100 can further include initiating a polarity switching mode 120 using the polarity switching circuit. The method 100 can further include initiating an electrolysis mode 130 within a delay time of completing the polarity switching mode to perform an electrolysis stage.PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0058] The saline environment can include native ions and can have a Debye length. These methods can be practiced in any saline environment which tends to be corrosive of electrodes during electrolysis. Non-limiting examples of saline environments can include ocean water, sea water, salt lake water, salt playa water, and industrial brine. Typically, the methods and sensors described herein can be practiced in situ within these bodies of water; however, in some cases, volumes of water can be removed and directed to ex situ processing locations such as a dedicated vessel, lab, or other non-native environment. Regardless, the saline environment can exhibit varied chemistry depending on the location and temperature of the body of water. In some cases, the native ions include both positive ions and negative ions and include one or more of sodium, chlorine, magnesium, potassium, sulfate, bicarbonate, strontium, bromide, borate, fluoride, silicate, and iodide. As a general guideline, the saline environment can have a salinity from about 1% to about 40% (e.g. Dead Sea), and in some cases about 2% to about 10%, such as about 3.5%.

[0059] FIG. 2 illustrates one example configuration for an electrolytic cell 200 which can be used in connection with the method. The electrolytic cell 200 can include a first electrode 202, a second electrode 204, and a polarity switching circuit 206. The first electrode and the second electrode can be spaced apart from one another to form a primary electrode gap 208 oriented in a primary plane (see FIG. 1 for one example). The polarity switching circuit 206 can be electrically connected to each of the first electrode 202 and the second electrode 204. Further, the polarity switching circuit 206 can be capable of altematingly applying a positive charge or a negative charge to each of the first electrode 202 and second electrode 204.

[0060] Although the electrodes can be formed in various configurations, in one example, the first electrode 202 and the second electrode 204 are planar and formed along the primary plane. In some examples, the first electrode and second electrode are formed as interdigitated electrodes. In some cases, these electrodes can be formed on a common substrate 209. As illustrated in FIG. 2, in some cases the electrodes can further include a co-electrode 205 electrically connected to the second electrode such that they share a common charge. Such co-electrodes 205 can be particularly useful when forming oxygen bubble generating electrodes. In general, any electrode pattern or configuration can achieve the intended anti-PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0061] degradation capabilities as long as the anode and cathode can conduct within an aqueous solution, creating an electric field from the anode towards the cathode.

[0062] The primary electrode gap 208 can be chosen based on a balance of providing sufficient distance beyond the Debye length to allow a suitable volume for the ion repulsion zone and power consumption constraints. In some examples, the primary electrode gap ranges from 100 pm to 200 pm; however, in general, an electrode gap distance greater than two times the Debye length (>13 nm for oceanic conditions) is sufficient to repel ions beyond the Debye length from each electrode intended to operate during later electrolysis (e.g. gap ranges from 26 pm to about 200 pm may be used). The gap distance can vary depending on the application, as it directly influences the electric field and, consequently, the electrostatic force. While a larger gap distance reduces the electric field strength by a function of the squared distance, a higher input voltage can compensate for this reduction. In one specific application, the gap distance was chosen to provide a 1 V input which generates an electrostatic force of 4.61 x 10’17N, sufficient to overcome the primary stiction force of the ions while avoiding potential electrolysis reaction during the polarity switching mode.

[0063] The Debye length can be a function of saline solution chemistry and temperature as described in more detail in the following section. In some examples, the Debye length is about 13 nm, and in some cases is 1 nm to 20 nm, in some cases 3 nm to 15 nm. As mentioned, the described mechanism utilizes polarity switching units to electrostatically repel positive and negative ions, preventing Ch production and the formation of large precipitates. Although the electrostatic repulsion is constrained by the short Debye length in seawater (e.g. ~13nm), the technique leverages this limited range to create an ion repulsion zone, where ions near the electrodes are repelled while those farther away remain unaffected during the polarity switch as they lie beyond the Debye length (FIG. 3A-3H). Note that the Debye length was calculated utilizing Eq. 1, where e0is permittivity constant, eris the relative permittivity, kbis the Boltzmann constant, T is the absolute temperature in Kelvin, n is the number density of ions per unit volume and e is the elementary charge.

[0064]

[0065] PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0066] Regardless, the electrodes can be formed of any suitable conductive materials. Nonlimiting examples of suitable conductive materials include copper, gold, chromium, silver, platinum, and graphite. Among these, platinum and graphite are particularly well-suited for electrolytic applications due to their high conductivity and relative inertness.

[0067] As generally illustrated in FIG. 3A-3H, the polarity switching mode can include at least one positive pulse and at least one negative pulse which are alternately applied across the primary electrode gap 208 to drive at least a portion of the ions at least the Debye length from each of the first electrode 202 and the second electrode 204 within an ion repulsion zone 210. The first electrode and the second electrode have opposite charges during the polarity switching mode. Further, the at least one positive pulse has a positive pulse amplitude and a positive pulse duration, and the at least one negative pulse has a negative pulse amplitude and a negative pulse duration.

[0068] FIG. 3A illustrates an initial state of the first electrode 202 and second electrode 204 where at least some ions including positive ions 212 and negative ions 214 are located adjacent a surface of the electrodes within the Debye length. FIG. 3A-3H only show four ions for clarity in illustration, while actual numbers of ions will normally be much greater. FIG. 3B shows a first step of the polarity switching mode, where a positive pulse is applied to form a positive electric field 216 and a negative electric field 218 extending the Debye length into the primary electrode gap 208. During this step, positive ions 212 migrate away from the surface due to electrostatic repulsion from the positive electric field 216. The pulse duration and magnitude can be chosen such that the positive ions 212 migrate out of the positive electric field 216. Similarly, any negative ions 214 associated with the second electrode 204 migrate out of the negative electric field 218. This can be achieved through a single positive pulse or multiple positive pulses alternated with multiple negative pulses. As illustrated in FIG. 3C, during a subsequent step, the polarity of each of the first and second electrodes is switched to form a positive electric field 216 associated with the second electrode 204 and a negative electric field 218 associated with the first electrode 202. In this manner, negative ions 214 which are oriented within the negative electric field 218 migrate away from the first electrode 202 and into the ion repulsion zone 210. At an end of the polarity switching mode, at least a portion of the positive ions 212 and the negative ions 214PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0069] have been driven into the ion repulsion zone 210 through successive application of positive and negative fields from each electrode.

[0070] The degree to which native ions are partially or fully driven into the ion repulsion zone can depend on factors such as pulse duration, pulse magnitude, number of pulses, and liquid conditions such as temperature and salinity. In some cases, the portion can include a majority of the native ions, in some cases includes greater than 95% of the native ions, and in other cases can include substantially all of the native ions.

[0071] The polarity switching circuit 206 can be formed on a common substrate (e.g. wafer) with the first and second electrodes, or can be formed separately. In some cases, the polarity switching circuit 206 can be operatively connected with multiple electrolytic cells 200 for simultaneous or independent operation from one another. Polarity switching can be achieved using various switching circuits, including but not limited to, DPDT switches, MOSFET-based switches, or timer-based IC switches. For applications involving underwater use, MOSFET -based and timer-based IC switching are particularly advantageous as they enable remote operation, making them more practical and effective for consumer applications.

[0072] The positive and negative pulses of the polarity switching can be adjusted based on saline chemistry, temperatures, and other factors. However, the positive and / or negative pulse amplitudes are typically maintained between -1.23 V and 1.23 V to prevent electrolytic reactions, as this range corresponds to the water breakdown voltage according to Gibbs free energy. The polarity switching mode is intended to prevent and mitigate sensor degradation caused by chlorine gas production during subsequent electrolytic reactions. This polarity switching mode can be achieved by repelling the ions associated with these later reactions, and ensuring that no or substantially no electrolytic reaction occurs during this stage. Notably, the polarity switching mode can be performed using either an initial positive or initial negative pulse from the first electrode.

[0073] In terms of the polarity pulsation duration, both positive and negative pulsing can be done in pulse durations ranging from 1 sec to 30 minutes for each polarity during the application. The number of pulses in each polarity can be varied depending on the conditions. However, as a general guideline, at least one positive pulse and at least one negative pulse can be performed, with subsequent pulses being less effective.PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0074] In some cases, it can be desirable to add a vertical elevated component (i.e. out of the primary plane) to the polarity switching driving force. Referring to FIG. 2, the electrolytic cell 200 can optionally further comprise a third electrode 220 spaced apart from the first electrode 202 and the second electrode 204 to form a secondary electrode gap 222 (shown in FIG. 3E-3H) where the third electrode 220 is non-coplanar with the primary plane. Note that FIG. 2 is shown with the third electrode 220 recessed in a chamber housing 224 which is illustrated in a disassembled position spaced away from the substrate 209. In one alternative, the third electrode 220 can be formed as a conductive mesh oriented in a secondary plane parallel to the primary plane and spaced apart by the secondary electrode gap 222. This mesh design is meant to encase the top of the primary electrolytic reacting electrode measuring 250 x 750 pm2to produce the z-axis repulsion. However, this design can vary in dimension based on the design of the primary electrolytic electrode ranging in the pm to mm scale. Copper can be a desirable material utilized for the mesh design, as it has the added capability to improve the electrode cleaning by removing its oxide which subsequently removes any excess ions that may attached to the electrode’s oxide layer. Otherwise, and conductive metals, such as gold, platinum, silver, or aluminum can also be utilized. In one example, the electrolytic cell can be formed on the microscale by integrating platinum (Pt)-based or other conductive materials as planar anti-degradation units (e.g. first and second electrodes) and a commercialized copper mesh as an elevated anti-degradation unit (e.g. third electrode) within a microfabricated bubble-based sensor, designed to repel ions from the bubble-generating electrode both vertically and horizontally (FIG. 2).

[0075] In these examples with a third electrode as an elevated component, the method can further comprise initiating a secondary polarity switching mode using the polarity switching circuit, wherein at least one positive pulse and at least one negative pulse are alternately applied across the secondary electrode gap to drive at least a portion of the ions at least the Debye length from each of the first electrode, the second electrode and the third electrode. Notably, the out-of-plane polarity switching can be performed simultaneously with the primary plane, or separately.

[0076] FIG. 3E-3H illustrate one example where the polarity switching mode occurs simultaneously with the first electrode and second electrode and are side views rather thanPATENT APPLICATION Attorney Docket No. 008464J8646.PCT

[0077] elevated views as in FIGs. 3A-3D. FIG. 3E illustrates an initial state of the first electrode 202 and third electrode 220 where at least some ions including positive ions 212 and negative ions 214 are located adjacent a surface of the electrodes within the Debye length. FIG. 3F shows the first step of the polarity switching mode, where the positive pulse is applied to form the positive electric field 216 and the negative electric field 218 extending the Debye length into the secondary electrode gap 222. During this step, positive ions 212 migrate away from the surface due to electrostatic repulsion from the positive electric field 216. The pulse duration and magnitude can be chosen such that the positive ions 212 migrate out of the positive electric field 216. Similarly, any negative ions 214 associated with the second electrode 204 migrate out of the negative electric field 218. As discussed previously, this can be achieved through a single positive pulse or multiple positive pulses alternated with multiple negative pulses. As illustrated in FIG. 3G, during a subsequent step, the polarity of each of the first and third electrodes is switched to form a positive electric field 216 associated with the third electrode 220 and a negative electric field 218 associated with the first electrode 202. In this manner, negative ions 214 which are oriented within the negative electric field 218 migrate away from the first electrode 202 and into the ion repulsion zone 210. At an end of the polarity switching mode, at least a portion of the positive ions 212 and the negative ions 214 have been driven into the ion repulsion zone 210 through successive application of positive and negative fields from each electrode.

[0078] In some examples, the third electrode does not operate during electrolysis such that electrolysis occurs in the primary plane. In this case, the secondary electrode gap 222 can be at least the Debye length (i.e. since the ions need to only be repelled from the first and second electrodes). In some alternatives, the third electrode 220 can operate during electrolysis either in series or in parallel with the first electrode 202 and second electrode 204. In these cases, the secondary electrode gap 222 can be at least twice the Debye length, as discussed above.

[0079] Once the polarity switching mode is completed, although the ions are now concentrated in the ion repulsion zone, without an applied voltage, the ions can tend to diffuse back toward the electrodes over time. Accordingly, the delay time before beginning electrolysis can be chosen to reduce the number of ions the migrate back to electrodePATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0080] surfaces. Acceptable delay times can also be a function of device design such as size of adjacent fluid chambers, microfluidic channels, location and size of fluid inlets to surrounding environment, etc. Such factors can also impact the amount of fluid flow versus static fluid. In some examples, the delay time is less than 10 minutes, in some cases less than 5 minutes, in some cases less than 1 minute, and in some cases less than 50 seconds.

[0081] The electrolysis mode can then be initiated. The electrolysis stage can be any suitable electrolytic reaction and application. Non-limiting examples of suitable electrolysis stages can include oxygen bubble generation (e.g. for use in CO2 sensors), desalination of seawater, and the like. In some examples, the electrolysis stage is oxygen bubble production for use as a CO2 sensor. One exemplary CO2 sensor is described in Tran, S., Noh, M., Kim, H. Hilton Head Workshop 2024: A Solid-State Sensors, Actuators and Microsystems Workshop and U.S. Provisional Patent Application No. 63 / 650,059, filed May 21, 2024 which are each incorporated herein by reference. In another example, an electrolysis stage can be utilized for desalination as described in Jiang, Q., Han, Y., Tang, W., et al. Nano Energy journal paper titled “Self-Powered Seawater Desalination and Electrolysis Using Flowing Kinetic Energy” published in July 2015 which is also incorporated herein by reference.

[0082] Performing the polarity switching mode can substantially reduce formation of undesirable chlorine gas. Accordingly, when the subsequent electrolysis stage is performed in the presence of chlorine ions the electrolysis can result in a reduction of chlorine gas production by at least 80% compared to electrolysis under common conditions performed without the polarity switching mode. Similarly, when electrolysis is performed after the polarity switching mode, the electrolysis can also often result in less than 1 ppm of CI2 production, and in some cases less than 0.85 ppm.

[0083] Despite the above-mentioned improvements, in some cases, there can still be some degradation in performance of the electrodes due to biofouling and oxidation at electrode surfaces over time. Accordingly, the methods can also optionally include initiating a reconditioning mode using the polarity switching circuit after the electrolysis stage. In this case, a polarity across the primary electrode gap (and optionally the secondary electrode gap) can be reversed with respect to the electrolysis stage at least once to reverse at least one ofPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0084] biofouling deposits and oxidation / reduction products at surfaces of the first electrode and the second electrode.

[0085] Advantageously, due to the design and operation of the electrolytic cell, the electrolytic cell can generally be free of barrier layers including membranes, electrostatic polyanion layers, and pH buffer layers. In particular, the cell can be free of such barrier layers oriented between the electrodes and the saline environment. This can dramatically decrease cost and improve long term performance.

[0086] Further, an electrolytic system can include a plurality of the electrolytic cells. In some cases, the plurality of electrolytic cells are oriented in a common substrate, although multiple electrolytic cells on separate substrates can be mechanically and electrically connected.

[0087] As generally illustrated in FIG. 2, in some cases the system can further include a chamber formed around the electrodes to allow fluid from the saline environment to collect with modest to no fluid flow. In another example, at least one microfluidic channel can be formed on the common substrate and can be adapted to direct a saline solution from the saline environment through the at least one microfluidic channel. In the example illustrated in FIG.

[0088] 2, the chamber housing 224 can substantially enclose a fluid environment and include a single opening 226 to allow fluid communication of fresh saline water into the enclosed fluid environment. In other examples, multiple openings can be provided to allow introduction and removal of fluid from the chamber. In one optional alternative, a micro-pump circuit can be included to allow for forced fluid flow into and / or out of the chamber. Such an additional pump can provide fresh saline samples into contact with the electrolytic cell.

[0089] In one example, the at least one microfluidic channel includes a base substrate and a polymer ceiling. In another more detailed example, the base substrate comprises a ceramic (e g. glass) and the polymer ceiling comprises PDMS.

[0090] In still another example, the elevated electrode (e.g. third electrode) can be integrated on a common substrate with the first and second electrodes. FIG. 4A and 4B show an electrolytic bubble sensor similar in many respects to that illustrated in FIG. 2. An electrolytic electrode assembly 402can include a primary bubble-generating electrode 404 and a pair of anti-corrosion electrodes 406 spaced apart on either side of the primaryPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0091] electrode 404 and supported on a support substrate 416. In this example, a set of two electrolytic electrode assemblies 402 are provided. A protective mesh electrode 410 can be oriented over the primary electrode 404 with an intervening interfacial dielectric layer 412 to prevent shorting between the primary electrode and the mesh electrode. However, in this case, the third electrode 410 is formed by integrating the Cu mesh directly within the top side of the PDMS microchannel with a 1 mm gap between electrode 404. A set of interdigitated electrodes 414 can also be provided to supply power to the protective mesh electrode 410. Note that the wafer substrate includes each of the bubble generating electrode 404, ionrepelling electrodes 406, and the interdigital capacitive sensing electrodes 414.

[0092] In one example, the mesh structure can also be modified such that the mesh covering will prevent accumulation of the ions through the release of oxide layer on the mesh surface. This cleaning can be accomplished when the mesh electrode (410), is made of copper (only copper). Over time, as this copper mesh electrode is submerged in water, an oxide layer builds on top of the mesh in the form of copper oxide. Additionally, particles such as NaCl will naturally build up on the electrode over time due to the constant diffusion of particles when the electrostatic repulsion is not enacted. However, these ions can be removed when the electrostatics repulsion via polarity switching is done, as this subsequently peels off the oxide layer through an oxidation reaction when the voltage from the polarity switch mechanism is applied across the Cu mesh, removing the oxide layer and the particulates that may be a top it while repelling other ions as initially intended. The oxide layer will then rapidly form again within 1 -5 minutes, acting as an additional protective layer for the primary electrolytic electrode.

[0093] The protective Cu mesh electrode can form a passivating oxide layer which protects the primary electrochemical electrodes from potential degradation. In operation, a small voltage can then be applied to the Cu mesh to electrochemically etch that naturally forming nanometer-scale oxide layer from the surface of the primary electrode, effectively removing accumulated ions and biological material on the primary electrode surface. In the presence of oxygen, this metal mesh electrode layer will naturally regenerate its oxide layer again, making this process continuously reusable. By integrating the polarity-switching electrostatics with the oxide electrochemical etching layer electrochemical processes such asPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0094] electrolysis can be sustained in high-salinity environments for extended periods without significant sensor degradation. This is primarily due to the oxide etching mechanism effectively resetting the device to its original state, mitigating the effects of corrosion and biofouling as described throughout this specification. In this manner, the combined integration of both the electrochemical etching of passivating oxide mesh electrodes along with the polarity switching electrodes can be operated such that biofouling and corrosion is mitigated. As discussed herein, through the use of polarity-switching electrostatics, ions that could degrade electrodes during the electrolytic process are repelled into the "ion-repulsion zone" where they remain trapped due to being outside the range of the electrostatic force, constrained by the Debye length within oceanic conditions. This prevents the production of corroding Ch gas when the electrochemical etching mechanism or the bubble generation activity in enacted. The mesh electrode can be composed of a metal that can naturally produce oxide, such as but not limited to copper, and will naturally form a passivating oxide layer in the presence of oxygen. As an example, this oxide layer on the mesh electrode can be chemically reduced with a small electrolytic voltage of 1.5 V, resulting in the oxide peeling off, along with any accumulating ion, debris, or biofouling on the surface returning the sensor to its original stage. In this way the oxide layer will then automatically and rapidly regenerate, providing continuous layers of protection of biofouling and ion accumulation of the sensors electrodes which can be electrochemically etched / peeled off to regularly clean the electrode surface.

[0095] Example 1

[0096] A low-power (e.g. 3 uW in one example) polarity-switching package was formed that encases an electrode to significantly reduce degradation in seawater conditions by electrostatically repelling oceanic ions (e.g., sodium, chlorine, magnesium, potassium) towards the ion repulsion zone. Initial experimental results showed that such a package enhanced the oxygen evolution reaction (OER), the generation of oxygen molecules through a chemical reaction in water, while reducing CE production and electrode degradation by 89% and 87%, respectively, without affecting the primary electrolytic process.

[0097] The example sensor was fabricated including a structure with integrated antidegradation units in two main stages: electrode development and microchannel developmentPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0098] (FIG. 5A-5I). The Pt-based planar electrode (50 x 375 pm2), positioned 100 pm away, repels ions on the plane, while the copper mesh (10 x 15 mm2) anti-degradation unit, elevated 2 mm above the plane, repels ions vertically (FIG. 3A-3H). This dual ion repulsion mechanism directs most oceanic ions toward the ion repulsion zone, taking advantage of the short Debye length in seawater to mitigate CL production and reduce electrode degradation.

[0099] During testing, each polarity cycle lasted 10 seconds (FIG. 3A-3H), and the electrostatic force was calculated using Eq. 2 and Eq. 3, where E is the electric field, V is the voltage, d is the distance between the ion and electrode, F is the electrostatic force, and n is the elementary charge.

[0100] E = Va

[0101] F = nE

[0102]

[0103] Note that a 1 V potential was applied to the anti -degradation units, remaining below the 1.23 V threshold to avoid unwanted electrolysis and CL production, while still generating sufficient electrostatic force.

[0104] FIG. 5A-5H shows one example fabrication process. In FIG. 5 A, LORI 0B photoresist was spin coated onto a 4-inch Pyrex glass wafer 502 at 1200 rpm for 60 seconds to produce a 1.65 pm for a future lift-off process. The wafer 502 was prebaked at 190 °C for 5 minutes. A nLOF 2020 negative photoresist layer was spin coated at 3500 rpm for 60 s for a thickness of 1.85 pm. The spin coated wafer was then soft-baked at 115 °C for 60 s. UV lithography was then performed at 350 W for 25 s to form a patterned electrode plate design 504. The wafer 502 with the patterned electrode plate design 504 was then post-bake at 95 °C for 1 min, and then developed in MIF300 for 90 s.

[0105] As shown in FIG. 5B, a 30 nm chromium layer was deposited using magnetron sputtering. A 300 nm platinum layer was then deposited with magnetron sputtering on the chromium layer. The wafer 502 was then placed into an ultrasonic acetone bath for 20 minutes to start the lift-off process leaving the patterned electrodes 506.

[0106] In FIG. 5C, LOR10B photoresist was spin coated for a second layer at 1200 rpm for 60 seconds to produce a 1.65 pm for a future lift-off process. This wafer was then prebaked at 190 °C for 5 minutes and then spin coated with a nLOF 2020 negative photoresist layer atPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0107] 3500 rpm for 60 s for a thickness of 1.85 pm. The wafer 502 was then soft-baked at 115 °C for 60 s and then subjected to UV lithography at 350 W for 25 s for patterned dielectric layer design 508. The wafer 502 with the patterned dielectric design 508 was then post-baked at 95 °C for 1 min and then developed in MIF300 for 90 s.

[0108] In FIG. 5D, a 60 nm TiCh layer was deposited with RF sputtering. The wafer 502 was then placed into an ultrasonic acetone bath for 20 minutes to start the lift-off process to form the patterned TiCh layer 510.

[0109] LOR10B photoresist was spin coated for a third layer at 1200 rpm for 60 seconds to produce a 1.65 pm for a future lift-off process of planar anti-degradation unit. The wafer was again prebaked at 190 °C for 5 minutes and then spin coated with a nLOF 2020 negative photoresist layer at 3500 rpm for 60 s for a thickness of 1.85 pm. The wafer 502 was then soft-baked at 115 °C for 60 s and subj ected to UV lithography at 350 W for 25 s for patterned anti-degradation unit design. The patterned wafer was then post-baked at 95 °C for 1 min and developed in MIF300 for 90 s. A 30 nm chromium layer was deposited with magnetron sputtering and then a 300 nm platinum layer was deposited with magnetron sputtering. The wafer was placed into an ultrasonic acetone bath for 20 minutes to start the lift-off process. The finished wafer was diced into 5 x 10 mm2components, each with a set of electrodes to form a lower electrode structure 511.

[0110] Referring now to FIG. 5E, microchannels were then formed by spin coating SU-8 2075 at 1000 rpm for 30 s to produce a 200-pm thick layer on a 4-inch silicon wafer 512 as a mold. The SU-8 mold was cured at 65 °C for 7 minutes and then at 95 °C for 40 minutes. The mold was subjected to UV lithography at 350 W for 25 s for patterned microchannel recess mold 514 and then post-baked at 65 °C for 5 minutes and then at 95 °C for 15 minutes. The recess mold 514 was then developed with a SU-8 developer (MicroChem) for 5 minutes to produce the patterned mold and then post-bake at 95 °C for 1 min.

[0111] In FIG. 5F, a liquid PDMS solution (Sylgard 186 Silicone Elastomer) was mixed with curing agent solution in a 10:1 ratio. The mixture 516 was poured in the recess mold 514 and cured at 100 °C for 60 minutes.

[0112] As shown in FIG. 5G, the cured PDMS 516 was removed from the mold and cut to fit the glass die with the integrated electrodes and to form the microchannel 518. Note thatPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0113] the figures only show a single die. However, these devices were batch fabricated on a 4-inch wafer including 12 dies. Prior to assembling the PDMS microchannel 518 to the glass wafer substrate 511, the PDMS and the glass wafer were cut and diced respectively into dies sizes (2.5 x 2.5 cm2) composing all of the previously mentioned components which occurs before steps illustrated in FIG. 5H and 51.

[0114] In FIG. 5H, a commercial Cu-mesh 520 was cut and bound inside of the microchannel 518 to form an elevated structure 522.

[0115] As shown in FIG. 51, the elevated structure 522 and the lower electrode structure 511 were then assembled by bonding together. The electrode plates were aligned within the channel on the PDMS by treating the glass slide and the PDMS layer with O2 plasma at 120 V for 30 s and then applying pressure to both layers until firmly attached. The glass slide was heated at 95 °C for 60 s. Sealant was applied to the outer boundary of the glass-PDMS interface. A 1.5 mm diameter inlet and outlet channel were formed on the PDMS layer (shown in FIG. 2).

[0116] FIG. 6 shows in SEM micrograph of one of the formed bubble generating electrodes. FIG. 7 is a micrograph of the copper mesh 520 oriented within the PDMS microchannel 518. Testing was conducted utilizing this bubble-based sensor (e.g. as more fully illustrated in FIG. 2) in which the planar and elevated anti -degradation unit was activated once each for 10 seconds for each polarity with an applied voltage potential of 1 V to repel the oceanic ion away from the bubble producing electrode. The bubble sensor was then subsequently activated for 10 seconds utilizing a 3.5 V source to produce bubbles. Note that the source of water used came from the Great Salt Lake to produce a similar condition to that of the ocean.

[0117] This concept was also validated in the macroscale using water from the Great Salt Lake (greater than 3.5% salinity), where large anti-degradation units minimized CL production by applying IV for 10 seconds to each polarity before the primary electrolytic reaction, ensuring oceanic ions were moved away from the primary electrode.

[0118] FIG. 8A illustrates a test setup, where one Great Salt Lake water sample was treated with the polarity-switching anti-degradation units (800), and another was treated with a standard electrolysis unit (810) as shown in FIG. 8B, to observe the differences during electrolysis. Anti-degradation units 800 include a pair of electrolytic electrodes 802 and aPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0119] pair of anti-degradation electrodes 804. During processing, ion free zones 806 were formed adjacent the electrolytic electrodes 802. The sample produced with the anti -degradation units 800 showed much clearer water, while the sample produced using standard electrolysis developed a yellow hue due to Ch production, which formed sodium hypochlorite (NaOCl). Note that the macro-scale test was conducted in a separate chamber, and the resulting water solution was transferred to a sample vial for clearer visibility.

[0120] Testing was then done to observe the amount of Ch produced over a 10 s electrolysis period with and without the anti -degradation unit for the microfabricated device. Initial results verified the usage of the ability of the polarity- switching anti-degradation unit to reduce Ch production by nearly 90%. FIG. 9 depicts the average Ch production for the tested sensors. GC-MS measurements revealed that the average bubble sensor produced 5.97 ppm of Ch during 10 seconds of electrolytic reaction in Great Salt Lake water, whereas the antidegradation integrated sensor produced only 0.72 ppm (720 ppb) of Ch under the same conditions, aligning with EPA guidelines for preventing environmental aquatic damage. This 90% reduction in Ch production confirms that the anti-degradation units effectively repelled most ions away from the bubble-generating electrode, significantly reducing Ch production.

[0121] The lower Ch production also minimized electrode degradation, as shown in FIG.

[0122] 10A-10B. Over a five-day period, with eight bubble-based measurement testing was conducted per day, the anti-degradation units resulted in a degradation of only 5.85%, nearly nine times better than the original bubble sensor in the same high-salinity solution (water from the Great Salt Lake). The integration of the anti -degradation units allowed the bubble sensor to perform almost as well as the original sensor under tap water conditions, which showed 3.46% degradation, thus verifying the anti -degradation unit integration into the bubble sensor for oceanic deployment.

[0123] Thus, the proposed technology is integrated to not only reduce the Ch production and degradation, but it also does not interfere with the primary electrolytic reaction intended electrolytic sensor.

[0124] Example 2

[0125] An electrolytic cell including an electrode assembly including a metal mesh layer over the primary electrolytic electrode, in combination with polarity-switching electrodes, asPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0126] illustrated in FIG. 4C was produced and tested. FIG. 11A-11J show the fabrication process steps for forming the sensor and electrode assembly as generally illustrated in FIG. 4C. As shown in FIG. 11A the electrodes were formed by spin coating LORIOB photoresist onto a 4-inch Pyrex glass wafer 1102 at 1200 rpm for 60 seconds to produce a 1.65 pm for a future lift-off process. A wafer was prebaked at 190 °C for 5 minutes and then spin coating a nLOF 2020 negative photoresist layer at 3500 rpm for 60 s for a thickness of 1.85 pm. The wafer was then soft-baked at 115 °C for 60 s and then subjected to UV lithography at 350 W for 25 s for patterned electrode plate design 1104. This patterned wafer was post-baked at 95 °C for 1 min and developed in MIF300 for 90 s. At FIG. 1 IB, 30 nm chromium layer was deposited with magnetron sputtering, and 300 nm platinum layer was deposited with magnetron sputtering as well. This wafer was then placed into an ultrasonic acetone bath for 20 minutes to start the lift-off process leaving the patterned electrodes 1106. Now referring to FIG. 11C, LORIOB photoresist was spin coated for a second layer at 1200 rpm for 60 seconds to produce a 1.65 pm for a future lift-off process. The wafer was then prebaked at 190 °C for 5 minutes. Spin coating a nLOF 2020 negative photoresist layer at 3500 rpm for 60 s for a thickness of 1.85 pm and then soft-baked at 115 °C for 60 s. The wafer was then subjected to UV lithography at 350 W for 25 s for patterned dielectric layer design 1108 and then post-bake at 95 °C for 1 min, followed by develop in MIF300 for 90 s. FIG. 1 ID shows deposition of a 60 nm TiCh layer with RF sputtering. The wafer was then placed into an ultrasonic acetone bath for 20 minutes to start the lift-off process leaving a patterned TiCL layer 1110.

[0127] As shown in FIG. HE, LORIOB photoresist 1112 was spin coated for a third layer at 1200 rpm for 60 seconds to produce a 1.65 pm for a future lift-off process of planar antidegradation unit. The wafer was prebaked again at 190 °C for 5 minutes, followed by spin coating a nLOF 2020 negative photoresist layer at 3500 rpm for 60 s for a thickness of 1.85 pm. The wafer was then soft-baked at 115 °C for 60 s and subjected to UV lithography at 350 W for 25 s for patterned anti-degradation unit design. This wafer was then post-baked at 95 °C for 1 min. and developed in MIF300 for 90 s. A 30 nm chromium layer was deposited with magnetron sputtering and a 300 nm platinum layer was also deposited with magnetron sputtering. The wafer was then placed into an ultrasonic acetone bath for 20 minutes to startPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0128] the lift-off process. The final wafer was then diced into 5 x 10 mm2components, each with a set of electrodes.

[0129] As shown in FIG. 1 IF- 1 II a wafer 1118 was spin coated with SU-82075 at 1000 rpm for 30 s to produce a 200-pm thick layer 1120 on a 4-inch silicon wafer. The SU-8 mold was cured at 65 °C for 7 minutes and then at 95 °C for 40 minutes. The wafer was subjected to UV lithography at 350 W for 25 s for patterned microchannel and then post-baked at 65 °C for 5 minutes and then at 95 °C for 15 minutes. The wafer was then developed with a SU-8 developer (MicroChem) for 5 minutes to produce patterned mold and post-baked at 95 °C for 1 min. Referring to FIG. 11G, a liquid PDMS solution (Sylgard 186 Silicone Elastomer) was mixed with curing agent solution in a 10:1 ratio and poured in the SU-8 mold and cured at 100 °C for 60 minutes. The cured PDMS 1122 was cut to fit on each glass component with electrode as shown in FIG. 11H. Commercial Cu-mesh 1124 was cut and bonded with the inside of the PDMS-based microchannel.

[0130] Referring now to FIG. Ill, the formed components were then assembled by bonding the electrode plates aligned within the channel on the PDMS by treating the glass slide and the PDMS layer with O2 plasma at 120 V for 30 s. Pressure was applied to both layers until firmly attached. The glass slide was heated at 95 °C for 60 s and sealant was applied to the outer boundary of the glass-PDMS interface. Both 1.5 mm inlet and outlet channels were formed on the PDMS layer.

[0131] Initial testing of the copper oxide peeling method was carried out using a copper mesh electrode measuring approximately 2 mm x 2 mm, with a mesh size of 450 pm x 450 pm. The mesh was immersed in 250 mb of aqueous solution collected from the Great Salt Lake for various time intervals. After each exposure period, the mesh surface was analyzed using scanning electron microscopy (SEM) to observe morphological changes, and energy-dispersive spectroscopy (EDS) was used to verify and quantify the accumulation of oceanic ions on the electrode surface.

[0132] Following this, the same copper mesh was re-immersed in the Great Salt Lake solution and subjected to different voltage applications (1 V, 2 V, and 3 V) in pulsed intervals — 1 second on, followed by 1 second off — for a total duration of 10 seconds. During this electrolytic process, the copper mesh acted as the cathode, and the naturally formingPATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0133] copper oxide layer was electrochemically reduced and peeled off, as illustrated in FIG. 12A-12C. Post-treatment, SEM-EDS analysis was repeated to assess the extent of ion removal and detect any remaining surface contaminants. More specifically, FIG. 12A-12C shows the copper mesh exposed to Great Salt Lake water for varying durations (30 minutes, 5 days, and 7 days), illustrating the progressive accumulation of particulates over time. On an actual sensor, such accumulation would degrade performance and accuracy. As shown in the figure, ion buildup increases significantly with time, as confirmed by elemental analysis using SEM-EDS. However, by applying a small voltage, these deposits can be completely removed. This occurs through the reduction of the underlying oxide layer, effectively detaching the accumulated material, as described by the chemical reaction in Equation 1.

[0134] CuO (s) + 2e — > Cu (s) + (h (g) (4)

[0135] The electrochemical reduction potential for copper oxide is approximately 1.5 V. As shown in FIG. 13, effective cleaning of the copper mesh oxide layer occurs only when a voltage exceeding 1.5 V is applied, with complete removal achieved using 3 V for 10 seconds, as confirmed by SEM-EDS analysis. During the reduction process, the oxide layer is etched away along with any accumulated surface material. Notably, the oxide layer rapidly reforms in the presence of oxygen, regenerating 1-5 nm within seconds. This selfregenerating property allows the method to be used repeatedly to restore the electrode to its original state, ensuring accurate sensing while preventing long-term degradation and corrosion.

[0136] Additional testing was conducted to better understand surface accumulation behavior and optimize the oxide regeneration and cleaning cycle. This involved quantifying the accumulation of biofouling and ions by comparing the weight of a clean copper mesh with that of a mesh exposed to Great Salt Lake water over time. These weight differences were correlated with previously observed 10% deviation points in sensor performance when using polarity-switching electrostatics. Voltage thresholds required to remove accumulated material at the 10% deviation point were then identified, allowing the sensor to be restored to its original state and maintain accurate sensing.PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0137] Initial characterization of the copper oxide peeling method confirmed its effectiveness in removing accumulated oceanic ions from the electrode surface, significantly mitigating sensor degradation and extending material lifespan by nearly eightfold. After immersing the copper mesh in Great Salt Lake water, SEM imaging revealed substantial particulate accumulation on the electrode surface. EDS analysis identified that approximately 55% of the mesh composition consisted of oceanic ions commonly found in seawater. However, following the application of electrolysis, which facilitates the natural peeling of the copper oxide layer, a marked reduction in ion accumulation was observed, as shown in FIG. 12A-12C. Further focused ion beam (FIB) analysis confirmed an eightfold decrease in oceanic ion presence, reinforcing the efficiency of the electrochemical reduction process in maintaining electrode cleanliness.

[0138] Additional results also demonstrated that the electrochemical oxide peeling mechanism should be optimized for 7-day period cleaning to mitigate sensor degradation while maintaining long-term performance. As shown in FIG. 14, the sensor experiences increasing deviation over time due to ion accumulation and biofouling. Once the deviation surpasses the 10% threshold, the sensor's accuracy is significantly impacted, necessitating surface cleaning to restore functionality. This highlights the importance of periodic oxide peeling to ensure prolonged sensor reliability.

[0139] FIG. 15 further quantifies the oxide peeling process, showing that at 3.5 V, the oxide layer is removed at a rate of approximately 2 to 2.5 nm / s. The data reveal that 10 seconds of electrolysis (2.5 mJ energy input) is sufficient to fully remove accumulated particulates and oxide layers after 7 days of accumulation, restoring the sensor surface to its original state. Extending the process to 20 seconds (5 mJ energy input) resulting in complete oxide removal for the thickest oxide that may form on the electrode surface, confirming the potential effectiveness of electrochemical treatment in maintaining electrode cleanliness. This process not only restores the electrode to its original state but also prevents long-term degradation and corrosion. Based on these findings, this method can extend the operational lifespan of this type of bubble-based sensor to approximately 385 days, assuming one measurement per day before oxide peeling is required, in this particular example.PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT

[0140] In alternative implementations, a copper layer can be deposited onto the bubblegenerating electrode within the bubble sensor, allowing the integration of the copper oxide peeling mechanism without additional power requirements. Since copper is conductive, the natural formation of the oxide layer, along with accumulated ions and particulates, will be automatically removed as the sensor generates bubbles. Furthermore, the incorporation of the electrostatic polarity-switching mechanism will help mitigate Ch generation.

[0141] While the flowcharts presented for this technology may imply a specific order of execution, the order of execution may differ from what is illustrated. For example, the order of two more blocks may be rearranged relative to the order shown. Further, two or more blocks shown in succession may be executed in parallel or with partial parallelization. In some configurations, one or more blocks shown in the flow chart may be omitted or skipped.

[0142] Reference was made to the examples illustrated in the drawings and specific language was used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the technology is thereby intended. Alterations and further modifications of the features illustrated herein and additional applications of the examples as illustrated herein are to be considered within the scope of the description.

[0143] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more examples. In the preceding description, numerous specific details were provided, such as examples of various configurations to provide a thorough understanding of examples of the described technology. It will be recognized, however, that the technology may be practiced without one or more of the specific details, or with other methods, components, devices, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the technology.

[0144] Although the subject matter has been described in language specific to structural features and / or operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features and operations described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. Numerous modifications and alternative arrangements may be devised without departing from the spirit and scope of the described technology.

Claims

PATENT APPLICATION Attorney Docket No. 00846-U8646.PCTCLAIMSWhat is claimed is:

1. A method for mitigating electrode degradation in saline conditions, comprising:exposing an electrolytic cell to a saline environment including native ions and having a Debye length, wherein the electrolytic cell comprises:a first electrode and a second electrode spaced apart from one another to form a primary electrode gap oriented in a primary plane; and a polarity switching circuit electrically connected to each of the first electrode and the second electrode, and which is capable of altematingly applying a positive charge or a negative charge to each of the first electrode and second electrode;initiating a polarity switching mode using the polarity switching circuit, wherein at least one positive pulse and at least one negative pulse are alternately applied across the primary electrode gap to drive at least a portion of the native ions at least the Debye length from each of the first electrode and the second electrode within an ion repulsion zone, wherein the first electrode and the second electrode have opposite charges during the polarity switching mode, and wherein the at least one positive pulse has a positive pulse amplitude and a positive pulse duration, and the at least one negative pulse has a negative pulse amplitude and a negative pulse duration; andinitiating an electrolysis mode within a delay time of completing the polarity switching mode to perform an electrolysis stage.

2. The method of claim 1, wherein the saline environment is one of ocean, sea, salt lake, salt playa, and industrial brine.

3. The method of claim 1, wherein the native ions include both positive ions and negative ions and include one or more of sodium, chlorine, magnesium, potassium, sulfate, bicarbonate, strontium, bromide, borate, fluoride, silicate, and iodide.PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT4. The method of claim 1, wherein the portion of the native ions includes a majority of the native ions, and in some cases includes greater than 95% of the native ions.

5. The method of claim 1, wherein the Debye length is about 13 nm.

6. The method of claim 1, wherein the first electrode and the second electrode are planar and formed along the primary plane.

7. The method of claim 6, further comprising a co-electrode electrically connected to the second electrode such that they share a common charge.

8. The method of claim 1, wherein the primary electrode gap is from 26 pm to 200 pm.

9. The method of claim 1, wherein the electrolytic cell further comprises a third electrode spaced apart from the first electrode and the second electrode to form a secondary electrode gap wherein the third electrode is non-coplanar with the primary plane.

10. The method of claim 9, further comprising initiating a secondary polarity switching mode using the polarity switching circuit, wherein at least one positive pulse and at least one negative pulse are alternately applied across the secondary electrode gap to drive at least a portion of the native ions at least the Debye length from each of the first electrode, the second electrode and the third electrode.

11. The method of claim 9, wherein the third electrode is formed as a conductive mesh oriented in a secondary plane parallel to the primary plane and spaced apart by the secondary electrode gap.

12. The method of claim 1 or claim 9, wherein the electrodes are formed from one or more of copper, gold, chromium, silver, platinum, and graphite.

13. The method of claim 1, wherein the first electrode and second electrode are formed as interdigitated electrodes.PATENT APPLICATION Attorney Docket No. 00846-U8646.PCT14. The method of claim 1, wherein the polarity switching circuit is one or more of DPDT switches, MOSFET-based switches, or timer-based IC switches.

15. The method of claim 1, wherein one or both of the positive pulse amplitude and negative pulse amplitude are between -1.23 to 1.23 V.

16. The method of claim 1, wherein one or both of the positive pulse duration and negative pulse duration is 1 sec to 30 minutes.

17. The method of claim 1, wherein the delay time is less than 1 minute.

18. The method of claim 1, wherein the electrolysis stage is oxygen bubble production for use as a CO2 sensor.

19. The method of claim 1, wherein the electrolysis stage can be utilized for bubble generation or desalination of seawater.

20. The method of claim 1, wherein the electrolysis stage is performed in the presence of chlorine ions and results in a reduction of chlorine gas production by at least 80% compared to electrolysis under common conditions performed without the polarity switching mode.

21. The method of claim 1, wherein the electrolysis stage is performed in the presence of chlorine ions and results in less than 1 ppm of CI2 production, and in some cases less than 0.85 ppm.

22. The method of claim 1, further comprising initiating a reconditioning mode using the polarity switching circuit after the electrolysis stage, wherein a polarity across the primary electrode gap is reversed with respect to the electrolysis stage at least once to reverse at least one of biofouling deposits and oxidation / reduction products at surfaces of the first electrode and the second electrode.

23. An electrolytic cell for use in a saline environment, comprising:PATENT APPLICATION Attorney Docket No. 00846-U8646.PCTa first electrode and a second electrode spaced apart from one another to form a primary electrode gap oriented in a primary plane;a third electrode spaced apart from the first electrode and the second electrode to form a secondary electrode gap wherein the third electrode is non-coplanar with the primary plane and electrically connected to the first electrode such that at least one voltage can be maintained across the first electrode gap and the second electrode gap; anda polarity switching circuit electrically connected to each of the first electrode, the second electrode and the third electrode, and which is capable of alternatingly applying a positive charge or a negative charge to each of the first electrode, second electrode and third electrode.

24. The electrolytic cell of claim 23, wherein the electrolytic cell is free of barrier layers including membranes, electrostatic polyanion layers, and pH buffer layers.

25. The electrolytic cell of claim 23, wherein the first electrode is shaped as a bubble producing electrode.

26. An electrolytic system comprising:a plurality of the electrolytic cells of claim 23 oriented in a common substrate; and at least one microfluidic channel formed on the common substrate and adapted to direct a saline solution from the saline environment through the at least one microfluidic channel.

27. The system of claim 26, wherein the at least one microfluidic channel includes a base substrate and a polymer ceiling.

28. The system of claim 27, wherein the base substrate comprises a ceramic (e.g. glass) and the polymer ceiling comprises PDMS.

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