Electrochemical oxygen concentrator

Abstract

An electrochemical oxygen concentrator device configured to produce high purity oxygen from ambient air comprises a proton exchange membrane separating an anode and a cathode, an air inlet, a water inlet, a water and oxygen outlet, and a water and air outlet. The device can further include a membrane electrode assembly with a cathode gas diffusion layer comprising a hydrophobic carbon cloth with a microporous layer.

Description

[0001] Electrochemical Oxygen Concentrator

[0002] CROSS-REFERENCE TO RELATED APPLICATION

[0003] This application claims priority to United States Provisional Application Number 63 / 550,724 that was filed on February 7, 2024. The entire content of the application referenced above is hereby incorporated by reference herein.

[0004] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0005] This invention was made with government support under Grant No. EB031385 awarded by the National Institutes of Health. The U.S. government has certain rights in the invention.

[0006] BACKGROUND

[0007] Oxygen (O2) is an important resource for patients with respiratory illness on supplemental oxygen therapy. Supplemental oxygen is required for both hospitalized patients and outpatients. Oxygen concentrators are one of the key devices used for oxygen generation, as they allow for on-demand oxygen generation from ambient air. More centralized methods of oxygen generation suffer from challenges such as limitation of resources, transportation requirements, and supply chain disruptions, especially during pandemics. Currently available oxygen concentrators work under the pressure swing adsorption (PSA) principle. PSA oxygen concentrators push ambient air through molecular filters that filter out most of the nitrogen in the air, leaving behind oxygen (air is made of about 78% nitrogen and 21% oxygen by weight) at a purity of about 65% to 95%. However, these oxygen concentrators use multiple filtering chambers with valves that are continuously switching on or off. As a result, PSA oxygen concentrators can be quite heavy, loud, have lots of moving parts, and consume significant amounts energy.

[0008] Thus, there is currently a need for oxygen concentrators that can deliver near 100% oxygen purity, require fewer moving parts, consume less energy, make less noise, and are smaller, lighter and easier to maneuver.

[0009] SUMMARY

[0010] Certain embodiments provide an electrochemical oxygen concentrator device comprising: a proton exchange membrane (PEM) separating an anode and a cathode; an air inlet; a water inlet; a water and oxygen outlet; and a water and air outlet. In certain embodiments, the air inlet is configured to receive ambient air.

[0011] In certain embodiments, the water and oxygen outlet is configured to release oxygen with a purity of about 50% to about 99%.

[0012] In certain embodiments, the water and oxygen outlet is configured to release oxygen with a purity of at least about 99%.

[0013] In certain embodiments, the water and air outlet is configured to release air with an oxygen content less than about 21% and a nitrogen content greater than about 78%.

[0014] In certain embodiments, the PEM is coated with at least one of an oxygen evolution catalyst layer and an oxygen reduction catalyst layer.

[0015] In certain embodiments, the device further comprises a membrane electrode assembly (MEA) comprising: an anode gas diffusion layer (GDL); a cathode GDL comprising a hydrophobic carbon cloth including a microporous layer; an oxygen evolution catalyst layer; an oxygen reduction catalyst layer; and the PEM.

[0016] In certain embodiments, the hydrophobic carbon cloth is treated with Polytetrafluoroethylene (PTFE).

[0017] In certain embodiments, the microporous layer comprises a carbon powder-based microporous material applied onto the PTFE-treated hydrophobic carbon cloth.

[0018] In certain embodiments, at least one of the microporous layer and the PEM is coated with the oxygen reduction catalyst layer.

[0019] In certain embodiments, the anode GDL comprises a titanium felt or mesh.

[0020] In certain embodiments, the at least one of the anode GDL and the PEM is coated with the oxygen evolution catalyst layer.

[0021] In certain embodiments, the device is configured to operate at a temperature of up to about lOO’C.

[0022] In certain embodiments, the device is configured to generate about 70 mL / min to about 100 mL / min of purified oxygen.

[0023] In certain embodiments, the device is configured to operate with an applied voltage under about 1.3 Volts.

[0024] In certain embodiments, the device further comprises a membrane electrode assembly (MEA) comprising: an anode gas diffusion layer (GDL) comprising titanium; a cathode GDL comprising titanium; an oxygen evolution catalyst layer; an oxygen reduction catalyst layer; and the PEM. Certain embodiments provide a membrane electrode assembly (MEA) comprising: an anode gas diffusion layer (GDL); a cathode GDL comprising a hydrophobic carbon cloth including a microporous layer; an oxygen evolution catalyst layer; an oxygen reduction catalyst layer; and a proton exchange membrane (PEM).

[0025] In certain embodiments, the hydrophobic carbon cloth is treated with Polytetrafluoroethylene (PTFE).

[0026] In certain embodiments, the microporous layer comprises a carbon powder-based microporous material applied onto the PTFE-treated hydrophobic carbon cloth.

[0027] In certain embodiments, at least one of the microporous layer and the PEM is coated with the oxygen reduction catalyst layer.

[0028] In certain embodiments, the anode GDL comprises a titanium felt, mesh, foam, nanofiber or other porous three-dimensional shape.

[0029] In certain embodiments, at least one of the anode GDL and the PEM is coated with the oxygen evolution catalyst layer.

[0030] Other objects, features, and advantages of the present invention will be apparent to one of skill in the art from the following detailed description and figures.

[0031] BRIEF DESCRIPTION OF DRAWINGS

[0032] The present application can be understood by reference to the following drawings, wherein like reference numerals represent like elements. The drawings are merely exemplary to illustrate certain features that may be used singularly or in combination with other features and the present application should not be limited to the embodiments shown.

[0033] FIG. 1 is a schematic of an embodiment of an electrochemical oxygen concentrator system in accordance with the present disclosure.

[0034] FIG. 2A is a front view of an embodiment of a proton-exchange-membrane-based (PEM- based) device in accordance with the present disclosure.

[0035] FIG. 2B is a schematic illustrating an embodiment of an enhanced internal membrane electrode assembly of the device of FIG. 2 A.

[0036] FIG. 2C is an exploded side view of the enhanced membrane electrode assembly of FIG. 2B

[0037] FIG. 3A is a graph showing Linear Sweep Voltammetry measurements using varying air flow rate at a set temperature for the device of FIG. 2B (Embodiment A) with a standard membrane electrode assembly. FIG. 3B is a graph showing Linear Sweep Voltammetry measurements using a set air flow rate at varied temperatures for the device of FIG. 2B (Embodiment A) with a standard membrane electrode assembly.

[0038] FIG. 4A is a graph showing Linear Sweep Voltammetry measurements using varying air flow rate at a set temperature for the device of FIG. 2B (Embodiment B) with an enhanced membrane electrode assembly.

[0039] FIG. 4B is a graph showing Linear Sweep Voltammetry measurements using a two different set air flow rates at varied temperatures for the device of FIG. 2B (Embodiment B) with an enhanced membrane electrode assembly.

[0040] FIG. 5 is a graph showing Linear Sweep Voltammetry measurements comparing the performance of the device of FIG. 2B (Embodiment A and Embodiment B) to the performance of a theoretical hybrid electrolyzer-fuel cell.

[0041] FIG. 6A is a graph of gas chromatography injection profiles showing that the device of FIG. 2B (Embodiment B) provides 99.3% oxygen purity compared to 80.2% oxygen purity for PSA oxygen concentrator.

[0042] FIG. 6B is a chart showing particle count analysis, indicating that the device of FIG. 2B (Embodiment B) provides oxygen with no particulates.

[0043] DETAILED DESCRIPTION

[0044] Referring now to the drawings wherein like reference numerals are used to identify like elements in the various views, FIG. 1 illustrates an exemplary embodiment of electrochemical oxygen concentrator (EO2C) system 100. By leveraging advancements in proton exchange membrane (PEM) technologies (e.g., PEM electrolyzers and PEM fuel cells, where oxygen is either a product or a reactant), the EO2C system 100 overcomes many of the limitations of existing mechanical and other high temperature electrochemical oxygen concentrators. The EO2C system 100 is scalable, as it can be used to produce oxygen generators of various sizes with various ranges of oxygen supply. For example, the EO2C system 100 can be used to make small portable devices (less than 2000 mL / min), stationary devices on wheels (1000 to 10,000 mL / min), or large industrial sizes for supplying hospitals.

[0045] The EO2C system 100 is a solid-state system that operates based on the isothermal compression principle. The EO2C system 100 comprises a PEM-based device 102 configured to efficiently concentrate oxygen with high purity of about 50% to greater than about 99% (e.g., about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or about 99%) from ambient air. The PEM-based device 102, a hybrid of an electrolytic unit and a fuel cell, is configured to use electric power to induce electrochemical reactions in ambient air that allow for the separation and concentration of oxygen (air is approximately 21% oxygen, 78% nitrogen, and 1% other gasses). The concentrated oxygen can then be collected and / or used directly for supplemental breathing.

[0046] As shown in FIG. 1, the PEM-based device 102 comprises a PEM 104 (e.g., Nafion™ perfluorosulfonic acid (PFSA) membrane) that separates an anode (positive electrode) 106 and a cathode (negative electrode) 108. The anode 106 and cathode 108 can be made from titanium, for example, and coated with nanoparticle catalysts for efficient operation. When ambient air is supplied to the cathode 108 and a direct current is applied to the PEM-based device 102 (e.g., current flowing into the anode and out of the cathode in the opposite direction of electron flow), oxygen molecules in the air are reduced in the presence of proton and electron to form water at ambient pressure Pl. This process is shown below in equation 1 :

[0047] The water formed in equation 1 is transported through the PEM 104 and oxidized at the anode 106 to form high purity oxygen (e.g., near 100% oxygen), which naturally concentrates based on downstream volume at pressure P2. This process is shown below in equation 2:

[0048] (It should be noted that Pl and P2 represent the partial pressures of oxygen in the gas phase. Thus, if the absolute pressure on both sides of the PEM 104 is the same, P2 at the anode would be expected to be approximately five times greater than Pl at the cathode due to its contribution to the pressure being based entirely on oxygen while Pl is based on oxygen, nitrogen, and other components of air.)

[0049] Adding equations 1 and 2 shows that the EO2C system 100 generates oxygen (O2) from ambient air, and that no net water is produced or consumed. This is illustrated below in equation 3:

[0050] O2(P1) ^ O2(P2) (Eq 3)

[0051] Referring now to FIGS. 2A-2C, embodiments of the presently disclosed PEM-based device 102 are shown. As shown in FIG. 2A, the presently disclosed PEM-based device 102 includes housing (e.g., anodized aluminum) with an input for air to the cathode 108 for oxygen generation. The typical PEM-based water electrolyzer cell has a four-port design in which there is one port for water inlet, one port for water and oxygen outlet, and two ports for hydrogen outlet. The purpose of the typical PEM-based water electrolyzer cell is to split water into hydrogen and oxygen using a PEM (Proton Exchange Membrane or Polymer-Electrolyte Membrane) coated with catalysts for oxygen evolution and hydrogen evolution on opposing sides of the membrane. The presently disclosed PEM-based device 102 differs from the typical PEM-based water electrolyzer cell in that the two hydrogen outlet ports are replaced with an air inlet port and an air and water outlet port, resulting in an electrochemical oxygen concentrator. In the embodiment shown in FIG. 2A, the upper right port is the inlet for air, the lower right port is the inlet for water, the upper left port is the outlet for concentrated oxygen and water, and the lower left port is the outlet for lean air (air with reduced O2 content) and water. It should be noted, however, that in some embodiments the location of the four ports can vary; for example, the inlet for air can be located in or near the lower portion of the PEM-based device 102, the inlet for water can be located in or near the upper portion of the PEM-based device 102, the outlet for concentrated oxygen and water can be located in or near the lower portion of the PEM- based device 102, and the outlet for lean air and water can be located in or near the upper portion of the PEM-based device 102. By introducing air to the negative electrode, the hydrogen evolution reaction (typical of water splitting) is effectively replaced with the oxygen reduction reaction, a characteristic of fuel cells. Thus, the PEM-device 102 operates in a hybrid manner - performing one half reaction from the electrolyzer (oxygen evolution) and one half from the fuel cell (oxygen reduction).

[0052] The PEM-based device 102 can further include an enhanced membrane electrode assembly (MEA) HOB, configured to simultaneously mitigate water flooding at the cathode 108 (e.g., water accumulation on the cathode surface) and augment O2 generation at the anode 106. As shown in the left-side portion of FIG. 2B (Embodiment A), typical PEM-based devices, such as the commercial water electrolyzer model LBE-PSC-1 made by LightBridge, Inc., include a standard MEA 110A comprising a gas diffusion layer (GDL) at the cathode and anode side, an oxygen evolution catalyst layer, an oxygen reduction catalyst layer, and a proton exchange membrane. The catalyst layers can include any acid-stable catalyst, such as iridium oxides, ruthenium oxides, Mn7.5O10Br3, Ruthenium-doped iridium oxides, and Mn- Co-, Ni-based oxides. As shown in the right-side portion of FIG. 2B (Embodiment B) and FIG. 2C, an example of an enhanced MEA HOB comprises a hydrophobic carbon cloth as the base material for the cathode GDL. This carbon cloth is treated with Teflon™, or Polytetrafluoroethylene (PTFE), which facilitates effective water displacement from the catalyst sites, thereby preventing flooding. [It should be noted that other materials besides carbon (e.g., titanium or platinized titanium) can be treated with any hydrophobic process (e.g., coating with manganese oxide polystyrene (MnO2 / PS) nano-composite, zinc oxide polystyrene (ZnO / PS) nano-composite, precipitated calcium carbonate, carbon nano-tube structures, silica nanocoating, fluorinated silanes and fluoropolymer; or laser roughening of materials to promote hydrophobicity) for use in an enhanced MEA.] A layer of carbon powder-based microporous material is applied onto the treated carbon cloth. This layer serves a dual purpose - it provides a smooth surface for catalyst application and sustains an electrically conductive nature while upholding a well-defined structure of open pores. These open pores enable efficient gas transport to the reactive zones (e.g., the area on and around the catalyst layer where all reactants are present). The oxygen reduction catalyst layer can be directly applied to the microporous layer. In an embodiment, the anode GDL of the enhanced MEA HOB comprises a titanium felt, mesh, foam, nanofiber, or other porous three-dimensional shape with catalyst coated directly on the GDL. In other embodiments, the anode GDL can comprise platinized titanium or passive layers of various nitrides (TiN, CrN, TiAlN, TiSiN, TiAlSiN, NbN, and their multilayer coatings), lead oxide, and tantalum materials applied to stainless steel, Ni alloys, aluminum, titanium, graphite, or any other conductive material. The PEM 104 is integrated between the anode 106 and cathode 108, ensuring the selective transfer of protons while preventing the mixing of gases. The enhanced MEA HOB offers efficient water management and enhanced gas transport. This results in improved overall performance, efficiency, and durability of the EO2C system 100.

[0053] The EO2C system 100, including the PEM-based device 102, can be used to produce oxygen from ambient air for a variety of applications. The following are non-limiting examples of applications that vary depending on the size scale and method of power supply for the PEM- based device 102:

[0054] • As a stand-alone wall-powered home oxygen concentrator for patients prescribed supplemental oxygen therapy (oxygen flow rates of 1 to 20 liters per minute or LPM).

[0055] • As a portable battery-powered home oxygen concentrator for patients prescribed supplemental oxygen therapy (oxygen flow rates of 0.2 to 3 LPM).

[0056] • For use as a wellness device for improved oxygen supply under non -prescribed situations such as for increasing wellness and comfort, and as a preventive strategy during pandemics (0.2 to 0.6 LPM).

[0057] • An on-board oxygen generating system for use by pilots in military aircraft or other specialized aircraft (oxygen flow rates of 1 to 10 LPM). • In passenger airlines as part of airplane air systems for control of oxygen in cabin air supply and for providing emergency oxygen supply (oxygen flow rates vary).

[0058] • As a standalone industrial-scale oxygen generator for hospitals - either as primary or backup system of oxygen supply (oxygen flow rates capacity of 500+ LPM).

[0059] • As a device for topical oxygen therapy for wound healing applications (oxygen flow rates in the range of 10-100 microliters per minute).

[0060] • As a stand-alone wall-powered large-output oxygen supply system for at-home high- pressure ventilation of respiratory patients.

[0061] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results.

[0062] EXAMPLES

[0063] Example 1 - Embodiment A Performance at Varied Air Flow Rates and Temperatures

[0064] The performance of the PEM-based device 102 with a standard MEA 110A (as shown in Embodiment A on the left side of FIG. 2B) was measured with varied air flow rate feeds and applied temperatures during Linear Sweep Voltammetry measurements (where applied voltage is stepped to increasing or decreasing values and current is measured and compared). FIG. 3A shows a comparison of varied air flow rates at a set temperature, and FIG. 3B shows a comparison of varied temperatures at a set air flow rate. The data shows that increasing the temperature and / or the air flow rate will decrease the applied voltage needed to get a specific current out of the PEM-based device 102 with a standard MEA 110A. At all operations, the purity of the oxygen was -100%. During testing, voltages of 1.3 V or greater were applied to the PEM-based device 102 to test the maximum O2 generation possible at temperatures up to 80sC. Through this testing, it was observed that around 70 mL / min of O2 was generated from the cell when currents were at 18.5 A and temperatures of 80sC (not shown in FIGS. 3A and 3B). In some embodiments, the PEM-based device can operate at a temperature of up to about 100’C and can generate greater than 100 mL / min of O2.

[0065] Example 2 - Embodiment B Performance at Varied Air Flow Rates and Temperatures

[0066] The performance of the PEM-based device 102 with an enhanced MEA HOB (as shown in Embodiment B on the right side of FIG. 2B and FIG. 2C) was measured with varied air flow rate feeds and applied temperatures during Linear Sweep Voltammetry measurements (where applied voltage is stepped to increasing or decreasing values and current is measured and compared). FIG. 4A shows a comparison of varied air flow rates at a set temperature, and FIG. 4B shows a comparison of varied temperatures at a two different set air flow rates (0.10 LPM and 0.75 LPM). Similar to FIGS. 3A and 3B in Example 1, the data shows that increasing the temperature and / or the air flow rate will decrease the applied voltage needed to get a specific current out of the PEM-based device 102 with an enhanced MEA HOB. At all operations, the purity of the oxygen was -100%.

[0067] Example 3 - Comparison of Embodiment A and Embodiment B to Theoretical Hybrid

[0068] FIG. 5 shows the best performance of the PEM-based device 102 with a standard MEA 110A (as shown in Embodiment A on the left side of FIG. 2B) and the best performance of the PEM-based device 102 with an enhanced MEA HOB (as shown in Embodiment B on the right side of FIG. 2B and FIG. 2C) in comparison to the best performance of a theoretical hybrid electrolyzer-fuel cell with the hydrogen activity removed. The theoretical performance data was derived by subtracting the voltage of a commercial fuel cell from the voltage of a commercial electrolyzer at corresponding current densities. This approach is analogous to directly feeding hydrogen from an electrolyzer into a hydrogen fuel cell, effectively negating the presence of hydrogen in the system. (It should be noted that this calculation does not account for actual losses that would occur in a real system combining hydrogen generation and consumption; however, these losses are irrelevant to the presently disclosed PEM-based device 102, which bypasses the hydrogen generation and consumption steps entirely.)

[0069] The improvement in performance of the PEM-based device 102 with an enhanced MEA HOB (Embodiment B) compared to the standard MEA 110A (Embodiment A) spanned over half of the total improvement expected based on the theoretical hybrid system. This can be seen through the reduction of the voltage needed at 10A from 1.1V for Embodiment A to 0.88V for Embodiment B (reduction of 0.22V) in comparison to the reduction of the voltage needed at 10A from 1. IV for Embodiment A to ,76V for the theoretical hybrid system (reduction of 0.34V). Thus, the PEM-based device 102 with an enhanced MEA HOB (Embodiment B) showed a performance improvement of 65% with respect to the maximum expected improvement.

[0070] Example 4 - Verification of >99% Oxygen Purity with Enhanced MEA Gas chromatography (GC) was used to compare the output gas from the PEM-based device 102 with an enhanced MEA HOB (as shown in Embodiment B on the right side of FIG. 2B and FIG. 2C) with ambient air and with the output gas from a Philips Respironics® Everflo PSA oxygen concentrator. A gas chromatograph equipped with a helium carrier gas and a helium ionizing detector was used to verify the output from the PEM-based device 102 with an enhanced MEA HOB through a comparison of injections of helium, air, pressure swing absorption oxygen, and electrochemical oxygen. Injections of 10 pL from each of the three sources — air, PSA, and the enhanced MEA 11 OB — were made, and the resulting injection profiles shown in Figure 6A. It was found that the 10 pL injection from the PSA unit contained 8.02 pL of oxygen (80.2% O2 purity) compared to 9.93 pL of oxygen (99.3% O2 purity) for the output from the enhanced MEA HOB and 20% O2 purity for ambient air. The GC testing range was expected to detect any H2, O2, N2, or CO present. Only O2 was detected in the output from the enhanced MEA HOB, and only O2 and N2 were detected in the PSA concentrator output from the GC runs. Additionally, particle count analysis was performed on the output from the gas from enhanced MEA HOB O2 outlet compared with both filtered air (positive control: particulates blocked from air) and unfiltered air (negative control: ambient air with particulates), as shown in Figure 6B. A TSI® ultrafine condensation particle counter (model 3025A) was used to continuously sample for particles in flowing gases via condensational growth to ~1 micron in supersaturated butanol vapor. At 1 micron size, particles are individually and automatically counted using laser scattering. Particles as small as 3 nm can be detected at 100% detection efficiency. Prior to use, the particle counter was challenged with a positive challenge (room air) and a leak test (HEPA filter). The GC results and the lack of even 3 nm particulates in the enhanced MEA HOB output compared to (unfiltered) ambient air demonstrates the ability of the enhanced MEA 110B EC to generate nearly 100% O2 with no particulates.

[0071] Although at least one embodiment of an electrochemical oxygen concentrator system has been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this disclosure. All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of the disclosure. Joinder references (e.g., attached, coupled, connected, and the like) are to be construed broadly and can include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily infer that two elements are directly connected and in fixed relation to each other. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure can be made without departing from the spirit of the disclosure as defined in the appended claims.

[0072] Various embodiments are described herein to various apparatuses, systems, and / or methods. Numerous specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments as described in the specification and illustrated in the accompanying drawings. It will be understood by those skilled in the art, however, that the embodiments may be practiced without such specific details. In other instances, well-known operations, components, and elements have not been described in detail so as not to obscure the embodiments described in the specification. Those of ordinary skill in the art will understand that the embodiments described and illustrated herein are nonlimiting examples, and thus it can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments, the scope of which is defined solely by the appended claims.

[0073] Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment,” or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment,” or the like, in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with the features structures, or characteristics of one or more other embodiments without limitation given that such combination is not illogical or non-functional.

[0074] It will be appreciated that the terms “proximal” and “distal” may be used throughout the specification with reference to a clinician manipulating one end of an instrument used to treat a patient. The term “proximal” refers to the portion of the instrument closest to the clinician and the term “distal” refers to the portion located furthest from the clinician. It will be further appreciated that for conciseness and clarity, spatial terms such as “vertical,” “horizontal,” “up,” and “down” may be used herein with respect to the illustrated embodiments. However, surgical instruments may be used in many orientations and positions, and these terms are not intended to be limiting and absolute. The terms “about” and “approximately” may be used throughout the specification when referring to a measurable value, such as an amount, a distance, a temporal duration, and the like. The terms “about” and “approximately” are meant to encompass variations of ±20% or ±10%, in certain embodiments ±5%, in certain embodiments ±1%, in certain embodiments ±0.1% from the specified value, as such variations are appropriate in accordance with the present disclosure. Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

Claims

WHAT IS CLAIMED IS:

1. An electrochemical oxygen concentrator device comprising: a proton exchange membrane (PEM) separating an anode and a cathode; an air inlet; a water inlet; a water and oxygen outlet; and a water and air outlet.

2. The device of claim 1, wherein the air inlet is configured to receive ambient air.

3. The device of claim 1 or claim 2, wherein the water and oxygen outlet is configured to release oxygen with a purity of about 50% to about 99%.

4. The device of any one of claims 1 to 3, wherein the water and oxygen outlet is configured to release oxygen with a purity of at least about 99%.

5. The device of any one of claims 1 to 4, wherein the water and air outlet is configured to release air with an oxygen content less than about 21% and a nitrogen content greater than about 78%.

6. The device of any one of claims 1 to 5, wherein the PEM is coated with at least one of an oxygen evolution catalyst layer and an oxygen reduction catalyst layer.

7. The device of any one of claims 1 to 6, further comprising a membrane electrode assembly (MEA) comprising: an anode gas diffusion layer (GDL); a cathode GDL comprising a hydrophobic carbon cloth including a microporous layer; an oxygen evolution catalyst layer; an oxygen reduction catalyst layer; and the PEM.

8. The device of claim 7, wherein the hydrophobic carbon cloth is treated with Polytetrafluoroethylene (PTFE).

9. The device of claim 8, wherein the microporous layer comprises a carbon powder-based microporous material applied onto the PTFE-treated hydrophobic carbon cloth.

10. The device of claim 7 or claim 8, wherein at least one of the microporous layer and the PEM is coated with the oxygen reduction catalyst layer.

11. The device of any one of claims 7 to 10, wherein the anode GDL comprises a titanium felt or mesh.

12. The device of any one of claims 7 to 11, wherein the at least one of the anode GDL and the PEM is coated with the oxygen evolution catalyst layer.

13. The device of any one of claims 1 to 12, wherein the device is configured to operate at a temperature of up to about 100sC.

14. The device of any one of claims 1 to 13, wherein the device is configured to generate about 70 mL / min to about 100 mL / min of purified oxygen.

15. The device of any one of claims 1 to 14, wherein the device is configured to operate with an applied voltage under about 1.3 Volts.

16. The device of any one of claims 1 to 15, further comprising a membrane electrode assembly (MEA) comprising: an anode gas diffusion layer (GDL) comprising titanium; a cathode GDL comprising titanium; an oxygen evolution catalyst layer; an oxygen reduction catalyst layer; and the PEM.

17. A membrane electrode assembly (MEA) comprising: an anode gas diffusion layer (GDL); a cathode GDL comprising a hydrophobic carbon cloth including a microporous layer; an oxygen evolution catalyst layer;an oxygen reduction catalyst layer; and a proton exchange membrane (PEM).

18. The MEA of claim 17, wherein the hydrophobic carbon cloth is treated with Polytetrafluoroethylene (PTFE).

19. The MEA of claim 18, wherein the microporous layer comprises a carbon powder-based microporous material applied onto the PTFE-treated hydrophobic carbon cloth.

20. The MEA of any one of claims 17 to 19, wherein at least one of the microporous layer and the PEM is coated with the oxygen reduction catalyst layer.

21. The MEA of any one of claims 17 to 20, wherein the anode GDL comprises a titanium felt, mesh, foam, nanofiber or other porous three-dimensional shape.

22. The MEA of any one of claims 17 to 21, wherein at least one of the anode GDL and the PEM is coated with the oxygen evolution catalyst layer.

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