Abstract:
Small, autonomous, low cost electrochemical gas generators containing an electrochemical cell assembly, a commercially available battery and a current controlling mechanism. Current control, which defines the gas generation rate, is achieved either electronically by means of a resistor or through mass transfer control by means of a gas permeable film of known permeability. In either case, the gas generation rates are generally from 0.1 to 10 cc/day. The gas source must contain an electrochemically active gas such as oxygen or hydrogen. Air is the preferred source for oxygen. These miniature gas generators, generally are less than 1.5 cm in diameter and length, require novel, compact, electrochemical cell assemblies. Various cell assemblies, generally 1 cm in diameter and less than 05 mm thick, are described. These miniature gas generators are used for the controlled release of fluids such as pheromones, fragrances, insect repellents, and the like.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    None. 
       STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND 
       [0003]    Typical miniature gas sources generate gases at rates from about 0.05 to 100 cc/day and are used for a variety of purposes. A primary use of the gas source is to produce mechanical work, such as may be required for delivering fluids at low flow rates. Many miniature gas sources use chemical means to generate the gases; but these are often unreliable, resulting in time-dependent generation rates. 
         [0004]    Another source for generating gases involves the use of an electrochemical means. Electrochemical means to generate gases generally are more accurate, reliable, albeit they require a power source, generally in the form of commercial batteries. 
         [0005]    Types of gases generated electrochemically typically include hydrogen, oxygen, and carbon dioxide. In some instances, as described by Winsel in U.S. Pat. No. 5,242,565, the battery is the power source as well as being the hydrogen gas generator. Other examples of electrochemical oxygen generators have been described by Maget in U.S. Pat. No. 6,010,317. Their applications to fluid delivery have also been described by Maget in U.S. Pat. Nos. 4,687,423; 4,886,514; 4,902,278; 5,928,194; 5,938,640; 5,971,722; 6,383,165, and 6,413,238. 
         [0006]    Additional examples of electrochemical generators releasing carbon dioxide and hydrogen have been described by Swanson, et. al., in U.S. Pat. No. 7,316,857 and by Maget in U.S. Pat. No. 6,780,304. Setting the gas generation rates of electrochemical generators, however, requires conventional current controllers. 
         [0007]    For commercial commodity products, such as releasers of pheromones, fragrances, insecticides, etc., a low cost for the gas generator is of paramount importance. The purpose of the present invention is to describe miniature and autonomous oxygen-gas generators that are cost-compatible with commercial commodity products, and in some instances are low cost gas sources that do not, but could, require electronic controls. 
       SUMMARY 
       [0008]    The above-noted problems, among others, are overcome by the electrochemical gas generator. Briefly stated, the electrochemical gas generator has a unique electrochemical cell assembly generating gases either through a controlled electric current [current-based] or through an oxygen-permeable film of a known permeability [film-based] placed at or near to the top of the electrochemical gas generator or the bottom of the electrochemical gas generator. The preferred gas to be generated is oxygen, though other gases may also be generated as necessary. 
         [0009]    The electrochemical cell assembly generates gases either through controlled electric current [current-based] or through an oxygen-permeable film of a known permeability [film-based]. Each type of cell assembly has an electrolytic membrane and a catalytically active electrode above and below the electrolytic membrane. 
         [0010]    In the current-based type, a conductive and porous current collector is above each electrode and an upper and a lower oxygen-impermeable film encircles and presses onto each current collector thereby forming an air-tight seal therearound. Gases are generated and released based on the current flow when the electrochemical gas generator is activated. 
         [0011]    In the film-based type, a conductive and porous current collector is above the upper electrode and an oxygen-permeable film of the conductive type of a pre-determined oxygen permeability is below the lower electrode, and an upper and a lower oxygen-impermeable film encircles and presses onto the upper current collector and onto the oxygen-permeable film thereby forming an air-tight seal therearound. Gases are generated and released based on the oxygen-permeability when the electrochemical gas generator is activated. 
         [0012]    The gas generators of this disclosure are small, autonomous, low cost electrochemical gas generators containing, as described above, an electrochemical cell assembly, a commercially available battery, and a current controlling mechanism which defines the gas generation rate and is achieved either electronically by means of a resistor or through mass transfer control by means of a gas permeable film of known permeability. In either case, the gas generation rates are generally from 0.1 to 10 cc/day. The gas source must contain an electrochemically active gas such as oxygen or hydrogen. Air is the preferred source for oxygen. These miniature gas generators, generally are less than 1.5 cm in diameter and length, require novel, compact, electrochemical cell assemblies. Various cell assemblies, generally 1 cm in diameter and less than 05 mm thick, are described. These miniature gas generators are used for the controlled release of fluids such as pheromones, fragrances, insect repellents, and the like. 
         [0013]    The foregoing has outlined the more pertinent and important features of the electrochemical gas generator in order that the detailed description that follows may be better understood so the present contributions to the art may be more fully appreciated. Additional features of the electrochemical gas generator will be described hereinafter which form the subject of the claims. It should be appreciated by those skilled in the art that the conception and the disclosed specific embodiment may be readily utilized as a basis for modifying or designing other structures and methods for carrying out the same purposes of the electrochemical gas generator. It also should be realized by those skilled in the art that such equivalent constructions and methods do not depart from the spirit and scope of the electrochemical gas generator as set forth in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    For a fuller understanding of the nature and objects of the electrochemical gas generator, reference should be had to the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0015]      FIG. 1A  is a cross-section view of one embodiment of the electrochemical gas generator. 
           [0016]      FIG. 1B  is an exploded view of the electrochemical gas generator illustrated in  FIG. 1A . 
           [0017]      FIG. 2A  is a cross-section view of another embodiment of the electrochemical gas generator. 
           [0018]      FIG. 2B  is an exploded view of the electrochemical gas generator illustrated in  FIG. 2A . 
           [0019]      FIG. 3A  is a cross-section detailed view of one embodiment of an electrochemical cell assembly which may be film-controlled or current-controlled. 
           [0020]      FIG. 3B  is a cross-section detailed view of another embodiment of an electrochemical cell assembly which is film-controlled. 
           [0021]      FIG. 4A  is a cross-section view of another embodiment of the electrochemical gas generator which is film-controller using conductive film. 
           [0022]      FIG. 4B  is an exploded view of the electrochemical gas generator illustrated in  FIG. 4A . 
       
    
    
     DETAILED DESCRIPTION 
       [0023]      FIGS. 1A and 1B  are representative of a preferred embodiment of the present miniature and autonomous electrochemical gas generator  10  the gas generation of which is controlled by the simplest form of current controller, a resistor  20  [the gas generated herein typically is oxygen]. It is small, compact, easy to manufacture and assemble, simple to use, efficient, and cost-effective. This particular electrochemical gas generator  10  is of the current-controlled resistor based type in that generation of gases is controlled by a commercial resistor. An important component of this electrochemical gas generator is the electrochemical cell assembly  30 . This particular electrochemical cell assembly  30  is illustrated in detail in  FIG. 3A  and a second embodiment is illustrated in detail in  FIG. 3B . 
         [0024]    This electrochemical gas generator  10  comprises a container  11  made of conductive material. The container  11  has a chamber  13  therein to accept a battery housing  19 , a battery  12 , and the resistor  20  with a first contact point  21  in communication with the battery  12  at one end and a second contact point  22  in potential communication with the activation arm  18  at the other end. Activation of this electrochemical gas generator  10  occurs when it is placed into a suitable container having a diameter approximately equal to or slightly greater than the diameter of the electrochemical gas generator  10  which causes the activation arm  18  to move in the direction of Arrow A and thereby come into contact with the second contact point  22  causing the process to begin. 
         [0025]    An inlet  14  [one or more for allowing entry of any oxygen-containing gas, such as, but not limited to, air] at the bottom of the container  11  permits the entry of air which will flow around the battery  12  and up to the electrochemical cell assembly  30  where oxygen will be extracted and released through the outlet  16  on top of the on the container  11 . Resting on top of the battery  12  in this embodiment is a conductive member  15  generally comprised either of, but not limited to, conductive rubber or a metal screen. The conductive member  15  ensures good electrical contact between the battery  12  and the electrochemical cell assembly  30 . 
         [0026]      FIG. 3A  illustrates in detail the electrochemical cell assembly  30  of this current-based current-controller generator  10 . It is composed of a solid electrolytic membrane  31  onto which electrodes  32  are embedded. Current collectors  33  are on the top and bottom of the electrolytic membrane  31  and are in intimate contact with each electrode  32  to insure low resistance electrical contacts. This membrane-electrode/current-collector  31 ,  32 ,  33  combination is encircled by, and partially sandwiched between, an oxygen impermeable film  34  which is used to seal off the edges by way of outward extensions  35 . As can be seen clearly in  FIGS. 1A and 1B , the oxygen impermeable film  34  with the outward extensions  35 , in conjunction with the sealing ring  23 , will prevent air from circulating around the electrochemical cell assembly  30  but forces the air to flow to the electrochemical cell assembly  30  from its air intake side  24 , to be processed, with oxygen being released at the discharge side  26  of the electrochemical cell assembly  30  and out of the electrochemical gas generator  10  through its outlet  16 . 
         [0027]    The top of the container  11  has a recess  17  which, when assembled with the electrochemical cell assembly  30  inside, presses on the electrochemical cell assembly  30 . This maintains a tight fit of the electrochemical cell assembly  30  therein and on the conductive member  15  in tight communication with the top of the battery  12 . An air-tight seal is formed to prevent air from flowing around the electrochemical cell assembly  30  and to prevent the generated oxygen to reverse flow and escape to the air intake side  24  of the electrochemical cell assembly  30 . 
         [0028]    Reference is now made to  FIG. 1B  for assembly of this current-based electrochemical gas generator  10 . First the sealing ring  23  is placed into the inverted housing  11  followed by the electrochemical cell assembly  30 , conductive member  15 , battery holder  19  with battery  12  and resistor  20  therein. The bottom of the housing  11  is crimped inward and upward. Once so assembled and properly crimped, this electrochemical gas generator  10 , when activated becomes operational. 
         [0029]    Referring now to  FIG. 3A , typical conventionally available components of the electrochemical cell assembly  30  include:
       [1] for the resistor [ 20 ], a Vishay low-power surface mount chip resistor;   [2] for the electrolytic member (cation or anion) [ 31 ], a typical membrane which is manufactured by DuPont® and known as Nafion®;   [3] for the electrodes [ 32 ], catalytically active materials such as platinum black or platinum activated carbons or graphite;   [4] for the current collector [ 33 ], which typically should be approximately 320 microns thick and less than 5 mm in diameter, porous conductive carbons or graphite paper or porous conductive materials such as conductive silicone rubber or a metal screen; and   [5] for the oxygen impermeable film [ 34 ] and outward extensions [ 35 ], DuPont&#39;s® commercially available Kapton® film which generally should be of the non-conductive type.       
 
         [0035]    As illustrated in detail in  FIG. 3A , the oxygen impermeable film  34  and its outward extensions  35  sandwich the membrane-electrode, current-collector combination  31 ,  32 , and  33  and, with the outward extensions  35 , prevents air from circulating around the electrochemical cell assembly  30 . 
         [0036]    There is a substantially wide mouth opening on both the bottom surface and the top surface of the electrochemical cell assembly which defines a respective intake side  24  [bottom] and a discharge side  26  [top]. When the electrochemical cell assembly  30  is combined with the container assembly  11  described above, the air-tight seal described above forces air or any other oxygen-containing gas source to flow to the electrochemical cell assembly  30  from the intake side  24  of the electrochemical cell assembly  30  to be processed, with oxygen being released at the discharge side  26  of the electrochemical cell assembly  30  and out of the electrochemical gas generator  10  through its outlet  16 . 
         [0037]    Electrochemical oxygen enrichment using air as a source has been previously described in the prior art. The process is typically conducted by applying a voltage across an electrochemical cell consisting of catalytic anode and cathode and an electrolytic member or ionic polymer such as DuPont&#39;s Nafion®. Electrode processes are: 
         [0000]      Cathodic reduction: O 2 (air)+4H + +4e − →2H 2 O 
         [0000]      Anodic oxidation: 2H 2 O→4H + +4e − +O 2    
         [0000]      The over-all reaction is: O 2 (air)→O 2 (pure, compressed) 
         [0038]    The correlation between current and gas generation rate, at 25° C. is 5.5 cc of oxygen/day-mA. Conversely, the amount of energy required to generate 1 cc of oxygen is 4.4 mA-hr. The over-all process can take place at a voltage of less than 1.5 volts and is therefore compatible with most commercial batteries. 
         [0039]    The amount of gas generated by batteries such as the 357 silver oxide button cell is ca. 36 cc of oxygen, while the 675 Zinc-air battery can release from 110-140 cc of oxygen. Larger volumes can be produced from commercial alkaline batteries such as AAA and AA. 
         [0040]    Since the rates of fluid deliveries of interest to this invention are generally less than 1 mL/day, the applied currents are less than 200 micro-amps. In fact, 20 micro-amps are adequate for delivery rates of 0.1 mL/day. Since air-operated electrochemical cells have a capacity of about 100 mA/cm 2 , or 550 cc of oxygen/day-cm 2 , it is apparent that to achieve the desired rates of 1 mL/day or less, the cell size can be extremely small, therefore, non-conventional electrochemical cell assemblies are required as compared to more conventional assemblies such as those described by Maget in U.S. Pat. No. 6,010,317. 
         [0041]      FIGS. 2A and 2B , in conjunction with  FIGS. 3A and 3B , illustrate a slightly modified version of an autonomous electrochemical oxygen generator which, for oxygen generation, is controlled by an oxygen permeable film, either conductive  115  or non-conductive  125 , thereby eliminating the need for the resistor  20  as required in the previously described electrochemical gas generator  10 . This electrochemical gas generator  110  is somewhat similar to the previously described electrochemical gas generator  10  in that it has a container  111 , with one or more oxygen inlets  114  on the bottom and an outlet  116  and activation member  118  on top of the container  111 . The oxygen inlet  114  and bottom however has an upward extending recess  117  thereat adapted to receive a compression-type fitting  120 , such as but not limited to washers, plugs, slugs, and lids, the purpose of which is described later herein. A chamber  113  within the container  111  houses the battery holder  119  and the battery  12 . 
         [0042]    This electrochemical oxygen generator  110  is film-based and, unlike the previously described current-based electrochemical gas generator  10 , is housed below the battery  12  and on the bottom of the container  111 . In assembling this generator  110 , a sealing ring  123  is placed on the floor [bottom] of the container  111 , followed by the electrochemical cell assembly  30 , and ending with the battery  12  in its holder  119 . 
         [0043]    In cases where the electrochemical cell assembly being used is that as illustrated in  FIG. 3A , construction is followed by placement of either a conductive oxygen-permeable film  115  or a non-conductive oxygen-permeable film  125  into the recess  117  followed by insertion of the compression-type fitting  120  into the recess and in contact with the conductive oxygen-permeable film  115  or a non-conductive oxygen-permeable film  125 . Similar to the previously described generator  10 , this is followed by crimping the container  111  inward and downward to achieve an electrical contact between the battery  12  and the electrochemical cell assembly  30  and the container  111 . 
         [0044]    With the compression-type fitting  120  so pressed into the recess  117  an intact and ready to use film-based electrochemical gas generator  110  is made. A ledge  122  supports the electrochemical cell assembly  30  and, with the sealing ring  123 , maintains an air-tight integrity of this electrochemical gas generator  110 . 
         [0045]    As so configured a large cavity  47  is defined below the electrochemical cell assembly  30  and the floor of the container  111 . A small cavity  37  is defined below the electrolytic membrane  31  and the lower segment of the oxygen-impermeable film  34 . As will be explained, the large cavity  47  serves an important function to the operation of this film-based electrochemical gas generator  110 . 
         [0046]    The compression-type fitting  120  should have one or more perforations  144  [one is shown] therein to permit access of air onto the oxygen-permeable film  115 ,  125 . The oxygen-permeable film  115 ,  125  allows a certain amount of oxygen to diffuse across the oxygen-permeable film  115 ,  125  and to access the electrochemical cell assembly  30  above. A raised circular ridge  121  on the top of the compression-type fitting  120  defines the active area for oxygen permeation through the oxygen-permeable film  115 ,  125 . The one or more perforations  144  are inside the circular ridge  121  and air for oxygen extraction contacts only the area of the oxygen-permeable film as defined by, and within, the circular ridge  121 . 
         [0047]    As previously described and illustrated in detail in  FIG. 3A , the upper and lower segments of the oxygen impermeable film  34  and the respective outward extensions  35  sandwich the membrane-electrode, current-collector combination  31 ,  32 , and  33  and, with the outward extensions  35 , prevents air from circulating around the electrochemical cell assembly  30  but forces oxygen to flow to the electrochemical cell assembly  30  to be processed, with oxygen being released at the discharge side  26  of the electrochemical cell assembly  30  and out of the electrochemical gas generator  110  through its outlet  116 , and as a result, the oxygen generation rate is now controlled by oxygen transfer through this oxygen permeable film  115 ,  125  thereby eliminating the need for the resistor  20 . 
         [0048]    In cases where no compression-type fitting  120  is being applied, such as illustrated in  FIGS. 4A and 4B  [to be described in detail later] the film must be conductive oxygen-permeable  115  as illustrated by the electrochemical cell assembly  130  in  FIG. 3B . This embodiment of  FIGS. 4A and 4B  simplifies the manufacture process and costs associated therewith. 
         [0049]    In the embodiment illustrated in  FIGS. 2A and 2B , the principle of operation of a film-based, or diffusion-based, oxygen generator eliminates the need for a resistor to control the current and thereby the oxygen generation. Conventionally-available and typical oxygen-permeable film  115 ,  125  should generally be of a silicone film and more specifically, if it is to be of the non-conductive type, a dimethylsilicone (DMS) film of known oxygen permeability such as produced by Silicone Products, Inc. It is the known permeability of the film which will dictate the quantity of oxygen to be generated and not the strength of the battery  12  rendering battery strength immaterial to its efficiency. 
         [0050]    The rate of oxygen transfer through the above-mentioned DMS film  125  is 60×10 −9  cc-cm/cm 2 -sec-cmHg pressure difference. If a specific oxygen partial pressure difference can be maintained across either type of oxygen-permeable film  115 ,  125 , the oxygen transfer rate will be constant. If the partial pressure of oxygen on the down-stream side of the oxygen-permeable film  115 ,  125  is small (near zero) the oxygen pressure difference is set at about 16 cm of Hg. The transfer rate of oxygen then becomes equivalent to 0.083 cc-cm/day-cm 2 . For a film thickness of 10 mils, the rate becomes equivalent to 3.3 cc/day-cm 2 . To achieve a 1 cc/day transfer rate, the film diameter should generally be 0.6 cm. 
         [0051]    To achieve the desired low oxygen pressure on the down-stream side of the oxygen-permeable film  115 ,  125 , a battery voltage of 0.9 and 1.7 volts is applied directly to the electrochemical cell assembly  30 , without current control. 
         [0052]    Each of the film-based generators  110 ,  210  involve a two stage process for oxygen generation: [1] oxygen diffusion; and [2] electrochemical oxygen concentration. 
         [0053]    With regard to the generator  110  illustrated in  FIG. 2A , oxygen within the large cavity  47 , as defined by the boundaries of the oxygen-permeable film and the electrochemical cell assembly  30  will be immediately scavenged and released as pure oxygen at the cell assembly anode. In fact, applicant has obtained oxygen partial pressures in cavity as low as 100 ppm, or 0.008 cm Hg, a negligible value as compared to 16 cm Hg of oxygen pressure in air. 
         [0054]      FIGS. 4A and 4B  in conjunction with  FIG. 3B  illustrates yet another embodiment of an electrochemical gas generator  210  also controlled by an oxygen-permeable film rather than a resistor  20  as previously described for the electrochemical gas generator  10 . In this embodiment, however, the oxygen-permeable film must be electrically conductive  115 . This electrochemical gas generator  210  is configured similarly to the previously described electrochemical gas generator  110  in that it has a container  211 , with one or more inlets  214  on the bottom [one being illustrated for the purpose of allowing entry of an oxygen-containing gas, such as but not limited to, air] and an outlet  216  and activation member  218  on top of the container  211 . A chamber  213  within the container  211  houses the battery holder  219  and the battery  12  securely positioned therein. A ledge  222  is defined on the bottom of the battery holder  219 . The bottom, or floor, of the container  211  has a raised ridge  221  defining a perimeter thereon having a clearly defined inner side and an outer side. There is no need for the compression-type fitting  120  as in the electrochemical gas generator  110  as previously described. 
         [0055]    In assembly of this embodiment, sealing ring  223  is first placed into the container  211  followed by the electrochemical cell assembly  130  [see  FIG. 3B ], battery  12 , and then the battery holder  219 . Container  211  is then crimped inward and downward to achieve electrical contact between the battery  12 , electrochemical cell assembly  130 , and the raised ridge  221 . The ledge  222  in combination with the sealing ring  223  supports the electrochemical cell assembly  130  and maintains the required air-tight integrity necessary for the electrochemical gas generator  230  to properly and most efficiently function. 
         [0056]    The one or more inlets  214  on the electrochemical gas generator  210  allows free access of any oxygen-containing gas, such as but not limited to, air to the electrochemical cell assembly  130  and the raised ridge  221 , defining the active area [inner side of the perimeter] for air access to, and oxygen transfer across, the conductive oxygen-permeable film  115  to the electrolytic membrane  131  and lower electrode  132 . 
         [0057]      FIG. 3B  illustrates in detail the electrochemical cell assembly  130  used in the above described electrochemical gas generator  210 . It is similar to the electrochemical cell assembly  30  previously described in that it has solid electrolytic membrane  131  onto which electrodes  132  are embedded on the top and on the bottom of the electrolytic membrane  131 . A single current collector  133  is on top of the top electrode  132  and in intimate contact therewith to insure a low resistance electrical contact. A major difference with this electrochemical cell assembly  130  is that the lower current collector  33  as described for the electrochemical cell assembly  30  is replaced by the conductive oxygen-permeable film  115 . Electrical conductivity is achieved by the addition of conductive materials to the film such as, but not limited to, carbon, graphite, silver, nickel, or other similarly conductive materials. 
         [0058]    This membrane-electrode-film electrochemical cell assembly  130  is partially sandwiched between upper and lower segments of oxygen impermeable film  134  which is used to seal off the edges of electrochemical cell assembly  130  by way of outward extensions  135 . As can be seen the oxygen impermeable film  134  sandwiches the membrane-electrode-current collector-film combination  131 ,  132 ,  133 ,  115  and, with the outward extensions  135  in conjunction with the sealing ring  123  [refer to  FIGS. 4A and 4B ], prevents air from circulating around the electrochemical cell assembly  130  but forces the air to flow to the electrochemical cell assembly  130  from its air intake side  124 , to be processed, with oxygen being released at the discharge side  126  of the electrochemical cell assembly  130  and out of the electrochemical gas generator  210  through its outlet  216 . 
         [0059]    Typical conventionally available components of the electrochemical cell assembly  130  include:
       [1] for the electrolytic member (cation or anion) [ 131 ], a typical membrane which is manufactured by DuPont® and known as Nafion®;   [2] for the electrodes [ 132 ], catalytically active materials such as platinum black or platinum activated carbons or graphite;   [3] for the current collector [ 133 ], which typically should be approximately 320 microns thick and less than 5 mm in diameter, porous conductive carbons or graphite paper or porous conductive materials such as conductive silicone rubber or a metal screen;   [4] for the oxygen permeable film [ 115 ], a conductive silicon rubber produced by Silicone Products, Inc., of known oxygen permeability; and   [5] for the oxygen impermeable film [ 34 ] and outward extensions [ 35 ], DuPont&#39;s® commercially available Kapton® film.       
 
         [0065]    This electrochemical gas generator  210  is activated by moving the activation member  218  in the direction of Arrow B which is then pressed and held in contact with the battery  12 . After this movement is completed, the electrochemical cell assembly  130  immediately extracts oxygen from the small cavity  137 . Since the oxygen-permeable film  115  is in intimate contact with the lower electrode  132 , and because the cavity  137  is extremely small, oxygen pressure in the small cavity  137  in instantly decreased to near zero. This difference in oxygen pressure as contrasted to the air pressure on the intake side  124  of the electrochemical cell assembly  130  becomes the driving force for oxygen transfer across the oxygen-permeable film  115  and subsequent release from the upper electrode [anode] and discharge from the electrochemical gas generator  210  from its outlet  216 . 
         [0066]    The present disclosure includes that contained in the present claims as well as that of the foregoing description. Although this electrochemical gas generator and cell assemblies have been described in its preferred forms with a certain degree of particularity, it is understood that the present disclosure of the preferred forms has been made only by way of example and numerous changes in the details of construction and combination and arrangement of parts and method steps may be resorted to without departing from the spirit and scope of the electrochemical gas generator and cell assemblies. Accordingly, the scope of the electrochemical gas generator and cell assemblies should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents. 
         [0067]    It must be understood, however, that there may be unforeseeable insubstantial modifications to electrochemical gas generator and cell assemblies that remain as equivalents and thereby falling within the scope of the electrochemical gas generator and cell assemblies described and claimed herein.