Abstract:
A device for achieving a controlled low emanation rate of small volumes of liquid solutions, such as single or multi-component solutions, fragrances, or pheromones, for pest and insect management or fragrance enhancement. The device has a housing with an upper chamber to hold a bladder containing desired liquid solution to be released, a lower chamber containing an electrochemical gas generator, a collector pad for receiving liquid solution from the bladder, and a cap which, when translated downward, activated the gas generator which fills the upper chamber with gas exerting pressure on the bladder which in turn forces the liquid solution from the bladder onto the pad for release to the environment. The gas generator is capable of releasing gases such as hydrogen, oxygen, or carbon dioxide at extremely small, pre-determined, and adjustable rates.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/943,755, filed on Jun. 13, 2007. 
     
    
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Applicant has received funding from the U.S. Department of Agriculture, Grant Number 2004-33610-15132. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The invention herein relates to vapor release devices/dispensers. More particularly it relates to small portable dispensers to disperse vapors into the surrounding environment. 
         [0005]    2. Description of the Prior Art 
         [0006]    In recent years there have been numerous applications for small, easily portable liquid and other fluid dispensers. One use of these devices is to provide for dispersion of gases and vapors into the environment. Typical are devices used to alter environmental scents, such as in homes and offices. Another important application, used for a large range of environmental conditions, such as temperature and elevation, is for the release of pheromones. Pheromones are chemical substances released by insects for the purpose of communication. 
         [0007]    Chemists have learned to reproduce these chemicals and entomologists have been successful in using them for the management of insects. Insect management requires the release, preferably at constant rates, of minute quantities of pheromones, generally less than 10 milligrams/day, over time periods of up to 12 months. The release of pheromones at these minute rates has been achieved mainly by diffusion of the pheromones through plastic materials, a process which is extremely temperature-sensitive and not field-reliable, since the rate also decreases with time and renders the releaser useless since a minimum threshold of pheromone concentration in the air is not maintained. 
         [0008]    Pheromone dispensers have to be economical since in current uses as many as 500-1,000 devices are needed per hectare to control insects. The requirements of low cost, accuracy of delivery, duration of delivery, environmental conditions ranging from sub-freezing to desert-like summer temperatures, elevations from sea level to 10-15,000 feet, and in some instances re-usability, are stringent for practical dispensers. 
         [0009]    Dispensers meeting some of these requirements have been described by Maget in U.S. Pat. No. 5,928,194 and Maget, et. al., in U.S. Pat. No. 6,383,165. An embodiment of the latter has been shown to be effective for the control of bark beetles, an insect responsible for the destruction of millions of acres of forest, worldwide. U.S. Pat. No. 6,383,165 is hereby incorporated by reference herein in its entirety, including the detailed description of the various devices used in the delivery of pheromones. In addition, my previously filed provisional application, 60/943,755, filed on Jun. 13, 2007, is also hereby incorporated by reference. 
         [0010]    The current device described herein, and in my provisional application [&#39;755], represents an improvement over the previous dispensers inasmuch as they are more economical to produce, easier to fill, include re-usable components, and yet achieve the same performance. Low cost, ease of storage and operation, including continuous delivery over long time periods, such as months, are features and capabilities necessary for commercial dispensers of fragrances as well as pheromones. 
       OBJECTS OF THE INVENTION  
       [0011]    One object is to provide practical, low cost, commercial electrochemical fluid dispensers capable of releasing fluids in the environment under controlled conditions, whether for environmental control reasons or for aesthetic reasons; these fluids being either highly volatile or having low vapor pressures. 
         [0012]    Another object is to show that by careful combination of the fluid pumping/release rates and fluid collection pad sizes and configuration, the fluid releaser system can be tailored to achieve, rapidly, steady state emission rates, even for multi-component fluid solutions. 
         [0013]    A further object is to provide users with dispensers that are easy to fill, transportable and easy to start, even under field conditions, without the need for special tools or equipment. 
         [0014]    The foregoing has outlined some of the more pertinent objects of the improved dispenser as set forth in this disclosure. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the improved dispenser. Many other beneficial results can be attained by applying the disclosed improved dispenser in a different manner or by modifying the improved dispenser within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the improved dispenser as set forth in this disclosure may be had by referring to the summary of the improved dispenser and the detailed description of the preferred embodiment in addition to the scope of the improved dispenser defined by the claims taken in conjunction with the accompanying drawings. 
       SUMMARY 
       [0015]    The above-noted problems, among others, are overcome by the improved electrochemical fluid dispenser releasing vapors of chemicals or any liquid solutions into the environment at controlled low emanation rates of small, pre-determined and adjustable volumes of such chemicals or liquid solutions for environmental control or for aesthetic reasons such as, but not limited to, fragrance enhancers. The device has a housing with an upper chamber to hold a bladder containing desired liquid solution to be released, a lower chamber containing an electro-chemical gas generator, a collector pad for receiving liquid solution from the bladder, and a cap which, when translated downward, activates the gas generator which fills the upper chamber with gas exerting pressure on the bladder which in turn forces the liquid solution from the bladder onto the pad for release to the environment. 
         [0016]    The gas generator is capable of releasing gases such as hydrogen, oxygen, or carbon dioxide at extremely small, pre-determined, and adjustable rates. The device allows the release of single or multi-component solutions, fragrances, and pheromones onto the collection pad from which it can emanate into the environment either directly or through one or more release vents in the cap or, is an embodiment having an outer wall to the housing, through release vents in the outer wall. 
         [0017]    The invention achieves the results of my previous patent U.S. Pat. No. &#39;165; however certain modifications and features have been incorporated to simplify filling, operation, and start-up. The cap is removable exposing a fill or exit port to the bladder. This makes the device reusable by filling the bladder with a desired liquid solution and replacing the gas generator. 
         [0018]    Additionally, in one embodiment, gas pressure is applied directly to the fluid before releasing it to the collection pad, rather than using a barrier interface between the gas and the fluid. The pheromone, pheromone solution, or fragrance under pressure generated from the electrochemical gas source, is delivered, via a conduit, to a collection pad from which it can emanate (evaporate). 
         [0019]    The present invention provides the necessary features to render the system operational and reliable under a variety of environmental conditions, while achieving constant release. More specifically, selection of a common solvent for all components of the fluid, thermal insulation, geometry of the fluid exit conduit and pad properties and sizes are needed to achieve the expected delivery profiles. 
         [0020]    For complex fluid mixtures, that is for fluids containing more than two components, an algorithm is required to predict the minimum pad size and geometry, to achieve, as rapidly as possible, the steady-state emanation conditions. 
         [0021]    The foregoing has outlined the more pertinent and important features of the various embodiments of the improved dispenser as set forth in this disclosure 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 improved dispenser will be described hereinafter which form the subject of the claims. 
         [0022]    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 improved dispenser as set forth in this disclosure. 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 improved dispenser as set forth in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    For a fuller understanding of the nature and objects of the improved dispenser as set forth in this disclosure, reference should be had to the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0024]      FIG. 1  is a side elevation view of one embodiment of the dispenser. 
           [0025]      FIG. 2  is a cut-away view of the dispenser of  FIG. 1 . 
           [0026]      FIG. 3  is an exploded cut-away view of a preferred embodiment of the dispenser. 
           [0027]      FIG. 4  is a detailed exploded view of the head, cap, and pad configuration of the dispenser. 
           [0028]      FIG. 5  is a partially exploded and partially cut-away view of a second embodiment of the dispenser. 
           [0029]      FIG. 6  is a cut-away exploded view of the dispenser of  FIG. 5 . 
           [0030]      FIG. 7  is a cut-away exploded front view of a third embodiment of the dispenser. 
           [0031]      FIG. 8  is a cut-away exploded side view of a third embodiment of the dispenser. 
           [0032]      FIG. 9  is a detailed plan view of the pad for use with the dispenser of  FIGS. 7 and 8 . 
           [0033]      FIG. 10 , as taken on line  10 - 10  of  FIG. 7 , is a cross section side view of the cap for use with the dispenser of  FIGS. 7 and 8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    General Description from Provisional Application 
         [0035]    In this section, reference to  FIGS. 1 through 6  relate to the figures associated with my provision application No. 60/943,755, filed on Jun. 13, 2007, and not to the figures associated with this current non-provisional application and are provided herein as a point of reference, support as necessary for this current non-provisional application, and for possible later submission of other non-provisional applications. Consequently, these figures are not reproduced herein but have been incorporated by reference above. 
         [0036]    An elongated reservoir  1 , in  FIG. 1  of provisional application [&#39;755], is located within a thermal insulation shroud  2 . The reservoir, fitted with fluid evacuation tubing  3 , holds a pheromone solution  4 , by way of illustration. A releaser head  5  is securely attached to reservoir  1  by means of a threaded connector  20 . A seal  6  is provided to prevent the leakage of gas around the threaded connector  20 . 
         [0037]    Releaser head  5  has two cavities; cavity  7  to hold gas generator  8  and cavity  9  to hold collection pad  10 . Gas generator  8  is equipped with a seal  11  which prevents gas leakages to the environment. A metal connector  12  wraps around gas generator  8 . Metal connector  12  closes the electrical circuit through resistor  13  that allows the current to flow through the circuit, once closed. On stand-by, ribbon  14  prevents electrical connector to close the circuit. By pulling ribbon  14  the circuit is closed and the generator is operative. The gas released by generator  8 , supplied via conduit  15 , applies pressure to the liquid in reservoir  1  and pushes fluid to collection pad  10  from which it can evaporate to the environment. 
         [0038]      FIG. 2  of provisional application [&#39;755] represents a variance of the embodiment of  FIG. 1  of provisional application [&#39;755]; the gas generator is now located at right angle from the device axis to allow for the axial location of fluid evacuation tubing  3 . 
         [0039]    Whenever high emanation rates are required, or when the released fluid contains compounds with extremely low vapor pressures, the collector pad size becomes large and it cannot anymore be accommodated within the cross-sectional area of the dispenser. 
         [0040]    In this case,  FIG. 3  of provisional application [&#39;755] provides a solution by wrapping the pad around the dispenser. In  FIG. 3  of provisional application [&#39;755], plastic reservoir  1  is fitted with an adaptor  19 , which also contains a section of fluid release tubing  3 . Adaptor  19  is designed to mate with gas generator holder  17 . Reservoir  1  is placed within an insulation shroud  2  that has a shoulder  2 A and a section  2 B with reduced diameter, designed to fit within releaser head  5  by sliding shroud  2  into head  5  until stopped by the shoulder  2 A. 
         [0041]    Releaser head  5  holds gas generator holder  17 , collector pad  10 , slot  24  and fluid exit channel  23  which, during assembly, is aligned with exit channel  23 A within adaptor  19 . The releaser head has vertical openings  21  to allow evaporation of the solution from the pad into the environment. During operation, the fluid leaving the reservoir through tubing  3  exits at  23 A and eventually through conduit  23  onto collector pad  10 . 
         [0042]    The gas generator is located within holder  17 . It has a seal  22  that prevents gas leakage once it is mated with adaptor  19 . Lid  18  holds the gas generator connectors  12 A and  12 B, which, during operation, are in electrical contact with gas generator  8 . 
         [0043]    On stand-by, a flat insulating ribbon, not shown, placed between generator  8  and contact  12 A, exits through slot  24 . To start operation, the ribbon is pulled, and the spring action of connector  12 A closes the electrical contact. The flat axially truncated dispenser geometry is employed to allow it to be attached to flat vertical surfaces. 
         [0044]    A similar configuration is illustrated in  FIG. 3A  of provisional application [&#39;755], albeit in this case some components are aligned in a different manner and the emanation slots are horizontal instead of vertical.  FIG. 3B  of provisional application [&#39;755] represents another variance of releasers of  FIGS. 1 ,  3  and  3 A of provisional application [&#39;755]. In this instance, the gas generator is sealed within an enclosure capped by an elastomeric push-button Start of operation is achieved by depressing the button. 
         [0045]    The storage sub-system consists of the reservoir  1 , the thermal insulation  2 , the tubing  3  and the stored fluid  4 . By separating the storage sub-system from the releaser head, it is possible to fill the reservoir by using conventional filling equipment and then attaching it to the releaser head. It also provides the option for the user to fill the dispenser at a selected site with a selected fluid. A similar two-part fluid dispenser is also described by Maget is U.S. Pat. No. 5,938,640. A self-contained system, U.S. Pat. No. 6,045,055, describes a closed assembly delivering fluid to plug(s) for emanation. For reasons discussed in the following such a system would not deliver fluid at a constant rate, unless provisions described in this invention are provided. 
         [0046]    The reservoir acts as a flexible bag or bladder. The material selected for its composition is judiciously selected for compatibility with the pheromone or fragrance solution, which includes mainly organic compounds which are excellent solvents. Glass, metals (steel, aluminum) and certain plastics are candidate materials. The optimum material for the bladder  62  and its intended purpose is a is a five-layer co-extruded barrier film produced by Dow Chemical referred to a Saranex. 
         [0047]    Furthermore, the reservoir material has to be as impermeable as possible to the gas produced by the gas generator. Again glass, metals and specific plastics are acceptable. Judicious selection of the plastic materials is required lest gas losses through diffusion prevent reliable operation of the dispenser. Also the choice of materials is further limited by the need for processability to be able to produce the required reservoir shapes. Plastic materials which can be molded or thermoformed are required. These include materials such as Delrin, Nylon, Teflon, PET or rigid PVC. With verbenone, a practical pheromone, we have encountered many problems with incompatibility with polyvinylchloride (PVC) polymers and terephtalates. 
         [0048]    The elongated geometry of the reservoir is also important. Since many pheromones are expensive, it is essential that maximum utilization be achieved. The reservoir geometry should be such that at least 95% of the fluid can be evacuated. 
         [0049]    Although the gas generation rate is rather insensitive to temperature, cyclic daily temperature excursions have an impact on the expansion/contraction of the gas phase above the liquid. This expansion/contraction is proportional to the extreme daily temperatures divided by the absolute temperature, or ΔT/T, where ΔT represents the maximum less minimum temperature and T is the absolute initial temperature. For example, a 15° C. circadian upward excursion from a nominal temperature of 20° C. would result in an impact of (15/293.2) or 5.1% in the volume change. For a gas volume of 100 cc, this would represent an uncontrolled delivery of 5.1 mL of fluid due to thermal differences, only. 
         [0050]    For a fluid evacuation conduit of less than 5.1 mL capacity, this would mean that on the down cycle (−15 C drop), the reservoir will “suck-in” air. This thermal siphon can have adverse effects over the long term whenever the chemicals in the solution are sensitive to oxidation. Another effect will be the uncontrolled nature of the fluid delivery, since thermal daily cycle vary with weather, seasons, and the like. 
         [0051]    To alleviate thermal excursion, the reservoir should be insulated to, as a minimum, dampen the thermal excursion range. However, this solution will only reduce the magnitude of the thermal cycle. 
         [0052]    The insulation material and external shroud also provide protection from natural or artificial light to prevent UV-induced breakdown of the solution chemicals. Furthermore, the insulation provides protection from breakage of the glass reservoir, if such reservoir material has to be used. 
         [0053]    To prevent air bubbles intake, an appropriate design of the conduit is important. The minimum conduit volume can be estimated from the worst case situation, that is the reservoir is filled with gas. From the previous example it should be at least 5.1 mL. 
         [0054]    The shape of the conduit should also consider the need to achieve fluid delivery continuum, if at all possible. This need will be further explored in the following discussion of fluid receiver pads. To achieve a delivery as continuous as possible, the linear fluid displacement should be maximized to result in a steady stream of fluid. A capillary conduit end  3 A, as illustrated in  FIG. 1  of provisional application [&#39;755] should be selected., since extremely small fluid delivery rates, i.e., about 5-10 microliters/hour are contemplated for the dispensers in question. In that instance a capillary with an inside diameter of 0.05 cm would be appropriate. It would result in a linear fluid displacement rate of 2.5-5 cm/hr, pushing the fluid towards the receiver pad. [Note: the linear displacement rate (L/t) in cm/hr is obtained from the following equation: L/t(cm/hr)=(4/pi)(R/D 2 ) where R is the liquid flow rate in mL/hr and D is the inside diameter of the capillary in cm]. 
         [0055]    Furthermore, to be able to evacuate mostly all of the fluid in the reservoir, as expected whenever expensive chemicals are being dispensed, it is important to provide the conduit with a geometry  3 B, as illustrated in  FIG. 1 , which allows nearly all the liquid to be extracted at the time of near delivery completion. [Note: some pheromones cost as much as S 1,000/gram]. 
         [0056]    The insulation has another function, namely preventing UV radiation to reach the reservoir contents. Pheromones are complex, often unsaturated, organic molecules susceptible to UV-induced oxidative degradation, which would result in the inactivation of the semiochemical. 
         [0057]    The releaser head includes means to attach the head to the reservoir sub-system, such as a screw-on interface  20 , the gas generation sub-system and the fluid collector. Economical gas generators are generally electrochemical cells, which are also compact and energy-efficient. 
         [0058]    The gas generators can be divided into two types: generators needing an access port to the environment and self-contained generators without need to access the environment. 
         [0059]    Generators of the first type include:
       a. oxygen concentrators requiring air intake to generate enriched oxygen as described by Maget in U.S. Pat. No. 4,522,698;   b. electrolytic decomposition of organic acids into carbon dioxide and hydrogen, whenever one gas has to be rejected to the environment, as described by Maget in U.S. Pat. No. 6,413,238 and a co-pending application;   c. water electrolysis producing oxygen and hydrogen, whenever one gas has to be rejected.       
 
         [0063]    Generators of the second type include:
       a. gas cells, producing only hydrogen as a gas, as described by Winsel in U.S. Pat. No. 5,242,565;   b. electrolytic decomposition of organic acids producing and utilizing both generated gases, CO 2  and H 2  as described by Maget in U.S. Pat. No. &#39;238;   c. electrolysis of water, when both gases O 2  and H 2  can be used.       
 
         [0067]    The selection of either of these electrochemical generation means is dependent on the chemical nature of the solution to be delivered. For example, many organic compounds or solutions are sensitive to degradation by oxygen, and therefore oxygen or oxygen-containing gases are not recommended. Hydrogen is mostly inactive but difficult to contain and H 2  losses through members of the dispenser can result in uncontrolled fluid delivery. CO 2  is generally inert to organic molecules and easy to contain. 
         [0068]    In most instances, the gas generator is driven by DC energy supplied from a small battery, hearing-aid cell or button cell. In few instances, such as for H 2  gas cells, the reaction between chemicals contained in the cell produces DC electric energy and a gas by-product. These gas cells do not require an auxiliary battery. 
         [0069]    The gas generation rates vary from 0.23 to 1.35 cc gas NTP/hour per milli-ampere, depending on the selected electrochemical process. Since small battery storage capacities do not generally exceed 200 mAhr, it will be apparent that these generators are capable to deliver only small quantities of fluids, generally not exceeding 250 mL, unless designed with the capability for battery replacement. 
         [0070]    There are, however, lower limits of gas generation and fluid delivery rates. They are considered to be about 5 microliters/hour, corresponding to cell currents of 4 to 25 microamps. Below these limits, thermal effects and diffusional losses become too significant to maintain control of the fluid delivery. These limits will have an impact on the composition of the fluid to be delivered. For example, pheromones are often delivered at rates of 1-2 milligrams/day, or about 1-2 microliters/day, or about 1% of the controllable delivery rates of the gas generator-driven dispensers. Therefore, to achieve this extremely low delivery schedule, the pheromone needs to be diluted in an appropriate inactive solvent. 
         [0071]    Channel  15  providing the gas to the reservoir is a narrow circular conduit adequate for gas transfer at low rates, but yet preventing liquid from the reservoir to splash onto the gas generator which, in some instances, could affect the generator performance. 
         [0072]    Orifice  16 , through which the start ribbon passes, also serves as an inlet air port for oxygen enrichment generators, or as a gas exit port for undesirable gas generator gases such as hydrogen or oxygen. 
         [0073]    It should be apparent that judicious selection of the gas generator is dependent on many variables and factors, such as environmental conditions, liquid composition, selection of the gas generator and design of the dispenser. This decision process will also have to include means to release the fluid into the environment. 
         [0074]    The fluid, released as a result of gas pressure exercised on the solution, is captured by a collection pad. The pad, made of natural or synthetic fibers, is available commercially from sources such as Waterman Corp. For additional protection of the pad from the environment, a water repellant layer of Tyvek (a DuPont product) is placed on the external side of the collector pad. The Tyvek layer will protect the pad from water, dust, etc. 
         [0075]    Although precise delivery of the solution is a necessary step to achieve reliable release, emanation of the pheromone(s) or fragrances from the collector pad is another critical step. Pad selection can not be casual for reasons presented in the following. 
         [0076]    For a multi-component pheromone solution, the rate of accumulation of the solution on the collector (dW/dt) results from the delivery rate of the fluid to the pad (R) less the evaporation rate. This relationship can be expressed symbolically by: 
         [0000]      ( dW/dt )= R−{[E/aδρ   f ( t )]Σ x   i ( t ) P   i }( W ) 
         [0000]    where: 
         [0077]    (W) is the weight (mg) of fluid on the pad at any time; R is the fluid delivery rate, in mg/hr; (a) is the retention coefficient of the pad (volume of fluid/volume of pad); ρ f  is the fluid density in the pad; δ is the pad thickness; (x i ) is the species (i) mole fraction in the liquid phase in the collector; P i  is the vapor pressure, in mm Hg, of the pure component (i); (E) is the specific evaporation rate from the collector in mg/hr-cm 2-mmHg and (t) is the time in hours. 
         [0078]    The value of (E) will depend on the environmental conditions such as wind velocity. Since the wetted area (A) in cm 2 , on the pad equals W/aρ f δ, it will be possible to determine the minimum pad area necessary to achieve a constant release rate from the pad. 
         [0079]    Dispenser release rate stability is achieved when (dW/dt)=0; i.e., the emanation rate is identical to the fluid release rate. Analytical solutions of the previous equation are possible only for pure components and binary solutions. To solve the equation for solutions containing more then two components it is necessary to resort to computer finite element analysis. 
         [0080]    We have developed such models and compared the results with experimental measurements. They have allowed us to select optimum pad properties and solution compositions to achieve pre-set requirements such as the daily release rates of individual components from a multi-component solution. Moreover, they have allowed us to release multiple pheromones from a single solution, whereas the art to this date consists of using one releaser for each individual component. 
         [0081]    High vapor pressure semiochemicals, a rare occurrence, require small collection pad areas of a few cm 2 , while most semiochemicals, displaying vapor pressures of less than 0.01 mmHg, require pad sizes of 15-20 cm 2 , even for components delivered at rates of a few milligrams/day. Similarly, fragrances consisting of a multiplicity of organic chemicals may evaporate singularly in an unpredictable manner unless adequate fluid dispersion throughout the pad is achieved in a timely fashion and the pad is of adequate size. 
         [0082]    Whenever gas and liquid are incompatible, because of possible chemical interaction, a barrier (thin plastic film) can be placed between gas and fluid. Such a device is described in Maget&#39;s U.S. Pat. No. 4,902,278 for a two-dimensional planar fluid delivery pump, and again in Maget, et. al., U.S. Pat. No. 6,383,165. Additionally, the film barrier also prevents fluid vapors to contact the gas generator. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THIS NON-PROVISIONAL  APPLICATION  
       [0083]    The benefits described above and in my provisional application [&#39;755] are incorporated in one preferred embodiment of the dispenser  50  as illustrated in  FIGS. 1 and 2  [ Figure 7  of my provisional application [&#39;755]]. This dispenser  50  requires only one gas seal and renders the dispenser orientation-insensitive, a feature of importance for transportation. A reservoir  25 , such as a plastic syringe, with a conventional exit port  26  is capped by syringe cap  27 . The distal end of the syringe  25  is fitted with an adaptor  28 , which contains the gas generation module  35 . 
         [0084]    Adaptor  28  is fitted with seals  36  to prevent liquid from escaping reservoir syringe  25 , and with a collapsible thin-walled plastic bag/bladder  29 , designed to hold the gas generated by generator module  35 . Reservoir  25  is surrounded by insulation  30  to dampen any large environmental circadian temperature variations within fluid  37  in fluid reservoir syringe  25 . As described earlier such fluids include, but are not limited to, pheromones or fragrance solutions. 
         [0085]    The lower part of the dispenser  50  is further placed within a shroud or housing  56  that provides protection from any external physical damage. The upper part of the dispenser  50  is covered by cap  31 , fitted with vent slots  32 , fluid collection pad  33 , and pin  34 . During the filling cycle syringe cap  27  is removed, and then put back into the sealing position. The dispenser  50  can be freely transported without spills. At the time of use, cap  31  is pushed downward, pin  34  penetrates the cap  31  to allow fluid to escape to be collected by pad  33  from which it can evaporate. The gas generator start-up operation is also the result of downward pressure applied to the cell module  38 , which promotes electrical contact between the battery  39  and the electro-chemical gas generator  35 . 
         [0086]    In this illustration the electro-chemical gas generator  35  produces oxygen as the motive gas. This form of electro-chemical gas generator  35  has been previously described by Maget, et. al., in U.S. Pat. No. 6,010,317. This electrochemical gas generator  35  comprises an electrochemical cell module  38  and a battery  39 . The electrochemical gas generator  35  is located in the adaptor  28 , where a seal  40  is provided to prevent gas losses. A contact strip  43  is connected to the battery terminal. The complete gas generation unit is sealed by means of friction plate  42  and is provided with an air intake port  44 . On stand-by the plate  42  is kept away from contact strip  43 . The generator is started by pushing plate  42  upward, thereby allowing contact between the contact strip  43  and the cell module  38 . The electrochemical gas generator  35  becomes operational and produces gas. The gas produced passes through the air exit port  41  and is captured in and by the expandable bag/bladder  29 . As the bag/bladder  29  inflates it pushes fluid  37  out of the reservoir syringe  25  and up to the collection pad  33 . 
         [0087]    In this embodiment the most critical component is the bag/bladder  29  which expands under generated gas pressure. The bag/bladder  29  should be relatively resistant to gas transmission or else gas losses therefrom would affect fluid delivery rates. Most plastic films designed for food preservation will be adequate, particularly films such as Saranex, available from Dow Chemicals Co. 
         [0088]      FIGS. 3 and 4  [ FIGS. 8A and 8B  of provisional application [&#39;755]] illustrate a first preferred dispenser  60  for volatile compounds. The releaser body  61  in this embodiment has an upper chamber  97  and a lower chamber  91  adjacent to the bottom of the body  61 . The upper chamber  97  and the lower chamber are separated by a chamber ledge  93  which has a gas exit port  95  therethrough. 
         [0089]    A reservoir head  63  has a centrally located downward extending collar  81  and an outer wall with a groove  71  around the outer wall. A slot  78  around the bottom of the reservoir head  63  adjacent to the collar  81  seats over and secures to the top  88  of the body  61 . The collar  81  has a fluid exit port  75  therethrough extending from the bottom  82 A of the collar  81  to its top  82 B. The top  82 B is approximately on the same horizontal plane as the outer wall of the reservoir head  63 . An inner chamber  89  is defined between the outer wall and the collar  81 . The bottom  82 A of the collar  81  is approximately concave in configuration. 
         [0090]    One or more slots  68  separated by head fins  83  reside between the outer wall of the reservoir head  63  and the bottom slot  78 .  FIG. 4  more clearly illustrates the slots  68  showing four. Before the reservoir head  63  is secured to the body  61 , the bladder  62  is heat-sealed to the collar  81  as best illustrated in  FIG. 3 . The bladder  62  is filled with suitable fluid  37  for the intended purpose. The fluid exit port  75  is sealed with a suitable sealing member  85  to prevent undesired evaporation or loss of the fluid  37  within the bladder  62 . An absorption pad  64  is placed over the reservoir head  63  and seal  85  covering the inner chamber  89 . 
         [0091]    The reservoir cap  65  is placed over the reservoir head  63  in such fashion that the protruding inner shoulder  70  around the inner surface of the side wall of the reservoir cap  65  removably seats into the groove  71  of the reservoir head  63 . As so seated, the downward extending approximately centrally located spike  73  on the underside of the top of the reservoir head  63  does not touch or penetrate the seal  85 . 
         [0092]    A plurality of axially displaced support members  77  extend outward from the spike  73  to the inner surface of the side wall of the reservoir cap  65 . The support members  77  provide structural support for the spike  73  and stabilize the pad  64  after the seal  85  is pierced by the spike  73 . 
         [0093]    As previously described, the collar  81  of the reservoir head  63  holds the thin film plastic bag/bladder reservoir  62  which is heat-sealed to the collar  81  which extends downward from the reservoir head  63 . The reservoir head  63  is ultrasonically welded and heat-sealed to the reservoir body  61  which typically is tubular in shape. The pad  64  rests on top of the reservoir head  63 . This pad  64  typically may be circular in configuration. A central port  84  in the pad  64  allows for fluid  37  contained within the reservoir bag/bladder  62  to be released therefrom and onto the pad  64 . On the outside top of the reservoir cap  65  is a tab  69  having an aperture  79  therethrough. 
         [0094]    For the dispenser  60  to properly function, the characteristics of the bladder  62  are such that it has an extremely low fluid/liquid diffusion rate and is impermeable to gas penetration. 
         [0095]    A typical material for the bladder is a heat-sealing thin film bag produced by Dow Chemical and referred to as Saranex which is a five-layer co-extruded barrier film. The composition of the collar  81  requires that it be made compatible plastic materials to accommodate the sealing of the bag  62  in a air-tight leak-free union. Generally the collar will be of a polyethylene composition and the bag will have a polyethylene layer such that each have virtually identical softening temperatures to make the leak-free air-tight seal between bag and collar. 
         [0096]    The reservoir cap  65  firmly, but removably, secures on top of the reservoir head  63  as described above. The reservoir cap  65  has multiple functions, the primary of which are to protect the pad  64  from the elements after the seal  85  is pierced, to securely attach the reservoir cap  65  to the reservoir body  61  by means of an internal shoulder or ridge  70  which fits against the groove  71  on the outer perimeter of the reservoir head  63  surface, and to provide means to suspend the dispenser  60  on an external object through an aperture  79  on the wing or tab  69  on the top of the reservoir cap  65 . 
         [0097]    An electrochemical gas generator  66  is seated into the bottom chamber  91  of the dispenser  60 . A ledge  93  with an aperture  95  therethrough maintains the electrochemical gas generator  66  in place and separates the electrochemical gas generator  66  from the reservoir bag/bladder  62 . The electro-chemical gas generator  66  also is fitted with a circular seal or O-ring  72  which ensures a gas tight contact with the bottom chamber wall  92  at the distal end of the tubular body  61 . Finally, a chamber cap  67 , with a small central port  74 , is placed tightly over the electrochemical gas generator  66  sealing the chamber  91  and preventing the electrochemical gas generator  66  from dislodging from the dispenser  60 . 
         [0098]    A typical generator  66  envisioned here is an electrochemical oxygen generator, producing pure oxygen from air, using a nested cell having a gas generator and battery to power the gas generator, as described by Maget et al, in U.S. Pat. No. 6,010,317. The dispenser  60  is filled via the fluid exit port  75  which is then sealed and protected from unintended release by means of a heat staked thin seal  85  such as, but not limited to, aluminized foil. 
         [0099]    Reservoir cap  65  as engaged onto reservoir head  63  by means of the shoulder  70  and groove  71  alignment, places the dispenser  60  on stand-by. At time of use, the reservoir cap  65  is firmly pressed onto the reservoir head  63  which pushes the shoulder  70  out of the groove  71  and downward. This action will cause the spike  73 , an integral part of the reservoir cap  65 , to pierce the seal  85  to allow fluid  37  to be pumped to the pad  64  surface once the electrochemical gas generator  66  is engaged. The generator  66  is engaged by pushing the chamber cap  67  into the lower chamber  91  provided at the bottom of the body  61  where the electrochemical gas generator  66  resides. This starts the pumping action. 
         [0100]    This action results in two important effects; internal electrical contact within the nested cell to initiate electrical contact to the electrochemical gas generator  66  which generates gas. The o-ring seal  72  around the electrochemical gas generator  66  prevents the gas from flowing downward and out the air intake port  74  which serves to “feed” air to the gas generator  66 . The only direction the generated gas may escape is through the gas exit port  95  and into the upper chamber  97 . 
         [0101]    As the gas builds up in the upper chamber, the pressure exerted by the gas on the bladder  62  causes the ejection of small pre-determined quantities of fluid  37  from the reservoir bag/bladder  62  and onto the pad  64 . The amount of fluid so ejected is determined by the amount of gas being generated by the electrochemical gas generator  66 . This amount may be adjusted as desired. Fluid evaporation from the pad  64  and out of the dispenser  60  takes place through the slots  68  provided in the reservoir head  63 . 
         [0102]    After all the fluid  37  is ejected, the dispenser may be refilled with fluid  37 . To accomplish this, the reservoir cap  65  is removed from the reservoir head  63  exposing the fluid exit port  75 . The bladder  62  is replenished via the fluid exit port  75  in the collar  81 . The fluid exit port  75  acts not only as the fluid release port when gas is being generated, but also acts as the fluid fill port as necessary. 
         [0103]      FIGS. 4 through 6  [ FIGS. 9A and 9B  of provisional application [&#39;755]] illustrate a dispenser  160  for fluids with low vapor pressure requiring larger evaporation surfaces than dispenser  60  can accommodate by its configuration. This dispenser  160  is similar to that illustrated in  FIGS. 3 and 4 , as described above, except for the body  61 , also generally tubular in configuration, consists of an outer wall  61 A and an inner wall  61 B bridged together internally by means of a bridge  118 , thus creating an annular cavity  117  which can now hold a large surface area pad  64  having four extended wings  64 A-D as illustrated in  FIG. 4 . This pad  64  with wings  64 A-D is inserted into the annular cavity  117  through the slots  68  provided in the reservoir head  63 . 
         [0104]    The top of the outer body  61 A is provided with side vents  98  that allow for free air motion over the complete pad surface from the top center of the pad  64  and out over the respective wings  64 A-D and out the side vents  98 . These side vents  98  provide for greater diffusion if they are vertically disposed as illustrated in  FIG. 5 . The slots  68  in the reservoir head  63  align with the side vents  98  in the outer wall  61 A after the pad  64  is placed thereon and its wings  64 A-D set down through the slots  68  and the reservoir cap  65  inserted over the outer wall  61 A. 
         [0105]    In this embodiment, the bottom slots  68  of the reservoir head  63  seat over the top of the inner wall  61 B. The bridge  118  between the inner wall  61 B and the outer wall  61 A prevent fluid  37  from escaping from any area except from the side vents  98 . The snap-activation described for the previously described dispenser  60  is the same for this dispenser  160 . The reservoir cap  65  is pushed down causing the spike  73  therein to pierce the seal  85 . The electro-chemical gas generator  66  is activated causing generated gas to enter the upper chamber  97  and exert pressure on the embedded bladder  62  forcing the fluid  37  therefrom and onto the pad  64 ,  64 A-D. 
         [0106]    Additionally, the annular cavity  117  is also designed to become a well for the pumped fluid. For example, since the pumping action of the electro-chemical gas generator  66  releases fluid in a continuous manner, an offset in evaporation rate (such as a reduction possibly due lower temporary temperatures) may result in excess fluid delivered to the pad  64 , beyond the pad&#39;s fluid storage capacity. The excess fluid will be stored in the annular cavity  117 , held in place by the annular bridge  118  between the outer wall  61 A and the inner wall  61 B and from there re-supply the pad  64  with fluid as the normal environmental conditions are reestablished. 
         [0107]    This embodiment is designed for higher-volume release and, because of such, primarily for use outdoors. To protect this dispenser  160  from the elements, particularly rain, a protective water-repellent film  99  covers the side vents  98 . A typical film for this purpose is Dupont&#39;s Tyvek® family of protective barriers and films. The film  99  prevents water from penetrating into the dispenser  160  yet allows free ‘breathing’ of the film  99  so as not to adversely affect the operation of the dispenser  160 . 
         [0108]      FIGS. 7 through 10  [ FIGS. 10A through 10D  of my provisional application [&#39;755]] illustrate a variance of the previously described dispensers  60 ,  160 . In this embodiment, the dispenser  200  is more user-friendly. For example, the dispenser  200  is on stand-by and is prevented from being accidentally snapped together by use of a removable outer shell “peel-away” pull tab or lock  217 . When the lock  217  is removed, a simple vertical compression action of the cap  230  simultaneously allows the sealing foil  85  to be pierced and the generator  66  to be snapped into place and activated thereby causing the gas generation and pumping action to begin in similar fashion as previously described for dispensers  60 ,  160 ; a single phase snap-action. 
         [0109]      FIGS. 7 and 8  represent a cross-section of the dispenser  200  in front elevation view and side elevation view, respectively. The dispenser  200  has a housing  210  with an inner wall  220  on each side on the housing  210  thereby defining a side space or side chamber  216  on each side of the housing  210  and a central space in between and within the inner walls  220 . Extending upward on each side of the housing  210  is an elongated tab  229  having a width-W 3  and an outward protruding stop member  213  on its top. Downward of the stop member  213 , the elongated tab  229  terminates at a step  219  on the outside surface of the housing  210 . 
         [0110]    On the inside bottom  214  of the housing  210  is an annular ring  215  having a pre-determined diameter-W 1 . Approximately centrally located within the annular ring  215  is an air intake port  274 . 
         [0111]    An inner body  201  seats into the central space or chamber  226 . The inner body  201  has outer groove  207 , a chamber ledge  293  near to its bottom defining an upper chamber  297  above the chamber ledge  293  and a lower chamber  291  below the chamber ledge  293 . The lower chamber  291  has a diameter-W 2  which is slightly larger than diameter-W 1 . This configuration permits the inner body  201  to slide downward such that the lower chamber  291  nests around the annular ring  215 . 
         [0112]    A gas exit port  295  in on the chamber ledge  293  which forms a pathway between the upper chamber  297  and the lower chamber  291 . Much like the previously described dispenser&#39;s  60 ,  160  mode of operation, an electrochemical gas generator  66 , with o-ring seal  72  abutting the lower chamber walls  292  in gas-sealing fashion, will be in and sealed within the lower chamber  291  but not activated. 
         [0113]    A reservoir head  263  is fitted with an reservoir bladder  62  around its collar  281  in similar fashion as previously described for dispensers  60 ,  160 . Unlike the previously described dispensers  60 ,  160 , the reservoir head  263  has a fluid exit port  275  and a separate fluid fill port  205 . The function of the fluid exit port  275  is as described previously, to permit the release of fluid  37  within the reservoir bladder  62  to escape when the seal  85  is breached and the electrochemical gas generator  66  is pumping gas into the upper chamber  297 . 
         [0114]    The reservoir head  263  also has an upstanding ridge or wall  268  for supporting the pad  264  to be placed therein or thereon. The seal  85  is placed between the pad  264  and the fluid exit port  275  to prevent premature evaporation or loss of fluid  37 . The wings  266  of the pad  264  insert over the reservoir head  263  and downward into the respective side chambers  216 . An aperture  265  in the pad  264  facilitates release of the fluid  37  in the reservoir bladder  62 . An energy director  206  under the ridge  268  and adjacent to the collar  281  function to facilitate the ultrasonic welding of the reservoir head  263  onto the inner body  201 . 
         [0115]    The inner body  201  and the reservoir head  263  are ultrasonically welded together using this, typically annular, energy director  206  as a guide and facilitator. This sealing of the inner body  201  to the reservoir head  263  is done after the reservoir bladder  62  has been attached to the collar  281  in similar fashion as previously described for dispensers  60 ,  160 . The reservoir bladder  62  is filled with fluid  37  through the fluid fill port  205  after which both the fluid fill port  205  and the fluid exit port  207  are sealed on top by a heat staked seal  85 ; preferably a metalized plastic film. 
         [0116]    Topping off this dispenser  200  and switching it from operational to non-operational mode is the cap  230 . The unique structure of the cap  230  serves to activate and de-activate the dispenser  200 , to support the pad  264  with a plurality of pad supports  238  on the inside top of the cap  230  protruding downward, and to permit evaporating fluid to escape from the dispenser  200  by way of the vents  232 . In between the pad supports  238 , and approximately centrally located inside the ceiling of the cap is a spike  273  which, when the cap  230  is pushed downward, pierces the seal  85 , activates the electro-chemical gas generator  66 , and begins the operation. 
         [0117]    Referring in particular to  FIG. 10 , on each inner side wall of the cap  230  is a registration slot  236  having a width-W 4  as defined by two vertically disposed inward protruding guides  234 . On the registration slot  236  are at least two horizontally disposed catches  233 A, the upper catch, and  233 B, the lower catch. These catches  233 A,  233 B register with the stops  213  on each side of the elongated tab  229 . Width-W 3  of the elongated tab  229  is slightly less than width-W 4  of the registration slot  236  thereby permitting the tabs  229  to translate up and down within the registration slot  236 . 
         [0118]    In stand-by mode, the stops  213  of the dispenser  230  are seated into catches  233 B wherein the bottom  239  of the cap  230  is above the step  219  on the housing  210 . In this position a gap  218  is defined from the bottom of the cap  230  and the cut-out on the housing  210 . A retaining tab or lock  217  seats through the gap  218  and into the groove  207  around the inner body  201  to prevent pre-mature activation of the dispenser  200 . 
         [0119]    To activate the dispenser  200  for the first time, the lock  217  is removed from the groove  207 ; this will permit the user to initiate the push down, snap-action, on the cap  230 . Until the lock  217  is removed the cap  230  cannot be pushed downward. Once so removed, the cap  230  is pushed downward to pierce the seal  85  and activate the electro-chemical gas generator  66 . Typically, the cap  230  is pushed downward such that the bottom  239  of the cap  230  rests on the step  219  of the housing  210  and also, typically, the stops  213  align with the upper catches  233 A. To deactivate the dispenser  200 , one need only to pinch the sides of the cap  230  and pull upward. The pinching action eases the pressure exerted by the stops  213  on the upper catches  233 A permitting their release and movement of the stops  213  to the lower catches  233 B. This action can stop an electrochemical gas generator  66  capable of being stopped from generating gas which in turn stops the pressure build up in the upper chamber  297  which forces the fluid  37  from the reservoir bladder  62 .