HIGH SURFACE AREA POLYMER ACTUATOR WITH GAS MITIGATING COMPONENTS

Abstract

A polymer actuator component and a polymer actuator assembly, power supply and method of using the activation are described.

Claims

1. An actuator assembly comprising, an anode electrode and a cathode electrode, an electrolyte and a volume changing polymeric actuator in contact with the anode electrode or the cathode electrode, wherein the electrodes are separated from each other by a porous membrane that facilitates modulation of the pH via charges or ionic separation.

2. An actuator assembly of claim 1 further comprising a metal hydride material in contact with and covering a surface of one or more of the electrodes.

3. The actuator assembly of claim 2, further comprising a sealed flexible outer housing enclosing the electrolyte, the anode electrode, the cathode electrode, and the volume changing polymeric actuator, allowing sealed entrance or exit points for the electrodes, wherein the volume changing polymeric actuator is configured to expand or contract in response to pH or chemical changes in the electrolyte induced by an electrical potential differential.

4. The actuator assembly of claim 3, characterized by one or more of the following features: (a) further comprising a second volume changing polymeric actuator, wherein the volume changing polymeric actuators are each adjacent to one of the electrodes and are separated from each other by the porous membrane; and wherein the volume changing polymeric actuators are configured to expand or contract simultaneously when the electric potential differential is applied; (b) wherein the volume changing polymeric actuator and the electrode in contact with the polymeric actuator are sealed inside a flexible container or bag made of the same material as the porous membrane; and wherein a portion of the electrode exiting the flexible container is continuously insulated from the electrolyte; wherein the flexible container or bag, or a portion of the flexible container or bag, preferably is comprised of an elastomeric material; (c) further comprising a rigid structure at least partially surrounding the volume changing polymer actuator material to facilitate a direction of actuation; wherein the rigid structure is pervious to the electrolyte, wherein at least a portion of the rigid structure preferably is porous; (d) wherein the volume changing polymeric actuator is comprised of particulates of an actuating material, the particulates of the actuating material and the electrolyte form a slurry, and wherein the actuator assembly further comprises a flexible and porous enclosure having an interior and an exterior, wherein the particulates of actuating material are contained in the enclosure interior, wherein one of the electrodes preferably is in contact with a surface of the enclosure exterior or in contact with the polymer actuator particulate within the enclosure interior, and/or wherein the enclosure is contained within a rigid porous container that allows fluidic access of the electrolyte to the actuating material within the enclosure.

5. The actuator assembly of claim 3, further comprising a gas adsorbant, and/or further comprising a storage area outside of the sealed flexible outer housing in fluid connection with the electrolyte inside the sealed flexible outer housing.

6. The actuator assembly of claim 1, characterized by one or more of the following features: (a) wherein the electrodes of the actuator assembly are configured to allow in-line electrical connectivity of the actuator assembly with at least one other actuator assembly; (b) wherein the electrolyte comprises an aqueous solution; (c) wherein the electrolyte comprises a non-aqueous solution; (d) wherein the polymeric actuator drives a platen or piston, wherein the platen or piston preferably pumps a fluid; and (e) further comprising a power source and a programmable controller, and optionally further comprising one or more sensors communicating feedback to the controller.

7. A polymeric actuator assembly comprising: a housing; a first electrode in contact with a first portion of an electrolyte; a second electrode in contact with a second portion of the electrolyte; a membrane separating the first portion of the electrolyte from the second portion of the electrolyte to support a pH difference between the first and second portions of the electrolyte when a voltage is applied between the first and second electrodes; a plurality of polymeric actuators disposed in the first portion of the electrolyte and configured to change volume in response to a pH change within the first portion of the electrolyte.

8. The polymeric actuator of claim 7, wherein at least one of the polymeric actuators comprises granules of a polymeric actuating material contained within a porous container, wherein the porous container preferably is a polymeric bag, and wherein the granules of polymeric actuating materials preferably comprise a slurry with the electrolyte.

9. A polymeric actuator component comprising (a) an actuating polymer that increases volume in response to a stimulus, cross linked to a hydrophobic polymer, or (b) a NH reactant and an epoxide, wherein the epoxide comprises a hydrophilic ether and a hydrophobic ether.

10. The polymeric actuator component of claim 9 (a), wherein the actuating polymer and the hydrophobic polymer comprise an NH reactant and an epoxide.

11. The polymeric actuator component of claim 10, characterized by one or more of the following features: (a) wherein the NH reactant in the actuating polymer and the NH reactant in the hydrophobic polymer comprise the same NH reactant; (b) wherein the epoxide in the actuating polymer comprises polyethylene diglycidyl glycol ether; (c) wherein the epoxide in the hydrophobic polymer comprises either neopentyl diglycidyl ether or polypropylene diglycidyl glycol ether; (d) wherein the NH reactant in the hydrophobic polymer comprises a polyether amine, (e) wherein the NH reactant in the actuator polymer comprises a polyether amine, wherein the NH reactant preferably comprises a polyether amine, more preferably a polyoxyalkyleneamine; (f) wherein the ratio of epoxide to NH reactant in the hydrophobic polymer is between about 1 to 1.5 and about 1 to 4, wherein the hydrophobic polymer preferably is oriented to protect the hydrophilic polymer from the external environment, and/or wherein the hydrophobic polymer seals the actuator polymer in a defined volume, and (g) wherein the ratio of epoxide to NH reactant in the hydrophobic polymer is about 1 to 2.0, wherein the hydrophobic polymer preferably comprises polyethyleneamine and water.

12. The polymeric actuator material of claim 9(b), characterized by one or both of the following features: (a) wherein the ratio of epoxide to NH reactant is about 1 to 2.85; (b) wherein the ratio of hydrophilic ether to hydrophobic ether is about 99 to 1.

13. A polymer actuator assembly of claim 7, comprising one or more polymer actuators, each actuator having one or more double layer capacitor electrodes.

14. The polymer actuator assembly of claim 13, wherein the polymer actuators are connected in series, forming a pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, wherein:

[0034] FIGS. 1A and 1B depict exemplary composite epoxy polymer actuator components before and after activation according to one aspect of the present invention;

[0035] FIG. 1C depicts an exemplary array of composite epoxy polymer actuator components in accordance with the present invention;

[0036] FIG. 2A depicts an exemplary actuator assembly of the present invention in schematic form;

[0037] FIG. 2B depicts another exemplary actuator assembly of the present invention in schematic form including, among other things, a plurality of actuating areas;

[0038] FIG. 2C depicts another exemplary actuator assembly of the present invention in schematic form including, among other things, a hydride material surrounding each electrode of the actuator assembly;

[0039] FIG. 3A depicts an exemplary actuator assembly of the present invention in schematic form including, among other things, a gas absorbent material;

[0040] FIG. 3B depicts an exemplary actuator assembly of the present invention in schematic form including, among other things a separate chamber to sequester gas(es) that may be produced in the actuator; and

[0041] FIG. 4 depicts an actuator assembly in schematic form, including a double layer capacitor electrode, according to one aspect of the present invention.

DETAILED DESCRIPTION

[0042] In the following description directional or geometric terms such as upper, lower, and side are used solely with reference to the orientation of the Figures depicted in the drawings. These are not to imply or be limited to a direction with respect to a gravitational reference frame but are utilized to distinguish directions relative to each other. Because components of the invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention.

[0043] Details in the various embodiments such as how current or wiring is routed to electrodes from power supplies are left out for illustrative simplicity since various methods of such routing is known in the art. The term electrolyte refers to and includes all aqueous, non-aqueous, polymer and solid electrolytes, including those that are generally well known in the art. The term electrodes refer to anodes and cathodes commonly used in electrochemical systems that are made of materials well known in the art such as metals, carbons, graphenes, oxides or conducting polymers or combinations of these. The term separator refers to any nano, micro or macro porous material that allows targeted ions to move through or across it faster than surrounding ion containing media. The term ion refers to ions and ion species as well as anion, cation, electrons and protons, and concentration values of these. The term housing refers to the exterior portion of the device which may be fabricated from flexible material, rigid material, elastic materials, non elastic materials or a combination of these such as rubbers, silicone, polyurethane, metalized polymer films and other plastics or polymers known in the art. The housing is configured to allow movement and expansion of the internal parts as well as allowing for filling the device with electrolyte, acting as a container and barrier to stop any electrolyte leakage or evaporation, allowing electrodes to make electrical contact with power source as well as to enter and exit the housing, if needed, and also the ability to vent any unwanted gas generation, if needed.

[0044] Referring to the drawings, an actuator 100 is comprised in part of a polymeric actuating material. In an exemplary embodiment these polymer actuators are formed from ion or pH responsive epoxy polymer Hydrogel based polymers. Examples of such polymers are described in commonly owned WIPO patent application WO 2008/079440 A2, Entitled SUPER ELASTIC EPOXY HYDROGEL, filed on Jul. 10, 2007 and published on Jul. 3, 2008. Other polymer actuator examples may contain polymers which have ionic functional groups, such as carboxylic acid, phosphoric acid, sulfonic acid, primary amine, secondary amine, tertiary amine, and ammonium, acrylic acid, methacrylic acid, vinylacetic acid, maleic acid, meta kurir yl oxy ethylphosphoric acid, vinylsulfonic acid, styrene sulfonic acid, vinylpyridine, vinylaniline, vinylimidazole, aminoethyl acrylate, methylamino ethyl acrylate, dimethylamino ethyl acrylate, ethylamino ethyl acrylate, ethyl methylamino ethyl acrylate, diethylamino ethyl acrylate, aminoethyl methacrylate, methylamino ethyl methacrylate, dimethylaminoethyl methacrylate, ethylamino ethyl methacrylate, ethyl methylamino ethyl methacrylate, diethylamino ethyl methacrylate, aminopropyl acrylate, methylaminopropyl acrylate, dimethylamino propylacrylate, ethylaminopropyl acrylate, ethyl methylaminopropyl acrylate, diethylamino propylacrylate, aminopropyl methacrylate, methyl aminopropyl methacrylate, dimethylaminopropyl methacrylate, ethylaminopropyl methacrylate, ethyl methylaminopropyl methacrylate, polymers, such as diethylamino propyl methacrylate, dimethylaminoethyl acrylamide, dimethylaminopropylacrylamide, and alpha kurir yl oxy ethyl trimethylammonium salts, are reported to be of use but these examples are for reference and not intended to limit the scope or use of the invention.

[0045] The invention in one aspect comprises new actuating polymers comprised of hydrophobic materials cross linked with smart hydrogel polymers using multiple di-epoxides or polyepoxides as the cross linking mechanism to adhere the materials together at the molecular level. The composite material also may be formed by using a single diepoxide or polyepoxide and then cross linking different layers of material via the polyamine components such as JEFF AMINE with different functionalities or polymer chains and back bones.

[0046] Previously filed PCT/US2007/073188 (hereby incorporated in its entirety), describes unique epoxy hydrogel polymers formed by reacting a polyether amine with a polyglycidyl ether. The resulting polymer is a super elastic hydrogel having various applications. The epoxy hydrogel can be produced by mixing ratios of ether reactants such as polyethylene glycol diglycidyl ether and polyoxyalkyleneamines and H2O resulting in an aqueous polymerization of the materials. Particularly preferred are polyoxyalkyleneamines such as commercially available from Huntsman Corporation under the brand name JEFF AMINE and other polyether amines as an epoxy component that is reacted with various ethers to form epoxy hydrogels. The polyoxyalkyleneamines contain primary amino groups attached to the terminus of a polyether backbone. They are thus polyether amines. The polyether backbone is based either on propylene oxide (PO), ethylene oxide (EO), mixed propylene oxide/ethylene oxide or may contain other backbone segments and varied reactivity provided by hindering the primary amine or through secondary amine functionality. In one embodiment of the invention, hydrophilic variants of hydrogel polymer actuators are cross linked based on JEFF AMINE T-403 and Polyethylene digycidyl glycol ether to hydrophobic variants of the gel by changing the diglycidyl (ether reactant) component and keeping the same epoxy-JEFF AMINE T-403 component.

[0047] Referring in particular to FIG. 1A, simple cylinders 10 comprised of half hydrophilic actuator material 12 and half non actuating hydrophobic material 14 cross linked together at the molecular level may be cast. The actuator material 12 is first placed into a mold or cast and partially cured. Then, a second material is added to the mold and both materials are allowed to totally cure. Ratios of di-epoxides to NH may be varied, and both neopentyl diglycidyl ether and polypropylene diglycidyl glycol ether may be substituted for the polyethylene diglycidyl glycol ether used in the actuator material. A mixture of JEFF AMINE T-403 and Neopentyl glycol diglycidyl ether yields a polymer with hydrophobic properties advantageous to actuator applications. In this way, two or more types of epoxy polymers may be adhered together even though they have very different properties.

[0048] In a specific embodiment, the hydrophobic polymer 14 is bonded to the actuator material 12. In FIG. 1C the hydrophobic polymer 14 is bonded to the actuator hydrophilic material 12 with addressable electrodes 6 and 7 electrically connected to the controller sensor or sensors and power source. A number of different chemicals may be added to JEFF AMINE T-403 in order to form a polymer with both hydrophobic properties and the ability to bind to an actuator gel such as that described in previously filed PCT/US2007/073188. For example, neopentyl glycol diglycidyl ether may be added to JEFF AMINE T-403 with an Epoxide/NH Reactant ratio of 1 to 2.85, the same Epoxide/NH Reactant ratio present in the standard actuator gel formulation. To ensure prompt polymerization, the ratio of epoxide/NH Reactant ratio may be decreased. Neopentyl glycol diglycidyl ether and JEFF AMINE T-403 mixtures with an Epoxide/NH Reactant ratio of 1 to 1.7, 1.8, 1.9, and 2.0 were all found to successfully polymerize after heating at 60 degrees C. for 5 hours and further curing at room temperature for 72 hours. The hydrophobicity of the polymers with these ratios yielded an approximate maximum of about 8-10% swelling after storage in water for up to three weeks. Furthermore, as the Epoxide/NH Reactant ratio is increased, the elasticity of the resultant polymer is also increased. As a result, a mixture of JEFF AMINE T-403 and neopentyl glycol diglycidyl ether with an Epoxide/NH Reactant ratio of 1 to 2.0 displays excellent adhesion with the actuator polymer 12, not only after curing, but also with hydration.

[0049] If desired, the hydrophobicity may be increased and the time required for polymerization decreased. Poly (propylene glycol) diglycidyl ether (PPGDGE) may be added to a mixture of Neopentyl glycol diglycidyl ether and JEFF AMINE T-403, maintaining an Epoxide/NH Reactant ratio of 1 to 2.0 or more Polymers with 10%, 26%, and 50% PPGDGE were synthesized and stored in water to test their hydrophobicity or resistance to swelling. All gels swelled between 12% and 15% after storage in water for two weeks. Further, it was surprisingly found that the addition of PPGDGE results in a decrease in polymer elasticity as compared to the base Neopentyl glycol diglycidyl ether and JEFF AMINE T-403 polymer.

[0050] In order to decrease gel curing time, Polyethyleneimine (1300 molecular weight) may be added to the base Neopentyl glycol diglycidyl ether and JEFF AMINE T-403 gel. The addition of 10% and 15% polyethyleneimine along with 10% water results in gels that polymerize more quickly. The gels completely polymerized after heating at 60 degrees C. for 5 hours and did not require further curing at room temperature to decrease gel stickiness.

[0051] The advantage of faster polymerization may be accompanied by a decrease in hydrophobicity. These gels including Polyethyleneimine were found to swell between 23% and 32% after storage in water for two weeks. Therefore, polymers with an increased hydrophobicity and decreased polymerization time are possible, but may be accompanied by performance tradeoffs, particularly in the hydrophobicity of the resultant polymer.

[0052] The length of the polymer chain and amine ratio versus Epoxide/NH Reactant ratios also may decrease polymerization time in a hydrophilic actuator gel. For example, varying compositions were evaluated using Polyethyleneimine, (branched polymers similar to Epomin SP-012) low mol. Wt. 50 wt. % soln. in water, both 2000 and 1300 molecular weights. Resulting gels were able to polymerize at room temperature in approximately 40 minutes, with ratios of epoxide to NH as high as 1 to 7 or more. These gels were comparatively brittle and stiff, showed a normal range of % hydration at approximately 400% consistent with our standard gel formulation

[0053] Initial actuation testing of new composite actuator structures comprised of a hydrophilic actuator polymer and a hydrophobic polymer depicted graphically in FIG. 1B successfully showed 100% swelling at each actuator portion under positive electric current of 1 mA. Accordingly, an addressable location peristaltic type of pump mechanism, or an array of actuators as shown in FIG. 1C may effectively be constructed of the examined composite polymers. Similarly, the examined polymers were shown to be smart and chemical responsive hydrogels, capable of being used in a variety of applications. Materials comprising these polymers may be cast in many layers and shapes that would be advantageous to a particular use and application.

[0054] In another embodiment of the invention, two or more of the di-epoxides are combined into one singular polymer actuator composition and the performance of the actuator material is adjusted according to the ratio of the dominant functional di-epoxide to the lesser functional di-epoxide. The ratio of the dominant functional di-epoxide to the lesser functional di-epoxide may be varied to advantageously vary actuation speed or flexibility of the material. In a particular embodiment, 1% neopentyl glycol diglycidyl ether is added to the JEFF AMINE T403 and PEGDE formulation mentioned in previous PCT/US2007/073188, resulting in a much faster actuator. This is not intended to limit the use or the materials used in a composite assembly made by cross-linking the functional layers.

[0055] A composite hydrogel material may be used as a sensor material structure, gel electrolyte material, selective ion permeable membrane, liquid filtration and treatment, wound care membrane, actuator or even acid scavenging material. This process also may be used to seal the external layer or layers of a composite structure such as an actuator thereby effectively sealing in the electrolyte held within or around the polymer to protect from evaporation. Additionally, internal materials may be protected from the external environment by UV exposure protection using the described composite hydrogels. The embodiments described above are just a few examples for which the composite hydrogel of the invention may be used for and are not meant to limit the scope of the invention.

[0056] In one application, the present invention concerns improvements made to a polymeric actuator including an increase in effective surface area to increase magnitude and repeatability of an expansion rate of a polymeric actuator. This has been accomplished by increasing the actual surface area of the polymer and by increasing the effective surface area, electrode improvements, and by gas mitigation methods. The improvements of this invention have been demonstrated to achieve a 400% increase in a volumetric expansion rate over prior art methods while reducing variability.

[0057] An exemplary embodiment of an actuator assembly 100 according to the present invention is schematically depicted with respect to FIG. 2A. Actuator assembly 100 includes a polymeric actuator material 113 and an associated electrode set including top electrode 106 and bottom electrode 108. Bottom electrode is in contact with metal hydride material 110. The electrode set and the polymeric actuator 113 are contained within housing 114. The housing 114 may be formed with folds, pleats or other excess material on the sides in order to allow for the large expansion rates of the actuator material as well as providing storage pockets or areas for any excess gas generated to collect without impacting the expansion rate of the actuator assembly. An electrolyte 112 is also contained within housing 114 in contact with the electrode set (106, 108) and actuator 113. Actuator 113 is a polymerized polymer actuator particulate made by grinding hydrated epoxy gel, and placing the gel into a flexible porous bag 116. The actuator 113 may also be comprised of two or more of the di-epoxides described above to vary the performance of the actuator material. Bag 116 is made of woven polypropylene mesh 116, 0.006 thick with 150 micron hole sizes and heat sealed. One or more bags can be used in the configuration to take advantage of volume and stroke aspects. A porous separator membrane 115 separates the pH gradient between electrode 108 and opposing electrode 106 while still allowing contiguous electrolyte 112.

[0058] Polymeric actuator 113 will expand or contract in response to a change in the electrolyte 112. There are several types of polymeric actuators 113 that may be used, including an acid-responsive polymeric actuator and a base-responsive polymeric actuator. An acid-responsive polymeric actuator expands in response to a decreased pH in electrolyte 112 surrounding polymeric actuator 113. This can be accomplished by providing a positive bias of electrode 106 relative to electrode 108. Applying the positive bias causes current to flow from electrode 106 to electrode 108 and causes a positive ion (H+) concentration in the electrolyte 112 surrounding actuator 113 to increase. The voltage applied between electrodes arranged in the aqueous solution consumes hydrogen ion and/or hydroxide ion as a result of electrode reaction or yields a concentration gradient due to electric double layer occurring on the surfaces of the electrodes, thereby changing the pH in the vicinity of the electrodes. Thus the electrolyte surrounding actuator 113 becomes more acidic (lower pH) and causes actuator 113 to expand.

[0059] Since the expansion speed of a solid polymer gel block is limited by the ability of the electrolyte or solvent to diffuse through the polymer actuator the speed of actuation may be increased by increasing the surface area of the polymer actuator material with access to the electrolyte. If the electrical bias is reversed, the positive ion flow reverses and electrolyte 112 surrounding actuator 113 becomes more basic (or less acidic) which causes an opposite or reverse effect on actuator 113.

[0060] A base-responsive polymeric actuator 113 also may be used. In that case, applying a negative bias to electrode 106 relative to electrode 108 will cause the pH in the electrolyte 112 surrounding polymeric actuator to increase which will in turn cause the base-responsive polymeric actuator 113 to expand. In this case the metal hydride 110 would be in contact with the electrode 106 in an aqueous electrolyte solution depending on the electrolyte, electrochemical reaction and type of gas produced during operation. When the polymeric actuator 113 expands, it causes the entire actuator assembly 100 to expand.

[0061] An alternative design of an actuator assembly 120 utilizing both acid responsive and base responsive actuators is depicted in FIG. 2B in schematic form. Actuator assembly 120 includes an acid responsive polymeric actuator cast gel 123A, a base responsive polymeric actuator cast gel 123B, a top electrode 128, and a bottom electrode 126 in contact with metal hydride 121 and then exiting the housing, all within housing 124. An electrolyte 122A surrounds top electrode 128 and acid responsive actuator 123A; a bottom electrolyte 122B surrounds bottom electrode 126 and base responsive actuator 123B. A porous separator membrane 125 separates the top electrolyte 122 A from the bottom electrolyte 122B while allowing ions to flow between electrolytes.

[0062] When a positive bias current is applied between top electrode 128 and bottom electrode 126 the pH of the top electrolyte 122A decreases while the pH of the bottom electrolyte 122B increases. The decreased pH (acidity increase) of top electrolyte 122A causes acid responsive polymer material 123A to expand while the increased pH (more basic) of bottom electrolyte 122B causes base responsive polymer material 123B to expand. Having two layers of actuators may double the total displacement obtainable for the entire actuator assembly 120. It is anticipated that additional layers of polymeric actuators with alternating layers of acid responsive and base responsive polymeric actuators can be used to further increase the maximum aggregate expansion of actuator assembly 120.

[0063] An alternative embodiment of an actuator assembly 130 is depicted with respect to FIG. 2C and includes the same embodiment of actuator assembly shown in FIG. 2A with the addition of a top electrode 136 with metal hydride material 131A in contact with top electrode 136, as well as the bottom electrode 138.

[0064] An alternative embodiment of an actuator assembly 130 is depicted with respect to FIG. 2C and includes the same embodiment of actuator assembly shown in FIG. 2A with the polymer actuator material as a cast gel, it is also possible to use multiple actuator material castings or bags in the same configuration, the same would be true for all of the configurations depicted, also shown is a top electrode 136 with metal hydride material 131A in contact with top electrode 136, as well as the bottom electrode 138.

[0065] Another polymer actuator assembly embodiment is shown in FIG. 3A wherein the top electrode 206 is in close proximity to gas adsorbing material 215 such as an activated carbon which can adsorb, for example, oxygen when wet. The gas adsorbing material is in contact with electrolyte 212 and adsorbs gas produced at electrode 206 as the gas migrates through electrolyte 212. Bottom electrode 208 is in contact with metal hydride material 210. The electrode set and the polymeric actuator material as a cast gel 213 are contained within housing 214. Contained within housing 214 is an electrolyte 212 in contact with the electrode set and actuator material 213. Separating electrode 208 from surrounding electrolyte 212 is a porous separator membrane 215. Polymeric actuator 213 will expand or contract in response to a change in the electrolyte 212, utilizing the same type of actuation mechanism and response described for FIG. 2A.

[0066] Yet another preferred polymer actuator assembly embodiment is shown in FIG. 3B wherein the actuator material 230 is a polymer particulate held in a porous flexible bag 223 and then the polymer particulate containing bag 223 is held in a firm porous structure 229 helping to contain and direct the swelling flexible bag 223 in one direction during the polymer material's 230 actuation response for efficiency of stroke or improved distance that the plate 228 can be pushed by flexible bag 223 expanding due to the swelling of the polymer material 230. The Top electrode 206 is inserted into the particulate bag 223 between the polymer particles 230 to maximize contact.

[0067] The assembly 224 is vented into another gas absorbing material 227 such as Oxisorb liquid form oxygen absorbent. The gas absorbent 227 is separated from the electrolyte by hydrophobic separator materials 226 that allow gas to penetrate while constraining electrolyte fluid. It is possible also to have no absorbent 227 in the vent in order to merely contain the gas in a separated compartment so the gas does not impact the actuation of the polymer materials. The separator material 226 is in contact with electrolyte 222 and allows gas produced at electrode 206 to collect as the gas migrates through electrolyte 222. Bottom electrode 208 is in contact with metal hydride material 221 which allows gas to adsorb to the metal hydride material 221. The electrode set (206, 208) and the polymeric actuator 223 are contained within housing 224 in contact with an electrolyte 222. A porous membrane 225 may separate electrode 208 from surrounding electrolyte 222.

[0068] Shown in all figures is the electrical power supply 101 and controller 103 for control of the actuator assembly's motion, speed and force. The embodiment in FIG. 3B also shows interaction with a sensor 105 for feedback and automated control of the actuator assembly.

[0069] There are many gas mitigation materials and techniques that are well known in the art of various analytical sciences and methods such as HPLC or other methods of chromatography, all of the embodiments described are meant to show possible actuator assembly configurations utilizing gas mitigation materials, components and techniques as part of the assembly and are not meant to limit the scope of the invention in any way.

[0070] In another aspect of the present invention, an electrode capable of double layer capacitance or charge storage is used to control gas generation within the actuator. For example, psuedocapacitor type electrodes may be used to control gas generation.

[0071] According to the present invention the electrical current builds a charge layer instead of generating gas at the electrolyte and electrode surface interface. This process continues until the electrode is fully charged, at which point, the charge is disbursed and the gas is produced.

[0072] As seen in the example shown in FIG. 4, the actuator assembly is contained in a flexible non permeable housing material 302 such as (but not limited to) a metalized polyethylene film. The housing contains the electrolyte 308, polymer actuator material 301, semi porous container for the polymer 303, the electrode in contact with or in the vicinity of the polymer 304, a semi porous separator membrane or sheet 305 located between the electrodes, a carbon PTFE capacitive layer coating 306 and the opposing electrode 307 in electrical connection with discharge circuit 309, controller and power source.

[0073] In one example of the present aspect of the invention, the electrode is discharged at a predetermined time in the charge cycle. In this example, the point at which the gas is generated is a function of the predetermined time, rather than the rate at which the energy accumulates within the capacitor. Once the discharge occurs, the charging process starts again, thereby eliminating gas generation at the electrode by using charge and discharge cycles.

[0074] To manufacture this type of electrode, a Teflon (PTFE) aqueous emulsion, such as those made by DuPont, is mixed with a high surface area carbon or other high surface area material, such as, for example, activated carbon; oxides such as, for example, metal oxides; as well as other materials such as metal hydrides. These materials can be used either on their own or mixed together to produce a desired performance curve of gas mitigation at the electrode. The high surface area material is mixed with the emulsion and pressed or coated onto the electrode and baked to the correct processing temperature to bind the mixture together and to the electrode, this process is well known in the art of battery and capacitor manufacturing. The electrode substrate can be perforated, expanded or plated with solid metals (such as but not limited a low cost aluminum or stainless steel foil), such as is well known in the art.

[0075] It should be emphasized that the above-described embodiments of the present invention, particularly, any preferred embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present invention. Many variations and modifications may be made to the above-described embodiments without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this invention and protected by the following claims.