Breast pump apparatus

Abstract

Based in the field of breastfeeding, a breast pump apparatus (100) for expressing breast milk is disclosed. The breast pump apparatus (100) comprises a container unit (110) for receiving expressed breast milk, and a pump unit (120) including a pump body (130) and a pumping device (140) for applying negative pressure to a pump volume defined by the pump body (130). The pump body (130) comprises an inlet portion (132) adapted to be received on a female breast and an outlet portion (134) adapted to channel expressed milk to the container unit (110). The pump body (130) comprises an actuator element (200, 300, 400) comprising an active material capable of deforming upon application of a control signal to it, wherein deformation of the actuator element modifies at least one of a shape and size of the pump volume.

Claims

1. A breast pump apparatus for expressing breast milk, comprising: a container unit for receiving expressed breast milk; and a pump unit including a pump body and a pumping device for applying negative pressure to a pump volume defined by the pump body, wherein the pump body comprises an inlet portion adapted to be received on a female breast, an outlet portion adapted to channel expressed milk to the container unit, and an actuator element comprising an active material capable of deforming upon application of at least one control signal and configured to have a bi-stable or multi-stable configuration, wherein a deformation of the actuator element in response to the at least one control signal modifies at least one of a shape or a size of the pump volume defined by the pump body to maintain a substantially constant free volume within the pump body when the inlet portion is in contact with the female breast, and wherein the actuator element is arranged at the pump body distant from the inlet portion.

2. The breast pump apparatus according to claim 1, wherein the actuator element comprises an electroactive polymer.

3. The breast pump apparatus according to claim 2, wherein the electroactive polymer comprises an ionic electroactive polymer.

4. The breast pump apparatus according to claim 1, wherein the actuator element is further configured to operate as a pressure sensor.

5. The breast pump apparatus according to claim 4, wherein the actuator element is configured to deform based on a sensed pressure.

6. The breast pump apparatus according to claim 5, wherein a feedback loop is employed to compensate for pressure variation based on the sensed pressure.

7. The breast pump apparatus according to claim 1, further comprising a plurality of additional actuator elements distributed over the inlet portion.

8. The breast pump apparatus according to claim 7, wherein a deformation of each additional actuator element of the plurality of additional actuator elements in response to the at least one control signal modifies a shape of the inlet portion.

9. The breast pump apparatus according to claim 8, wherein each additional actuator element of the plurality of additional actuator elements is arranged at the inlet portion.

10. The breast pump apparatus according to claim 9, wherein the plurality of additional actuator elements are configured to detect a lump in the female breast, and the deformation of at least one additional actuator element of the plurality of additional actuator elements is modified in response to the detection of the lump to reduce pain.

11. The breast pump apparatus according to claim 9, wherein the at least one control signal comprises a first control signal and an overlaid second control signal, wherein application of the first control signal to each additional actuator element statically adjusts a shape of the additional actuator element, and wherein application of the second control signal to each additional actuator element implements a massage function, wherein the massage function includes at least one of increased force or vibration.

12. The breast pump apparatus according to claim 11, wherein the second control signal is a faster time varying signal than the first control signal.

13. The breast pump apparatus according to claim 8, wherein the plurality of additional actuator elements are spatially arranged to allow execution of a massage pattern in response to the at least one control signal.

14. A breast pump apparatus for expressing breast milk, comprising: a pump body defining a pump volume; and a pumping device configured to apply negative pressure to the pump volume, wherein the pump body comprises an inlet portion adapted to be in contact with female breast, an outlet portion adapted to channel expressed milk from the female breast to a container unit, and a plurality of actuator elements distributed over the inlet portion, each actuator element comprising an active material capable of deforming upon application of at least one control signal, wherein a deformation of each actuator element of the plurality of actuator elements in response to the at least one control signal modifies a shape of the inlet portion, and wherein the plurality of actuator elements are spatially arranged to allow execution of a massage pattern in response to the at least one control signal, and wherein at least one actuator element of the plurality of actuator elements is configured to operate as a pressure sensor.

15. The breast pump apparatus according to claim 14, wherein the plurality of additional actuator elements are configured to be controlled individually in response to the at least one control signal.

16. The breast pump apparatus according to claim 14, wherein the plurality of actuator elements are distributed radially over the inlet portion.

17. The breast pump apparatus according to claim 14, wherein the massage pattern comprises a spiral massage pattern.

18. The breast pump apparatus according to claim 14, wherein the at least one control signal comprises a first control signal and an overlaid second control signal, wherein application of the first control signal modifies the shape of the inlet portion, and application of the second control signal implements execution of the massage pattern.

19. A breast pump apparatus for expressing breast milk, comprising: a pump body defining a pump volume; and a pumping device configured to apply negative pressure to the pump volume, wherein the pump body comprises an inlet portion adapted to be in contact with a female breast, an outlet portion adapted to channel expressed milk from the female breast to a container unit, and a plurality of actuator elements distributed over the inlet portion, each actuator element comprising an active material capable of deforming upon application of at least one control signal, wherein a deformation of each actuator element of the plurality of actuator elements in response to the at least one control signal modifies a shape of the inlet portion, and wherein the plurality of actuator elements are spatially arranged to allow execution of a spiral massage pattern in response to the at least one control signal, and wherein the plurality of actuator elements are configured to detect a lump, and the deformation of at least one actuator element of the plurality of actuator elements is modified in response to the detection of the lump.

20. The breast pump apparatus according to claim 19, wherein at least one actuator element of the plurality of actuator elements is further configured to operate as a pressure sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following drawings:

(2) FIG. 1 shows schematically and exemplarily an embodiment of a breast pump apparatus according to the state of the art,

(3) FIG. 2 shows schematically and exemplarily an electroactive polymer device which is not clamped,

(4) FIG. 3 shows schematically and exemplarily an electroactive polymer device which is constrained by a backing layer,

(5) FIG. 4 shows schematically and exemplarily a first example of a breast pump apparatus according to the invention,

(6) FIG. 5 shows schematically and exemplarily a second example of a breast pump apparatus according to the invention,

(7) FIG. 6A-6C show schematically and exemplarily examples of massage patterns implemented in the breast pump apparatus according to FIG. 5,

(8) FIGS. 7A and 7B show schematically and exemplarily a third example of a breast pump apparatus according to the invention,

(9) FIGS. 8A, 8B, 8C and 8D show schematically and exemplarily an embodiment of a breast pump in accordance with the invention with a single EAP in the funnel;

(10) FIGS. 9A and 9B show schematically and exemplarily an embodiment of a breast pump in accordance with the invention with multiple EAPs in the funnel;

(11) FIGS. 10A, 10B and 10C show schematically and exemplarily another embodiment of a breast pump in accordance with the invention with multiple EAPs in the funnel;

(12) FIGS. 11A and 11B show schematically and exemplarily still another embodiment of a breast pump in accordance with the invention with multiple EAPs in the funnel;

(13) FIGS. 12A, 12B, 12C and 12D show schematically and exemplarily another embodiment of a breast pump in accordance with the invention; and

(14) FIG. 13 shows schematically and exemplarily another embodiment of a breast pump in accordance with the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(15) The breast pump apparatus 100 illustrated in FIG. 1 and in particular pump body 130 thereof has a shape and size which is not controllable.

(16) A breast pump apparatus 1 according to embodiments of the invention, more precisely pump body 130 thereof, further comprises an actuator element 200, 300, 400, which will be discussed with reference to FIGS. 4 to 7 below, which is capable of deforming upon application of a control signal to it. The deformation of the actuator element modifies at least one of a shape and size of the pump volume of pump body 130 and allows an adaptation to the specific user's needs.

(17) In the following, the actuator element 200, 300, 400 comprises an electroactive material (EAM), in particular an electroactive polymer (EAP). Electroactive materials (EAM) are a class of materials within the field of electrically responsive materials. When implemented in an actuation device, subjecting an EAM to an electrical drive signal can make them change in size and/or shape. This effect can be used for actuation and sensing purposes. There exist inorganic and organic EAMs. A special kind of organic EAMs are electroactive polymers (EAPs). Electroactive polymers (EAP) are an emerging class of electrically responsive materials. EAPs, like EAMs can work as sensors or actuators, but can be more easily manufactured into various shapes allowing easy integration into a large variety of systems. Other advantages of EAPs include low power, small form factor, flexibility, noiseless operation, and accuracy, the possibility of high resolution, fast response times, and cyclic actuation. An EAP device can be used in any application in which a small amount of movement of a component or feature is desired, based on electric actuation. Similarly, the technology can be used for sensing small movements. The use of EAPs enables functions which were not possible before, or offers a big advantage over common sensor/actuator solutions, due to the combination of a relatively large deformation and force in a small volume or thin form factor, compared to common actuators. EAPs also give noiseless operation, accurate electronic control, fast response, and a large range of possible actuation frequencies, such as 0-20 kHz.

(18) FIGS. 2 and 3 show two possible operating modes for an electroactive polymer (EAP) device that comprises an EAP layer 14 sandwiched between electrodes 10, 12 on opposite sides of the EAP layer 14. While in FIG. 2 the EAP layer is freely moveable, in FIG. 3 the whole EAP layer and its electrodes are clamped with one side to a support carrier layer 16. A voltage difference (drive signal) applied over the electrodes 10 and 12 is used to provide an electric field over the EAP layer to cause the EAP layer to expand in all directions as shown. While in FIG. 2 this leads to deformation of the EAP layer due to the layer being freely suspended, the same actuation in FIG. 3 leads to bending of the device due to the restrained freedom of motion by the clamping. Using device engineering a vast variety of device outputs can be invoked upon actuation of the EAP layer, i.e. upon driving of the device. Thus, to obtain the asymmetric curving around an axis as shown, molecular orientation (film stretching) may for example be applied, forcing the movement in one direction. The expansion in one direction may result from the asymmetry in the EAP layer, or it may result from asymmetry in the properties of the carrier layer, or a combination of both.

(19) An electroactive polymer (EAP) based device, like those of FIG. 2 and FIG. 3, typically is an analogue device, which means that the drive vs. output response curve is a continuous curve. Hence, any signal other than a zero level/intensity signal will lead to an actuation output. In one example, these devices require continuous driving in order to maintain their actuated state. In other examples, also different examples of EAP based devices are contemplated, for instance which maintain in their actuated state. Alternatively or additionally, also other actuator elements different from EAP based devices are contemplated, such as optoactive polymer (OAP) based devices and the like.

(20) Further, for certain classes of EAP, application of a small force (mechanical load) to the device generates an electrical signal in response. This allows a single EAP structure to be used both for actuation and for sensing.

(21) FIG. 4 shows schematically and exemplarily a first example of a breast pump apparatus 1 according to the invention. A plurality of components of breast pump apparatus 1 are identical to those of breast pump apparatus 100 described with reference to FIG. 1 above and the description thereof is thus omitted.

(22) In addition, breast pump apparatus 1 comprises five actuator elements 200 disposed radially around a central opening of inlet portion 132. A bending direction of the actuator elements 200 can be in radial or angular direction or a combination of both. When actuated, the shape of inlet portion 132 changes. In one example, inlet portion 132 is formed as a massage cushion, wherein control of the actuator elements 200 results in an adapted shape of the massage cushion. In this example, actuator elements 200 are individually controlled so that the shape of inlet portion 132 can be fitted according to the preferences of the user prior to expression. As indicated above, a good fit can improve the suction performance of breast pump apparatus 1 and can avoid pain or irritation for the user.

(23) Deformation of the actuator elements 200 is controlled by providing a control signal to each of actuator elements 200. The shape adaptation induced by actuator elements 200 can be adjusted manually, such as by pressing a button on a control unit of breast pump apparatus 1, or automatically via feedback from a pressure sensor, which can control the adjustment of each actuator element 200 until an optimum vacuum is achieved. The actuator element 200 itself can be operated as a pressure sensor using, for instance, a different control signal as described above. While five actuator elements 200 have been employed in this example, the amount of actuator elements 200 can be varied as needed.

(24) In addition to implementing an adaptation of shape of inlet portion 132, breast pump apparatus 1 can further implement a massage function through, for instance, superimposing a second control signal on actuator elements 200, which are usually statically controlled in order to maintain a desired deformed shape. Depending on the superimposed control signal, an increased force in a certain area, which requires individual control of each actuator element 200, or a vibration signal, which induces stimulation of the expression, can be performed. In one example, the actuator elements 200 are actuated in sequence to simulate massage patterns on the breast.

(25) FIG. 5 shows a further example of breast pump apparatus 1 schematically and exemplarily, which implements actuator element arrays 300 instead of actuator elements 200 shown in FIG. 4. In this example, each actuator element array 300 is divided into four individually controllable actuator element sections, resulting in an increased spatial resolution of deformations that can be carried out by controlling actuator element arrays 300. For example, more complex massage patterns for massaging the breast as will be described with reference to FIG. 6 can be implemented through operation of actuator element arrays 300.

(26) FIGS. 6A to 6C show three non-limiting examples of suitable patterns for massaging the breast and in particular the breast excluding the nipple. These examples have shown to be efficient in order to increase the milk expression when done manually in the past. In accordance therewith, these patterns have shown to be beneficial when implemented in an automatic manner in breast pump apparatus 1. Each of FIGS. 6A to 6C shows schematically and exemplarily a breast 50 with a nipple 52 located in the center of breast 50.

(27) In FIG. 6A, an arrow 54 indicates a circular motion on the breast area around but not including the nipple 52. This circular motion can be repeated as desired.

(28) In FIG. 6B, a circular and spiral motion 56 starting from the edge and continuing around the breast is illustrated. It is started at the edge of the breast and moved towards the nipple 52. If a lump is encountered, more time is applied on it in order to make it more likely that the woman feels no pain.

(29) In FIG. 6C a comb shaped pattern 58 is illustrated, in which pressure starts from the edge of the breast and advances as several fingers or teeth of the comb towards the nipple 52.

(30) Preferably, the massage patterns of FIG. 6A, FIG. 6B and FIG. 6C are implemented by breast pump apparatus 1 in this sequence. However, also other sequences of these massage patterns or alternative/additional massage patterns can of course be used.

(31) FIGS. 7A and 7B show schematically and exemplarily two views on a third example of a breast pump apparatus 1, more precisely of pump body 130 thereof including a third embodiment of actuator element 400.

(32) In FIGS. 7A and 7B, in addition to inlet portion 132 and outlet portion 134, a pumping device mounting portion 136 is illustrated. A manual or electronic pumping device, such as pumping device 140 illustrated in FIGS. 4 and 5, can be mounted on pumping device mounting portion 136. A negative pressure can then be applied and maintained within a pump volume defined within pump body 130 through operation of pumping device 140.

(33) Actuator element 400 is shown at a position opposite to inlet portion 132, i.e. at a position distant from the user's nipple when having the breast pump apparatus 1 in operation and the breast seamlessly fitted against inlet portion 132. In FIG. 7A, actuator element 400 is shown deflected outwardly, while it is bent inwardly in FIG. 7B. By bending to the inside, actuator element 400 reduces the pump volume within pump body 130. Thereby, by actuation of actuator element 400, the free volume within pump body 130 is maintained substantially constant despite varying sizes of nipples, such that a suction efficiency can be ensured. Preferably, the volumetric displacement is in the order of magnitude of 10 ml, wherein also other magnitudes are of course contemplated.

(34) Preferably, actuator element 400 can in the way described above act simultaneously as a pressure sensor and actuator, wherein a feedback loop can then be employed to compensate for pressure variation. Pressure variation causes a force on the actuator element 400, which can then be used for deflecting, if needed. Additionally or alternatively, actuator element 400 can have a bi-stable or multi-stable configuration to avoid the effects of pressure variation, wherein the actuator element 400 then can remain in the deflected position without the continuing need for application of the control signal.

(35) FIGS. 8A, 8B, 8C and 8D show an embodiment of a single EAP in the funnel to mimic baby tongue pressure. In this exemplary embodiment one EAP insert (63) is used and positioned in between the hard plastic funnel (61) and the cushion (62). When a voltage is applied on the EAP (63), it will stretch and, due to the carrier layer, the composite will bend as shown in FIGS. 8B and 8D. This can either by a flat composite (FIGS. 8A and 8B) or a curved shaped composite (FIGS. 8C and 8D). These EAPs can also be used to measure forces that the nipple (60) exerts on that position on the wall.

(36) FIGS. 9A, 9B, 10A, 10B and 10C show the use of two or more EAPs to mimic baby behavior, or to measure the forces at multiple spots. In this embodiment multiple EAPs are used to mimic the baby lips' motion. For example, 2 EAPs (63) facing each other are used to mimic the baby lips as shown in FIGS. 9A and 9B. Instead of two EAPs, an EAP in the form of a ring can also be placed around the nipple to exert a uniform pressure onto the nipple. Multiple EAPs (63), e.g. in the form of 3 successive rings, can also be used to make a peristaltic rolling motion as shown in FIGS. 10A, 10B and 10C.

(37) FIGS. 11A and 11B show an embodiment where EAPs (63) are positioned such that they stimulate the areola tissue in order to get a faster Milk Ejection Reflex MER or a more comfortable experience.

(38) In all above embodiments, the EAPs are positioned between the hard plastic funnel and the soft cushion. However, the EAPs (63) can also be directly positioned onto or embedded in the hard plastic funnel (61) or in the cushion (62) as shown in FIGS. 12A and 12B, or FIGS. 12C and 12D, respectively.

(39) FIG. 13 shows an embodiment where EAP valves (63) regulate pressure between two pressure levels Po and Patm to realize alternating pressure on the lactiferous ducts. In this another alternative embodiment, the EAP acts as a valve which regulates the air pressure in a cavity surrounding the nipple. The cavity is connected to the vacuum of the pump (Po) and also to ambient (Patm), with the EAP acting as a switch to control between both pressure states and create a peristaltic pressure motion. The EAP in off state blocks the air vent to ambient and an actuated EAP blocks the under pressure (Po), so that the cavity can be regulated between the two states. The cavities as such are designed to compress the nipple slightly at ambient pressure. Be actuating the EAP, the under pressure is removed locally and the (air-filled) cavity exerts a pressure on the nipple. If multiple EAP valves are present and are operated in a sequence this could mimic the baby suckling behavior. This embodiment could potentially create more pressure and stroke than a single EAP could deliver. An embodiment is shown on FIG. 13 by way of an example. The example has two EAP valves per cavity. Embodiments with one valve per cavity are also possible.

(40) Although in the detailed description herein above the construction and operation of the breast pump apparatus according to the invention has been described for EAPs, the invention can in fact be used for devices based on other kinds of EAM material. Hence, unless indicated otherwise, the EAP materials hereinabove can be replaced with other EAM materials. Such other EAM materials are known in the art and the person skilled in the art will know where to find them and how to apply them. A number of options will be described herein below.

(41) A common sub-division of EAM devices is into field-driven and current or charge (ion) driven EAMs. Field-driven EAMs are actuated by an electric field through direct electromechanical coupling, while the actuation mechanism for current or charge driven EAMs involves the diffusion of ions. The latter mechanism is more often found in the corresponding organic EAMs such as EAPs. While Field driven EAMs generally are driven with voltage signals and require corresponding voltage drivers/controllers, current driven EAMs generally are driven with current or charge signals sometimes requiring current drivers. Both classes of materials have multiple family members, each having their own advantages and disadvantages.

(42) Field driven EAMs, can be organic or inorganic materials and if organic can be single molecule, oligomeric or polymeric. The organic materials and especially polymers are an emerging class of materials of growing interest as they combine the actuation properties with material properties such as light weight, cheap manufacture and easy processing.

(43) The field driven EAMs and thus also EAPs are generally piezoelectric and possibly ferroelectric and thus comprise a spontaneous permanent polarization (dipole moment), are electrostrictive and thus comprise only a polarization (dipole moment) when driven, but not when not driven or are dielectric relaxor materials. Such polymers include, but are not limited to, the sub-classes: piezoelectric polymers, ferroelectric polymers, electrostrictive polymers, relaxor ferroelectric polymers, dielectric elastomers, liquid crystal elastomers.

(44) The lack of a spontaneous polarization means that electrostrictors display little or no hysteretic loss even at very high frequencies of operation. The advantages are however gained at the expense of temperature stability. Relaxors operate best in situations where the temperature can be stabilized to within approximately 10? C. This may seem extremely limiting at first glance, but given that electrostrictors excel at high frequencies and very low driving fields, then the applications tend to be in specialized micro actuators. Temperature stabilization of such small devices is relatively simple and often presents only a minor problem in the overall design and development process.

(45) A first notable subclass of Field driven EAPs are piezoelectric and electrostrictive polymers. While the electromechanical performance of traditional piezoelectric polymers is limited, a breakthrough in improving this performance has led to PVDF relaxor polymers, which show spontaneous electric polarization (field driven alignment). These materials can be pre-strained for improved performance in the strained direction (pre-strain leads to better molecular alignment). Normally, metal electrodes are used since strains usually are in the moderate regime (1-5%). Other types of electrodes (such as conducting polymers, carbon black based oils, gels or elastomers, etc.) can also be used. The electrodes can be continuous, or segmented.

(46) Another subclass of interest of field driven EAPs is that of dielectric elastomers. A thin film of this material may be sandwiched between compliant electrodes, forming a parallel plate capacitor. In the case of dielectric elastomers, the Maxwell stress induced by the applied electric field results in a stress on the film, causing it to contract in thickness and expand in area. Strain performance is typically enlarged by pre-straining the elastomer (requiring a frame to hold the pre-strain). Strains can be considerable (10-300%). This also constrains the type of electrodes that can be used: for low and moderate strains, metal electrodes and conducting polymer electrodes can be considered, for the high-strain regime, carbon black based oils, gels or elastomers are typically used. The electrodes can be continuous, or segmented.

(47) A first notable subclass of ionic EAPs is Ionic Polymer Metal Composites (IPMCs). IPMCs consist of a solvent swollen ion-exchange polymer membrane laminated between two thin metal or carbon based electrodes and requires the use of an electrolyte. Typical electrode materials are Pt, Gd, CNTs, CPs, Pd. Typical electrolytes are Li+ and Na+ water-based solutions. When a field is applied, cations typically travel to the cathode side together with water. This leads to reorganization of hydrophilic clusters and to polymer expansion. Strain in the cathode area leads to stress in rest of the polymer matrix resulting in bending towards the anode. Reversing the applied voltage inverts bending. Well known polymer membranes are Nafion? and Flemion?.

(48) In more detail, IPMCs are composed of an ionic polymer like Nafion or Flemion whose surfaces are chemically plated or physically coated with conductors such as platinum or gold, or carbon-based electrodes. Under an applied voltage, ion migration and redistribution due to the imposed voltage across a strip of IPMCs result in a bending deformation. The polymer is a solvent swollen ion-exchange polymer membrane. The field causes cations travel to cathode side together with water. This leads to reorganization of hydrophilic clusters and to polymer expansion. Strain in the cathode area leads to stress in rest of the polymer matrix resulting in bending towards the anode. Reversing the applied voltage inverts the bending.

(49) Another notable subclass of Ionic polymers is Conjugated/conducting polymers. A conjugated polymer actuator typically consists of an electrolyte sandwiched by two layers of the conjugated polymer. The electrolyte is used to change oxidation state. When a potential is applied to the polymer through the electrolyte, electrons are added to or removed from the polymer, driving oxidation and reduction. Reduction results in contraction, oxidation in expansion.

(50) In one example the EAM or EAP material is an electrostrictive polymer, such as a relaxor ferroelectric material. Such materials can have an electrostrictive constant that is high enough for good practical use, i.e. advantageous for simultaneous sensing and actuation functions. Relaxor ferroelectric materials are non-ferroelectric when zero driving field (i.e. voltage) is applied to them, but become ferroelectric during driving. Hence there is no electromechanical coupling present in the material at non-driving. The electromechanical coupling becomes non-zero when a drive signal is applied and can be measured through applying the small amplitude high frequency signal on top of the drive signal, in accordance with the procedures described above. Relaxor ferroelectric materials, moreover, benefit from a unique combination of high electromechanical coupling at non-zero drive signal and good actuation characteristics.

(51) The most commonly used examples of inorganic relaxor ferroelectric materials are: lead magnesium niobate (PMN), lead magnesium niobate-lead titanate (PMN-PT) and lead lanthanum zirconate titanate (PLZT). But other are known in the art.

(52) Examples of field-driven EAPs are piezoelectric polymers, ferroelectric polymers, electrostrictive polymers (such as PVDF based relaxor polymers or polyurethanes), dielectric elastomers and liquid crystal elastomers (LCE). Thus, preferably the EAP material is a relaxor ferroelectric polymer such as e.g. PVDF based relaxor ferroelectric based polymer. Such materials can be any one chosen from the group of materials herein below.

(53) The sub-class electrostrictive polymers includes, but is not limited to:

(54) Polyvinylidene fluoride (PVDF), Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), Polyvinylidene fluoride-trifluoroethylene-chlorofluoroethylene (PVDF-TrFE-CFE), Polyvinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (PVDF-TrFE-CTFE), Polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyurethanes or blends thereof.

(55) The current driven EAMs and EAPs comprise conjugated polymers, Ionic Polymer Metal Composites, ionic gels and polymer gels.

(56) Examples of ionic-driven EAPs are conjugated polymers, carbon nanotube (CNT) polymer composites and ionic polymer-metal composites (IPMC). An ionic polymer-metal composite (IPMC) is a synthetic composite nanomaterial that displays artificial muscle behavior under an applied voltage or electric field.

(57) The sub-class dielectric elastomers includes, but is not limited to: acrylates, polyurethanes, silicones.

(58) The sub-class conjugated polymers includes, but is not limited to: polypyrrole, poly-3,4-ethylenedioxythiophene, poly(p-phenylene sulfide), polyanilines.

(59) The materials above can be implanted as pure materials or as materials suspended in matrix materials. Matrix materials can comprise polymers.

(60) To any actuation structure comprising EAM material, additional passive layers may be provided for influencing the behavior of the EAM layer in response to an applied drive signal.

(61) In some cases, thin film electrodes are added when the polymer itself lacks sufficient conductivity (dimension-wise). The electrolyte can be a liquid, a gel or a solid material (i.e. complex of high molecular weight polymers and metal salts). Most common conjugated polymers are polypyrolle (PPy), Polyaniline (PANi) and polythiophene (PTh).

(62) An actuator may also be formed of carbon nanotubes (CNTs), suspended in an electrolyte. The electrolyte forms a double layer with the nanotubes, allowing injection of charges. This double-layer charge injection is considered as the primary mechanism in CNT actuators. The CNT acts as an electrode capacitor with charge injected into the CNT, which is then balanced by an electrical double-layer formed by movement of electrolytes to the CNT surface. Changing the charge on the carbon atoms results in changes of CC bond length. As a result, expansion and contraction of single CNT can be observed.

(63) Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

(64) In the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality.

(65) A single unit or device may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.