Related Patent Application

[001] The present invention claims priority to Singapore patent application no. 10202250083P filed on 7 June 2022, the disclosure of which is incorporated in its entirety.

Field Of Invention

[002] The invention relates to seamless chamber actuators to provide force feedback for virtual reality (VR), augmented reality (AR), haptics, resistance training or rehabilitation applications; these seamless chamber actuators have substantially near-zero fluid inflation volume and are thus very compact, relative small in size, easy to customise into a wearable device, fast to actuate, provide high-force output from a small, compact size, and so on. When configured for VR, AR or haptic feedback, these seamless chamber actuators may be used to simulate point forces, vibrations or impact; these seamless chamber actuators may be used to pinch a moveable member for resistance training or to perform a movement for rehabilitation; performing a movement can also be achieved by forming a bending seamless chamber actuator.

BACKGROUND OF THE INVENTION

[003] Haptic technology, also known as haptics, refers to the science and technology of creating tactile sensations or haptic feedback through the use of actuators. These actuators are utilized in various industries and applications to enhance user experiences, improve safety, and enable realistic touch sensations.

[004] In the field of consumer electronics, haptic actuators are widely adopted and have become an integral part of numerous devices. These actuators can be found in everyday gadgets such as smartphones, tablets, gaming controllers, smartwatches, fitness trackers, as well as virtual reality (VR) or augmented reality (AR) devices and other wearable devices. A purpose of haptic actuators in consumer electronics is to provide users with tactile feedback, thereby enhancing overall user sensation or experience. By simulating various sensations like vibrations, texture, or physical resistance, haptic actuators add an extra dimension of interaction and immersion to consumer electronic devices. Wearable devices, such as smartwatches and fitness trackers, utilize haptic actuators to deliver notifications, alerts, and feedback to users. For example, a gentle vibration on the wrist can notify the wearer about incoming messages, calls, or reminders without the need to check the device's screen constantly. Additionally, haptic feedback can be utilized during fitness activities to provide users with cues or reminders, such as vibrations indicating progress towards fitness goals or specific exercise durations.

[005] In virtual reality (VR) and augmented reality (AR) devices, haptic actuators play a pivotal role in creating a sense of presence and realism. VR headsets and controllers incorporate haptic feedback to simulate various sensations, such as the feel of touching virtual objects, experiencing the impact of virtual interactions, or perceiving the texture of virtual surfaces. This integration of haptics heightens the overall immersion and engagement in virtual environments, making the experiences more lifelike and compelling.

[006] In the medical and healthcare fields, haptic actuators have diverse applications in a range of devices and systems. Surgical simulators and training tools employ haptic feedback to replicate the tactile sensations encountered during surgical procedures. Surgeons and medical professionals can practice and refine their skills in a virtual environment with realistic touch sensations, allowing them to develop better surgical precision and proficiency. Furthermore, haptic actuators are utilized in rehabilitation equipment and prosthetic devices. For individuals undergoing physical therapy or rehabilitation programs, haptic feedback can assist in motor skill development, gait training, and sensory stimulation. By providing tactile cues and responses, haptic actuators aid in the rehabilitation recovery process and may help improve mobility and coordination.

[007] Haptic technology significantly contributes to the field of assistive technology as well. Haptic actuators are incorporated into assistive devices designed for individuals with disabilities, such as prosthetics or mobility aids. These actuators provide sensory feedback, enabling users to perceive and interact with their environment more effectively. Haptic feedback can enhance the overall quality of life for individuals with disabilities by facilitating better control, improving spatial awareness, and enabling a more natural and intuitive interaction with assistive devices. [008] However, despite the advantages of these haptic actuators, there remain challenges when incorporating the actuators into the devices. One key challenge associated with haptic actuators is the size and form factor for portable feedback devices. Portable feedback devices have limited and compact space, therefore there is a need to develop haptic actuators that are compact, relatively small in size, easy to customise into an application, fast to actuate, provide high-force output from a small, compact size, and so on, and to fit snugly into these devices while still providing sufficient feedback and sensation.

SUMMARY OF INVENTION

[009] The present invention seeks to provide actuators with substantially zero-volume actuation chamber for creating force feedback or haptic sensation. Preferably, the actuators can be used to help patient rehabilitation or be used in or with a wearable apparel for body haptic sensation in VR or AR.

[0010] In one embodiment, the present invention provides a seamless chamber actuator comprising: a base layer wherein an inside face is formed with a flat groove; a membrane or tape is disposed over the flat groove, with the membrane/tape having a surface area; and a second layer is fusedly formed over the base layer and the membrane/tape, so that a substantially zero-volume fluid actuation chamber is formed by the flat groove and the surface area of the membrane/tape; wherein, when a fluid pressure is supplied into the flat groove, the substantially zero-volume fluid actuation chamber is inflated and the fluid pressure acts on the surface area of the membrane/tape, the second layer responds by deforming and bulging out to provide a haptic sensation, and the second layer returns to its unactuated state when the fluid pressure is released. Preferably, a port that is fluidly connected to the flat groove for supplying a fluid pressure for actuation.

[0011] Preferably, the seamless chamber actuator further comprises a top layer fusedly formed over the second layer, with the top layer having an aperture such that when the second layer responds to a fluid pressure, the second layer deforms and bulges out through the aperture to provide a haptic sensation. Preferably, the second layer is made from a material with stiffness or hardness that is lower than a material stiffness of the base layer or the top layer. [0012] Preferably, the seamless chamber actuator further comprises: a torsion housing being mounted onto the top layer, with the torsion housing comprising a strip of cloth being wound up by a torsion spring and an end of the cloth is disposed between the torsion housing and the top layer of the seamless chamber actuator; wherein, when a fluid pressure is supplied to the port, the second layer responds by deforming through the aperture and jamming the cloth against the torsion housing, and a resulting induced friction holds the end of the cloth in position.

[0013] Preferably, the seamless chamber actuator further comprises: integrating a plurality of the torsion housing in parallel to form a wrist housing, wherein the wrist housing is configured with a glove and ends of the cloths extending from the wrist housing are weaved into the respective fingers of the glove.

[0014] In another embodiment, the seamless chamber actuator comprises: a base layer; a flat groove, a perforated membrane/tape and a corrugated layer formed over the base layer and the perforated membrane/tape; and a substantially zero-volume fluid actuation chamber is formed between the base layer and the corrugated layer; wherein, when a fluid pressure is supplied into the substantially zero-volume fluid actuation chamber, the seamless chamber actuator responds by bending towards the base layer. Preferably, a port is fluidly connected to the substantially zero- volume fluid actuation chamber for actuation.

[0015] Preferably, each corrugation of the corrugated layer is configured with an interior actuation chamber, which is fluidly connected to the substantially zero-volume fluid actuation chamber.

[0016] Preferably, the base layer and the corrugated layer are formed from a single material of a predetermined stiffness or hardness, or the base layer and the corrugated layer are formed from two materials of different predetermined stiffness or hardness. Preferably, the corrugated layer is formed with a material of lower stiffness or hardness than that of the base layer.

[0017] In another embodiment, the present invention provides a method for providing haptic sensation comprises actuating the above seamless chamber actuators to provide force or vibration force sensation in a virtual reality or augmented reality application, or force feedback or assistive force for patient rehabilitation.

[0018] In another embodiment, the present invention provides a method for controlled bending about a joint or joints; Preferably, the above torsion housing or wrist housing is attached on a side of the joint or joints and the end of the cloth attached to a side opposite the joint or joints; and actuating the second layer to jam a position of the end of the cloth, so that an angle of bending about the joint or joint is held in position for force feedback or to maintain an assistive force. This method for controlled bending about a joint or joints can also be used with the above bending actuator.

[0019] Preferably, the above seamless chamber actuators can be configured as part of or with a wearable apparel for providing haptic sensation or for providing force feedback or assistive force for patient rehabilitation. Preferably, components of these seamless chamber actuators may be formed by 3D printing.

[0020] One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments described herein are not intended as limitations on the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To facilitate an understanding of this invention, there is illustrated in the accompanying drawings the preferred embodiments from an inspection of which when considered in connection with the following description, the invention, its construction and operation and many of its advantages would be readily understood and appreciated.

[0022] FIG. 1 illustrates a seamless chamber actuator according to a first embodiment, whilst FIG. 2 illustrates an exploded view of the seamless chamber actuator, and FIG. 3 illustrates a sectional side view of the seamless chamber actuator;

[0023] FIGs. 4-6 illustrate a seamless chamber actuator according to a second embodiment; [0024] FIG. 7 illustrates the above seamless chamber actuator being configured for connection with a barb connector;

[0025] FIG. 8 illustrates the above seamless chamber actuator being configured for direct connection with a fluid tubing;

[0026] FIGs. 9-10 illustrate the above seamless chamber actuator being configured with an elongate actuator area for generating a higher force sensation or feedback;

[0027] FIG. 11 illustrates the above seamless chamber actuator being configured in an apparel for body force sensation;

[0028] FIGs. 12-13 illustrate the above seamless chamber actuator being integrated with a torsion housing according to a third embodiment;

[0029] FIG. 14 illustrates the seamless chamber actuator shown in FIG. 12 for flexing a lower arm about an elbow joint; whilst FIG. 15 illustrates jamming motion control of arm flexion at different flexing positions;

[0030] FIGs. 16-19 illustrate the seamless chamber actuators shown in FIG. 12 being configured with a glove;

[0031] FIG. 20 illustrates a seamless chamber actuator being configured as a bending actuator according to a fourth embodiment;

[0032] FIG. 21 illustrates the bending actuator shown in FIG. 20 being formed in 3 different stiffness materials; whilst FIGs. 22-24 illustrate performance of three bending actuators when actuated with compressed air, and FIG. 25 is a graph showing the bending performance; and

[0033] FIG. 26 illustrates the bending actuator shown in FIG. 20 being applied for controlled or assistive bending of a finger. DETAILED DESCRIPTION OF THE INVENTION

[0034] From hereon, spatially relative terms, such as “top”, “bottom”, “left”, “right”, and the like, may be used herein for ease of description to describe one technical element or feature's relationship to another technical element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the technical features in use or operation in addition to the orientation depicted in the figures.

[0035] For example, if a technical feature within the figures is turned over, its elements described as “top” of other elements or features would then be oriented “bottom” of the other elements or features. Thus, the exemplary term “top” can encompass both an orientation of above and below. The device may be otherwise oriented and the spatially relative descriptors used herein are interpreted accordingly.

[0036] For example, if a technical feature within the figures is flipped horizontally, its elements described as “left” of other elements or features would then be oriented “right” of the other elements or features. Thus, the exemplary term “left” can encompass both an orientation of left and right. The device may be otherwise oriented and the spatially relative descriptors used herein are interpreted accordingly.

[0037] The present invention will now be described in greater detail, by way of examples, with reference to the figures. For ease of reference, common reference numerals or series of numerals will be used throughout the figures when referring to the same or similar features common to the figures.

[0038] FIG. 1 shows a seamless chamber actuator 100 according to a first embodiment of the present invention, whilst FIG. 2 shows an exploded view of the seamless chamber actuator 100 and FIG. 3 shows a sectional side view of the seamless chamber actuator 100.

[0039] The seamless chamber actuator 100 is made up of a base layer 110 and a second layer 150 of pliable materials being fused over the base layer 110, with a substantially zero- volume fluid actuation chamber 108 formed therebetween according to a first embodiment. Preferably, the base layer 110 and the second layer 150 of pliable materials are fabricated by a three-dimensional (3D) printer, preferably a Fused Deposition Modelling (FDM) 3D printer or Stereolithography (SLA) 3D printer. Preferably, the base layer 110 is fabricated using a 3D printing material with 75D Shore hardness (which is obtainable from Ninjatek Armadillo), whilst the second layer 150 is fabricated using a 3D printing material X60 with Shore hardness 60A (which is obtainable from Diabase); in other words, the base layer 110 is configured with a higher material stiffness than the second layer 150. The second layer 150 deforms under a load and returns to its unactuated shape upon release of the load.

[0040] In FIGs. 1-2, one edge of the seamless chamber actuator 100 has a material extension 102, and a fluid supply port 104 is configured within the material extension 102. Now referring to FIG. 2, an inside surface of the base layer 110 is formed with a flat groove 106; preferably, the flat groove 106 is substantially 0.2 to 0.3 mm in depth; the flat groove 106 is fluidly connected from the port 104, to which a fluid tubing T supplies fluid power, such as, compressed air for actuating the seamless chamber actuator 100. To 3D print the second layer 150 onto the base layer 110 and over the flat groove 106, a membrane or tape 130 is disposed over the groove 106 before 3D printing. After 3D printing, materials of the base layer 110 and the second layer 150 around the membrane/tape 130 are fused together to form an air-tight fluid actuation chamber, ie. the substantially zero-volume fluid actuation chamber 108 thus formed has an air gap of substantially 0.2 to 0.3 mm provided by the groove 106 and a surface area of the membrane/tape 130. When an air pressure is supplied through the port 104, the air pressure exerts (from below, as seen in FIG. 2) on the membrane/tape 130 and the second layer 150 responds by deforming, extending or bulging out, as illustrated by the dashed line 152 in FIG. 3; when the air pressure in the port 104 is released, the second layer 150 returns to its unactuated state; in this way, the bulging of the second layer 150 by supplying compressed air to the port 104 is used to simulate a sensory or haptic sensation, for example, in a VR or AR application. In one embodiment, the second layer 150 can be configured with a dimension of substantially 10 mm x 10 mm, or with lower or higher dimensions according to desired haptic sensations; with such a small size of the second layer 150, the seamless chamber actuator 100 can be provided to simulate a substantially point force sensation. It is also possible to supply the air pressure to the port 104 according to a fluctuating pattern and the elastic response of the second layer 150 can thus simulate some vibration sensations. As can be realised, the sensing force created by deforming and bulging of the second layer 150 is determined by the surface area of the membrane/tape 130, the air pressure supply at the port 104 and elasticity of the second layer 150. Preferably, the base layer 110 is made of a higher stiffness or hardness material and thicker material so that the seamless chamber actuator 100 is dimensionally stable.

[0041] FIGs. 4-6 show a seamless chamber actuator 100a according to a second embodiment of the present invention. The seamless chamber actuator 100a is made up of a base layer 110a, a second layer 150a, a membrane/tape 130a and a top layer 170; the base layer 110a, the second layer 150a and the membrane/tape 130a are correspondingly similar to those used in the above seamless chamber actuator 100. As seen from FIGs. 4-6, the top layer 170 is provided with an aperture 172, which may be substantially similar in area or shape to the membrane/tape 130a. Preferably, the base layer 110a and the top layer 170 are formed of the same material of stiffness or hardness which is higher than that of the second layer 150a. Preferably, the base layer 110a and the top layer 170 being similar to the materials of the base layer 110 described in the above embodiment, and the second layer 150a being similar to the above second layer 150. The seamless chamber actuator 100a is also similar provided with a port 104a for supplying fluid pressure for actuating this seamless chamber actuator 100a; when air is supplied to the port 104a, air pressure acts from below the membrane/tape 130a and the second layer 150a responds by deforming and bulging up through the aperture 172, as indicated by the dashed line 152a in FIG. 6. By providing the top layer 170, the area of the second layer 150a to provide haptic sensation is now determined by the shape and dimensions of the aperture 172, which can be visually distinguished (as compared to the first embodiment); in addition, the top layer 170 adds rigidity to the seamless chamber actuator 100a. It is possible that a material extension 102 of the top layer 170 disposed substantially above the port 104a (ie. an area denoted by 174) be provided with a higher thickness; thus, the thickened area 174 of the top layer 170 further adds rigidity around the port 104a.

[0042] In FIGs. 1-2 and 4-5, the seamless chamber actuator 100,100a are shown with a rectangular or quadrilateral shape, but the shape is not so limited. For example, the seamless chamber actuator 100,100a can also be polygonal or round in shape, as can be seen in FIG. 11 when a plurality of the seamless chamber actuators 100,100a are configured in an apparel 190 to provide haptic sensation. Preferably, the second layer 150,150a has a thickness of substantially 0.4 to 0.8mm, and more preferably, substantially 0.6 mm. Preferably, the top layer 170 is also 3D printed, with a material of substantially 75D Shore hardness, and a thickness of substantially 1 mm or more. The top layer 170 may be fabricated with a flat surface or with the thickened area 174 above the port 104. The base layer 110,110a may be thick relative to the second layer 150,150a, and may be substantially 5 mm, or more; the thickness of the seamless chamber actuator 100,100a, at least at the material extension 102, may also depend on a selected size of the port 104,104a, associated fitting 120 and pneumatic tubing T size.

[0043] FIG. 7 shows the above seamless chamber actuator 100,100a being provided with the port 104,104a and an associated barb fitting 120 for pneumatic tubing T connection. In another embodiment, the material extension 102 is configured with a reduced cross-sectional area, so that the pneumatic tubing T can be inserted directly over the material extension 102 and this dispenses away with the use of any fitting at the port 104,104a; this direct tubing connection at the port 104,104a is shown in FIG. 8.

[0044] FIGs. 9 and 10 show a seamless chamber actuator 100b being configured with an elongate actuator body, when compared with the above seamless chamber actuator 100,100a. The actuator body refers to the seamless chamber actuator excluding the material extension 102, and may be substantially 25 mm long x 10 mm wide. The structure and arrangement of the base layer 110, the second layer 150, the membrane/tape 130 and the top layer 170 are as described for the corresponding components in the above actuators 100,100a.

[0045] FIGs. 12-13 show the above seamless chamber actuator 100b is mounted with a torsion housing 220 to form a jamming actuator 200, which provides another embodiment of the present invention. The torsion housing 220 may be separately formed and then mounted onto the above seamless chamber actuator, preferably with the seamless chamber actuator 100b, by a mounted means; for example, a mounting means may be by way of an adhesive, such as, a curable epoxy.

[0046] As seen from FIG. 13, the torsion housing 220 is made up of a shell 220 having an extension body 221. The shell 220 and the extension body 221 is open at a bottom side, as seen in FIG. 13. Disposed inside the shell 220 is a strip of cloth 242 being wound up by a torsion spring 240, so that a free end of the cloth 242 can be pulled through the open bottom and out at the right-hand end, as seen in FIGs. 12 or 13. The cloth 242 is chosen for its flexibility but is relatively inextensible. The torsion spring 240 keeps the cloth 242 in a substantially constant tension. Preferably, the torsion housing 220 is made up of two parts; these two parts may snap into place by known means and be taken apart for fixing or adjusting the strip of cloth 242 and the torsion spring 240. The torsion housing 220 is also provided with a pair of holes 222 for securing the jamming actuator 200 at a point of application, for example, about a joint or joints. In use, the free end of the cloth 242 is pulled out and connected to a body part; to keep the body part in position, the seamless chamber actuator 100b component is actuated so that the second layer 150 is deformed or extended and the extended second layer 150 pinches the cloth 242 against the extension body 221, and induced friction thus keeps the cloth 242 in position; the pinching force on the cloth 242 can thus be varied by controlling the fluid pressure connected to the port 104 or by varying the length of the extension body 221. In practice, jamming actuator 200 is provided with the extension body 221 having predetermined dimensions, a predetermined torsion spring 240 force, and the pinch force desired at the second layer 150 is controlled by varying the fluid pressure.

[0047] FIG. 14 shows an application of the above jamming actuator 200 for controlling an angle of flexing of an arm about an elbow joint. As shown in FIG. 14, the jamming actuator 200 is fixedly located on an upper arm (by using the securing holes 222) whilst the free end of the cloth 242 is connected to a lower arm (LA) below the elbow joint; when the jamming actuator 200 is not actuated, the lower arm can flexed up and down freely; upon actuation, the second layer 150 pinches or jams the cloth 242 against the extension body 221, thereby maintaining the position of the arm at various angles of flexion, as shown in FIG. 15. This application can be used to provide force feedback on the arm; this application can also be applied to the fingers (as will be described with a variation of this jamming actuator), to the legs, neck or torso, which are made up of joints; for example, when a load is applied on the arm and the jamming force of the second layer 150 is slowly released until the arm is held in force equilibrium at a fluid pressure at the port 104, and with a known friction coefficient at the surface of the second layer 150, a force feedback can be calibrated with the fluid pressure. In another application, the jamming actuator 200 applies a jamming force on the cloth 242 to provide assistive force, for example, for holding an item in the hand or pushing against a wall, or measuring a force resistance during a rehabilitation exercise. In yet another application, the jamming actuator 200 can be used to provide passive rehabilitation by allowing a patient to stretch the arm in a jammed position to improve muscle memory.

[0048] The above jamming actuators 200 can be configured in parallel to form a glove jamming actuator 200a according to another embodiment of the present invention. For example, FIG. 16 shows five parallel jamming actuators 200 are integrated into a wrist housing 220a and each strip of the cloth 242 is weaved onto the glove for each finger. When the glove jamming actuator 200a is not actuated, the fingers in the glove can move freely; upon actuation, for example on selected fingers, the associated second layers 150 of the glove jamming actuator 200a jam the associated strips of cloths 242 against the wrist housing 220a and induced friction on the respective strip of cloth 242 controls bending of the respective finger. As described above, the glove jamming actuator 200a can also be used to provide force feedback, assistive force or motion, or passive rehabilitation of muscles. FIG. 17 shows the glove jamming actuator 200a is in the non-actuated state, whilst FIGs. 18-19 show the glove jamming actuator 200a are in the actuated states.

[0049] In addition, the above jamming actuator 200 and the glove jamming actuator 200a can also be integrated with electronic controls and fluid pressure sensing to provide force feedback and haptic sensation in VR or AR applications.

[0050] FIG. 20 shows a bending actuator 300 according to yet another embodiment of the present invention. The bending actuator 300 is 3D printed according a variation of the above embodiments. As shown in FIG. 20, the bending actuator 300 is formed with a base layer 310, a flat groove 306, a perforated membrane (or tape) 330, a corrugated layer 350, with a fluid chamber 308 formed between the base layer 310 and the perforated membrane 330 but the fluid chamber 308 is fluidly connected via the flat groove 306 to a port 304. As in the above embodiments, the fluid chamber 308 is narrow, for example of substantially 0.2 to 0.3 mm gap, and is described as a substantially zero-volume actuation chamber, which is also identified by similar series numeral as 108. In another embodiment, each fold of corrugation of the corrugated layer 350 is formed with a narrow component fluid chamber 308a, which is fluidly connected to the substantially zero-volume actuation chamber 308 via apertures 332 located on the perforated membrane 330. The width of the component fluid chamber 308a may be substantially 0.2 to 0.5 mm and this width depends on the nozzle size for 3D printing. The folds of the corrugations are spaced apart at a pitch of p, which may be substantially 3 mm, for example; preferably, the apertures 332 are also spaced apart at pitch p. In FIG. 20, the walls 351 of the folds of the corrugated layer 350 are shown to be straight; however, it is not so limited; the walls 351 of the folds of the corrugated layer 350 may be serpentine.

[0051] In a first configuration, the base layer 310 is formed with a material of higher stiffness or hardness (such as, NF 85A Shore hardness, which is obtainable from NinjaFlex, whilst the corrugated layer 350 is formed with an elastic material of lower stiffness or hardness (such as, X60 with a Shore hardness of 60D, which is obtainable from Diabase) to provide a bending actuator being made of two-composite materials; in a second configuration, both the bottom layer 310 and the corrugated layer 350 are formed with a relatively hard material (such as, NF 85A with Shore hardness 85A, which is obtainable from NinjaFlex); in a third configuration, both the bottom layer 310 and the corrugated layer 350 are formed with an elastic material (such as, X60 with a Shore hardness of 60D, which is obtainable from Diabase). FIG. 21 shows three bending actuators 300 formed according to these three configurations.

[0052] FIGs. 22-24 show these three bending actuators 300 after being actuated with fluid pressure supplied to the respective ports 104. As can be seen from FIGs. 22-24, when the fluid chambers 308 are inflated in 20 kPa increment to substantially 300 kPa, side-walls of the corrugations of the corrugated layers 350 become extended and the bending actuators 300 respond by bending towards the base layer 310. As observed from FIGs. 22-24, the bending actuator 300 formed with stiffer NF bend the least, possibly due to the hardness of the NF material.

[0053] Finite element models (FEM) of the bending actuators 300 were carried out to study stresses caused by bending of the actuators. From FIG. 23, the bending actuator 300 made of X60 elastic material has the highest bending angle at 300 kPa, compared to that made of X60-NF composite bending actuator shown in FIG. 24. From finite element analysis (FEA), the bending actuator 300 made with X60 single elastic material showed the higher Von Mises stress at the bend areas compared to the X60-NF composite materials bending actuator. Laboratory testing of these bending actuators 300 were also carried out and the results are shown in FIG. 25. These laboratory testing results show that the X60-NF compositematerials bending actuator 300 may provide longer reliability.

[0054] The results of bending performance suggest the bending actuator 300 made with X60- NF composite materials can be useful for a wearable application. FIG. 26 shows an application of the bending actuator 300 being employed as an assistive device for rehabilitating a finger of a stroke or hemiparetic patient. The bending actuator 300 can also be applied over other joints, such as, an elbow or knee. Still further, the bending actuator 300 can be configured as part of a wearable apparel for providing haptic sensation. [0055] While specific embodiments have been described and illustrated, it is understood that many changes, modifications, variations and combinations of variations disclosed in the text description and drawings thereof could be made to the present invention without departing from the scope of the present invention. For example, the torsion housing 220 and the wrist housing 220a may not be formed by 3D printing. In the above description, the torsion housing 220 and wrist housing 220a are mounted on the seamless chamber actuator 100b; in another embodiment, it is also possible that the torsion housing 220 or wrist housing 220a is mounted on the seamless chamber actuator 100.