Device for providing haptic stimuli to a body part of a user and method for manufacturing the device

Abstract

Described is a device for providing haptic stimuli to a body part of a user, the device comprising an actuating element configured to deform between a non-actuated state and an actuated state upon electrothermal activation, wherein the actuating element comprises a laminated structure including a flexible layer comprising liquid crystal elastomer (LCE); a conductive layer, electrically couplable to an electrothermal activator, and comprising an electrically conductive polymer; and an priming layer provided in between the flexible layer and the conductive layer and comprising an priming polymer, wherein the electrically conductive polymer derives from 3,4-ethylenedioxythiophene (EDOT) monomer units, while the priming polymer derives from vinyl or vinylidene monomer units. Also described is a method of manufacturing said device for providing haptic stimuli to a body part of a user.

Description

[0001] DEVICE FOR PROVIDING HAPTIC STIMULI TO A BODY PART OF A USER AND METHOD FOR MANUFACTURING THE DEVICE

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The invention relates to a device for providing haptic stimuli to a body part of a user, the device comprising an actuating element configured to deform between a non-actuated state and an actuated state upon electrothermal activation. The invention further relates to a method of manufacturing the device for providing haptic stimuli to a body part of a user. The invention also relates to an electronic apparatus, a vehicle and a surgical robot comprising the device.

[0004] BACKGROUND OF THE INVENTION

[0005] The invention is in the field of devices that can provide haptic stimuli to a body part of a user. The advantages of the invention become particularly apparent in smart wearable devices, as will be explained further below.

[0006] Conventional smart wearable devices commonly depend on visual or auditory alerts for providing stimuli to a user. This is particularly disadvantageous in environments where silence is required or when the user cannot directly engage with a screen. Additionally, conventional wearables provide limited accessibility for users with visual or auditory impairments.

[0007] Smart wearable devices capable of providing haptic feedback may be employed for tackling the abovementioned problems. Smart wearable devices capable of providing haptic feedback are known from the art. However, traditional haptic feedback methods heavily rely on vibration-based feedback, which offers a single, non-directional sensation. This type of haptic feedback lacks the subtlety and range to replicate the nuanced sensations of texture, sliding, or other complex tactile interactions. Additionally, present haptic feedback technologies are often cumbersome, hindering their adoption as everyday wearables.

[0008] Traditional actuation methods, which typically rely on rigid components, fail to provide the necessary adaptability and responsiveness demanded by sophisticated smart devices. For example, CN112566605A discloses a device for applying haptic stimuli that includes a stiff support configured to contact a body part wherein a containing element keeps the body part in contact with the stiff support, and an actuating element configured to push the stiff support into the containing element and apply pressure. Rigid heating elements of the prior art are not able to withstand and adapt to shape changes of an actuating element, causing durability issues. Additionally, users of devices utilizing stiffer materials for haptic feedback experience discomfort or irritation associated with prolonged wear of such devices.

[0009] Thus, there is a need to develop novel devices for providing haptic stimuli which are capable of replicating the nuanced sensations of texture, sliding, or other complex tactile interactions, while at the same time comprising the necessary adaptability and responsiveness to be integrated into a durable and comfortable smart wearable device.

[0010] SUMMARY OF THE INVENTION

[0011] It is an object of the invention therefore to provide an improved device comprising an actuating element for providing haptic stimuli to a body part of a user, which is capable of replicating nuanced, complex tactile interactions, while at the same time comprising the necessary adaptability and responsiveness to be integrated into a durable and comfortable smart wearable device. A second object relates to providing an actuating element, configured to deform between a nonactuated state and an actuated state upon electrothermal activation. A further object relates to providing a laminated structure, comprising a flexible layer and a conductive layer electrically coupled to an actuator. Yet another aim relates to providing a strong adhesion between the flexible layer and the conductive layer. The invention also aims at providing a method of manufacturing the novel device for providing haptic stimuli to a body part of a user.

[0012] According to a first aspect, the invention provides for this purpose a device for providing haptic stimuli to a body part of a user, the device comprising a load-bearing soft structural component and, associated therewith, an actuating element configured to deform between a non-actuated state and an actuated state upon activation, comprising at least one of electric, thermal and photonic activation, and thereby deform the load-bearing structural component, wherein the actuating element comprises a laminated structure including a flexible layer comprising liquid crystal elastomer; a conductive layer, comprising an electrically conductive polymer and electrically couplable to an activator comprising at least one of an electric, thermal and photonic activator; and a priming layer provided in between the flexible layer and the conductive layer and comprising a priming polymer. The present invention tackles the challenge of integrating precise, electrically controlled actuation within flexible applications, such as smart wearables. The necessary adaptability and responsiveness demanded by sophisticated smart devices are provided by applying a conductive layer - preferably a custom blend of an electrically conductive polymer derived from 3,4- ethylenedioxythiophene (EDOT) monomer units and specific additives (disclosed in more detail in the fabrication method) - as a flexible coating atop a liquid crystal elastomer (LCE). This strategic combination results in a lightweight, highly responsive material adept at undergoing precise shape changes or movements in direct response to electrical stimuli. The application of this enhanced conductive coating significantly boosts the electrical and mechanical performance of the LCE, ensuring more efficient and dependable actuation.

[0013] When at least one of electricity, heat and photon input is applied through the conductive layer, it evenly heats the LCE, energizing the aligned molecules to shift out of their orderly state, thus causing the material to change shape or contract along the direction of alignment. It is essential for the conductive layer to comprise a material that allows for uniform heating and flexibility for accommodating the LCE’s shape changes without compromising performance. An electrically conductive polymer derived from 3, 4-ethylenedioxy thiophene (EDOT) monomer units is found to be well suited for the specific application. All of the above allows for the precise electrical triggering of shape changes, opening new possibilities in the design and functionality of adaptable, responsive devices.

[0014] In a second aspect of the invention, there is provided a method of manufacturing the improved device for providing haptic stimuli to a body part of a user. The method comprises providing the flexible layer, providing the priming layer on top of the flexible layer, providing the conductive layer on top of the priming layer and consolidating the layers to obtain the actuating element.

[0015] The manufacturing process involves mixing reactive mesogens with a vinyl or non-vinyl to form a base material. This material is then partially polymerized to create a preliminary, shapeless form. To endow this material with its transformative capability, it is stretched significantly and crosslinked by means of exposure to UV light, which solidifies its structure in this elongated state and aligns the reactive mesogens in a specific direction. This alignment is crucial for the material's ability to change shape.

[0016] In a third aspect, an apparatus is provided that makes use of the invented device. Suitable apparatuses include an electronic apparatus comprising a user input device, and the invented device, wherein the user input device is configured to activate the device for providing haptic stimuli to a body part of a user. Another aspect relates to a vehicle comprising at least one sensor, and the invented device, wherein the at least one sensor is configured to activate the device for providing haptic stimuli to a body part of a user. Yet another aspect relates to a surgical robot comprising the invented device for remotely controlling relaying information on pressure.

[0017] DETAILED DESCRIPTION OF THE INVENTION

[0018] The invention as disclosed above in summary will now be elucidated further. The invention discloses a device for providing haptic stimuli to a body part of a user, the device comprising a load-bearing soft structural component and, associated therewith, an actuating element configured to deform between a non-actuated state and an actuated state upon activation, comprising at least one of electric, thermal and photonic activation, and thereby deform the load-bearing structural component, wherein the actuating element comprises a laminated structure including a flexible layer comprising liquid crystal elastomer; a conductive layer, comprising an electrically conductive polymer and electrically couplable to an activator comprising at least one of an electric, thermal and photonic activator; and a priming layer provided in between the flexible layer and the conductive layer and comprising a priming polymer.

[0019] The laminated structure is configured to improve the adhesion and to provide the flexibility and conductivity which optimize the laminated structure for being applied into device for providing haptic stimuli to a user.

[0020] For providing a strong adhesion between the LCE and the conductive polymer, a priming layer is provided in between the respective layers. An appropriate primer material may be any material which is capable of forming hydrogen bonds with the LCE and the conductive polymer derived from EDOT monomer units. Such materials may include, for example, alcohols and amides.

[0021] The invention’ s distinctiveness may be rooted in achieving optimal adhesion and flexibility of the coating made of electrically conductive polymer, which may require the incorporation of specific additives (disclosed in more detail in the fabrication method). This aspect may contribute to ensuring that the coating may not only adhere effectively to the LCE substrate but may also retain its flexibility to allow for efficient electrothermal actuation without compromising the material's integrity or performance.

[0022] In a preferred embodiment, the priming polymer comprises moieties capable of hydrogen bonding.

[0023] Any polymer suitable for this purpose may be used, either alone or in combination with a suitable solvent for the polymer. A preferred embodiment relates to a device wherein the priming polymer is water-soluble and is selected from the group of acrylic polymers, such as polyacrylic acid, and vinyl ester polymers and its derivatives, such as polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) and mixtures thereof, preferably polyvinyl alcohol (PVA).

[0024] As will be elucidated below, it has advantages when the device comprises a priming layer that is applied by spin coating the priming polymer on the flexible layer and / or the conductive layer.

[0025] The electrically conductive polymer to be used in the actuating element is preferably derived from 3,4-ethylenedioxythiophene (EDOT) monomer units to form poly(3,4-ethylenedioxythiophene) (PEDOT). A suitable PEDOT polymer may be poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). PEDOT:PSS may be particularly suitable for the application since it allows for uniform heating and flexibility for accommodating the LCE’s shape changes, without compromising performance. In an alternative embodiment, the electrically conductive polymer derived from EDOT monomer units may be poly(3,4-ethylenedioxythiophene)-tetramethacrylate (PEDOT-TMA).

[0026] In a preferred embodiment, the conductive layer may comprise a composite, comprising a mixture of the conductive polymer and specific additives. Appropriate additives may act as surfactants, changing the morphology of the conductive layer. One type of appropriate additive may comprise an ionic additive, such as trimethyl-octyl-ammonium-bromide which acts as a surfactant. Such an additive may serve the purpose of enhancing the conductivity of the conductive layer. Another type of appropriate additive may comprise a non-ionic additive, comprising any molecule capable of hydrogen bonding to the conductive polymer. Suitable examples include glycol, glycerol, sorbitol, polyethylene glycol (PEG) and PVA, with sorbitol the preferred non-ionic additive. Such an additive may serve the purpose of enhancing the flexibility of the conductive layer.

[0027] In a preferred embodiment of the device, the poly (3,4-ethylenedioxythiophene) comprises a mixture of PEDOT:PSS with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and sorbitol, wherein the ratio of PEDOT:PSS to LiTFSI is from 0.1 to 10 parts by dry weight, more preferably from 0.5 to 5 parts by dry weight, such as 1 to 4 parts by dry weight, and 1-5 wt.% sorbitol based on the total weight of a solution of PEDOT:PSS and LiTFSI, preferably 1.5 to 3 wt.%, such as 2 wt.%. As will be elucidated below, it has advantages when the device comprises a conductive layer that is applied by slot-die coating of the conductive polymer on the flexible layer comprising the liquid crystal elastomer (LCE).

[0028] The composition of the LCE affects the material properties of the LCE. Additionally, the average thickness of the priming layer and the average thickness of the conductive layer may also affect the physical properties of the respective layer. It is another aspect of the invention to find an appropriate combination of LCE composition and layer thicknesses such that the final performance of the device is optimized.

[0029] For this purpose, the LCE may comprise a mesogenic core comprising 4-(6-(acryloyloxy) n- oxy)phenyl-4-(6-(acryloyloxy)m-oxy)benzoate, with n being any one of pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and m being any one of pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, preferably wherein n and m are hexyl.

[0030] It has been established that a device according to a preferred embodiment makes use of a liquid crystal elastomer that further comprises a polymethylhydrosiloxane (PMHS) backbone, and a HIM crosslinker given by the following formula: wherein x= 2-10 and y = 2-20.

[0031] More preferably, x= 4-8 and y=4- 12, even more preferably x=5-7 and y=6- 10. A HIM crosslinker having x-6 and y=8 performs particularly well.

[0032] This embodiment provides a LCE with improved biocompatibility and is based on a polysiloxane polymer chain with mesogens attached as side chains. The underlying reaction mechanism is known in the art. However, this embodiment uses a novel crosslinker that has not been previously utilized in polysiloxane-based liquid crystal elastomer synthesis. The distinctiveness of the HIM crosslinker may be attributed to its oligomeric structure, which includes two mesogens within its chain. This design endows the crosslinker with liquid crystal properties, thereby enhancing the overall properties of the liquid crystal elastomer.

[0033] In a preferred embodiment, the LCE may furthermore comprise a vinyl inclusion. The inclusion of a vinyl may be used for tuning the actuation temperature, particularly for lowering it. In a preferred embodiment, a molecule with two aromatic rings may be used, which may lower the actuation temperature to around 30-40 degrees Celsius. This temperature is appropriate to be used in haptic feedback applications. Alternatively, molecules with three aromatic rings may be used. The resulting actuation temperature would in that case be around 80-90 degrees Celsius. While this may be appropriate for some applications, it may not be desirable for haptic feedback applications.

[0034] In a preferred embodiment, the average thickness of the priming layer may be from 1-50, preferably from 5-40 nm, more preferably from 10-30 nm, and most preferably from 15-25 nm. In a preferred embodiment, the average thickness of the conductive layer may be from 1-50 pm, preferably from 2-40 pm, more preferably from 3-30 pm, and most preferably from 5-25 pm.

[0035] The use of LCE as the actuating medium may provide a significant advantage in terms of wearer comfort, as the material may conform more naturally to the user’s body part’s contours. This may not only enhance the tactile experience but may also reduce the potential for discomfort or irritation associated with prolonged wear of devices utilizing stiffer materials for haptic feedback. By focusing on a soft material approach, the device of the invention may offer a more comfortable, adaptable, and user-friendly solution for haptic feedback in wearable technology.

[0036] The wording ‘soft’ in the context of this disclosure is meant to denote any material that is relatively easy to deform, including rubber-like materials, and also provides for a soft feel. A suitable modulus of elasticity is preferably below 2 GPA.

[0037] In order to be able to actuate the LCE, the conductive layer may be electrically couplable to the activator by electrically conducting areal couplings. These couplings may preferably be solid areal couplings. An area of the flexible layer adjacent to said areal coupling may then comprise non- aligned LCE. In this way, changing of the shape or contraction of the LCE upon actuation may be prevented in this area. This, in turn, may benefit the adhesion at the interface of the solid areal couplings and the conductive layer, since changing of shape or contraction of the LCE with respect to the non-flexible solid areal couplings would potentially result in detachment. In a preferred embodiment, the device may further comprise the electrothermal activator and the conductive layer may be electrically coupled to the actuator electrothermal activator. The electrothermal activator may provide an electrical input in the form of a voltage to the conductive layer of the actuating element. The current induced by this voltage may cause resistive heating to occur in the actuating element. Resistive heating may evenly increase the temperature over the surface of the LCE, energizing the aligned molecules to shift out of their orderly state, thus causing the material to change shape or contract along the direction of alignment. It is essential for the conductive layer to comprise a material that allows for uniform heating and flexibility for accommodating the LCE’s shape changes without compromising performance.

[0038] In an embodiment, the actuating element may be configured to abut against a body part of a user. The body part may be a circumferential portion of a digit of a user, preferably a digit of a hand of a user. The actuating element may be wound around at least a part of the body part of the user, such that in the actuated state, the actuating element may exert a compressive and / or shearing force onto the body part of the user.

[0039] In order to optimally take advantage of the device’s ability to provide nuanced, complex tactile stimuli to a user, a more appropriate, wearable configuration of the device may be provided. In a preferred embodiment, the device may comprise a soft load-bearing structural component in the form of an open ring component configured to abut against a body part of a user. The body part may be a circumferential portion of a digit of a user, preferably a digit of a hand of a user. The open ring component may be made of any deformable material. For example, the open ring component may be made of any material with a non-zero elastic modulus below 2 GPa. The open ring component may be made of, for example, a synthetic rubber or elastomer. In a preferred embodiment, the open ring component may be made of an elastomer different from the LCE, preferably comprising a photocurable polymer resin such as Elastic 50A resin.

[0040] A particularly suitable resin for making the load-bearing structural component has a post-cured ultimate tensile strength of between 3-4 MPa (ASTM D 412-06 (A)), a stress at 50% elongation of between 0.5-1.5 MPa (ASTM D 412-06 (A)), an elongation at Break of between 120-200% (ASTM D 412-06 (A)), and a Shore Hardness of between 45-65 (ASTM 2240).

[0041] The device may furthermore comprise the actuating element such that upon electrothermal activation thereof, the open ring component may be deformed between the non-actuated state and the actuated state. The deformation of the open ring component may exert a compressive and / or shearing force onto the body part of the user. The actuating element may extend in a circumferential direction around at least a portion of the open ring component. The actuating element may extend in a circumferential direction around the entire open ring component.

[0042] The open ring component may have a first end, a second end that is spaced apart from and opposed to the first end, and a circumferential opening defined between the first end and the second end. In a preferred embodiment, the actuating element may extend in a circumferential direction across the circumferential opening.

[0043] In a preferred embodiment, the mesogen alignment direction of the LCE may extend parallel to a circumferential direction of the open ring component, such that upon actuation, a reduction of the width of the circumferential opening may be caused relative to the non-actuated state. This reduction in width may cause the open ring component to exert a compressive force onto the body part.

[0044] The unique property of LCE allows for a direct squeeze effect on the user’ s body part through electrothermal actuation, rather than structural deformation. This material innovation enables a nuanced form of tactile feedback that is inherently different from the approaches based on physical alterations of the device's shape or size.

[0045] In another preferred embodiment, the mesogen alignment direction of the LCE may instead extend under a non-zero angle with a circumferential direction of the open ring component, such that upon actuation, a shearing movement of the first and second ends relative to each other may be caused relative to the non-actuated state. This shearing movement may cause the open ring component to exert a shearing force onto the body part.

[0046] An embodiment of the device of the invention may be envisioned for exerting both a compressive force and a shearing force. Such a device may comprise an LCE in which the mesogen alignment direction may extend parallel to a circumferential direction of the open ring component as well as an LCE in which the mesogen alignment direction may extend under a non-zero angle with a circumferential direction of the open ring component. For this purpose, the use of several individually aligned layers of LCE may be practical. The skilled person will appreciate that various embodiments are conceivable, utilizing a combination of elements, such that they would be able to configure an embodiment of the device capable of providing both abovementioned functionalities. For example, in an embodiment, the device may comprise an inner open ring component, to which an actuating element for exerting one of a shearing force and compressive force is connected. The device may further comprise an outer op ring component, which may be concentric to the inner open ring component, to which an actuating element for exerting the other of the shearing force and the compressive force is connected. Alternatively, the device may comprise one open ring component, to which two actuating elements may be connected. One of the actuating elements may be configured to exert a shearing force, while the other actuating element may be configured to exert a compressive force. In yet another embodiment, the device may comprise one open ring component and one actuating element. In this case, the laminated structure of the single actuating element may be different from the laminated structure as described up to now in this description. The single actuating element may then comprise two layers of LCE material, with different alignment directions. In order to be actuated individually then, the different LCE layers preferably are not in direct contact with each other. The skilled person will appreciate that various embodiments are conceivable, which may use thermally and / or electrically insulating layers as a part of different laminated structures. Preferably, the laminated structure would comprise a layer configuration in which strain at the interface of different layers is mitigated, for example by using a symmetrical configuration. In all of the above embodiments, the LCE for exerting a shearing force and the LCE for exerting a compressive force may be actuated separately from each other.

[0047] Additionally, a circumferentially disposed surface of the open ring component facing the body part may comprise a corrugated surface over at least a portion of the circumferentially disposed surface. Preferably, the circumferentially disposed surface facing the body part may comprise a corrugated surface over at least a portion of the circumferentially disposed surface facing the body part at or near the first and / or second end. Namely, the ends of the open ring component may be where the compressive and / or shearing forces may be largest. In this way, the sensation of texture, friction or directional cues may be optimally simulated.

[0048] The above features may present a solution to the practical challenges of wearable notifications by providing haptic stimuli that go beyond mere tapping or vibrating. The open ring component may smoothly slide or press against the body part of the user to mimic the feeling of touching different surfaces or moving objects. Upon actuation, the open ring component may move sideways or press down more firmly, creating a variety of sensations. In useful embodiments, the body part is a circumferential portion of a digit, a limb or other extremity of the user.

[0049] In another embodiment, a surface of the load-bearing soft structural component faces the body part and comprises a corrugated surface over at least a portion of the surface. In a second aspect of the invention, there is provided a method of manufacturing the novel device, and in particular the actuating element thereof, for providing haptic stimuli to a body part of a user. The method comprises providing the flexible layer, providing the priming layer on top of the flexible layer, providing the conductive layer on top of the priming layer, preferably by means of slot-die coating, and consolidating the layers to obtain the actuating element.

[0050] In a preferred embodiment, the providing of the flexible layer may comprise stretching the flexible layer before cross-linking the LCE and thereafter cross-linking the LCE to obtain aligned LCE.

[0051] Another embodiment relates to a method wherein cross-linking the liquid crystal elastomer is carried out by photocuring with UV-light.

[0052] Yet another embodiment provides a method wherein providing the priming layer on top of the flexible layer is carried out by spin coating of the priming polymer or a solution thereof.

[0053] Yet another embodiment relates to a method wherein providing the conductive layer on top of the priming layer is carried out by slot-die coating of the conductive polymer or a solution thereof.

[0054] In a preferred embodiment, the conductive layer may be electrically couplable to the actuator by electrically conducting areal couplings, preferably solid areal couplings, and wherein an area of the flexible layer adjacent to said areal coupling is not stretched before cross-linking the LCE to obtain non-aligned LCE in said area.

[0055] The alignment of the LCE material may be controlled to allow for the integration of rigid contacts. The contact points on the edges of the conductive layer may comprise of non-aligned material, enabling rigid contacts to be made with soft, flexible material without breakage due to strain and modulus differences during actuation with device operation. This alignment and contact design may allow for product-grade reliability during operation. This configuration may be achieved through controlling the strain of the material during the alignment phase of the cross-linking process, where the non-aligned areas are kept with no strain and aligned areas are strained during curing. Curing may be achieved using exposure to UV light, causing the initially shapeless polymer chains to be cross-linked.

[0056] Next, the fabrication process of the laminated structure of the invention will be discussed in more detail, with reference particularly to a preferred embodiment. The preferred LCE material used in this invention, when coated with the PEDOT:PSS composite, exhibits an electrical resistance of approximately Ik ohm. The LCE base consists of a Micheal- thiol addition reaction in a vinyl or non-vinyl-based reaction. The LCE is synthesized in a two-step crosslinking method involving a mold and controlled mechanical stretching at 200% strain for liquid crystal alignment; the stretched configuration is cured with 100mW / cm2 UV light at -20 degrees Celsius. Reversible deformation of the final material is based on loss of order of liquid crystal alignment due to thermal effects originating from the PEDOT:PSS composite coating

[0057] The PEDOT:PSS formulation and weight ratio of chemicals, and their chemical structures will be referred to in the detailed description of the figures, specifically in FIG. 3. The PEDOT:PSS is applied onto the LCE through slot-die coating with parameters with a gap height of 600 microns, platform movement speed of 2 mm / s, and flow rate of 17 microliters per second. For this process, the PEDOT:PSS has a gel-like viscosity to facilitate the application, with Newtonian behavior; this produces a layer between 10-20 microns. Optimal actuation of the haptic feedback mechanism within the self-actuating ring is achieved with an electrical input of around 10 volts. The actuation response of the LCE-PEDOT ring, at a 10V driving force, is shown in Graph 1.

[0058] In a preferred embodiment, the LCE primer material consists of PVA. The primer material is spin- coated onto the cured LCE through spin coating at 2000 rpm for 30 seconds; the spin-coated PVA has a concentration 3 wt.% in DI water; this creates primer layer of around 20 nanometer.

[0059] The resin base of the open ring component consists of elastic 50A from FormLabs, which is cured with 100mW / cm2 UV light. The resin used for the ring is passive. The integrated spring mechanism in the ring's design ensures a quick return to the original state after actuation, contributing to the rapid relaxation post-stimulation; this allows for relaxation times below 5 seconds. This efficient mechanism, underpinned by the contraction and subsequent expansion of the LCE upon cooling, provides a clear actuation profile for the ring, making it a promising candidate for responsive haptic devices.

[0060] According to another aspect of the invention, a method of manufacturing a device as claimed comprises: providing a non-active, internally ribbed and / or smooth, load-bearing soft structural component; providing the actuating element with electrically conducting areal couplings; associating the actuating element and the load-bearing soft component by providing a photo-curable soft polymer material onto surface areas of the actuating element and the loadbearing soft component and contacting said surface areas; and photo-polymerizing the photo-curable soft polymer material to integrate the actuating element and the load-bearing soft component in a form suitable for providing haptic stimuli to a body part (200) of a user.

[0061] The invention may not only present a solution to the practical challenges of wearable notifications but may also open up expansive new possibilities for user interaction within immersive digital environments. It may signify a leap forward in wearable technology, bridging the gap between digital feedback and human sensory experiences.

[0062] Customizable squeeze patterns may also be used for receiving private messages and / or notifications. The application of this advanced haptic feedback may range from receiving a message from a friend to a receiving a reminder to stand up and stretch. Additionally, the device may capitalize on the human-like touch sensation to foster emotional connections, offering a novel way to convey feelings or receive comfort through these customizable squeeze patterns. These features may enrich the user experience, extending beyond the capabilities of current smart devices.

[0063] The device’s utility may furthermore be amplified in virtual reality (VR) and augmented reality (AR) settings, where it may pioneer the incorporation of tactile feedback for a more immersive experience. For instance, a user may feel the sensation of running the body part, for example a finger, across a smooth silk fabric, the roughness of sandpaper, or even the push of a button, all without looking or using another device. The device of the invention may allow users to engage with digital environments through touch, enhancing the realism and interactivity of VR and AR applications, making everything from navigating maps on a phone to feeling the texture of virtual objects in a game incredibly real.

[0064] Thereto, in a third aspect of the invention, an electronic apparatus is provided comprising a user input device, and an embodiment of the invented device, wherein the user input device is configured to activate the device for providing haptic stimuli to a body part of a user. Yet another aspect relates to a vehicle comprising at least one sensor, the invented device and any embodiment thereof, wherein the at least one sensor is configured to activate the device for providing haptic stimuli to a body part of a user. Yet another aspect of the invention provides a surgical robot comprising the invented device and any embodiment thereof for remotely controlling relaying information on pressure.

[0065] As has been disclosed hereinabove, the invention provides a haptic system utilizing programmable soft material actuators, comprising a non-active, internally ribbed and / or smooth, load-bearing soft structural component integrated with an active soft actuator component, programmable shape memory behaviour that induces contraction on-demand upon electric and / or thermal and / or photonic stimuli to achieve a haptic squeezing and / or shear and / or pressure action.

[0066] Further provided in an embodiment is a soft toroidal wearable haptic system according to the above, wherein the active soft actuator component comprises a programmable liquid crystal oligomer network material, with or without electrical-functionalization.

[0067] Further provided in an embodiment is a soft toroidal wearable haptic system according to the above, wherein the liquid crystal oligomer network active soft actuator component achieves haptic sensations.

[0068] Further provided in an embodiment is a soft toroidal wearable haptic system according to the above, wherein the liquid crystal oligomer network active soft actuator component achieves a haptic squeezing or shearing or pressure effect through the contraction of the material in the programmed direction with the activation of the selected electrothermal stimuli generated by a complementary electronic driver system for the active soft actuator component.

[0069] Further provided in an embodiment is a soft toroidal wearable haptic system according to the above, wherein the incident of the non-active, internally ribbed and / or smooth component, driven by the contraction of the active soft actuator component, incidents on the digits, limbs or extremities in any location of the body of the user to generate the aforementioned haptic sensations.

[0070] Further provided in an embodiment is a soft toroidal wearable haptic system according to the above, wherein the area of incidence of the non-active component is provided with the means to enhance haptic sensations.

[0071] Further provided in an embodiment is a soft toroidal wearable haptic system according to the above, wherein the area of incidence of the non-active component is provided with the means to enhance haptic sensations through the presence of elevated structures. Further provided in an embodiment is a soft toroidal wearable haptic system according to the above, wherein the area of incidence of the non-active component is provided with the means to enhance haptic sensations through the control of skin-friction drag through friction-enhancing layers and structures.

[0072] Further provided in an embodiment is a soft toroidal wearable haptic system according to the above, wherein the liquid crystal oligomer network active soft actuator component is obtained by a method comprising three stages, wherein in a first stage a loosely crosslinked network is obtained by reaction between a liquid crystalline acrylate and excess of a thiol with a base catalyst, and wherein in a second stage a deformation is established in the network that causes orientation of the obtained liquid crystal chains that are fixed by a reaction initiated by vinyl additions in a photo crosslinking reaction, and wherein in a third stage the material is electrically functionalized by compositing and / or coating with a poly(3,4-ethylenedioxythiophene)-based material.

[0073] Further provided in an embodiment is a soft toroidal wearable haptic system according to the above, wherein the liquid crystal oligomer network active soft actuator component is obtained by a method comprising three stages, wherein in a first stage a loosely crosslinked network is obtained by reaction between an excess of liquid crystalline acrylate and a thiol with a base catalyst, and wherein in a second stage a deformation is established in the network that causes orientation of the obtained liquid crystal chains that are fixed by a photo-crosslinking reaction, and wherein in a third stage the material is electrically functionalized by compositing and / or coating with a poly(3,4- ethylenedioxythiophene)-based material.

[0074] Further provided in an embodiment is a soft toroidal wearable haptic system, according to any one or more of claims 1-10, wherein the poly(3,4-ethylenedioxythiophene)-based material comprises a mixture of PEDOT:PSS with LiTFSI and sorbitol, with the ratio of 1 part PEDOT:PSS to 4 parts LiTFSI by dry weight, and 2 wt.% sorbitol based on the total solution weight of PEDOT:PSS and LiTFSI, applied using a spin-coating process for the PVA primer layer for adhesion and a slot-die coating process for the PEDOT:PSS composite layer.

[0075] Further provided in an embodiment is a method for manufacturing a haptic system utilizing programmable soft material actuators, comprising the following:

[0076] Construction of a non-active, internally ribbed and / or smooth, load-bearing soft structural component; physically joining the programmed and electrically-functionalized liquid crystal oligomer network active soft actuator component with added electrical contacts; addition of photo-curing soft polymer material into the vacant area between joints between the non-active, internally ribbed and / or smooth, load-bearing soft structural component and electrically-functionalized liquid crystal oligomer network active soft actuator component with added electrical contacts; photo-polymerizing the photo-curing soft polymer material of the filled areas for integrating active and non-active soft materials in a toroidal and / or complex form.

[0077] Further provided in an embodiment is a method according to the above, wherein the non-active, internally ribbed and / or smooth, load-bearing soft structural component is a photo-curing soft material, such as photo-curing polymer resin.

[0078] Further provided in an embodiment is an electronic apparatus with user input and device output provided to and with a haptic system according to the above.

[0079] Further provided in an embodiment is the use of soft material contraction in a haptic system according to the above for providing information and action responses or confirmation through a haptic squeezing and / or shear action.

[0080] Further provided in an embodiment is the use of functionalized soft materials in a haptic system according to the above for sensing user actions in real or virtual space to provide information and data to an electronic controller module.

[0081] Further provided in an embodiment is the use of functionalized soft materials in a haptic system according to the above for providing sensual stimulation to the user.

[0082] Further provided in an embodiment is the use of electrothermal soft materials in a haptic system according to the above for providing thermal haptics effects to the user actions through the heating of the active soft actuator component.

[0083] Further provided in an embodiment is the sole use of soft materials for standalone haptics according to the above.

[0084] Further provided in an embodiment is an electronic apparatus according to the above, wherein the apparatus is chosen from the group of smartphones, smart watches, and VR systems. Further provided in an embodiment are vehicles wherein a haptic ring connected to the sensors of cars are provided with a haptic feedback according to the above for providing warnings to its users.

[0085] Further provided in an embodiment is a surgical robots with haptic rings to users providing haptic systems according to the above for remotely controlling relaying information on pressure.

[0086] In other embodiments of the invention, there is provided a multilayer actuating element consisting of at least three layers comprising at least a liquid crystal elastomeric, an elastic electrically- conductive layer and a third priming layer that strongly chemically or mechanically couples the first two layers.

[0087] Further provided in an embodiment is a multilayer actuating element, according to he above, wherein the initial set-up of molecular orientations can be used to program the deformation scheme of the actuating element.

[0088] Further provided in an embodiment is a multilayer actuating element, according to the above, wherein the application of electric current triggers a programmed electrothermal deformation originating from the electrically conductive layer.

[0089] Further provided in an embodiment is an electronic driver apparatus that can program and execute the actuation of a multilayer actuating element according to the above.

[0090] Further provided in an embodiment is the use of soft material contraction in any electronic system according to the above for providing device deformation through the electrically-driven deformation of a smart multilayer elastomeric actuating element.

[0091] Further provided in an embodiment is a soft material-actuation integrated electronic system according to the above, wherein the apparatus is chosen from the group of devices including smartphones, smart watches, VR systems, and soft robots making use of internal or external actuation behaviour.

[0092] Further provided in an embodiment is the delivery of a heating effect that originates from the electrothermal actuation of the elastomeric multilayer actuating element, according to the above. Further provided in an embodiment is a layering method and composition for manufacturing a multilayer actuating element active with liquid crystal network and / or liquid crystal oligomer networks utilizing poly(3,4-ethylenedioxythiophene)-based conductive material, hydrogen-bond forming polymer priming, and coating techniques thereof, comprising of:

[0093] Inducing, mechanically or chemically, liquid crystal molecular alignment of the liquid crystal network and / or liquid crystal oligomer networks within the centre of a free-film actuator strip and avoiding alignment in the edges of the strips, wherein this alignment configuration is arrested through the photo-curing of the active soft actuator component with UV light;

[0094] Coating of water-soluble priming material on the active soft actuator component free-film strip inducing the formation of hydrogen-bonding with the proceeding application of conductive PEDOT:PSS to bind the LCON and the conductive PEDOT:PSS together indirectly.

[0095] Further provided in an embodiment is the specialized composition of the active conductive material according to the above, comprising of a poly(3,4-ethylenedioxythiophene)-based material, wherein the poly(3,4-ethylenedioxythiophene)-based material comprises a mixture of PEDOT:PSS with LiTFSI and sorbitol, with the ratio of 1 part PEDOT:PSS to 4 parts LiTFSI by dry weight, and 2 wt% sorbitol based on the total solution weight of PEDOT:PSS and LiTFSI, applied using a spincoating process for the PVA primer layer and a slot-die coating process for the PEDOT:PSS composite layer.

[0096] Further provided in an embodiment is a fabrication method of a liquid crystal network and / or liquid crystal oligomer networks active soft actuator component free-film strip, according to the above, wherein the coating methods of PEDOT;PSS material on the primed active soft actuator component free-film strip comprises of spin-coating methods slot-die coating.

[0097] Further provided in an embodiment is the fabrication method of a liquid crystal network and / or liquid crystal oligomer networks active soft actuator component free-film strip, according to the above, wherein the coating methods of water-soluble priming material, such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl pyrrolidone and poly aery lie acid, on the active soft actuator component free-film strip.

[0098] Further provided in an embodiment is a non-alignment of the liquid crystal network and / or liquid crystal oligomer networks active soft actuator component free-film strip edges, according to claim 8, for the purposes of attaching and connecting electrodes to the free-film strip edges without the electrodes experiencing stress, entailing the risk to disconnected or become unattached, during the actuation of the liquid crystal network and / or liquid crystal oligomer networks active soft actuator component free-film strip upon activation of stimuli.

[0099] Further provided in an embodiment is a the fabrication method of biocompatible liquid crystal polymer via the synthesis of a crosslinker that induces a polysiloxane main chain with two liquid crystal mesogen groups attached as side chains, wherein polymethylhydrosiloxane and SFD4034 are reagents for the HIM crosslinker.

[0100] BRIEF DESCRIPTION OF THE FIGURES

[0101] Examples of the invention will now be elucidated with reference to the following figures, without however being limited thereto. In the figures:

[0102] Figures 1A-B schematically show an actuating element in a non-actuated state and the actuating element in an actuated state, respectively, in accordance with an embodiment of the invention. Figures 2A-C show chemical formulae of exemplary constituents of a flexible layer, a priming layer and a conductive layer, in accordance with embodiments of the invention.

[0103] Figure 2D illustrates a crosslinking polymerization step on a stretched LCE according to an embodiment of the invention.

[0104] Figures 3A-B show camera images of an LCE coated with a PEDOT composite, in its non-actuated state and in its actuated state, respectively, in accordance with an embodiment of the invention.

[0105] Figure 4A-B schematically show a first schematic view and a second schematic view, respectively, of a device for providing haptic stimuli to a body part of a user, in accordance with an embodiment of the invention.

[0106] Figure 5 shows a camera image of a body part of a user wearing the device for providing haptic stimuli to a body part of a user, in accordance with an embodiment of the invention.

[0107] Figure 6 shows a flowchart of a method of manufacturing the device for providing haptic stimuli to a body part of a user, in accordance with an embodiment of the invention.

[0108] Figure 7 shows a flowchart of the method of manufacturing the device for providing haptic stimuli to a body part of a user, in accordance with an embodiment of the invention.

[0109] Figure 8 shows a step in the method of manufacturing the device in accordance with an embodiment of the invention.

[0110] Figure 9 shows yet another step in the method of manufacturing the device in accordance with an embodiment of the invention.

[0111] DESCRIPTION OF EXEMPLARY EMBODIMENTS Figures 1A-B schematically show an actuating element (110) in a non-actuated state and the actuating element (110) in an actuated state, respectively, in accordance with an embodiment of the invention.

[0112] Referring to figure 1A, it shows the actuating element (110) in the non-actuated state. The actuating element (110) comprises a laminated structure of a flexible layer (111) at the bottom, a conductive layer (113) on the top, and an priming layer (112) disposed between the flexible layer (111) and the conductive layer (113). The flexible layer (111) comprises a liquid crystal elastomer (LCE). The conductive layer (113) comprises an electrically conductive polymer, wherein the electrically conductive polymer is derived from 3,4-ethylenedioxythiophene (EDOT) monomer units. The priming layer comprises an priming polymer, wherein the priming polymer is derived from vinyl or vinylidene monomer units.

[0113] An average thickness of the priming layer (112) may range from 1-50 nm. Preferably, the thickness of the priming layer (112) may range from 5-40 nm, more preferably from 10-30 nm, and most preferably from 15-25 nm.

[0114] An average thickness of the conductive layer (113) may range from 1-50 pm. Preferably, the thickness of the conductive layer (113) may range from 2-40 pm, more preferably from 3-30 pm, and most preferably from 5-25 pm.

[0115] Referring to figure IB, it shows the actuating element (110) in the actuated state. The actuating element (110) comprises the same laminated structure as in figure 1A. In an actuated state, the flexible layer (111) may contract. This contraction may cause a length of the flexible layer (111) to decrease in size. The conductive layer (113) may not show such contraction behavior in the actuated state. If the adhesion of the flexible layer (111) to the conductive layer (113) is maintained upon contraction of the flexible layer (111), the actuating element (110) is forced to bend. In the bent configuration, the adhesion may be maintained while the length of the flexible layer (111) may be smaller than a length in a corresponding direction of the conductive layer (113). In the actuated state, then, the contracted flexible layer (111) forms the inner side of an arch and the conductive layer (113) forms the outer layer of said arch.

[0116] Figures 2A-C show chemical formulae of exemplary constituents of the flexible layer (111), the priming layer (112) and the conductive layer (113), in accordance with embodiments of the invention. The annotations may depict a molar ratio of each constituent in a mixture. Referring to figure 2A, it shows chemical formulae of exemplary constituents of LCE materials with vinyl inclusion. In a preferred embodiment, the LCE may comprise a vinyl inclusion. The chemical formulae correspond to that of benzoic acid, 4-[[6-[(l-oxo-2-propen-l- yl)oxy]hexyl]oxy]-, 4-[[6-[(l-oxo-2-propen-l-yl)oxy]hexyl]oxy]phenyl ester (SFD0022), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Irgacure 8|9), pentaerythritol tetra(3- mercaptopropionate) (PETMP), triethylene glycol divinyl ether (TEGDE), glyoxal, bis(diallyl acetal) (GDA), 2,2’-(ethylenedioxy)diethanethiol (DODT) and dipropylamine (DPA).

[0117] Referring to figure 2B, it shows a chemical formula of an priming polymer according to a preferred embodiment. The chemical formula corresponds to the chemical formula of poly(vinyl alcohol) (PVA). In an alternative embodiment, a different priming polymer may be selected from a group of acrylic polymers and vinyl ester polymers and its derivatives.

[0118] Referring to figure 2C, it shows a chemical formula of an electrically conductive polymer derived from EDOT monomer units according to a preferred embodiment. The chemical formula corresponds to the chemical formula of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). In an alternative embodiment, a different electrically conductive polymer derived from EDOT monomers units may be selected, for example poly(3,4-ethylenedioxythiophene)- tetramethacrylate (PEDOT-TMA).

[0119] With reference to figure 2A, a first synthesis step involves (A) the oligomerization of Liquid crystal RM (SFD0022) with chain extender (DODT) and crosslinker PETMP using (B) Real Michael-thiol addition (Thiols -> SFD0022) with B being DPA. The LCE of this embodiment was prepared using the following chemicals: SFD0022, Irgacure 819, PETMP, DODT, TEGDE, GDA, and DPA as shown in figure 2A. Each chemical was weighed and dissolved in chloroform according to the molar ratios with respect to SFD0022 specified: SFD0022 (1.0), Irgacure 819 (0.040), PETMP (0.240), DODT (0.784), TEGDE (0.127), GDA (0.032), and DPA (0.042). The solution was then poured into a Teflon petri dish and left to evaporate overnight to form semicrosslinked oligomers. To ensure complete removal of chloroform, the dish was placed in a vacuum oven at 40°C for 4 hours.

[0120] As shown in figure 2D, a second polymerization step involved the thiol-ene reaction initiated by UV-light. Stage (A) shows a free standing oligomer film, stage (B) illustrates a mechanically induced alignment of reactive Mesogens and stage (C) shows a locked aligned LCE using (D) thiol-ene radical polymerization. This may be achieved as follows. The free-standing film was stretched to 200% strain to induce nematic alignment through the application of mechanical force. To preserve this alignment, the stretched film was subsequently cured under UV light at an intensity of 100 mW / cm2for 20 minutes on each side, utilizing an Excelitas Technologies OMNICURE® SERIES 2000 UV source, which operates within the 300-400 nm wavelength range of a mercury vapor short arc. Portions of the film were covered with aluminum foil during the curing process to prevent exposure to UV light, thereby leaving certain areas uncured and without alignment. These uncured regions are intended for the attachment of connections such as electrodes.

[0121] The molar ratios of the monomers used in the synthesis of the LCE (also denoted as the Liquid Crytal Oligomer Network or LCON) film designed for actuation at 30°C, and specifically tailored for applications in haptic feedback rings, were as follows:

[0122] Molar

[0123] CAS nr.

[0124] Chemical acronym ratios

[0125] SFD0022 151464-39-0 1.00

[0126] Irgacure 819 162881-26-7 0.04

[0127] PETMP 7575-23-7 0.24

[0128] DODT 14970-87-7 0.78

[0129] TEGDE 765-12-8 0.13

[0130] GDA 16646-44-9 0.03

[0131] DPA 142-84-7 0.04

[0132] In the above, the chemical acronyms relates to:

[0133] SFD0022: This compound is a reactive mesogen, which is responsible for imparting the unique anisotropic properties characteristic of liquid crystal materials. The rigid structure of SFD0022, which contains two benzene rings, facilitates a lower energy requirement for the mesogens to transition to the isotropic phase, thereby lowering the transition temperature. Depending on the application, other reactive mesogens with longer rigid structures could be employed, but SFD0022 offers a distinct advantage due to its lower transition temperature.

[0134] DODT : Serving as a thiol-based chain extender, DODT increases the flexibility and length of the polymer chains, allowing the LCON film to be mechanically stretched. This stretching induces alignment within the film due to the strain force applied, which is essential for the film's functionality. PETMP: This compound acts as a crosslinker, contributing to the flexibility of the film. Without PETMP, the resultant film would be a sticky gel, indicating its crucial role in achieving the desired mechanical properties.

[0135] TEGDE: A chain extender that reduces the transition temperature to approximately 30°C, which is the target temperature for the haptic ring application. TEGDE contains reactive vinyl groups that participate in a secondary thiol-ene reaction, initiated by Irgacure 819 under UV light, to lock the alignment of the film.

[0136] GDA: Another crosslinker that helps to further lower the transition temperature to the desired ~30°C. GDA features four vinyl groups that also react in the secondary thiol-ene reaction, initiated by the photoinitiator Irgacure 819 under UV light, to solidify the alignment within the LCON film.

[0137] This combination of components and their precise ratios enables the synthesis of an LCON film with the requisite properties for haptic feedback applications, particularly in devices operating around 30°C.

[0138] It should be mentioned that, in addition to the previously discussed LCON composition, a highly effective actuating LCON film can also be synthesized using the composition detailed as follows:

[0139] Chemical acronym CAS nr. Molar ratios

[0140] This embodiment is optimized to actuate at 45 °C and is composed of the following monomers: SFD0022, Irgacure 819, PETMP, DODT, and DPA. This specific LCON composition can be used for other temperature-responsive devices.

[0141] Another preferred embodiment proposes novel LCE chemistry based on poly siloxanes. This embodiment results in a more biocompatible LCE based on a polysiloxane polymer chain with mesogens attached as side chains. The innovation lies in the use of a novel crosslinker that has not been previously utilized in polysiloxane-based liquid crystal elastomer synthesis. The distinctiveness of this crosslinker is attributed to its oligomeric structure, which includes two mesogens within its chain. This design endows the crosslinker with liquid crystal properties, thereby enhancing the overall properties of the elastomer. The relevant chemical formulae are shown below:

[0142] Monomers used in the side -chain liquid crystal polysiloxane elastomer synthesis are (A) polymethylhydrosiloxane (PMHS) as backbone polymer, (B) SFD4034 as a liquid crystal side chain, and (C) the novel liquid crystal oligomer crosslinker developed for enhanced material properties with x-6 and y=8. Suitable molar ratios of these components are as follows:

[0143] Chemical acronym CAS nr. Molar ratios

[0144] PMHS 1

[0145] SFD4034 0.87

[0146] HIM Crosslinker 0.17

[0147] Referring to figure 8, the electro-functionalization of the produced LCON (e-LCON) is illustrated. After obtaining the aligned LCON film (A), the surface was treated with UV-ozone and (B) spin- coated with a 5 wt.% PVA solution at 3000 rpm for 30 seconds using a SUSS MicroTec RC8 spin coater. The coated LCON film was then left in a vacuum desiccator overnight to dry the PVA layer. Following the drying process, the PVA-coated LCON film underwent an additional UV- ozone treatment for 20 minutes. Subsequently, PEDOT:PSS compositions were prepared based on the dry weight of PEDOT:PSS (1,3 wt\%) with a ratio of 1:2 PEDOT:PSS : Additive. Used additives were Li TFSI and Sorbitol. The LCON film was coated with a PEDOT:PSS composite using a Ussila (C) slot-die coater. The slot-die gap was set to 0.8 mm, the dispense rate was 0.25 pL / s, and the platform speed was 2 mm / s. Finally, the e-LCON with the conductive coating (D) was placed in a vacuum desiccator for 2 days to ensure thorough drying. Finally, to integrate the e-LCON into an electrical circuit, electrodes were attached to it. As disclosed hereinabove, the LCON contains uncured, non-aligned regions specifically designed for this purpose. Copper film and copper wires were attached to these regions using electrically conductive adhesive, ensuring a reliable connection. The result of this is shown in figure 9, where the electro-functionalized LCON with attached electrodes is shown, ready for integration into an electronic circuit.

[0148] Figures 3A-B show camera images of an LCE coated with a PEDOT composite, in its non-actuated state and in its actuated state, respectively, in accordance with an embodiment of the invention.

[0149] Referring to figure 3A, it shows the camera image of the LCE coated with the PEDOT composite in its non-actuated state. On both ends, the actuating element (110) is connected to an electrothermal activator (140). For obtaining a proof-of-concept, the electrothermal activators (140) may be crocodile clips connected to an electrical power source. In the device (100), the electrothermal activators (140) may instead be an integral part of the device (100). In the nonactuated state, no electrical signal is provided to the actuating element (110), such that the actuating element (110) retains its original shape.

[0150] Referring to figure 3B, it shows the camera image of the LCE coated with the PEDOT composite in its actuated state. On both ends, the actuating element (110) is connected to an electrothermal activator (140), again represented by crocodile clips. In this case, the left crocodile clip corresponds to the positive terminal of the electrical power source, while the right crocodile clip corresponds to the negative terminal of the electrical power source. Upon providing an electrical input, the temperature of the actuating element (110) may raise and the actuating element (110) may be electrothermally actuated such that it may deform and / or contract in a direction in which the mesogens were aligned during manufacturing. A deformation can clearly be observed in the actuated state of figure 3B when compared to the non-actuated state of figure 3A. The electrical input provided by the electrical power source may be a voltage of around 10 Volts.

[0151] Figure 4A-B schematically show a first view and a second view, respectively, of a device (100) for providing haptic stimuli to a body part (200) of a user, in accordance with an embodiment of the invention.

[0152] Referring to figure 4A, it shows the first view of the device (100) for providing haptic stimuli to a body part (200) of a user according to an embodiment. Besides the actuating element (110), the device (100) may furthermore comprise an open ring component (120). The open ring component (120) may have a first end (121), a second end (122) and a circumferential opening (123) defined between the first end (121) and the second end (122). The open ring component (120) may be made of an elastomer different from the LCE. In a preferred embodiment, the elastomer different from the LCE may comprise 50A resin.

[0153] The actuating element (110) may extend in a circumferential direction across the circumferential opening (123). A first end of the actuating element (110) may be connected to the open ring component (120) at or near the first end (121), while a second end of the actuating element (110) may be connected to the open ring component (120) at or near the second end (122). The actuating element (110) may be connected to the open ring component (120) at an outside facing circumferentially disposed surface of the open ring component (120).

[0154] The actuating element (110) may be connected to the open ring component (120) such that the flexible layer (111) faces the open ring component (120). The flexible layer (111) may be in direct contact with the open ring component (120). The actuating element (110) may further be connected to the open ring component (120) such that the conductive layer (113) faces away from the open ring component (120).

[0155] Electrically conducting areal couplings (130) may be attached to the conductive layer (113). In a preferred embodiment, these electrically conducting areal couplings (130) may be solid areal couplings. These electrically conducting areal couplings (130) may electrically couple the actuating element (110) to the electrothermal activator (140). For example, a first electrically conducting areal coupling (130) may electrically couple the actuating element (110) to a negative (-) terminal of an electrical power source, while a second conductive areal coupling (130) may electrically couple the actuating element (110) to a positive (+) terminal of an electrical power source. In figure 4A in particular, the first electrically conducting areal coupling (130) is shown as being detached from the conductive layer (113) of the actuating element (110), while the second electrically conducting areal coupling (130) is shown as being attached to the conductive layer (113) of the actuating element (110).

[0156] In a preferred embodiment, an area of the flexible layer (111) adjacent to the electrically conducting areal couplings (130) may comprise non-aligned LCE. In figure 4A, this is indicated by a cross in the particular areas of the flexible layer (111).

[0157] Referring to figure 4B, it shows the second view of the device (100) for providing haptic stimuli to a body part (200) of a user. The device (100) may be rotated 180 degrees with respect to the first view, without flipping over the device (100). In addition to what is shown in figure 4A, figure 4B shows an inside facing circumferentially disposed surface of the open ring component (120) which may comprise a corrugated surface (124) over at least a portion of said surface. When the device (100) is worn by the user, the corrugated surface (124) may contribute to simulating the sensation of texture, friction or directional cues onto the body part (200) of the user. In a preferred embodiment, said portion may be located at or near the first (121) and / or second end (122) of the open ring component (120). The corrugated surface (124) may comprise a sawtooth structure, or any other type of corrugated surface (124) that may simulate the sensation of texture, friction or directional cues.

[0158] Figure 5 shows a camera image of a user wearing the device (100) for providing haptic stimuli to a body part (200) of a user, in accordance with an embodiment of the invention.

[0159] Referring to figure 5, it shows the device (100) for providing haptic stimuli to a body part (200) of a user. The device (100) may comprise the actuating element (110), the open ring component (120), the electrically conducting areal coupling (130) and the electrothermal activator (140).

[0160] The actuating element (110) may extend in a circumferential direction across the circumferential opening (123) of the open ring component (120). In the particular embodiment of figure 5, the open ring component (120) may further comprise an outer layer. The actuating element (110) may be connected to the open ring component (120) as described with reference to figure 4, in addition to being covered by the outer layer. The outer layer may prevent direct exposure of the actuating element (110) to its surroundings and may thus provide additional protection.

[0161] The electrically conducting areal couplings (130) may be provided on the conductive layer (113) of the actuating element (110), at the portion of the actuating element (110) that is covered by the outer layer. The first electrically conducting areal coupling (130) may be seen through the outer layer. The second electrically conducting areal coupling (130) may not be observable in figure 5.

[0162] The electrothermal activator (140) may be electrically coupled to the conductive layer (113) of the actuating element (110) by the electrically conducting areal couplings (130). The electrothermal activator (140) was added schematically to the camera image of figure 5.

[0163] The open ring component (120) of the device (100) may be configured to abut against the body part (200) of the user. In a preferred embodiment, the body part (200) of the user may be a circumferential portion of a digit of a user, preferably a circumferential portion of a digit of a hand of a user. When wearing the device (100), the inside facing circumferentially disposed surface of the open ring component (120) may be a circumferentially disposed surface of the open ring component (120) that faces the body part (200) of the user.

[0164] In case the mesogen alignment direction of the LCE extends parallel to the circumferential direction of the open ring component (120), actuation of the actuating element (110) may cause a reduction of the width of the circumferential opening (123) such that the open ring component (120) may exert a compressive force onto the body part (200) of the user.

[0165] In case the mesogen alignment direction of the LCE extends under a non-zero angle with the circumferential direction of the open ring component (120), actuation of the actuating element (110) may cause a shearing movement of the first (121) and second end (122) relative to each other, such that the open ring component (120) may exert a shearing force onto the body part (200) of the user. A shearing movement may be induced throughout the open ring component (120), though may be maximal at the first (121) and second end (122), where in a preferred embodiment the corrugated surface (124) may be located.

[0166] Figure 6 shows a flowchart of a method (300) for manufacturing the device (100) for providing haptic stimuli to a body part (200) of a user, in accordance with an embodiment of the invention.

[0167] Referring to figure 6, the method (300) comprises providing (310) the flexible layer (111), providing (320) the priming layer (112) on top of the flexible layer (111), providing (330) the conductive layer (113) on top of the priming layer (112), and consolidating (340) the layers to obtain the actuating element (110).

[0168] Figure 7 shows a flowchart of the method (300) for manufacturing the device (100) for providing haptic stimuli to a body part (200) of a user, in accordance with an embodiment of the invention.

[0169] Referring to figure 7, providing (310) the flexible layer (111) may comprise determining (311) whether the area of the flexible layer (111) is adjacent to one of the electrically conducting areal couplings (130), and when this is not the case, stretching (312) the flexible layer (111), and then, in either case, cross-linking (313) the LCE. Furthermore, providing (330) the conductive layer (113) on top of the priming layer (112) may comprise slot-die coating (331) the conductive layer (113) on top of the priming layer (112).

Claims

CLAIMS1. A device (100) for providing haptic stimuli to a body part (200) of a user, the device (100) comprising an actuating element (110) configured to deform between a non-actuated state and an actuated state upon activation, comprising at least one of electric, thermal and photonic activation, wherein the actuating element (110) comprises a laminated structure including a flexible layer (111) comprising liquid crystal elastomer (LCE); a conductive layer (113), comprising an electrically conductive polymer and electrically couplable to an activator comprising at least one of an electric, thermal and photonic activator (140); and a priming layer (112) provided in between the flexible layer (111) and the conductive layer (113) and comprising a priming polymer, wherein, optionally, the device further comprises a load-bearing soft structural component, associated with the actuating element (110), and configured to deform upon activation of the actuating element (HO).

2. A device as claimed in claim 1 , wherein the priming polymer comprises moieties capable of hydrogen bonding.

3. A device (100) as claimed in claim 1 or 2, wherein the priming polymer is water-soluble and selected from the group of acrylic polymers, such as poly aery lie acid, and vinyl ester polymers and its derivatives, such as polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) and mixtures thereof, preferably polyvinyl alcohol (PVA).

4. Device as claimed in any one of the preceding claims, wherein the electrically conductive polymer comprises a poly(3,4-ethylenedioxythiophene) (PEDOT).

5. A device (100) as claimed in claim 4, wherein the electrically conductive polymer is selected from the group of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and poly(3,4-ethylenedioxythiophene)-tetramethacrylate (PEDOT-TMA), preferably is poly(3,4- ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS).

6. A device as claimed in claim 5, wherein the poly(3,4-ethylenedioxythiophene) comprises a mixture of PEDOT:PSS with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and sorbitol, wherein the ratio of PEDOT:PSS to LiTFSI is from 0.1 to 10 parts by dry weight, more preferably from 0.5 to 5 parts by dry weight, such as 1 to 4 parts by dry weight, and 1-5 wt.% sorbitol based on the total weight of a solution of PEDOT:PSS and LiTFSI, preferably 1.5 to 3 wt.%, such as 2 wt.%.

7. A device as claimed in any one of the preceding claims, wherein the conductive layer is applied by slot-die coating of the conductive polymer on the flexible layer (111) comprising the liquid crystal elastomer (LCE).

8. A device as claimed in any one of the preceding claims, wherein the priming layer is applied by spin coating the priming polymer on the flexible layer (111) and / or the conductive layer.

9. A device (100) as claimed in any one of the preceding claims, wherein the liquid crystal elastomer comprises a mesogenic core, comprising 4-(6-(acryloyloxy) n-oxy)phenyl-4-(6- (acryloyloxy)m-oxy)benzoate, with n being any one of pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and m being any one of pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, preferably wherein n and m are hexyl.

10. A device as claimed in any one of the preceding claims, wherein the liquid crystal elastomer further comprises a polymethylhydrosiloxane (PMHS) backbone, and a HIM crosslinker given by the following formula:wherein x= 2-10 and y = 2-20.

11. A device (100) as claimed in any one of the preceding claims, wherein the liquid crystal elastomer comprises a vinyl inclusion.

12. A device (100) as claimed in any one of the preceding claims, wherein an average thickness of the priming layer (112) is from 1-50 nm, more preferably from 5-40 nm, more preferably from 10-30 nm, and most preferably from 15-25 nm.

13. A device (100) as claimed in any one of the preceding claims, wherein an average thickness of the conductive layer (113) is from 1-50 pm, more preferably from 2-40 pm, more preferably from 3-30 pm, and most preferably from 5-25 pm.

14. A device (100) as claimed in any one of the preceding claims, wherein the conductive layer (113) is electrically couplable to the activator (140) by electrically conducting areal couplings(130), preferably solid areal couplings, and an area of the flexible layer (111) adjacent to said electrically conducting areal couplings (130) comprises non-aligned liquid crystal elastomer.

15. A device (100) as claimed in any one of the preceding claims, further comprising the activator (140), wherein the conductive layer (113) is electrically coupled to the activator (140).

16. A device (100) as claimed in any one of the preceding claims, wherein the load-bearing soft structural component comprises a toroidal component configured to abut against a body part (200) of a user.

17. A device as claimed in any one of the preceding claims, wherein the load-bearing soft structural component comprises an open ring component (120) configured to abut against a body part (200) of a user, the open ring component (120) having a first end (121), a second end (122) that is spaced apart from and opposed to the first end (121), and a circumferential opening (123) defined between the first end (121) and the second end (122), wherein the device (100) comprises the actuating element (110) such that upon activation thereof, the open ring component (120) is deformed between the non-actuated state and the actuated state of the actuating element, and preferably, wherein the actuating element (110) extends in a circumferential direction across the circumferential opening (123).

18. A device (100) as claimed in any one of the preceding claims, wherein the load-bearing soft structural component (120) is made of an elastomer other than the liquid crystal elastomer.

19. A device (100) as claimed in claim 18, wherein the elastomer other than the liquid crystal elastomer comprises a photocurable polymer resin, such a 50A resin.

20. A device (100) as claimed in claim 17, wherein a mesogen alignment direction of the liquid crystal elastomer extends parallel to a circumferential direction of the open ring component (120), causing a reduction of the width of the circumferential opening (123) in the actuated state relative to the non-actuated state, and a compressive force of the open ring component (120) onto the body part (200).

21. A device (100) as claimed in claim 17, wherein a mesogen alignment direction of the liquid crystal elastomer extends under a non-zero angle with a circumferential direction of the open ring component (120), causing a shearing movement of the first (121) and second ends (122) relative to each other in the actuated state relative to the non-actuated state, and a shearing force of the open ring component (120) onto the body part (200).

22. A device (100) as claimed in any one of the preceding claims, wherein the body part (200) is a circumferential portion of a digit, a limb or other extremity of the user.

23. A device (100) as claimed in any one of the preceding claims, wherein a surface of the load-bearing soft structural component (120) faces the body part (200) and comprises a corrugated surface (124) over at least a portion of the surface.

24. A method (300) of manufacturing the actuating element (110) of a device (100) as claimed in any one of the preceding claims, the method (300) comprising: providing (310) the flexible layer (111), providing (320) the priming layer (112) on top of the flexible layer (111), providing (330) the conductive layer (113) on top of the priming layer (112), and consolidating (340) the layers to obtain the actuating element (110).

25. A method (300) as claimed in claim 24, wherein providing (310) the flexible layer (111) comprises stretching (312) the flexible layer (111) before cross-linking (313) the liquid crystal elastomer and thereafter cross-linking (313) the liquid crystal elastomer to obtain aligned liquid crystal elastomer.

26. A method as claimed in claim 25, wherein cross-linking the liquid crystal elastomer is carried out by photocuring with UV-light.

27. A method (300) as claimed in any one of claims 24-26, wherein providing (330) the priming layer on top of the flexible layer is carried out by spin coating of the priming polymer or a solution thereof.

28. A method (300) as claimed in any one of claims 24-27, wherein providing (330) the conductive layer (113) on top of the priming layer (112) is carried out by slot-die coating (331) of the conductive polymer or a solution thereof.

29. A method (300) as claimed in any one of claims 24-28, wherein the conductive layer (113) is electrically couplable to the activator (140) by electrically conducting areal couplings (130), preferably solid areal couplings, and wherein an area of the flexible layer (111) adjacent to said electrically conducting areal couplings (130) is not stretched before cross-linking (313) the liquid crystal elastomer to obtain non-aligned liquid crystal elastomer in said area.

30. A method of manufacturing a device (100) as claimed in any one of claims 1-23, comprising: providing a non-active, internally ribbed and / or smooth, load-bearing soft structural component; providing the actuating element with electrically conducting areal couplings; associating the actuating element and the load-bearing soft component by providing a photo-curable soft polymer material onto surface areas of the actuating element and the load-bearing soft component and contacting said surface areas; and photo-polymerizing the photo-curable soft polymer material to integrate the actuating element and the load-bearing soft component in a form suitable for providing haptic stimuli to a body part (200) of a user.

31. An electronic apparatus comprising a user input device, and a device (100) as claimed in any one of claims 1-23, wherein the user input device is configured to activate the device for providing haptic stimuli to a body part (200) of a user.

32. An electronic apparatus as claimed in claim 31, chosen from the group of smartphones, smart watches, and virtual reality (VR) systems.

33. A vehicle comprising at least one sensor, and a device (100) as claimed in any one of claims 1-23, wherein the at least one sensor is configured to activate the device for providing haptic stimuli to a body part (200) of a user.

34. A surgical robot comprising a device (110) as claimed in any one of claims 1-23 for remotely controlling relaying information on pressure.

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