Device and method for medium delivery

Abstract

A device for medium delivery to the skin of a user is presented. The device comprises an ultrasound transducer arranged to generate a sound field to act on the skin and a coupling element. The coupling element is arranged for contacting skin of a user of the device and the coupling element is arranged to position the ultrasound transducer at a defined distance N ≥≈ N0 from the skin, wherein N0 is the boundary distance between a near field and a far field of the sound field generated by the ultrasound transducer. A further device for medium delivery and a method for medium delivery are also described.

Description

[0001] Device and method for medium delivery

[0002] BACKGROUND

[0003] Ultrasound can be used to enhance the application of a medium, like creams or gels, to the skin of a user or recipient in a medical or aesthetic context. This process is often referred to as "sonophoresis" or "ultrasound-assisted drug delivery." Using ultrasound to non-invasively enhance the application of a medium may provide various advantages like improved absorption, targeted delivery, increased efficacy, a reduction in the amount of product used, and faster results. To improve absorption, ultrasound waves create micro-vibrations in the skin that may help open up the skin's pores and create temporary pathways, making it easier for the medium to penetrate the skin. This enhances the absorption of active ingredients in the product, leading to better therapeutic or cosmetic results. Furthermore, ultrasound may result in the application of the medium precisely to the desired area, allowing for more targeted delivery of the medium. This is particularly useful in medical applications where specific skin conditions or injuries need to be treated without affecting surrounding tissue. Ultrasound-assisted application may further enhance the efficacy of certain topical medications or cosmetic products by ensuring that a larger portion of the product reaches the intended skin layers or tissues. On the same token, with enhanced absorption, less medium may be required to achieve the desired effect, potentially reducing product waste and cost. Ultrasound usage may increase the penetration of the medium into the skin, potentially leading to faster and more noticeable results, which is desirable in both medical and cosmetic contexts. Finally, ultrasound-assisted substance delivery is a non-invasive technique, which means it doesn't require needles or surgery. This may make it more comfortable for patients and users.

[0004] Conventional solutions on the market do not consider the near field and the far field properties in terms of ultrasound delivery. Rather, known devices regularly provide the transducer in direct contact with the skin, while a gel / cream is applied prior to ultrasound application, which may lead to uneven or non-repeatable results when applying ultrasound. Prior manual application of the ultrasound conducting medium between the transducer and the skin relies on the consumer and thus may vary. Providing near field ultrasound waves to the skin may also limit the intensity from the transducer in order not to cause any damage to the skin.

[0005] Accordingly, there may be a need to improve the application of ultrasound waves to the skin. SUMMARY

[0006] Aspects of the present disclosure provide a device and a method for medium delivery to the skin of a user according to the independent claims.

[0007] According to a first aspect of the present disclosure, there is provided a device for medium delivery to the skin of a user, comprising an ultrasound transducer arranged to generate a sound field to act on the skin, and a coupling element. The coupling element is arranged to position the ultrasound transducer at a defined distance N >~ No from the skin, wherein No is the boundary distance between a near field and a far field of the sound field generated by the ultrasound transducer. Optionally, the coupling element is arranged for contacting skin of a user of the device.

[0008] According to a second aspect of the present disclosure, there is provided a device for medium delivery to the skin of a user, comprising an ultrasound transducer, and a coupling element, wherein the coupling element is arranged to position the ultrasound transducer at a defined distance N >~ No from the skin, wherein the coupling element comprises a reservoir for retaining a coupling medium, and wherein the sound field generated by the ultrasound transducer is transmitted through the coupling medium to the skin. Optionally, the coupling element is arranged for contacting skin of a user of the device.

[0009] According to a third aspect of the present disclosure, there is provided a method for medium delivery to the skin of a user, comprising the steps of arranging the ultrasound transducer at a defined distance N >~ No from skin of a user, and generating, by using an ultrasound transducer, a sound field, to act on the skin, wherein No is the boundary distance between a near field and a far field of the sound field of the ultrasound transducer.

[0010] By “arranged to position the ultrasound transducer at a defined distance N >~ No from the skin”, it is meant that the coupling element is configured (or comprises properties) to cause the sound field generated by the ultrasound transducer to travel through the distance N >~ No before reaching the skin. The coupling element may thus be alternatively referred to as a distancing element. For example, if the coupling element comprises a reservoir for retaining a coupling medium, the dimensions of the reservoir may be configured such that the sound field travels through the coupling medium in the reservoir through the distance N >~ No before reaching the skin. The value of No may be a value in a range dependent on the properties (e.g., viscosity) of the coupling medium.

[0011] In order to improve the application of ultrasound waves on skin, it may be beneficial to arrange the application of ultrasound waves to the skin in a reliable and repeatable manner. For example, it may be beneficial to consistently hold the ultrasound device off the skin at a set distance while allowing passage of ultrasound without or with minor attenuation of the sound waves. The present disclosure provides a technical concept of maintaining a set distance between the ultrasound transducer and the skin through an ultrasound transmissible medium. The ultrasound transmissible medium may be held in place using pressure. This may be understood in a similar manner to a syringe, which has one or more openings or small orifices or in contact with the skin. Surface tension may hold the ultrasound transmissible medium in place. The device may comprise a mechanism, like one or more plunger-type elements, which may be arranged to push the ultrasound transmissible medium out of the one or more openings in a controlled manner. In case the mechanism / plunger is not moving, the ultrasound transmissible medium may remain in place. In case the mechanism / plunger is moving, e.g., slowly, the ultrasound transmissible medium may be expelled onto the skin.

[0012] The device may follow along the same principles as a syringe. The device may have an internal volume containing the ultrasound transmissible medium, and an opening, e.g., a small orifice, where the device is in contact with the skin to be treated. Through the opening, the skin is in contact with the ultrasound transmissible medium. The opening may be directly below the transducer, e.g., aligned with the longitudinal axis of the device, for example considering the longitudinal extension of device, at a set distance.

[0013] The ultrasound transmissible medium may be held in the internal volume of the device by surface tension along the opening. At the same time, the device is arranged to that the distance between the ultrasound transducer and the skin is such that the ultrasound energy acting on the skin is in the far field of the ultrasound transducer.

[0014] Ultrasound generated by a transducer can be logically divided into two zones with distinct physical properties, the near field and the far field. The near field has a more varied sound field with variations in the pressure levels generated, whereas the far field has a more uniform pressure level throughout and is more predictable. Having the far field in contact with the skin helps to generate consistent results, whereas having the near field in contact with the skin may lead to varying, inconsistent and / or unpredictable ultrasound conditions during ultrasound application.

[0015] This ultrasound transmissible medium may not be limited to liquids, it may equally consist of or contain a gel and / or material for cosmetic skin applications itself. The ultrasound transmissible medium may thus not only be provided for transmitting the ultrasound waves but also consist of or contain material that is intended for application to the skin. The ultrasound waves may thus facilitate reception of the material contained in the internal volume by the skin.

[0016] One further embodiment may be a device that operates in a similar manner to a syringe. Like a plunger moving in a barrel of a syringe for expulsion of a substance maintained in the internal volume of the syringe / the barrel through an opening at the opposite end of the plunger end arranged outside of the barrel, the device may have one or more plungerlike elements movable to adjust, in particular to reduce, the internal volume of the device holding the ultrasound transmissible medium. Thereby, the internal volume may be reduced so that ultrasound transmissible medium contained in the internal volume is expunged through the opening towards the skin. In an example, the opening may be arranged at a set distance directly below the transducer, seen in the longitudinal extension of the device, in order to maintain an ultrasound transmissible medium between the transducer and the skin. The distance of the opening to the transducer, the size of the opening or orifice and the back pressure to keep a constant flow of liquid / gel out of the hole onto the skin when the device is activated may be variable parameters, depending on the specific application, the type of the ultrasound transmissible medium and the physical parameters of the ultrasound waves.

[0017] The coupling element configured to ensure that only the far field of the ultrasound waves generated by the ultrasound transducer interacts with the skin for enhancing skin permeability may also be referred to or be embodied as an attachment. The attachment or the coupling element may be removable and in particular interchangeable, so that a particular attachment / coupling element may be chosen from a plurality of different attachments / coupling elements having different sets of physical properties. Thereby, a particular attachment / coupling element may be chosen so that its set of physical properties is adapted to or is matching with a particular application requirement. E.g., changing the frequency of generated ultrasound waves and / or a change of the coupling medium to a coupling medium having different physical properties may result in a change of No for that particular application scenario. Therefore, by changing the attachment to provide a different distance N between the ultrasound transducer and the skin surface may be beneficial to adapt the device to the changing parameters.

[0018] This may ensure the same field and in particular the same field parameters are experienced by all parts of the skin to provide more uniform and reproducible results. Providing a defined distance from the transducer through a coupling medium to the skin ensures a reproducible sound field interaction with the skin every time it is used. Potentially, application of ultrasound waves in the far field may allow the use of higher intensities, which would otherwise cause damage if the transducer were in direct skin contact. The present disclosure provides a direct coupling through an ultrasound transmissible medium between the skin and the transducer with minimal attenuation of the acoustic pressure.

[0019] To avoid air bubbles entering the device, or rather the reservoir, during the stage of bringing the device into contact with the skin, an increase in pressure within the reservoir may be provided, e.g. by using plunger type elements, which may also be used to reduce the volume of the reservoir. In other words, in order to prevent air pockets from becoming trapped in the reservoir when bringing the device in contact with the skin, back pressure or a pressure build-up in the device, in particular in the reservoir 14, may be provided, e.g., from a (refillable) reservoir 14, to push ultrasound transmissible medium 15 out of the opening, e.g., at a set flow rate. Such a mechanism of expulsing ultrasound transmissible medium from the device / the opening may further be beneficial in case the ultrasound transmissible medium within the reservoir of device may contain a cosmetically active substance, intended for skin delivery. Thereby, the ultrasound transmissible medium may be applied to the skin surface with a set flow rate while the ultrasound waves interact with the skin to facilitate interaction of the ultrasound transmissible medium with the skin.

[0020] According to an embodiment of the present disclosure, N may be approximately («) No or N may be equal to (=) No. No may be the value where the near field transitions to the far field, and hence, may be defined by the physical properties of the coupling medium and the ultrasound waves.

[0021] According to an embodiment of the present disclosure, the distance No may be calculated by the equation No= — = — ; where No is the boundary distance / transition point between near field and far field; D is the diameter of the ultrasound transducer of a circular transducer; is the wavelength of the ultrasound wave; f is the frequency of the ultrasound wave; v is the velocity of the ultrasound wave in the medium.

[0022] According to an embodiment of the present disclosure, the distance No may be calculated by the equation where No is the boundary distance / transition point between near field and far field; a,b are the side lengths of the ultrasound transducer of a rectangular transducer with a<b; A is the wavelength of the ultrasound wave; f is the frequency of the ultrasound wave; v is the velocity of the ultrasound wave in the medium.

[0023] Since No is the distance where the near field goes over into the far field of the ultrasound transmission, No at the same time is the minimum distance between the ultrasound transducer and the skin surface to effect the application of far field ultrasound waves onto the skin. A distance that is lower than No, in particular significantly lower, can only effect ultrasound waves in the near field. Consequently, No may be employed when determining the dimensions of the device.

[0024] The provided equations for calculating No allow determining the physical properties or dimensions of the device, e.g., the housing, required to assure application of the ultrasound waves in the far field. Further, by specifying the wavelength of the ultrasound wave or the frequency of the ultrasound wave and the velocity of the ultrasound wave in a particular ultrasound transmissible medium, the device may be adapted to a range of media to be used. According to an embodiment of the present disclosure, the coupling element may comprise a reservoir for retaining a coupling medium, and the sound field generated by the ultrasound transducer may be transmitted through the coupling medium to the skin.

[0025] According to an embodiment of the present disclosure, the coupling medium may be a medium to be applied to the skin of the user.

[0026] The reservoir corresponding to the internal volume may thus sit between the ultrasound transducer and the skin. The coupling medium / the ultrasound transmissible medium may be contained within said reservoir, in particular may completely fill the reservoir so that it provides a transmission path from the ultrasound transducer to the surface of the skin essentially completely through the coupling medium. The transmission of the ultrasound waves may thus be directly influenced by the physical properties of the coupling medium. The reservoir may be fillable and / or refillable by the user, thereby assuring that sufficient coupling medium is present within the reservoir to effect the ultrasound transmission. A user refillable reservoir may further allow the user to choose a particular coupling medium for a particular intended application. E.g., in case the coupling medium comprises a substance that is intended to be worked into the skin by using the device, a user may choose a particular coupling medium containing a desired substance, thereby deciding on the product to be applied to the surface of the skin.

[0027] According to an embodiment of the present disclosure, the coupling medium may be a medium out of the group consisting of at least one of an ultrasound transmissible medium, a non-solid medium, a liquid medium, an aqueous medium, a water-based fluid, an oil-based fluid, waterbased liquid medium, an oil-based liquid medium, water-based gel and an oil-based gel.

[0028] According coupling medium may allow a preferred transmission of ultrasound waves. In particular, the wavelength of the ultrasound wave or the frequency and the velocity of the ultrasound wave in the medium may be such that the device may be designed as a rather compact device that can easily be operated by the user. Further, according coupling media may allow for incorporation of substances intended for application to the skin surface into themselves and / or the media themselves may be intended for application to the skin surface.

[0029] According to an embodiment of the present disclosure, the coupling element may comprise a distal end, wherein the distal end may be adapted to be arranged adjacent to the skin of a user of the device, and wherein the distal end may comprise at least one opening arranged to apply the coupling medium retained in the reservoir to the skin.

[0030] Providing an opening where the device is in contact with the skin allows the ultrasound transmissible medium to directly get in contact with the skin. Thereby, the ultrasound energy transmitted within the ultrasound transmissible medium may act on the medium itself to facilitate application of the medium to the skin surface. E.g., an ultrasound wave transmitted through the ultrasound transmissible medium may act so to provide a local force on molecules of the ultrasound transmissible medium. Such may allow that the ultrasound transmissible medium transmits said force of molecules arranged in the vicinity of the skin surface to the skin, thereby effecting the application of the medium to the skin surface.

[0031] According to an embodiment of the present disclosure, the ultrasound transducer may be arranged to generate the sound field in the direction of the at least one opening.

[0032] An according arrangement may allow a simplified construction of the device in that contacting the ultrasound transmissible medium by the ultrasound transducer and the propagation of the ultrasound waves through the ultrasound transmissible medium towards the opening is facilitated. Further, it may allow the selection of a wide variety of ultrasound transducers as such in orientation may allow the use of transmitters exhibiting omnidirectional, hemispherical or a further focused emission pattern, where the focus is in the direction of the opening.

[0033] According to an embodiment of the present disclosure, the at least one opening may be aligned with the ultrasound transducer along a longitudinal axis of the device.

[0034] An according arrangement may provide a preferred transmission of the ultrasound waves from the ultrasound transmissible medium to the skin surface, as the opening may present its maximum diameter to the arriving ultrasound wave front emanating from the ultrasound transducer. In other words, the plane in which the opening is arranged may be essentially parallel to the ultrasound wave front arriving at the opening.

[0035] According to an embodiment of the present disclosure, the at least one opening may be sized so to retain the coupling medium in the reservoir by its surface tension while no sound field is generated by the ultrasound transducer.

[0036] According to an embodiment of the present disclosure, the at least one opening may comprise a mesh element to retain the coupling medium in the reservoir while no sound field is generated by the ultrasound transducer.

[0037] According to an embodiment of the present disclosure, the at least one opening may comprise a medium permeable element to retain the coupling medium in the reservoir while no sound field is generated by the ultrasound transducer.

[0038] Accordingly, it is avoided that the medium is exiting the reservoir while the device is not in operation. In other words, leakage of the medium from the device is avoided. In particular a mesh element or a medium permeable element may allow to increase the effective diameter of the opening while avoiding unintentional leakage of the medium to the exterior. An increase in the effective diameter of the opening in turn allows a more effective transmission of ultrasound waves to the skin surface and / or ultrasound transmissible medium application to the skin surface.

[0039] According to an embodiment of the present disclosure, the device may further comprise a movable element, wherein the movable element may be arranged to controllably reduce the volume of the reservoir, for expulsion of coupling medium from the at least one opening.

[0040] Here, the device may comprise a syringe functionality that may allow the controlled expulsion of coupling medium from the internal volume of the reservoir to the outside of the device through the at least one opening for application of the ultrasound transmissible medium to the skin surface. By controlling the rate of volume reduction, the amount of ultrasound transmissible medium applied to the skin may be adapted to the operation of the device. Further, the amount of ultrasound transmissible medium applied to the skin may be adapted to the medium itself, its physical properties like e.g., viscosity or an amount of effective substance within the ultrasound transmissible medium to be applied to the skin surface. For example, an ultrasound transmissible medium containing 10% of effective substance may require only half the amount applied to the skin surface of an ultrasound transmissible medium containing 5% of effective substance. The device may be arranged to receive an indication about such properties of the ultrasound transmissible medium. Alternatively or additionally, the device may be arranged to receive an indication from the user about a suggested amount of applied medium or volume of applied medium over a defined time period. The amount or volume of applied medium over time may also either depend on the physical properties of the ultrasound wave generated or the generation of the ultrasound wave is adapted thereto in turn.

[0041] According to an embodiment of the present disclosure, the device may be arranged for expulsion of coupling medium from the at least one opening by the generated sound field.

[0042] According to an embodiment of the present disclosure, the ultrasound transducer may be arranged to generate, via the generated sound field, cavitation in the region of the at least one opening.

[0043] The propagation of the ultrasound wave within the ultrasound transmissible medium may result in an expulsion of medium through the at least one opening. For example, the ultrasound wave may excite molecules of the ultrasound transmissible medium, which in turn react by an increase in local movement which may result in an expulsion of the medium from the at least one opening. It is conceivable that such an expulsion may be combined with the expulsion by a controllable reduction of the volume of the reservoir as described previously.

[0044] In particular cavitation occurring in the region of the at least one opening may facilitate expulsion of the medium from the internal volume of the reservoir to the skin of the user, thereby applying the ultrasound transmissible medium to the skin of the user. According to an embodiment of the present disclosure, the coupling element may be arranged to vary the distance N to adapt the distance N to at least one characteristic of the generated sonic / sound field and / or the coupling medium and / or the ultrasound transducer may be arranged to adapt at least one characteristic of the generated sonic / sound field to the coupling medium and / or the distance N, wherein the at least one characteristic may be one characteristic of the wavelength of the ultrasound wave, the frequency of the ultrasound wave and the velocity of the ultrasound wave in the coupling medium.

[0045] E.g. by varying the length of the coupling element, in particular dependent on one or more physical properties of the ultrasound wave and / or the coupling medium, the distance between the ultrasound transducer and the opening may be varied. For example, in case the coupling element is at least two cylindrical or tube-shaped element, where one of the elements is arranged at least partly within the other element, the length may be varied by moving one of the cylindrical or tube-shaped elements relative to the other cylindrical or tube-shaped element. Alternatively or additionally, the position of the ultrasound transducer within the interior volume of the reservoir may be changed. For example, the ultrasound transducer may be moved closer to or further away from the opening, thereby adapting the effective distance between the ultrasound transducer and the opening to the one or more physical properties of the ultrasound wave and / or the coupling medium.

[0046] According to an embodiment of the present disclosure, No may be in the range of 1mm to 100 mm and / or the frequency f may be in the range of 20 kHz to 10 MHz and / or the diameter D may be in the range of 1cm to 10cm and / or the intensity of the sound field may be in the range of 0.01 to 10 W / cm2. In particular, No may be in the range of 10 mm to 90 mm, further in particular, No may be in the range of 20 mm to 80 mm, further in particular, No may be in the range of 30 mm to 75 mm, further in particular, No may be in the range of 40 mm to 70 mm, further in particular, No may be in the range of 50 mm to 65 mm, further in particular, No may be at or in the range of about 60 mm. Further, in particular, the intensity of the sound field may be in the range of 0.01 to 8 W / cm2, further in particular, the intensity of the sound field may be in the range of 0.02 to 5 W / cm2, further in particular, the intensity of the sound field may be in the range of 0.03 to 3 W / cm2, further in particular, the intensity of the sound field may be in the range of 0.04 to 1 W / cm2, further in particular, the intensity of the sound field may be in the range of 0.04 to 0.5 W / cm2, further in particular, the intensity of the sound field may be in the range of 0.045 to 0.01 W / cm2, further in particular, the intensity of the sound field may be in the range of 0.05 to 0.08 W / cm2, further in particular, the intensity of the sound field may be in the range of 0.055 to 0.06 W / cm2, further in particular, the intensity of the sound field may at or about 0,058 W / cm2. According to an embodiment of the present disclosure, the generated sound field may generate cavitation in the region of the skin.

[0047] Inducing cavitation in the region of the skin or skin surface may allow a preferred interaction with the skin or in other words between the skin, the transmitted ultrasound energy and / or the coupling medium / ultrasound transmissible medium. In particular in case where the ultrasound transmissible medium comprises further substances intended for interaction with or application to the skin / skin surface, cavitation may allow the local introduction or provision of an increased level of energy. Inducing cavitation while at the same time assuring that the ultrasound transducer is sufficiently far away from the skin allows generation or use of an increased level of ultrasound energy while assuring that the skin surface is not damaged, irritated or otherwise negatively impacted.

[0048] BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 shows an exemplary embodiment of a device for medium delivery according to the present disclosure.

[0050] Figure 2 shows a further exemplary embodiment of a device for medium delivery according to the present disclosure.

[0051] Figure 3 shows an exemplary application scenario of a device for medium delivery according to the present disclosure.

[0052] Figure 4 shows a further exemplary application scenario of a device for medium delivery according to the present disclosure.

[0053] DETAILED DESCRIPTION

[0054] Now referring to Figure 1, which shows an exemplary embodiment of a device for medium delivery according to the present disclosure.

[0055] The device for medium delivery 10 in figure 1 is depicted only schematically. The device 10 comprises an electromechanics section 11, housing electrical, electronical and / or mechanical components of the device 10, which however is not depicted in further detail in figure 1. Device 10 comprises ultrasound transducer 12, which in this embodiment is arranged partly within a reservoir or internal volume 14. It is equally conceivable that ultrasound transducer 12 only borders a boundary or wall of the reservoir 14. The reservoir 14 comprises a coupling medium in the form of an ultrasound transmissible medium 15. In the embodiment depicted in figure 1, the ultrasound transmissible medium 15 substantially completely fills the reservoir 14. The ultrasound transducer 12 is fixed in position to the housing of the device (e.g., the electromechanics section 11) by a retaining structure (comprising for example, mechanical catches).

[0056] The reservoir 14 comprises an opening or orifice 16 where the reservoir 14 opens to the outside of the device 10. The opening 16 is a way for the ultrasound transmissible medium 15 to exit the reservoir 14 and thus the device 10. The ultrasound transducer 12 is arranged to emanate ultrasound waves from its lower side 12a, which waves are not depicted in figure 1. A distance N - 18 between the lower side 12a, where an ultrasound wave would emanate from, to the opening 16 is depicted as a black arrow. As can be seen in figure 1, the area where the ultrasound transducer 12 is arranged to emanate the ultrasound wave from, i.e., its lower side 12a, is opposite to the opening 16. In other words, ultrasound transducer 12 is adapted to emanate ultrasound waves in the direction of the opening 16.

[0057] The ultrasound transducer 12 may have a frequency within the range from 20 kHz to 10 MHz and may be embedded within the device 10. The reservoir 14 may be considered a coupling element providing an offset between the ultrasound transducer 12 / its lower side 12a and the opening 16. The offset can be seen to correspond to the distance N 18.

[0058] As mentioned, the reservoir 14 may be filled with an ultrasound transmissible medium 15, which may be a fluid, such as water or other desirable or suitable liquid or fluid. Alternatively or additionally, the reservoir 14 may also be filled with a gel or cream or other medium able to transmit ultrasound energy or waves.

[0059] Not depicted in figure 1, the device 10 is intended to have contact with the skin in the region of the opening 16, which may be a circular hole, a mesh or any other suitable element that allows transmission or propagation of an ultrasound wave and / or ultrasound transmissible medium 15. The size of the opening 16 may be chosen to be large enough to cover a sufficiently large skin area sufficient to deliver ultrasound energy and / or ultrasound transmissible medium 15, but at the same time small enough to ensure the effect of surface tension with the ultrasound transmissible medium 15 and / or to ensure that the ultrasound transmissible medium does not leak. The size of the opening 16 may vary according to the ultrasound transmissible medium 15 used in device 10. The effective opening 16 may be made larger via use of an element like a mesh comprising a plurality of holes, thereby being able to cover a larger surface area of skin while still preventing leakage.

[0060] Exemplarily, the shape of the reservoir 14in figure 1 is cylindrical, but may have any suitable or feasible shape or cross section, such as a cone, a rectangle or the like. The reservoir 14 / coupling element ensures that the ultrasound transducer 12 is placed at a defined distance N >= No from the opening 16, to ensure that a skin area arranged adjacent to the opening 16 is in the or at the border of the far field of the ultrasound waves generated by the ultrasound transducer 12. Being in the far field provides waves which are much more predictable in terms of the generated pressure. It may also ensure that the ultrasound transducer 12 is reliably coupled to the skin, as ultrasound waves in the near field may not reliably transmit their energy, or at least a significant part thereof, to the skin. The transducer 12 may be unfocused or focused above the hole or mesh. An unfocused transducer may be a transducer having an ultrasound generating element shaped as a plane or flat ceramic. A focused transducer may have a set radius of curvature to focus the sounds field at a point at a defined distance away, e.g., 50 mm in front of the transducer face. Alternatively, a focused transducer may also be an unfocused transducer further comprising an acoustic lens in front of the transducer to focus the sound field at a defined distance in front of the transducer.

[0061] Now referring to Figure 2, which shows a further exemplary embodiment of a device for medium delivery according to the present disclosure.

[0062] The embodiment of figure 2 generally corresponds to the embodiment of figure 1. Additionally to figure 1, the embodiment of figure 2 exemplarily comprises plunger type elements 20, in figure 2 exemplarily arranged at opposite sides of the ultrasound transducer 12. The plunger type elements 20 depicted in figure 2 may be independent elements, or may indeed be a single element working uniformly on the sides of ultrasound transducer 12 or at least partly surrounding ultrasound transducer 12. Generally, a device 10 according to the present disclosure for medium delivery 10 may comprise any suitable arrangement of one or more plunger type elements 20 adapted to controllably reduce the internal volume of the reservoir 14.

[0063] The plunger type elements 20 in figure 2 exemplarily move downwards towards the end or side of the device 10 where the opening 16 is arranged at. Thereby, the internal volume of the reservoir 14 is reduced so that ultrasound transmissible medium 15 is expulsed from opening 16 as depicted by arrow 24. In other words, the device 10 is arranged to expulse 24 ultrasound transmissible medium 15 from the opening 16 while the ultrasound transducer 12 may generate ultrasound waves. The expulsed 24 ultrasound transmissible medium 15 may thus be applied to or act on skin surface of a user of the device 10 as is depicted in the following figures.

[0064] Now referring to Figure 3, which shows an exemplary application scenario of a device for medium delivery according to the present disclosure.

[0065] Figure 3 again relates to the embodiments depicted in figure 1. However, the embodiments of exemplary application scenarios of figures 3 and 4 may also be implemented using the device 10 of figure 2.

[0066] In figure 3, the lower end of device 10 is arranged in contact with skin 32 of a user. In other words, the opening 16 of device 10 is arranged adjacent to the skin surface of skin 32, so that ultrasound waves 30 emanating from the ultrasound transducer 12, in particular from its lower end 12a, are transmitted to the skin surface through the ultrasound transmissible medium 15, while passing through the opening 16. The ultrasound transmissible medium 15 is also in surface contact with the skin 32 of the user via opening 16 so that the ultrasound waves 30 are able to propagate directly through the ultrasound transmissible medium 15 from the ultrasound transducer 12 to the skin 32. The ultrasound waves 30 arriving at the skin 32 may provide a desired effect to the skin 32, in particular to the surface of the skin 32 and / or may facilitate applying ultrasound transmissible medium 15 to the surface of the skin 32.

[0067] The distance between the ultrasound transducer 12 and the opening 16 and thus also the skin surface of skin 32 again is distance N - 18, as depicted by the black arrow. Consequently, the ultrasound waves 30 thus operate in the far field or at the border between the near field and the far field of the ultrasound waves emitted by ultrasound transducer 12.

[0068] Now referring to Figure 4, which shows a further exemplary application scenario of a device for medium delivery according to the present disclosure.

[0069] Generally, the application scenario of figure 4 corresponds to the application scenario of figure 3 with the difference that the device 10 is arranged and operating to cause cavitation 40 within the ultrasound transmissible medium 15 in the region of the opening 16. Cavitation 40 may only occur at the point where the ultrasound transmissible medium 15 is directly in contact with the skin of the user, the ultrasound waves 30 may be focused directly to this point / the opening 16 / the skin 32 in the region of the opening 16.

[0070] Setting the distance of the ultrasound transducer 12 to the skin 32 to the far field or the boundary distance between the near field and the far field may allow the transducer to function at higher amplitudes and intensities than transducers in direct skin contact. In direct contact scenarios, generating cavitation may not even be realizable, as otherwise the ultrasound transducer touching the skin may lead to damage, irritation or otherwise undesired effects at the skin.

Claims

CLAIMS1. Device for medium delivery to the skin of a user, comprising an ultrasound transducer arranged to generate a sound field to act on the skin, and a coupling element, wherein the coupling element is arranged to position the ultrasound transducer at a defined distance N >« No from the skin, and wherein No is the boundary distance between a near field and a far field of the sound field generated by the ultrasound transducer.

2. Device according to claim 1, wherein N ~ No or N = No.

3. Device according to any one of the preceding claims, wherein the distance Nois calculated by the equation_ D2_ D2fN° ~ 41 “ ~4 v whereNo is the boundary distance / transition point between near field and far field;D is the diameter of the ultrasound transducer of a circular transducer;X is the wavelength of the ultrasound wave; f is the frequency of the ultrasound wave; v is the velocity of the ultrasound wave in the medium.

4. Device according to any one of the preceding claims, wherein the distance Nois calculated by the equationwhereNo is the boundary distance / transition point between near filed and far field; a,b are the side lengths of the ultrasound transducer of a rectangular transducer with a<b;X is the wavelength of the ultrasound wave; f is the frequency of the ultrasound wave; v is the velocity of the ultrasound wave in the medium.

5. Device according to any one of the preceding claims, wherein the coupling element comprises a reservoir for retaining a coupling medium, and wherein the sound field generated by the ultrasound transducer is transmitted through the coupling medium to the skin.

6. Device according to claim 5, wherein the coupling medium is the medium to be delivered to the skin of the user.

7. Device according to any one of claims 5 and 6, wherein the coupling medium is a medium out of the group consisting of at least one of an ultrasound transmissible medium, a non-solid medium, a liquid medium, an aqueous medium, a water-based fluid, an oil-based fluid, water-based liquid medium, an oil-based liquid medium, water-based gel and an oil-based gel.

8. Device according to any one of claims 5 to 7, wherein the coupling element comprises a distal end, wherein the distal end is adapted to be arranged adjacent to the skin of a user of the device, and wherein the distal end comprises at least one opening arranged to apply the coupling medium retained in the reservoir to the skin.

9. Device according to claim 8, wherein the ultrasound transducer is arranged to generate the sound field in the direction of the at least one opening, and / or wherein the at least one opening is aligned with the ultrasound transducer along a longitudinal axis of the device.

10. Device according to any one of claims 8 and 9, wherein the at least one opening is sized so to retain the coupling medium in the reservoir by its surface tension while no sound field is generated by the ultrasound transducer, and / orwherein the at least one opening comprises a mesh element to retain the coupling medium in the reservoir while no sound field is generated by the ultrasound transducer, and / or wherein the at least one opening comprises a medium permeable element to retain the coupling medium in the reservoir while no sound field is generated by the ultrasound transducer.

11. Device according to any one of claims 5 to 10, further comprising a movable element, wherein the movable element is arranged to controllably reduce the volume of the reservoir, for expulsion of coupling medium from the at least one opening.

12. Device according to any one of claims 5 to 10, wherein the device is arranged for expulsion of coupling medium from the at least one opening by the generated sound field.

13. Device according to any one of claims 8 to 12, wherein the ultrasound transducer is arranged to generate, via the generated sound field, cavitation in the region of the at least one opening.

14. Device according to any one of the preceding claims, wherein the coupling element is arranged to vary the distance N to adapt the distance N to at least one characteristic of the generated sound field and / or the coupling medium, and / or wherein the ultrasound transducer is arranged to adapt at least one characteristic of the generated sound field to the coupling medium and / or the distance N; wherein the at least one characteristic is one characteristic of the wavelength of the ultrasound wave, the frequency of the ultrasound wave and the velocity of the ultrasound wave in the coupling medium.

15. Device according to any one of the preceding claims, wherein No is in the range of 1 mm to 60 mm; and / or wherein the frequency f is in the range of 20 kHz to 10 MHz; and / or wherein the diameter D is in the range of 1cm to 10cm; and / or wherein the intensity of the sound field is in the range of 0.01 to 10 W / cm2.

16. Device for medium delivery to the skin of a user, comprising an ultrasound transducer, and a coupling element, wherein the coupling element is arranged to position the ultrasound transducer at a defined distance N >« No from the skin, wherein the coupling element comprises a reservoir for retaining a coupling medium, and wherein the sound field generated by the ultrasound transducer is transmitted through the coupling medium to the skin.

17. Method for medium delivery to the skin of a user, comprising the steps of arranging an ultrasound transducer at a defined distance N >« No from skin of a user, and generating, by using the ultrasound transducer, a sound field, to act on the skin, wherein No is the boundary distance between a near field and a far field of the sound field of the ultrasound transducer.

18. Method according to claim 17, transmitting the sound field generated by the ultrasound transducer through a coupling medium to the skin.

19. Method according to claim 17 or 18, wherein the coupling medium is a medium to be applied to the skin of the user out of the group consisting of at least one of an ultrasound transmissible medium, a non-solid medium, a liquid medium, an aqueous medium, a water-based fluid, an oil-based fluid, water-based liquid medium, an oil-based liquid medium, water-based gel and an oil-based gel.

20. Method according to any one of claims 17 to 19, generating, via the generated sound field, cavitation in the region of the skin.

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