DESCRIPTION
TITLE OF INVENTION DEVICE FOR FLUID INJECTION THERAPY
TECHNICAL FIELD
[0001]
The present invention relates to a device for fluid injection therapy such as carboxytherapy.
BACKGROUND ART
[0002]
Dark circles on a skin is a consumer’s big concern and is still an unaddressed issue. Cosmetics are the only at-home solutions but are not completely satisfactory to many. On the other hand, more invasive procedures do exist, but have to be performed in clinics.
[0003]
Carboxytherapy is a medical treatment, widely used with success in different fields of medicine. For example, WO 2014/142970 discloses a carboxytherapy device for injecting CO2 gas into a skin. Carboxytherapy consists in injection of CO2 into dermis and shows very strong performance in facial anti-aging, especially for reduction of dark circles. Indeed, dark circles result from a variety of factors including deep facial anatomy (such as dermal capillary network), contributions from the skin (such as excessive pigmentation), aging degradation of soft tissue (such as thin skin, or shadowing due to skin laxity), etc. The variety of factors make the problem of dark circles very complicated. CO2 injection brings multiple benefits such as oxygenation, improvement of microcirculation, anti-inflammation, and collagen stimulation, which can cater to the above multifactorial problem. The clinically observed cosmetic benefit is an improvement of under-eye circle pigmentation, i.e. brightening around the eyes.
[0004]
In the medical treatment, typical volume per injection is between few microliters to few milliliters. However, the amount of gas comes with some adverse effects such as pain.
DISCLOSURE OF INVENTION
[0005]
An object of the present invention is to provide a device for fluid injection therapy which can reduce an adverse effect such as pain in fluid injection therapy including carboxytherapy.
[0006]
In order to achieve the above-described object, one aspect of the present invention provides a device for fluid injection therapy. The device comprises an injecting unit including a fluid container configured to store a fluid for the fluid injection therapy, one or more hollow needles, each hollow needle having an inner passage configured to deliver the fluid from the fluid container into a skin, and a filter between the fluid container and the one or more hollow needles, the filter being configured to control the flow of the fluid, and a charging unit configured to be removably attached to the injecting unit and supply the fluid to the injecting unit.
[0007]
According to one aspect of the device, the filter may have at least one hole or slit to control the flow rate of the fluid into the inner passage of the one or more hollow needles.
[0008]
According to one aspect of the device, the at least one hole or slit and the inner passage may form a microfluidic channel together.
[0009]
According to one aspect of the device, the fluid container may have an expandable and contractable shell to change the inner volume of the fluid container.
[0010]
According to one aspect of the device, the flow rate of the fluid exiting the one or more hollow needles may be between 0.1 mL/min and 60 mL/min.
[0011]
According to one aspect of the device, the filter may have one or more holes having a diameter between 0.01 pm and 10 pm and/or one or more slits having a width between 0.01 pm and 10 pm.
[0012]
According to one aspect of the device, the one or more hollow needles may have an inner diameter between 10 pm and 150 pm.
[0013]
According to one aspect of the device, the one or more hollow needles may have a length between 20 pm and 1 ,000 pm.
[0014]
According to one aspect of the device, the one or more hollow needles may have a water- soluble or water-dispersible plug at the end thereof.
[0015]
According to one aspect of the device, the charging unit may include a fluid storage configured to store the fluid with pressure higher than an ambient pressure, and a pressure regulator configured to control the pressure of the fluid supplied to the injecting unit from the fluid storage.
[0016]
According to one aspect of the device, the pressure regulator may be configured to reduce the pressure of the fluid from the fluid storage to supply the reduced pressure of the fluid to the injecting unit.
[0017]
According to one aspect of the device, the fluid injection therapy may be carboxytherapy and the fluid may be carbon dioxide.
BRIEF DESCRIPTION OF DRAWINGS
[0018]
Non-limiting and representative embodiments of the present invention will now be explained in detail below referring to the attached drawings so that the present invention can be better understood.
[0019]
FIG. 1 A is a plan view of the device 1 for fluid injection therapy in a non-expanded state according to the first embodiment.
[0020]
FIG. IB is a plan view of the device 1 for fluid injection therapy in an expanded state according to the first embodiment.
[0021]
FIG. 2 is a plan view of the injecting unit 10 according to the first embodiment.
[0022]
FIG. 3 is a front view of the injecting unit 10 according to the first embodiment.
[0023]
FIG. 4 is a cross-sectional view of the injecting unit 10 according to the first embodiment along the line IV-IV in FIG. 3.
[0024]
FIG. 5 is a perspective view of the filter 18 according to the first embodiment.
[0025]
FIG. 6 is a schematic view of how to inject a CO2 gas into the skin S using the injecting unit 10.
[0026]
FIG. 7 is a perspective view of the filter 18 according to the second embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION
[0027]
Hereafter, the embodiments of the present invention will be described in a detailed manner. The XYZ coordinate system is defined as shown in the drawings, but this is not intended to limit the invention.
[0028]
A carboxytherapy device for injecting a CO2 gas into a skin will be described below through an example. However, a fluid to be injected is not limited to CO2, but may be any fluid including a gas such as N2O, NO, O2, or H2, mixture gas, liquid, mixture liquid, medical solution, or other fluid, or a combination thereof.
[First Embodiment]
(Device for Fluid Injection Therapy)
[0029]
A device 1 for fluid injection therapy according to the first embodiment will be described with reference to FIGS. 1 A to 6. FIG. 1 A is a plan view of the device 1 for carboxytherapy in a non-expanded state and FIG. IB is a plan view of the device 1 for carboxytherapy in an expanded state, according to the first embodiment.
[0030]
Referring to FIGS. 1A and IB, the device 1 includes an injecting unit 10 and a charging unit 50. The injecting unit 10 and the charging unit 50 are removably attached to each other. Instead, the injecting unit 10 and the charging unit 50 may be integrally formed. The device 10 is deformed from a non-expanded state in FIG. 1A to an expanded state in FIG. IB by supplying a CO2 gas from the charging unit 50 to the injecting unit 10.
(Injecting unit 10)
[0031]
FIG. 2 is a plan view of the injecting unit 10 in the non-expanded state according to the first embodiment. FIG. 3 is a front view of the injecting unit 10 according to the first embodiment. FIG. 4 is a cross-sectional view of the injecting unit 10 according to the first embodiment along the line IV-IV in FIG. 3.
[0032]
Referring to FIGS. 2 and 4, the injecting unit 10 stores a CO2 gas inside and is applied to a skin S of the user as a patch device to inject the CO2 gas into the skin S. The injecting unit 10 includes a gas container 12 (an example of “fluid container”), a support member 14, hollow needles 16, a filter 18, and a connector 20.
[0033]
The gas container 12 is a main body of the injecting unit 10. The inner space of the gas container 12 serves as a gas chamber for the CO2 gas. The gas container 12 stores the CO2 gas inside, for example in pressure higher than the ambient pressure. The inner pressure is, for example, between 0.1 MPa (1 bar) and 1 MPa (10 bar), preferably between 0.15 MPa (1.5 bar) and 0.4 MPa (4 bar) in particular for CO2 gas, and more preferably between 0.15 MPa (1.5 bar) and 0.3 MPa (3 bar). The charged volume inside the gas container 12 is, for example, between 0.1 mL and 10 mL depending on the status of the skin S.
[0034] In this embodiment, the gas container 12 has an expandable and contractable shell 13 so that the gas container 12 expands as shown in FIG. IB with increasing internal pressure, e.g. in response to the supply of the CO2 gas. Thereby, the expandable/contractable shell 13 can change the inner volume of the gas container 12 and the gas container 12 accommodates different pressures of the CO2 gas. For example, the shell 13 of the gas container 12 is made of a flexible and/or elastic material such as plastic elastomer, silicone, or polymer layer. Additionally or alternatively, the shell 13 may have a bellows structure or any expandable structure. Further alternatively, the gas container 12 may have a hard and non-flexible shell 13.
[0035]
As shown in FIGS. 2 and 4, the gas container 12 in the non-expanded state has a generally oval-sphere shape with a long axis along the Y direction and has a distal end 12a and a proximal end 12b in the X direction. The gas container 12 in the non-expanded state is thin in the X direction so as to be suitable to stay on the face or skin S of the user during the application. As shown in FIGS. 2 to 4, an adhesive layer 13a is provided on the distal end 12a of the gas container 12 to help the injecting unit 10 to stay on the face or skin S of the user.
[0036]
The support member 14 is provided on the distal end 12a of the gas container 12 to support the hollow needles 16 thereon. For example, the support member 14 is attached to the gas container 12 around the filter 18. e.g. with adhesive 24. The adhesive 24 may be a part of the adhesive layer 13 a. Instead, the support member 14 may be formed integrally with the gas container 12 or formed as a part of the gas container 12.
[0037]
The support member 14 has a contact surface 22 to be in contact with the skin S. In this embodiment, the support member 14 is made of a flexible material such as plastic elastomer, silicone, or polymer layer so as to conform to the shape of the skin S of the user during the application.
[0038]
As shown in FIGS. 2 and 4, the hollow needles 16 are provided on the contact surface 22 of the support member 14. In use, the hollow needles 16 penetrate into the skin S and deliver the CO2 gas into the skin S therethrough. Each of the hollow needles 16 has a cylindrical shape, which is preferably at least partially tapered.
[0039]
The outer diameter of the hollow needles 16 can be determined depending on the application. For example, the outer diameter (e.g. the maximum outer diameter) of the hollow needles 16 is between 40 pm and 200 pm. For example, the outer diameter of the hollow needles 16 may be no less than 60 pm, 70 pm, 80 pm, 90 pm, or 100 pm, and no more than 190 pm, 180 pm, 170 pm, 160 pm, or 150 pm. If the outer diameter of the hollow needles 16 is too small, the needles 16 would be easily broken during the insertion into the skin S. On the other hand, if the outer diameter of the hollow needles 16 is too large, it would cause pain. In this embodiment, the hollow needles 16 are hollow microneedles.
[0040]
The injecting unit 10 can have one or more hollow needles 16. For example, 16 hollow needles 16 are shown in FIG. 3. The number of hollow needles 16 may be 1, 2, 3, 4, 6, 8, 9, 12, 16, 25, 36, or any other number. The plurality of hollow needles 16 may be arranged regularly or irregularly (randomly) on the contact surface 22. It should be noted that the injecting unit 10 does not have to have multiple hollow needles 16 since a single hollow needle 16 is enough to provide the sufficient amount of the CO2 gas into the skin S in use because of fast and effective diffusion of the CO2 gas.
[0041]
As shown in FIG. 4, each of the hollow needles 16 has an inner passage 26 and a water- soluble or water-dispersible plug 28 within the inner passage 26.
[0042]
The inner passage 26 penetrates each of the hollow needles 16 in communication with the gas chamber inside the gas container 12 through the holes 30 of the filter 18. The inner passage 26 allows the CO2 gas from the gas container 12 to pass therethrough.
[0043]
The diameter of the inner passage 26, i.e. the inner diameter of the hollow needles 16, can be determined depending on the application. For example, the diameter of the inner passage 26 is between 10 pm and 150 pm. For example, the diameter of the inner passage 26 may be no less than 20 pm, 30 pm, 40 pm, or 50 pm, and no more than 140 pm, 130 pm, 120 pm, 110 pm, or 100 pm. If the diameter of the inner passage 26 is too small, it would take much time to complete the injection of the CO2 gas. On the other hand, if the diameter of the inner passage 26 is too large, the total diameter of the hollow needles 16 would be too large and cause pain. The diameter of the inner passage 26 does not have to be constant, but may vary, e.g. along the longitudinal direction thereof.
[0044]
The length of the hollow needles 16 can be determined depending on the target depth. For example, the hollow needles 16 have a length between 20 pm and 1,000 pm, and for cosmetic application, the hollow needles 16 may have a length between 50 pm and 250 pm to deliver the gas into a shallow layer of the skin S such as stratum comeum SI or epidermis S2 (see FIG. 6). Thereby, the injecting unit 10 with the hollow needles 16 having a length between 50 pm and 250 pm can reduce the user’s pain since the hollow needles 16 are inserted into a shallow layer such as stratum comeum S 1 or epidermis S2, but not into deep layers such as dermis S3. If the length of the hollow needles 16 is too large, it would cause pain. On the other hand, if the length of the hollow needles 16 is too small, it would be difficult to insert the hollow needles 16 into the skin S.
[0045]
The water-soluble or water-dispersible plug 28 blocks the distal end of the inner passage 26 to prevent the CO2 gas in the inner passage 26 from leakage to the outside. The water- soluble or water-dispersible plug 28 is made of water-soluble or water-dispersible material, e.g. water-soluble or water-dispersible polymer. For example, the water-soluble or water- dispersible material is at least one selected from the group consisting in hyaluronic acid, monosaccharides, disaccharides, oligosaccharides, polysaccharides, dextrins, dextrans, polyethylene glycols, polyvinyl alcohols, poly(methylvinylether/maleic anhydride), polyvinylpyrrolidone, poly(methyl/vinyl ether/maleic acid) (PMVE/MA), hydrolized collagen, and esters thereof, and poly(methyl/vinyl ether/maleic anhydride) (PMVE/MAH). Thus, when the hollow needles 16 are inserted into the skin S, the water-soluble or water-dispersible plug 28 is dissolved in water or bodily fluid so that the CO2 gas inside the hollow needles 16 is released into the skin S.
[0046]
The material of the hollow needles 16 except for the water-soluble or water-dispersible plug 28 is, for example, metal such as stainless steel, silicone compound, biodegradable polymer, thermoplastic resin, water-soluble polymer, etc. Biodegradable polymer is, for example, polyglycolic acid (PGA) or polylactic acid (PLA). Thermoplastic resin is, for example, medical silicone, polymer materials, ultraviolet curing resins, polydimethylsiloxane, polycarbonate, or cyclic olefin copolymer. Water-soluble polymer is, for example, carboxymethyl cellulose (CMC), methyl cellulose (MC), hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC), polyvinyl alcohol (PVA), polyacrylic acid-based polymer, polyacrylamide (PAM), polyethylene oxide (PEO), purulan, alginate, pectin, chitosan, chitosan succinamide, or oligochitosan.
[0047]
As shown in FIG. 4, the filter 18 is provided at the distal end 12a of the gas container 12. For example, the distal end 12a of the gas container 12 has an opening for attachment of the filter 18. The filter 18 is a thin member such as a porous membrane, film, or plate and has at least one hole 30 therethrough. The filter 18 can cover the exit of the gas container 12 to the inner passages 26, through which the CO2 gas can pass. The filter 18 can slow down or limit the flow of the CO2 gas from the gas container 12 through the filter 18.
[0048]
FIG. 5 is a perspective view of the filter 18 according to the first embodiment. As shown in FIG. 5, the filter 18 according to the first embodiment has a plurality of holes 30. While the holes 30 allow the CO2 gas to pass therethrough, the filter 18 partially blocks the CO2 gas going from the gas container 12 to the inner passage 26 due to the small cross-sectional areas of the holes 30.
[0049]
The thickness of the filter 18 can be determined depending on the application. For example, the thickness of the filter 18 is between 50 pm to few millimeters, preferably between 50 pm to 500 pm. The number of the filter 18 is not limited to one, but a plurality of filters may be provided to achieve an optimum flow rate of the CO2 gas.
[0050]
The diameter of the holes 30 can be determined depending on the target flow rate. For example, the diameter of the holes 30 is between 0.01 pm and 10 pm. For example, the diameter of the holes 30 is no less than 0.02 pm, 0.05 pm, 0.1 pm, 0.2 pm, 0.5 pm, or 1 pm, and no more than 9 pm, 8 pm, 7 pm, 6 pm, or 5 pm.
[0051]
The material of the filter 18 can be determined appropriately depending on the fluid intended to be injected. For example, the filter 18 may be a woven filter, membrane filter, or porous material filter made of polymer, metal wires, etc. The material of the filter 18 is not particularly limited, but may include paper, polymer, metal, or ceramic. For example, the filter 18 may be made of nylon, PES (polyethersulfone), or PVDF (polyvinylidene fluoride).
[0052]
The holes 30 of the filter 18 and the inner passage 26 of the hollow needles 16 form a fluidic channel 32 together. The CO2 gas in the gas container 12 passes through the holes 30 and is distributed to each of the inner passages 26 to exit the hollow needles 16 to the outside. For the CO2 application, the holes 30 and the inner passages 26 are preferably designed in microscale and thus form a microfluidic channel 32 together. This micro fluidic channel 32 provides a fluidic resistance to control the flow rate of the CO2 gas exiting the hollow needles 16, without additional input.
[0053]
The flow rate of the exiting CO2 gas can be determined by means of the design of the microfluidic channel 32, depending on the application. For example, the flow rate of the CO2 gas exiting the hollow needles 16 is between 0.1 mL/min and 60 mL/min. For example, the flow rate of the CO2 gas is no less than 0.2 mL/min, 0.5 mL/min, 1 mL/min, 2 mL/min, 5 mL/min, or 10 mL/min, and no more than 55 mL/min, 50 mL/min, 45 mL/min, 40 mL/min, 35 mL/min, or 30 mL/min. If the flow rate of the CO2 gas is too small, it would take much time to complete the injection of the CO2 gas. On the other hand, the flow rate of the CO2 gas is too large, the fast injection of the CO2 gas could lead to expansion of the skin, which might lead to further adverse effects.
[0054]
The connector 20 connects the gas container 12 to a one-way valve 66 of the charging unit 50 to allow the charging unit 50 to charge the CO2 gas into the gas container 12. The connector 20 is a rigid cylindrical portion provided on the proximal end 12b of the gas container 12. Any known connecting mechanism is possible for the connector 20.
[0055]
The injecting unit 10 may be entirely a single-use unit and disposable. Alternatively, the support member 14 may be removably attached to the gas container 12 and separated from the gas container 12 to be discarded. In such a case, the support member 14 may be a singleuse part and disposable together with the hollow needles 16. Since the gas container 12 can be used repeatedly by disposing the support member 14 and the hollow needles 16, it is cost- effective. It is also possible to use the support member 14 and the hollow needles 16 multiple times as long as they are subject to effective sterilization.
(Charging Unit 50)
[0056]
Returning back to FIG. 1A, the charging unit 50 stores a CO2 gas inside and charges the CO2 gas into the injecting unit 10. The charging unit 50 includes a gas storage 52 and a pressure regulator 54.
[0057]
The gas storage 52 is a cartridge for storing the CO2 gas in high pressure (e.g. more than several MPa or tens MPa) with variation by the usage of the gas. Conventional and exchangeable gas cylinder can be used as the gas storage 52.
[0058]
The gas storage 52 is removably connected to the pressure regulator 54. The pressure regulator 54 delivers the CO2 gas from the gas storage 52 to the gas container 12 and regulates the pressure of the delivered CO2 gas. The pressure regulator 54 controls the pressure of the CO2 gas, which is to be delivered to the gas container 12, to be constant and reduces the pressure of the CO2 gas from the gas storage 52 down to a supply pressure for the gas container 12. The supply pressure can be determined depending on the application. For example, the supply pressure is between 0.15 MPa (1.5 bar) and 0.4 MPa (4 bar). Thereby, the pressure regulator 54 can maintain the pressure of the CO2 gas consistently and steadily supply the moderate pressure of the CO2 gas to the gas container 12.
[0059]
As shown in FIG. 1A, the pressure regulator 54 includes a pressure indicator 60, an operating unit 62, an injection switch 64, a one-way valve 66, and a gas storage connector 68.
[0060]
The pressure indicator 60 visually indicates the pressure of the CO2 gas to be supplied to the gas container 12. The user can control the supply pressure by checking the pressure indication of the pressure indicator 60.
[0061]
The operating unit 62 is a unit for the user to adjust the supply pressure. For example, the operating unit 62 may be embodied as a manual dial member as shown in FIG. 1 A.
[0062]
The injection switch 64 is a unit for the user to start/stop the injection of the CO2 gas into the gas container 12. For example, the injection switch 64 may be embodied as a manual button as shown in FIG. 1A. For example, the injection switch 64 can be configured as a button to start the injection of the CO2 gas into the gas container 12 when the user presses the injection switch 64 and to stop the injection when the user releases the injection switch 64.
[0063]
The one-way valve 66 allows the CO2 gas to pass therethrough only in one direction, i.e. the +X direction in FIG. 1A. Specifically, the one-way valve 66 allows the CO2 gas from the gas storage 52 to pass therethrough (the +X direction), but prevents the CO2 gas from the gas container 12 from passing therethrough (the -X direction). Thereby, the one-way valve 66 can prevent counter flow of the CO2 gas in the -X direction.
[0064]
The gas storage connector 68 connects the gas storage 52 to the pressure regulator 54. Any known connecting mechanism is possible for the gas storage connector 68.
(Method of Using the Device for Fluid Injection Therapy)
[0065]
A method of using the device 1 according to the present embodiment will be discussed below.
[0066]
The user first attaches the connector 20 of the injecting unit 10 to the one-way valve 66 of the pressure regulator 54 to assemble the device 1 as shown in FIG. 1A. The user also attaches the gas storage 52 to the gas storage connector 68. Then, the user adjusts the supply pressure of the CO2 gas by means of the operating unit 62 and the injection switch 64, and injects the CO2 gas into the gas container 12 by operating the injection switch 64. After the completion of the filling the gas container 12 with necessary amount of the CO2 gas (e.g. 0.1 mL to 10 mL), the user stops the gas injection into the gas container 12 by operating the injection switch 64. FIG. IB shows the injecting unit 10 in the expanded state after the injection of the CO2 gas into the gas container 12. Then, the user detaches the injecting unit 10 from the charging unit 50 for a portable application.
[0067]
FIG. 6 is a schematic view of how to inject a CO2 gas into the skin S using the injecting unit 10. As shown in FIG. 6, the user positions the contact surface 22 of the injecting unit 10 adjacent to a target skin S. The support member 14 and/or the gas container 12 conforms to the shape of the skin S. Before the application of the injecting unit 10, the water-soluble or water-dispersible plug 28 blocks the inner passage 26 to prevent the CO2 gas inside the gas container 12 from leakage. Then, the user presses the contact surface 22 and the hollow needles 16 against the skin S. Thereby, the hollow needles 16 penetrate stratum comeum SI of the skin S, and the water-soluble or water-dispersible plug 28 is dissolved in water or bodily liquid.
[0068]
After the water-soluble or water-dispersible plug 28 is dissolved, the CO2 gas is released slowly through the inner passage 26 of the hollow needles 16. The pressure of the CO2 gas in the injecting unit 10 needs to be higher than the atmosphere pressure. The CO2 gas in the substratum comeum layer diffuses into the deeper layer of the skin S as shown in FIG. 6.
[0069]
As described above, the micro fluidic channel 32 inside the injecting unit 10 can control the flow rate of the CO2 gas into epidermis S2, e.g. to be between 0.1 mL/min and 60 mL/min. This is relatively slow release compared with conventional technology and thus results in less or no pain or discomfort. Moreover, in a case where the length of the hollow needles 16 is relatively small compared with conventional technology, the hollow needles 16 may be inserted up to shallow depth of the skin S, e.g. to stratum comeum SI or an upper part of epidermis S2, but not to dermis S3. Therefore, it results in less or no pain or discomfort. It should be noted that since the insertion depth of the hollow needles 16 depends on the needle length, the hollow needles 16 with a sufficient length may be inserted up to dermis S3.
[0070]
Total treatment time will be, for example, between few minutes and few hours, depending on the purpose or the area of the treatment. During the treatment, the injecting unit 10 can stay on the skin S due to the adhesive layer 13a adhering to the skin S. After the completion of the injection of the CO2 gas into the skin S, the user gets the injecting unit 10 off and separates the support member 14 with the hollow needles 16 from the gas container 12 to discard the support member 14 for hygiene. It should be noted that the user may change the application position of the injecting unit 10 on the skin S as necessary during the treatment.
(Effect)
[0071]
According to the device 1, the filter 18 between the gas container 12 and the hollow needles 16 can control the flow rate of the gas so as to achieve slow injection to shallow depth of the skin S and slow release of the gas. Thereby, the device 1 can reduce adverse effect, e.g. pain or discomfort, of fluid injection therapy such as carboxytherapy. In this way, fluid injection therapy using the device 1 can have significantly better performance than topical application and long lastingness while being less invasive than existing procedures.
[0072]
Moreover, since the injecting unit 10 is removable from the charging unit 50, the injecting unit 10 has good portability and is easy to handle and hold by hand.
[Second Embodiment]
[0073]
The second embodiment will be described below. The second embodiment is different from the first embodiment in that the filter 18 has one or more slits 130 instead of holes 30. The description of the same constitution as the first embodiment will not be repeated below.
[0074]
FIG. 7 is a perspective view of the filter 18 according to the second embodiment. As shown in FIG. 7, the filter 18 according to the second embodiment has one or more slits 130. While the slits 130 allow the CO2 gas to pass therethrough, the filter 18 partially blocks the CO2 gas going from the gas container 12 to the inner passage 26 due to the restriction of the flowing channel by the slits 130.
[0075]
The width of the slits 130 can be determined depending on the target flow rate. For example, the width of the slits 130 is between 0.01 pm and 10 pm. For example, the width of the slits 130 is no less than 0.02 pm, 0.05 pm, 0.1 pm, 0.2 pm, 0.5 pm, or 1 pm, and no more than 9 pm, 8 pm, 7 pm, 6 pm, or 5 pm.
[0076]
It should be noted that the filter 18 may have both one or more holes and one or more slits.
[Example]
[0077]
Ex-vivo tests were performed on pig skin, using Optical Coherence Tomography and histology tests to assess the feasibility of delivering CO2 in stratum corneum or epidermis. The experimental was performed using a handy device consisting of an injecting unit having a single hollow microneedle and a charging unit including a CO2 cartridge connected to a pressure regulator.
[0078]
CO2 bubbles were observed into the skin using Optical Coherence Tomography after injection, even with very short hollow microneedles having a length of 70 pm with needle penetration limited to stratum comeum and epidermis. Accordingly, it has been proved to be feasible to inject CO2 gas into the skin with no needle penetration into dermis by means of the device according to the present application.
[0079]
After the CO2 injection, impact on surrounding tissues was checked using histology. No major tissue damage was observed and tissue integrity was kept.