GB2562778A

GB2562778A - Controlled release device

Info

Publication number: GB2562778A
Application number: GB1708401.3A
Authority: GB
Inventors: Wilson Richard; Pillow Jonathan
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2017-05-25
Filing date: 2017-05-25
Publication date: 2018-11-28
Also published as: WO2018215778A2; GB201708401D0; WO2018215778A3

Abstract

A device, comprising a substrate and a shutter, for release of an active ingredient (AI) in a temperature range of T1 to T0. The substrate comprises the AI and a matrix from which the AI substantially only diffuses above temperature T1. The shutter comprises one or more heat sensitive members that may be made of bimaterial and shield the substrate from the atmosphere above temperature T0. The AI may be a repellent, insecticide or pesticide that may target a pest active within the temperature range. The matrix may be polymeric with a glass or first order transition temperature T1. A foil comprising a plurality of heat-sensitive members and apertures arranged to be open or closed dependent upon the temperature. The apertures may be arranged in an array, they may open or close at different temperatures and in different directions. The foil may be laminated with a layer containing an AI.

Description

Controlled Release Device

Field of the invention

The present invention relates to a device for temperature-controlled release of an active ingredient (Al), methods for controlling release of an Al, foils having controllable porosity and methods for controlling the porosity of foils.

Background to the invention

There are many circumstances in which it is desirable to be able to control the release of an Al, and controlled release technology is applied in a variety of technological areas. Imprecise or limited control over release of AIs can result in inefficiencies, for example if an Al is released when it is not needed. Further problems include the possibility of AIs in some applications to have unwanted side effects if overused or used inefficiently. Examples include the build-up of resistance to insecticides or pesticides among some pest or insect populations. There is therefore a need to provide devices and methods for controlled release of an Al with improved control over how, when and in what circumstances an Al is released.

US 2003/0091464 discloses a dispenser for controlling the release of volatile materials within a contained environment comprising a housing having an opening therein, a volatile material positioned within the housing, and a temperature responsive 20 component in operable association with the opening to regulate said opening in order to contain or release the volatile material.

Summary of the invention

The present invention provides a device which is capable of controlled release of an active ingredient over a specific temperature range. Thus, in a first aspect, the present invention provides a device for temperature-controlled release of an active ingredient (Al) comprising a substrate and a shutter comprising a heat-sensitive member movable between an open position in which the substrate is exposed to the atmosphere and a closed position in which the substrate is shielded from the atmosphere, wherein:

the substrate comprises the Al and a matrix, the Al being able to diffuse from the matrix into the atmosphere at or above a temperature Ti and substantially not being able to diffuse from the matrix into the atmosphere below U;

the heat-sensitive member is configured to be in the closed position above a temperature T_o and in an at least partially open position below T_o; and

Ti is less than T_o.

In a second aspect, the present invention provides a foil comprising a plurality of heat-sensitive members and a plurality of apertures, wherein each heat-sensitive member is associated with an aperture, and each heat-sensitive member is configured 5 to move between an open position and a closed position, the position of the shutter being dependent on the atmospheric temperature, wherein an aperture is exposed when its associated heat sensitive member is in the open position and shielded when its associated heat sensitive member is in the closed position.

In a third aspect, the invention provides a device for temperature-controlled release of an active ingredient (Al) comprising a laminate comprising a foil according to the second aspect and a layer comprising the active ingredient.

The invention also provides use of a device according to the first or third aspect for controlling release of an active ingredient (Al) into the atmosphere.

Brief description of the figures

Figure 1A is a perspective view of an exemplary device according to an embodiment of the invention with the shutter in the open position.

Figure 1B is a perspective view of the device shown in Figure 1A with the shutter in the closed position.

Figure 1C is a series of section views of the device shown in Figures 1A and 1B at increasing temperatures.

Figure 2 is a perspective view of an exemplary device according to an embodiment of the invention with the shutter in the open position.

Figure 3A is a perspective view of an exemplary device according to an embodiment of the invention with the shutter in the open position.

Figure 3B is a perspective view of the device shown in Figure 3A with the shutter in an alternative configuration of the open position.

Figure 3C is a perspective view of the device shown in Figures 3A and 3B with the shutter in the closed position.

Detailed description of the invention

The present invention provides a device for temperature-controlled release of an active ingredient (Al) comprising a substrate and a shutter comprising a heatsensitive member movable between an open position in which the substrate is exposed to the atmosphere and a closed position in which the substrate is shielded from the atmosphere, wherein:

the substrate comprises the Al and a matrix, the Al being able to diffuse from the matrix into the atmosphere at or above a temperature Ti and substantially not being 5 able to diffuse from the matrix into the atmosphere below Tp the heat-sensitive member is configured to be in the closed position above a temperature T_o and in an at least partially open position below T_o; and

Ti is less than T_o.

The device of the present invention is capable of controlled release of an active 10 ingredient over a specific temperature range i.e. the range from Ti to T_o.

There may be a sharp transition from non-release of the Al below Ti to release of the Al at or above Ti, or the transition maybe gradual, with release increasing until the rate of release is limited only by the kinetic energy of the Al molecules. Likewise, there maybe a sharp transition from release of the Al below T_o to non-release of the Al 15 at T_o, or the transition may occur over a range of temperatures with the rate of release of the Al reducing until it reaches a minimum at T_o.

In some embodiments of the present invention, Ti and/or T_o are predetermined. In such embodiments, Ti and T_o maybe selected so that the Ti and T_o define a temperature range over which release of the Al is desired. Release of the Al may be undesirable below a certain temperature (e.g. below Ti) because the Al may for example be less effective below that temperature, or there may be reduced need for the Al below that temperature. For example, if the Al is an insect repellent designed to repel a particular species of insect, the insect may not be active below a certain temperature. Likewise, release of the Al maybe undesirable above a certain temperature (e.g. above

T_o), because for example the Al may be less effective above that temperature, or there may be reduced need for the Al above a certain temperature. For example, if the Al is an insect repellent designed to repel a particular species of insect, the insect may not be active above a certain temperature. The device of the present invention advantageously enables controlled release of an Al so that the Al is released into the atmosphere only at a particular temperature or range of temperatures.

A skilled person will appreciate that the Al used should be suitably volatile so as to be able to diffuse into the atmosphere at temperatures within the range defined by Ti and T_o. A skilled person will be able to choose from known AIs having a desired function (e.g. insect repellent, insecticidal or a pesticidal properties) which are suitable for use within a desired Ti- T_o temperature range.

In some embodiments, the Al is an insect repellent, insecticide or a pesticide.

In such embodiments, Ti and T_o may define a temperature range in which an insect or pest (e.g. an insect or pest sensitive to the Al) is active. In some embodiments, an insect or pest (e.g. an insect or pest sensitive to the Al) has a peak activity (i.e. is most active) at a temperature or range of temperatures falling within the temperature range defined by Ti and T_o. The activity of an insect of pest as used herein typically refers to activities of the insect and/or pest that are undesirable from the point of view of the user of the device, e.g. feeding and/or reproducing.

In embodiments where the Al is an insect repellent, insecticide or a pesticide, it maybe, for example, an insect repellent, insecticide or a pesticide capable of acting on insects and/or pests including flies, midges, mosquitoes, ticks, fleas, mites, lice, leeches, ants, bedbugs, termites, snails, slugs and cockroaches. In some preferred embodiments, the insect repellent, insecticide or a pesticide is a mosquito repellent. In some embodiments the Al may be an insecticide or a pesticide capable of acting on insects and/or pests which are active within a temperature range of Ti to T_o. Suitable insect repellents, insecticides and pesticides are known in the art and include birch bark extract, A/V-diethyl-m-toluamide (DEET), p-menthane-3,8-diol (PMD), icaridin, nepetalactone, citronella oil, neem oil, bog myrtle extract, dimethyl carbate, tricyclodecenyl allyl ether, IR3535 (3-[N-butyl-N-acetyl]-aminopropionic acid, ethyl ester), dimethyl phthalate, indalone, 2,3,5,6-tetrafluoro-4(methoxymethyl)phenyl]methyl-2,2-dimethyl-3-(i-propenyl)cyclopropane carboxylate, 2,3,5,6-tetrafluoro-4-methylphenyl]methyl-2,2-dimethyl-3-(i-propenyl)cyclopropane carboxylate, 2,3,5,6-tetrafluorophenyl)methyl-3-(2,2-dichlorovinyl)-2,2dimethylcyclopropane carboxylate, 2,3,5,6-tetrafluoro-4(methoxymethyl)phenyl]methyl-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate, 2,3,5,6-tetrafluoro-4-(methoxymethyl)phenyl]methyl-2,2-dimethyl-3-(2methyl-i-propenyl)cyclopropane carboxylate, 2,3,5,6-tetrafluoro-430 (methoxymethyl)phenyl]methyl-3-(3,3,3-trifluoro-i-propenyl)-2,2dimethylcyclopropane carboxylate, 3-Phenoxybenzyl(iRS,3RS;iRS,3SR)-3-(2,2dichlorovinyl)-2,2-dimethyl-cyclopropane carboxylate and combinations thereof.

Typically, in embodiments where the AI is an insect repellent, insecticide or a pesticide (e.g. a mosquito repellent), Ti will be in the range of io°C to 25°C, e.g. 12°C to 18°C or about 15°C. Typically, in such embodiments, T_o will be in the range of 35°C to 55°C, e.g. 4O°C to 5O°C or about 45°C. For example, Ti and T_o may define a temperature range of about io°C to about 55°C, about 12°C to about 5O°C, about 15°C to about 45°C, about 18°C to about 4O°C, or about 25°C to about 35°C.

In the device of the present invention the AI is able to diffuse from the matrix into the atmosphere above a temperature Ti and substantially not being able to diffuse from the matrix into the atmosphere below T,. As used herein, the term “substantially 10 not being able to diffuse from the matrix into the atmosphere below Ti” means that the rate of diffusion of the AI from the matrix into the atmosphere below Ti is preferably 10% or less (e.g. 5% or less) of the rate of diffusion of the AI from the matrix into the atmosphere above Ti. Matrices in which AIs can be dissolved or dispersed are known in the art and include polymer matrices. In some embodiments, the matrix is a polymeric material. The matrix may be a monolithic polymeric material. Polymeric materials include homopolymers, block copolymers, random co-polymers, terpolymers and mixtures thereof. In some embodiments, the matrix is a polymer matrix (e.g. monolithic polymer matrix). Typically, when the matrix is a polymeric material, the polymeric material is an amorphous polymeric material or a polymeric material with a high degree of amorphous character (e.g. a degree of crystallinity of less than 50%, less than 40%, less than 30%, less than 20% or less than 10%). The polymeric material may comprise a cellulose derivative, polyfethylene glycol) (PEG), poly(N-vinyl pyrrolidone), poly(n-propyl methacrylate), poly(isobutyl methacrylate), and/or poly(ethyl methacrylate). The polymer may be crystalline or amorphous. A crystalline polymer may comprise a crystalline backbone and / or crystalline side chain groups, optionally a crystalline polymer as described in US 5120349, the contents of which are incorporated herein by reference.

Ti may be predetermined, for example in accordance with a temperature above which release of the AI is desired, and below which release of the AI is not desired. Ti is 30 preferably a temperature at which a phase change occurs in the matrix material. Thus, below Ti the matrix may have a phase which substantially prevents the AI from diffusing out of the matrix and into the atmosphere. Above Ti, the matrix may have a phase that allows the AI to diffuse out of the matrix and into the atmosphere. Movement of the AI in the matrix above Ti may be governed by Fick’s laws of diffusion, and movement into the atmosphere maybe driven by the loss of material by evaporation at the surface.

In embodiments where the matrix is a polymeric material, Ti may be a first order transition temperature or a second order transition temperature of the polymer.

In the case of a crystalline polymer, Ti may be a first order transition temperature of transition from a crystalline to a non-crystalline state. In the case of an amorphous polymer, Ti may be a second order transition temperature, preferably the glass transition temperature (T_g) of the polymeric material. Below the Ti of a polymeric material, the polymeric material maybe hard and glassy, with little or no translational 10 motion between polymer chains, and the Al may not be able to diffuse to a substantial extent. The Ti of a polymeric material indicates the temperature at and above which the polymeric material is soft, as translational motion of the polymer chains becomes possible thereby allowing diffusion of the Al through the polymeric material. The Ti of a polymeric material maybe as determined by differential scanning calorimetry (DSC).

In a device of embodiments of the present invention, the shutter is in an open position below T_o, thereby exposing the substrate to the atmosphere. At temperatures above Ti and below T_o, the Al is therefore able to diffuse from the matrix into the atmosphere. The shutter is in a closed position above T_o, thereby shielding the substrate from the atmosphere. At temperatures above T_o, although the Al is able to 20 diffuse through the matrix, the shutter forms a physical barrier between the substrate and the atmosphere thereby substantially preventing the Al in the matrix from diffusing into the atmosphere. When the or each shutter is in its closed position, the Al is substantially not able to enter the atmosphere. For example, the rate of diffusion of the Al from the matrix into the atmosphere may when the or each shutter is in the 25 closed position may be less than 10%, less than 5%, less than 3%, less than 2% or less than 1% than the rate of diffusion of the Al from the matrix into the atmosphere in the absence of the shutter and at a temperature Ti.

Diffusion of the Al into the atmosphere above Ti is preferably controlled solely by the configuration of the shutter. The shutter is disposed between the substrate and 30 the atmosphere. The shutter may be a layer disposed on one surface of the substrate. There may be a non-heat sensitive barrier between the substrate and the atmosphere on all parts of the device on which the shutter is not disposed.

As used herein, the term atmosphere refers to a body of fluid (e.g. air) external to the device. The atmosphere may itself be an enclosed space, e.g. a room, building, tent or temporary structure, or vehicle, or may be the outside air.

The shutter comprises at least one heat sensitive member. For each heat sensitive member present in the shutter, the shutter further comprises an associated aperture which, when exposed to the atmosphere, also exposes the substrate to the atmosphere. In some embodiments there is only one heat sensitive member present in the shutter. In other embodiments the shutter comprises a plurality of heat sensitive members e.g. arranged in an array (e.g. 2 or more, 4 or more, 9 or more, 16 or more, 25 10 or more, 36 or more, 49 or more, 64 or more, 81 or more, too or more, too or less, 81 or less, 64 or less, 49 or less, 36 or less, 25 or less, 16 or less, 9 or less, 4 or less). The heat sensitive member or members act to expose its associated aperture to the atmosphere below a temperature Thm, and shield its associated aperture from the atmosphere above Th_m. In embodiments where the shutter comprises more than one hear sensitive member, Thm for each heat sensitive member may be the same or different.

In embodiments where there is only one heat sensitive member present in the shutter, T_o is equal to Thm. Thus, below Thm the aperture and therefore the substrate is exposed to the atmosphere, and above Thm the aperture and therefore the substrate is 20 shielded from the atmosphere.

In embodiments where there is more than one heat sensitive member and Thm is the same for each heat sensitive member, T_o is equal to Thm. Thus, below Thm all the apertures, and therefore also the substrate, are exposed to the atmosphere. Above Thm, all the apertures are shielded from the atmosphere, and therefore the substrate is shielded from the atmosphere.

In embodiments where there is more than one heat sensitive member and Thm is different for different heat sensitive members, the shutter can be configured to partially shield the substrate from the atmosphere at a temperature between T_ps and T_o, wherein T_ps is a temperature above Ti and below T_o. T_o is equal to the highest Thm of all the heat 30 sensitive members and the partial shielding temperature T_ps is equal to the lowest Thm of all the heat sensitive members. Thus, below the lowest Thm of all the heat sensitive members, all the apertures are exposed to the atmosphere and therefore the substrate is exposed to the atmosphere. Above the lowest Thm of all the heat sensitive members, but below the highest Thm of all the heat sensitive members, at least the aperture associated with the heat sensitive member having the lowest Thm is shielded from the atmosphere, and at least the aperture associated with the heat sensitive member having the highest Thm is exposed to the atmosphere. In this situation the substrate is partially 5 shielded from the atmosphere. However as at least the aperture associated with the heat sensitive member having the highest Thm is exposed to the atmosphere, the substrate is still exposed to the atmosphere. Above the highest Thm of all the heat sensitive members, all the apertures are shielded from the atmosphere, and therefore the substrate is shielded from the atmosphere. The shutter is in the closed position 10 only when all the apertures are shielded from the atmosphere.

The foil of the invention is substantially as described herein in connection with the shutter of the device of the invention in embodiments where the shutter comprises a plurality of heat sensitive members arranged in an array, and a plurality of associated apertures, except that each heat sensitive member may individually be configured to 15 shield its associated aperture below Thm and expose its associated aperture above Thm, or expose its associated aperture at a temperature below Thm and shield its associated aperture at a temperature above Thm. A heat sensitive member may be configured to shield its associated aperture below Thm and expose its associated aperture above Thm, for example in embodiments where the heat sensitive member comprises a bimetallic 20 member by reversing the position of the first and second materials described above.

In some embodiments the or each heat sensitive member may comprise a bimaterial member. In some such embodiments, the or each heat sensitive member may consist of a bimaterial strip. In other embodiments, the or each heat sensitive member may comprise a bimaterial hinge and an impermeable flap. In embodiments 25 where there is more than one heat sensitive member in the shutter, one or more heat sensitive members may each consist of a bimaterial strip, and one or more heat sensitive members may each comprise a bimaterial hinge and an impermeable flap.

In some embodiments the heat sensitive member and immobile regions of the shutter are formed of the same material or materials. In some such embodiments, the 30 shutter may comprise or consist of a bimaterial layer disposed on the surface of the substrate and fixed to the substrate other than at the location of a heat sensitive member, and the heat sensitive member may be an extension of the bimaterial layer, which extension is not fixed to the substrate and extends from the rest of the shutter on one side.

In some embodiments, the heat sensitive member may contact the surface of the substrate when the heat sensitive member is shielding its associated aperture from the atmosphere (i.e. above Thm). In such embodiments the surface of the substrate maybe patterened (e.g. with ridges or bumps) or coated (e.g. with a non-stick coating such as poly(tetrafluoroethane)) to prevent the heat sensitive member sticking to the surface of the substrate.

Bimaterial members are known and work on the principle that different materials expand and contract at different rates. Thus, a bimaterial member may have an first side and a second side, with an first material at the first side fixed to a second 10 material at the second side. In the device of the present invention, the first side may be the side facing the atmosphere when the shutter is in the closed position, and the second side maybe side facing the substrate when the shutter is in the closed position. The first material and second material are different. The dimensions of the bimaterial member as well as the identity of the first and second materials may be selected so that, 15 below Thm, the first material is contracted to a greater extent than the second material, and the bimaterial member is curled so as to be concave when seen from the first side and convex when seen from the second side. As the temperature reaches Thm, the first material expands at a greater rate than the second material, and the bimaterial member straightens out.

The mathematics governing the behaviour of bimaterial members is well understood with the radius of curvature (R), or it’s reciprocal (k) dependent on the Young’s Moduli (E), the thermal expansivities (a), the thicknesses (h) and the change in temperature (ΔΤ), as expressed in the following equation:

In this case, Δε = (ctA - αΒ).ΔΤ, wherein A and B refer to the first material and the second material. A skilled person will be able to select appropriate first and second materials and thicknesses thereof in order to achieve an appropriate Thm.

Suitable materials include metals and metal alloys, and polymeric materials.

Examples of metals and metal alloys suitable for the first and/or second materials include steel, copper, brass and aluminium. Examples of polymeric materials suitable for the first and/or second materials include polypropylene and nylon. In some embodiments, the first and second material are each a metal or metal alloy (i.e. the biomaterial member is a bimetallic member). In some embodiments, one of the first and second materials is a metal or metal alloy and the other is a polymeric material. In one such embodiment one of the first and second materials is aluminium and the other is nylon. In some embodiments, the first and second materials are each a polymeric material. In one such embodiment, one of the first and second materials is polypropylene and the other is nylon.

Suitable thicknesses will be determined by a skilled person in combination with 10 the choice of first and second material to give a desired curvature at a desired temperature, and also to ensure that the thickness of the materials is sufficient to enable a reasonably robust film that can physically withstand usage without unwanted distortion or breakage. In some embodiments the total thickness of the bimaterial member maybe in the range of 10-100 microns.

In embodiments where the or each heat sensitive member comprises a bimaterial member, the heat sensitive member can be configured so that as temperature increases from a temperature below Thm, the straightening action of the bimaterial member causes the associated aperture to be shielded as the temperature reaches Th_m. Likewise, the heat sensitive member can be configured so that as temperature reduces from a temperature above Thm, the curling action of the bimaterial member causes the associated aperture to be exposed as the temperature reaches Thm.

A heat sensitive member may consist of a bimaterial strip. The bimaterial strip may be fixed to the rest of the shutter at one edge, and be free on all other edges. A heat sensitive member may comprise a bimaterial hinge and an impermeable flap. The 25 bimaterial hinge may be attached to the rest of the shutter at one edge, and attached to the impermeable flap at the other edge. The impermeable flap may be attached to the bimaterial hinge at one edge and free on all other edges. The impermeable flap is typically made of a material impermeable to the AL The impermeable flap is typically made of a rigid material and is typically not heat sensitive. The impermeable flap 30 therefore typically retains substantially the same shape and dimensions over the operating temperature of the device (e.g. over a temperature range of 5°C to 6o°C).

The invention is illustrated below with reference to the exemplary embodiments shown in the figures.

Figures 1A and 1B show an exemplary device 100 according to an embodiment of the invention in which one heat sensitive member 11 is present in the shutter to. The shutter to is in the open position in Fig. 1A and in the closed positon in Fig. 1B. When the shutter to is in the open position the substrate 20 is exposed to the atmosphere allowing the AI to diffuse into the atmosphere at temperatures above Ti. Diffusion of the AI from the substrate 20 into the atmosphere is represented in Fig. 1A by an arrow. In Figure 1B the shutter 10 is in the closed position and the substrate 20 is shielded from the atmosphere. The AI cannot diffuse into the atmosphere, even above Ti, as represented by the arrow with a cross through it.

In Figures 1A and 1B, the heat sensitive member 11 is a bimaterial strip. The bimaterial strip 11 is fixed to the rest of the shutter at one edge, and is free on all other edges. In Fig. 1A, the temperature is below T_o and the bimaterial strip 11 curls away from the rest of the shutter 10 to expose the substrate 20 to the atmosphere. In Figure 1B, the temperature is above T_o and the bimaterial strip 11 is substantially flat and extends towards the rest of the shutter 10 so as to shield the substrate 20 from the atmosphere.

Figure 1C shows the device of Figures 1A and 1B as temperature increases. Below Ti the shutter is in the open position but the temperature is below the T_g of the polymeric matrix (shown by the dotted substrate) and no release occurs. Above Ti and 20 below T_o, the shutter is in the open position and the temperature is above the T_g of the polymeric matrix (shown by the hatched substrate) and release occurs. Above T_o the temperature is above the T_g of the polymeric matrix (shown by the hatched substrate), but the shutter is in the closed position, and no release occurs. Although schematically shown in Figure 1C as accompanying an increase in temperature, the changes described 25 above are reversible and would occur in reverse as temperature is reduced from above T_o to below Ti. In other embodiments, it will be appreciated that the polymeric matrix maybe a crystalline polymer in which release occurs at above a first order transition temperature of the polymer.

Figure 2 shows an alternative embodiment of the device too in which the heat 30 sensitive member 11 comprises a bimaterial hinge 12 and a rigid impermeable flap 13.

The bimaterial hinge 12 is fixed to the rest of the shutter 10 at one edge, and fixed to the impermeable flam 13 at an opposite edge. In Fig 2 the temperature is below T_o and the bimaterial hinge 12 curls away from the rest of the shutter 10 to direct the rigid impermeable flap 13 away from the substrate 20, thereby exposing the substrate 20 to the atmosphere. Above T_o (not shown in the figures) the bimaterial hinge 11 straightens so as to direct the impermeable flap 12 across the surface of the substrate 20, thereby shielding the substrate 20 from the atmosphere.

Figures 3A 3B and 3C show an exemplary device 100 according to an embodiment of the invention in which the shutter 10 comprises nine heat sensitive members 11. Fig 3A illustrates the device below a temperature T_o, and also below a temperature T_ps. Figure 3B illustrates the device below a temperature T_o but above a temperature T_ps. Figure 3C illustrates the device above a temperature T_ps and also above a temperature T_o.

The shutter 10 is in an open position in Figs. 3A and 3B, and in the closed positon in Fig. 3C. The heat sensitive members in Figs. 3A, 3B and 3C function in an analogous way to the heat sensitive member described above in connection with the embodiment of Fig. 1A nad Fig 1B.

In Fig. 3B the shutter 10 is in the open position because the substrate 20 is exposed to the atmosphere through apertures associated with four of the nine heat sensitive members 11b. However, the apertures associated with five of the heat sensitive members 11a are shielded from the atmosphere. The substrate 20 is therefore partially shielded from the atmosphere in Fig 3B.

In the figures the sides of the device 100 are shown cut away in order to illustrate the arrangement of the shutter 10 and the substrate 20. However a device according to the present invention will typically have a non-heat sensitive barrier between the substrate and the atmosphere on all parts of the device on which the shutter is not disposed, so that diffusion of the Al into the atmosphere above Ti can be controlled solely by the configuration of the shutter.

The invention has been described above with reference to various exemplaiy embodiments. However, a skilled person will appreciate that various modifications to the embodiments described above can be made while remaining within the scope of the invention as defined by the following claims.

Claims

1. A device for temperature-controlled release of an active ingredient (Al) comprising a substrate and a shutter comprising a heat-sensitive member movable

5 between an open position in which the substrate is exposed to the atmosphere and a closed position in which the substrate is shielded from the atmosphere, wherein: the substrate comprises the Al and a matrix, the Al being able to diffuse from the matrix into the atmosphere at or above a temperature Ti and substantially not being able to diffuse from the matrix into the atmosphere below Tq

10 the heat-sensitive member is configured to be in the closed position above a temperature To and in an at least partially open position below To; and

Ti is less than To.

2. A device according to claim 1 wherein the Al is an insect repellent, insecticide or 15 a pesticide.

3. A device according to claim 2 wherein the Al is an insect repellent, insecticide or pesticide capable of acting on insects and/or pests having a peak activity within a temperature range from Ti to To.

4. A device according to any one of the preceding claims, wherein the heatsensitive member comprises a bimaterial member.

5. A device according to claim 4 wherein the heat-sensitive member consists of a 25 bimaterial strip.

6. A device according to claim 4 wherein the heat-sensitive member comprises a bimaterial hinge and an impermeable flap.

30

7. A device according to any one of the preceding claims wherein the matrix is a polymeric material.

8. A device according to claim 7 wherein Ti is the glass transition temperature (Tg) of the polymeric material.

9- A device according to claim 7 wherein the polymeric material is crystalline and wherein Ti is a first order transition temperature of the polymer material.

10. A device according to any one of the preceding claims wherein the shutter

5 comprises only one heat-sensitive member.

11. A device according to any one of claims 1 to 9, wherein the shutter comprises a plurality of heat-sensitive members.

10

12. A device according to any one of the preceding claims wherein the Al is a mosquito repellent.

13. A foil comprising a plurality of heat-sensitive members and a plurality of apertures, wherein each heat-sensitive member is associated with an aperture, and each

15 heat-sensitive member is configured to move between an open position and a closed position, the position of the shutter being dependent on the atmospheric temperature, wherein an aperture is exposed when its associated heat sensitive member is in the open position and shielded when its associated heat sensitive member is in the closed position.

14. A foil according to claim 13, wherein the plurality of apertures are arranged in an array.

15. A foil according to claim 13 or 14 wherein at least one of the heat sensitive 25 members is in an at least partially open position below a temperature Thm and in the closed position above temperature Thm.

16. A foil according to any one of claims 13 to 15 wherein at least one of the heat sensitive members is in the closed position below a temperature Thm and in an at least

30 partially open position above temperature Thm.

17. A foil according to claim 15 or 16, wherein Thm is the same for each of the plurality of heat-sensitive members.

35

18. A foil according to any of claims 13 to 16 wherein the Thm of at least one heat- sensitive member is different from the Thm of at least one other heat-sensitive member.

19- A foil according to any one of claims 18 to 23, wherein each heat-sensitive

5 member comprises or consists of a biomaterial strip or comprises a biomaterial hinge and an impermeable flap.

20. A device for temperature-controlled release of an active ingredient (Al) comprising a laminate comprising a foil according to any one of claims 13 to 19 and a

10 layer comprising the active ingredient.

21. Use of a device according to any one of claims 1-12 or 20 for controlling release of an active ingredient (Al) into the atmosphere.