WO2013186628A1

WO2013186628A1 - Transdemal device for the fluorometric detection of an analyte in a biological fluid and analysis apparatus associated with said transdermal device

Info

Publication number: WO2013186628A1
Application number: PCT/IB2013/001256
Authority: WO
Inventors: Mohammad Hassan MOSHEN DARAI; Fouroghalzaman KATOUZIANTEHRANI MOGHADAM
Original assignee: Delta Instruments S.R.L.
Priority date: 2012-06-15
Filing date: 2013-06-17
Publication date: 2013-12-19
Also published as: ITUD20120114A1

Abstract

A non-invasive transdermal device (10) for the fluorometric detection of an analyte in a biological fluid comprises a patch (12) configured to extract a desired quantity of interstitial liquid from the skin of a patient in order to evaluate the level of analyte in the biological fluid.

Description

"TRANSDERMAL DEVICE FOR THE FLUOROMETRIC DETECTION OF AN ANALYTE IN A BIOLOGICAL FLUID AND ANALYSIS APPARATUS ASSOCIATED WITH SAID TRANSDERMAL DEVICE" FIELD OF THE INVENTION

The present invention concerns a non-invasive transdermal device for the fluorometric detection of an analyte in a biological fluid inside or immediately under the skin, such as interstitial fluid, and an associated portable analysis apparatus. The two are usable, by way of non-restrictive example, to evaluate the glycemia, or level of glucose, in the blood, in particular in humans, for example in those suffering from diabetes, or in general to analyze and monitor other biological parameters in a living being, either human or animal.

BACKGROUND OF THE INVENTION

It is known that to determine physiological health condition chemical analyses are often carried out to detect the presence or concentration of levels of analytes in biological fluids. This practice is common for example in the diagnosis of diabetes and in the management of said pathology. Indeed, as well as administering insulin, it is crucial for the health of the diabetes patient to regularly monitor the level of glucose in the blood.

In particular, the levels of glucose in the blood can generally vary in the course of the day and depending on the period, also according to the diet.

It is known that the complications deriving from diabetes can be reduced or even eliminated by periodic, do-it-yourself verifications of the glucose level, made throughout the day, also known as self monitoring glucose. In particular, it is advised that a patient with type 1 diabetes should control his/her glucose level at least 4 times a day, even if 5-7 controls a day are not infrequent, whereas a patient with type 2 diabetes should make at least 2 checks a day on the glucose level.

At present, in most cases, the controls carried out by patients use reactive chemical strips that provide to take a blood sample using needles, usually from the fingers or arms. However, this procedure is inconvenient, invasive and painful, and often constitutes a psychological barrier against the correct performance of the analysis, especially for younger or more elderly patients, and has a high level of risk for hemophiliacs, as well as being a possible source of spreading infections of illnesses connected to the blood.

There is therefore a great need to simplify the do-it-yourself glycemia analysis, making it less invasive and painful.

Documents US-6,952,263, US-B-6,574,425, US-B-6,503, 198 and US-B- 7,577,469 describe a non-invasive system for detecting an analyte in a biological fluid, which includes a transdermal patch and an optical detection device, in particular based on colorimetric detection. This known system suffers from the disadvantage that it is not repeatable with any reliability of the results obtained, either on different persons or on the same person. In particular, the mechanism on which the analysis is based is highly dependent on the time of application of the patch, and also the basal and ambient temperature. Furthermore, the optical detection device too is very influenced by external factors. In addition, the known system is affected by the absorption of sweat in which, unlike hematic glucose, the glucose level is not correlated to diabetes.

Document WO-A-2010/013264 describes a known portable device for the laser measuring of glycemia in the blood.

Purpose of the present invention is to obtain a transdermal device for the fluorometric detection of an analyte in a biological fluid and an analysis apparatus associated with the transdermal device which are reliable, precise, not painful and not invasive in performing the analysis and which therefore improve the patient's compliance.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

Unless otherwise defined, all the technical and scientific terms used here and hereafter have the same meaning as commonly understood by a person with ordinary experience in the field of the art to which the present invention belongs.

Even if methods and materials similar or equivalent to those described here can be used in practice and in the trials of the present invention, the methods and materials are described hereafter as an example. In the event of conflict, the present application shall prevail, including its definitions. The materials, methods and examples have a purely illustrative purpose and shall not be understood restrictive ly.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

In accordance with the above purpose, a non-invasive transdermal device for the fluorometric detection of an analyte in a biological fluid according to the present invention comprises a transdermal patch configured to extract a desired quantity of interstitial liquid from the skin of a patient in order to evaluate the level of analyte in the biological fluid.

According to one form of embodiment of the present invention, the patch comprises:

- a first external surface, to be applied in contact with the skin, provided with a plurality of protruding micro-needles sized to penetrate into the epidermis sufficiently to extract, due to the capillarity effect, the necessary quantity of interstitial liquid from the most external layer of the skin, without reaching the pain receptors under the skin;

- at least an internal fluorescence biosensor to detect the level of analyte in the biological fluid by means of interaction with the interstitial liquid extracted by the micro-needles.

Thanks to the micro-needles that penetrate into the epidermis without reaching the pain receptors, but sufficiently to be able to extract the interstitial liquid in the desired quantities, the present invention is non-invasive and painless.

Furthermore, thanks to the micro-needles, no multiple wounds, which could be the source of infections, irritation, bleeding (critical for hemophiliacs), and potential allergic reactions, are generated during the repetition of the daily monitoring. Nor is there any development of inflammation on the local tissue due to the implantation of traditional biosensors under the skin. Consequently, the invention makes available a device to monitor the concentration of an analyte, for example the glucose level in the daily monitoring of patients suffering from diabetes, which is comfortable and adaptable to the patient, improving the patient's compliance.

Moreover, thanks to the fluorescence biosensor contained therein, and which is designed with specific binding for the analyte, for example glucose, the invention has great specificity for detecting the level of the analyte looked for.

Moreover, if the analyte is glucose, there is great accuracy in measuring the glucose level in the blood thanks to the reliable correlation with the level of glucose in the interstitial liquid.

In a variant form of embodiment, advantageous to ensure that the microneedles do not reach the pain receptors under the skin, each of the micro-needles has a length between 200 micrometers and 270 micrometers, preferably between 240 micrometers and 260 micrometers, even more preferably between 245 micrometers and 255 micrometers. An example form of embodiment provides that each of the micro-needles has a length of about 250 micrometers.

In another variant form of embodiment, each micro-needle comprises a hollow lateral casing which has a micro-channel inside, which can have an internal diameter comprised between 10 micrometers and 100 micrometers, and which terminates with a pointed perforation end, a lateral aperture being provided on the surface of the casing which puts the internal micro-channel in communication with the external environment. The provision of the lateral aperture for extracting the interstitial liquid, separated and positioned unconstrained from the pointed perforation end, prevents any blockage of the micro-channel and of the aperture itself following the perforation.

In another form of embodiment, the patch is multi-layered and comprises a plurality of layers overlapping each other, of which at least one external layer which has the first external surface on which the micro-needles are provided and another layer which includes the fluorescence biosensor.

In a variant form of embodiment, the layer which includes the fluorescence biosensor is a dry chemical component which contains the fluorescence biosensor, or a wet chemical component which provides a hydrogel matrix in which the fluorescence biosensor is dispersed.

In a variant form of embodiment, the patch also comprises another layer formed by a porous membrane, intermediate between the external layer which has the first external surface on which the micro-needles are provided and the layer which includes the fluorescence biosensor.

In a variant form of embodiment, the porous membrane is configured to allow the passage only of molecules of a size less than about 100 - 150 Dalton.

The present invention also concerns a fluorometric analysis apparatus which can be associated to a transdermal device as described above, which includes an external box-like container which comprises a fluorometric measuring chamber to which the device is associated and provided with an emitter/receiver of electromagnetic radiation associated to an electronic processing device.

In a variant, the measuring chamber is contained inside the box-like container and a sliding tray is provided to receive the transdermal device, for the purposes of the fluorometric measuring, mobile between an external position and a position completely included in the box-like container, inside the measuring chamber, so that the sliding tray, in its closed position, is positioned above the emitter/receiver so as to take the transdermal device into cooperation with the emitter/receiver inside the measuring chamber.

In another variant, the measuring chamber is made on an external wall of the box-like container, and closing means are provided to selectively close the measuring chamber, and at least a screening mean which can be placed around the transdermal device to prevent the passage of light radiation toward the transdermal device during fluorometric measuring.

The present invention also concerns a diagnostic kit that includes a transdermal device and a fluorometric analysis apparatus as described above

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a schematic perspective view of a transdermal device according to the present invention;

- fig. 2 is a schematic section of part of the device in fig. 1 ;

- fig. 3 is an enlarged detail of part of fig. 1 ;

- fig. 4 is a view in separate parts of a transdermal device according to the present invention;

- fig. 5 is a schematic perspective view of an apparatus according to the present invention;

- fig. 6 is a schematic perspective view of a variant of an apparatus according to the present invention.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one form of embodiment can conveniently be incorporated into other forms of embodiment without further clarifications.

DETAILED DESCRIPTION OF SOME FORMS OF EMBODIMENT

With reference to the attached drawings, a non-invasive transdermal device 10 is described which functions as a fluorescent biosensor for the fluorometric detection of an analyte in a biological fluid, for example to detect the level of glucose in the interstitial liquid of the skin for daily monitoring in diabetes.

The device 10 comprises a multi-layered patch 12 (fig. 1), to be applied on the patient's skin, to extract a desired quantity of interstitial liquid, from which the glucose level in the blood can be evaluated, as described in more detail hereafter. The patch 12 has a first external surface 14, to be applied in contact with the skin, provided with a plurality of protruding micro-needles 16 that penetrate into the skin. The plurality of micro-needles 16 can be organized in an orderly array, for example 3x3 or 4x4.

For ease of understanding, in figs. 1-4 the sizes of the micro-needles 16 do not respect their real proportions with respect to the other parts of the patch 12.

The micro-needles 16 are sized to penetrate into the epidermis sufficiently to extract, due to the capillarity effect, the necessary quantity of interstitial liquid from the outermost layer of the skin, but without reaching the pain receptors under the skin. In an example form of embodiment, the micro-needles 16 have a preferred length of between 245 micrometers and 255 micrometers, for example 250 micrometers, so as to stop before the pain receptors under the skin. In one form of embodiment, the micro-needles 16 have an internal diameter between about 10 micrometers and 100 micrometers, so as to guarantee the desired capillarity effect.

In one form of embodiment, each micro-needle 16 comprises a hollow lateral casing 60 which has a through micro-channel 62 inside which develops axially and which can have an internal diameter between about 10 micrometers and 100 micrometers (figs. 2 and 3). The lateral casing 60 has a lower base 61 and terminates at the upper part with a pointed perforation end 64, which can be shaped with a curvilinear, convex or concave section, or with a linear development such as conical or other desired shape, to perforate the skin, allowing the micro-needle 16 to enter. Just under the pointed end 64, on the surface of the lateral casing 60, there is a through lateral aperture 66, which puts the internal micro-channel 62 in communication with the external environment, to allow the passage of the interstitial liquid toward the inside of the patch 12, once the micro-needle 16 has perforated the skin thanks to the pointed end 64. Making the lateral aperture 66 on the lateral surface, under the pointed end 64, is advantageous because it prevents the lateral aperture 66 from becoming occluded or blocked by the skin that is perforated when the micro-needle 16 is inserted.

In a variant, the lateral aperture 66 lies on a plane orthogonal to the axis of the micro-channel 62. In another variant, the lateral aperture 66 lies on a plane inclined but not orthogonal to the axis of the micro-channel 62.

The patch 12 includes inside it a fluorescence biosensor 13 that comprises a reactive substrate compound specific for glucose bonded with a fluorescent substance, or fluorophore, which therefore, in contact with glucose, changes the intensity of fluorescence. The change in intensity is read by a fluorometer which then supplies the value of the glucose level desired.

The fluorescent substance can be any substance that emits radiations after being excited by an electromagnetic radiation with a different wavelength, in particular that works in the range of wavelengths of incident radiation between 180 nm and 900 nm. For example, a substance that absorbs a wavelength in the region of about 360 nm can be used.

There are various systems to detect glucose levels using fluorescence, of which the most common is a FRET (Forster resonance energy transfer) reversible competitive assay between glucose and a polymer marked with a fluorescent substance, or fluorophore such as fluorescein, for the binding site of a protein, for example concanavalin A. Consequently, the analyte competes with a known concentration of marked polymer for the binding site of the protein, for example concanavalin A. Consequently, the FRET value falls between the binding site and the polymer, which represents the competing ligand, when the concentration of analyte increases. The specific substrate compound can therefore be a marked protein-polymer, for example concanavalin A-dextran, where the glucose competes with the marked dextran polymer with the fluorophore to occupy the binding sites with the concanavalin A.

The fluorescence biosensor 13 can be attached on an inert support 15, for example polymer micro-spheres, such as polypropylene, generally used for this purpose in the state of the art.

In particular, advantageously the specific substrate compound is attached, for example adsorbed, on the surface of the inert support 15, while the fluorescent substance is attached to the marked polymer of the specific substrate compound.

Consequently, the interstitial liquid taken by the micro-needles 16 takes the glucose possibly contained therein into contact with the specific glucose-reactive substrate. The fluorescent substance, following the interaction of the glucose with the protein, which frees the marked protein, changes its behavior into emission of electromagnetic radiation when excited by a suitable source of light.

The quantity of glucose that binds with the specific glucose-reactive substrate can therefore be read optically by means of a fluorometer which correlates the different emission of electromagnetic radiation with the glucose level present in the blood, supplying said value at outlet.

In particular, the analyte, for example the glucose, preferentially binds with the protein, such as concanavalin A, rather than with the polymer marked with the fluorophore, such as dextran-fluorescein. Therefore, the presence of the analyte causes an increase in the free polymer marked with the fluorophore, which results in an increased emission of intensity of fluorescence detectable by the fluorometer. Therefore, the intensity of the fluorescence emitted is used as a measurement of the concentration of glucose and is proportional thereto.

Advantageously, the fluorometric reading, being based on a substrate-specific mechanism, depends neither on the time nor on the basal temperature of the patient or of the environment.

In a basic form of embodiment, the patch 12 in particular comprises a plurality of layers 21, 22, 23 overlapping each other, of which at least one external first layer 21 and a third layer 23 disposed on the side opposite the first layer 21 (figs. 2 and 4). In another form of embodiment, a second internal layer 22 is provided, intermediate between the first layer 21 and the third layer 23.

For ease of understanding, in figs. 1-4 the sizes of the layers 21, 22, 23 with respect to the micro-needles 16 do not respect their real proportions.

The first external layer 21 is the layer that goes into contact with the patient's skin, to extract the interstitial liquid. The first layer 21 therefore has the first external surface 14 on which the micro-needles 16 are provided. The first layer 21 can be made in a single piece with the micro-needles 16, or as a separate body that is subsequently constrained to the micro-needles 16.

For example, if the first layer 21 and the micro-needles 16 are made in plastic polymer material, such as polycarbonate, polymethyl methacrylate, silicone, Teflon, it is advantageous to make the first layer 21 inclusive of the microneedles 16, by means of a single molding, thus achieving a single body. In other solutions, the first layer 21 and the micro-needles 16 can be made of metal material, such as steel or tungsten, coated with biocompatible material, or composite materials, for example with a base of carbon fibers, coated with biocompatible material. The solution that adopts the use of a plastic polymer material is advantageous in that it allows a better capillarity effect and therefore a more effective extraction of the interstitial liquid.

The second layer 22 is formed by a porous membrane 27, the holes 28 of which are configured, sized and made to allow the passage only of molecules of a size less than about 100 - 150 Dalton, substantially filtering and blocking larger molecules, preventing them from entering inside the patch 12. This allows only determinate molecules or ions desired for the analysis to pass inside the patch 12, so that they reach the fluorescence biosensor 13 inside the patch 12.

The second layer 22 can be constrained to the first layer 21 by means of an adhesive layer 19, in particular for example one that adheres under pressure.

The third layer 23 is the layer actively involved in detecting the glucose level present in the interstitial liquid and which therefore is directly subjected to optical reading by the fluorometer as discussed above. To this purpose, the third layer 23 includes the fluorescence biosensor 13 formed by the specific substrate - fluorescent substance.

The third layer 23 can be configured as a dry chemical component that contains the fluorescence biosensor 13, possibly constrained to the inert support 15.

Or, in an advantageous solution for the capillarity effect as described above, to absorb the interstitial liquid and capture the analytes contained therein, the third layer 22 can be configured as a wet chemical component that contains the fluorescence biosensor 13 formed by the specific substrate - fluorescent substance, possibly constrained to the inert support 15, dispersed in a hydrogel matrix 17, or a reticulated porous polymer matrix filled with water in which the fluorescence biosensor 13 is trapped, possibly attached to the inert support 15. The fluorescence biosensor 13 can be trapped for example either physically or chemically.

Hydrogels with a natural polymer constituent can be used, including hyaluronan, alginic acid, pectin, carrageenan, chondroitin sulphate, dextran, dextran sulphate, chitosan, polylysine, collagen, carboxymethylchitin, fibrin, agarose, pullulan, or hydrogels with a synthetic polymer constituent such as PEG, PEGA, PAC, PLA, PLGA, PCL, PHB, PVA, PVVP, P(HEMA), p(bis-carboxy- phenoxy-phosphazene), p(GEMA-sulphate) and others, or hybrids of the two.

In general, the third layer 23 can be deposited on the second layer 22 and constrained thereto by spreading or other technique suitable for the purpose.

The third layer 23 is the layer that is exposed to the emission of electromagnetic radiation that excites the fluorescent substance in the fluorometer.

The patch 12, in some variant forms of embodiment, can comprise a fourth layer 24 that can be associated, by means of known techniques, to the third layer 23 and disposed on the opposite side with respect to the second layer 22. The fourth layer 24 can advantageously be made of material transparent to optical radiation, to allow the fluorometric reading. The fourth layer 24 can also have a protective function.

The patch 12, in some other variant forms of embodiment, can comprise a fifth layer 25, which can be directly associated with the third layer 23, or can be applied on the fourth layer 24, if provided, in any case on the opposite side to the second layer 22. The fifth layer 25 is therefore the outermost layer of the patch 12 which is opposite the first external layer 21.

The fifth layer 25 can have an advantageous structural and support function and can be made for example of metal, such as aluminum, or a fibrous material, such as a fabric, a non-woven fabric or other material used in the medical field or in patches and suitable for the purpose. The fifth layer 25 is preferably the peelable type, that is, easily removable, so as to expose the third layer 23 or the transparent fourth layer 24 if provided, to the electromagnetic emission during the fluorometric measuring.

For example, one form of embodiment, not restrictive of the field of the present invention, provides that the patch 12 has sizes of 1 cm x 1 cm x 0.3 cm.

The present invention also includes a portable analysis apparatus or fluorometer 30, usable in association with the transdermal device 10 to perform the fluorometric measurement so as to determine the glucose level in the blood (figs. 5 and 6).

The apparatus 30 includes a box-like container or shell 32 which comprises, externally or internally, a fluorometric measuring chamber 42 in which the fluorometric reading of the patch 12 is carried out. Inside the measuring chamber 42 an emitter/receiver 34 of electromagnetic radiation is provided, for example a photometer comprising a laser photo diode.

The emitter/receiver 34 is associated to an electronic processing device 36, such as a microchip, an electronic card or analogous device able to receive an electric signal correlated to the measurement carried out by the emitter/receiver 34 and to process it, as a function of a database correlating the quantity of fluorescence detected, the standard emission in fluorescence of the fluorescence biosensor 13 and, evaluating the difference in the emission of fluorescence, to calculate the quantity of glucose present in the interstitial liquid, to supply at outlet the value of the glucose level that can be displayed on a screen 38, such as a liquid crystal display or other.

The apparatus 10 is configured so that, when the fluorometric reading is made on the patch 12, the measuring chamber 42 is obscured, so that the emission and detection of the electromagnetic radiations involved in the fluorometric measuring are not disturbed or influenced by other sources of light.

In the variant shown in fig. 5, the apparatus 30 is usable once the patch 12 has been removed from the patient's skin. In particular, in this variant the fluorometric measuring chamber 42 in which the patch 12 once removed is positioned is contained inside the shell 32.

Furthermore, in this variant, the shell 32 comprises a sliding tray 40 sliding between an external position and a position completely included in the shell 32, inside the fluorometric measuring chamber 42, as indicated by arrow F in fig. 5. In this position, completely included in the shell 32, the sliding tray 40 functions as a mean for closing the fluorometric measuring chamber 42, which is thus obscured during the fluorometric measuring.

The emitter/receiver 34 is disposed on an internal wall of the measuring chamber 42, so that the sliding tray 40, in its closed position, is positioned above the emitter/receiver 34. In this way, when the sliding tray 40 is in the open position, it is possible to place the patch 12 inside it. By subsequently moving the sliding tray 40 to the closed position, the patch 12 is taken into cooperation with the emitter/receiver 34, inside the fluorometric measuring chamber 42. Closing the sliding tray 40 causes the fluorometric measuring chamber 42 to be obscured. For the purposes of precision, in particular so that the patch 12 is correctly positioned and aligned with the emitter/receiver 34 inside the fluorometric measuring chamber 42, the sliding tray 40 can be provided with a lowered housing seating 44, mating in shape with that of the patch 12, in which to stably position the patch 12.

The position of the housing seating 44 is made on the sliding tray 40 so that, when the latter is in the closed position, contained inside the shell 32, the housing seating 44 is aligned with the emitter/receiver 34, thus automatically positioning the patch 12 correctly in the measuring chamber 42.

In order to carry out this operation, it is also necessary to orient the patch 12 with its first surface 14 that has the micro-needles 16 oriented toward the bottom of the housing seating 44 and the third layer 23, possibly associated with the transparent fourth layer 24, oriented in the opposite direction, generally upward, so as to be able to be exposed to the radiation emitted by the emitter/receiver 34. Then, once the excitation is terminated, it is necessary to emit a correlated quantity of fluorescence radiation that is detected by the emitter/receiver 34 and transformed into a mating electric signal which is then processed, as discussed above, by the electronic processing device 36.

In the variant shown in fig. 6, the apparatus 30 is usable directly on the patient's skin, without removing the patch 12 therefrom.

In particular, in this variant the fluorometric measuring chamber 42 is made on an external wall of the shell 32, in a suitable hollow that is provided with selectively openable closing means 50, for example windows or hinged lids, to protect the emitter/receiver 34 housed inside the measuring chamber 42 when not in use, and to allow access thereto so as to perform the fluorometric measuring.

For the purposes of obscuring at least a part of the measuring chamber 42 during the fluorometric reading, the variant provides a screening mean 52, mating in shape with that of the patch 12, for example movable or retractable from the measuring chamber 42 as indicated by arrow G in fig. 6, such as a flexible screening member, bellows or equivalent, which can be removed manually or automatically by means of a reversible elastic mechanism, so as to delimit an obscured space that surrounds the patch 12 laterally during the measuring. With this variant, it is sufficient to open the closing means 50 and to rest the shell 32 on the skin in the zone where the patch 12 has been applied, with the provision of positioning the screening mean 52 around the patch 12. Since it has not been removed from the skin, the latter is in contact with the skin with its first external surface 14 and therefore it is already correctly oriented with the third layer 23, possibly associated with the fourth layer 24, facing toward the emitter/receiver 34. This reciprocal positioning causes the measuring chamber 42 to be completely obscured, so that the fluorometric reading step can be started.

Claims

1. Non-invasive transdermal device for the fluorometric detection of an analyte in a biological fluid, characterized in that it comprises a patch (12) configured to extract a desired quantity of interstitial liquid from the skin of a patient in order to evaluate the level of analyte in the biological fluid, wherein said patch (12) comprises:

- a first external surface (14), to be applied in contact with the skin, provided with a plurality of protruding micro-needles (16) sized to penetrate into the epidermis sufficiently to extract, due to the capillarity effect, the necessary quantity of interstitial liquid from the most external layer of the skin, without reaching the pain receptors under the skin;

- at least an internal fluorescence biosensor (13) to detect the level of analyte in the biological fluid by means of interaction with the interstitial liquid extracted by the micro-needles (16).

2. Device as in claim 1, characterized in that each of the micro-needles (16) has a length between 200 micrometers and 270 micrometers, preferably between 240 micrometers and 260 micrometers, even more preferably between 245 micrometers and 255 micrometers.

3. Device as in claim 1 or 2, characterized in that each micro-needle (16) comprises a hollow lateral casing (60) which has a micro-channel (62) inside and which terminates with a pointed perforation end (64), a lateral aperture (66), being provided on the surface of the lateral casing (60) which puts the internal micro-channel (62) in communication with the external environment.

4. Device as in any claim hereinbefore, characterized in that the fluorescence biosensor (13) comprises a reactive substrate compound specific for said analyte bonded with a fluorescent substance.

5. Device as in claim 4, characterized in that the analyte is the glucose present in the blood and the fluorescence biosensor (13) comprises a polymer bonded with a protein marked with said fluorescent substance.

6. Device as in claim 5, characterized in that the polymer is dextran and the protein is concanavalin A.

7. Device as in any claim hereinbefore, characterized in that the patch (12) is multi-layered and comprises a plurality of layers (21, 22, 23) overlapping each other, of which at least one external layer (21) which has the first external surface (14) on which the micro-needles (16) are provided and another layer (23) which includes the fluorescence biosensor (13).

8. Device as in claim 7, characterized in that the layer (23) which includes the fluorescence biosensor (13) is a dry chemical component which contains the fluorescence biosensor (13), or a wet chemical component which provides a hydrogel matrix (17) in which the fluorescence biosensor (13) is dispersed.

9. Device as in claim 7 or 8, characterized in that the patch (12) also comprises another layer (22) formed by a porous membrane (27) intermediate between the external layer (21) which has the first external surface (14) on which the microneedles (16) are provided and the layer (23) which includes the fluorescence biosensor (13).

10. Device as in claim 9, characterized in that the porous membrane (27) is configured to allow the passage only of molecules of a size less than about 100 - 150 Dalton.

11. Device as in claim 7, 8, 9 or 10, characterized in that the patch (12) comprises another layer (24) made with material transparent to optic radiation, applied on the layer (23) which includes the fluorescence biosensor (13) and a possible fifth support layer (25) that can be peeled off.

12. Fluorometric analysis apparatus which can be associated to a transdermal device (10) as in any claim hereinbefore, characterized in that it includes an external box-like container (32) which comprises a fluorometric measuring chamber (42) to which the device (10) is associated and provided with an emitter/receiver (34) of electromagnetic radiation associated to an electronic processing device (36).

13. Apparatus as in claim 12, characterized in that the measuring chamber (42) is contained inside the box-like container (32) and a sliding tray (40) is provided to receive the device (10), said sliding tray (40) being mobile between an external position and a position completely included in the box-like container (32), inside the measuring chamber (42), so that the sliding tray (40), in its closed position, is positioned above the emitter/receiver (34) so as to take the device (10) into cooperation with the emitter/receiver (34) inside the measuring chamber (42).

14. Apparatus as in claim 12, characterized in that the measuring chamber (42) is made on an external wall of the box-like container (32), closing means (50) being provided to close the measuring chamber (42) and at least a screening mean (52) which can be placed around the device (10) to stop the passage of light radiation toward the device (10).