Lancet, in particular for use in the field of allergy testing

Abstract

The invention relates to a lancet (10) extending along a longitudinal axis (X) and comprising a head (11) that is suitable for being fixedly or detachably connected to, or formed as one piece with, a gripping means (12); the head comprises a base comprising an upper face forming a stop; the head also comprises at least two tips (13) extending from the upper face of the base in the direction of the longitudinal axis, each tip comprising a concave surface (13a), the concavity of which is oriented in the direction of the longitudinal axis, the tips being distributed around the longitudinal axis in such a way that the concave surfaces of the tips together define a volume capable of capable of retaining, by capillary action, a quantity of test liquid; the head also comprises, between the tips, a cavity formed in the base. The invention is intended to be used in the field of allergy testing.

Description

[0001] DESCRIPTION

[0002] Title of the invention: lancet, in particular for allergy tests

[0003] Technical field

[0004] The invention relates to the field of lancets for microscarification of the skin, for administering a reproducible quantity of liquid at a given depth, for skin tests such as allergy tests, or for vaccination.

[0005] Allergy testing involves bringing an allergen solution into contact with cells under the surface layer (the epidermis) of a patient's skin, an epidermis that is approximately 0.8 to 1.6 mm thick. This involves breaking the skin without causing bleeding, which involves piercing the epidermis and penetrating the skin, without penetrating the dermis too deeply.

[0006] US5632728 describes a lancet comprising a handle terminating in two sharp points spaced close enough that the points form a small hole in the skin when the needle is simultaneously rotated and pressed against the skin. The spacing also causes liquid to adhere to and between the points when the tip of the lancet is dipped into skin test fluid or vaccination fluid. The rotation causes frictional breaking of the skin which has the disadvantage of activating mast cells in the skin; the characteristic signs of inflammation can thus be triggered by friction regardless of the presence of allergenic fluid; this rotation technique is thus likely to generate false positives or bleeding among allergy test results.Furthermore, it is observed in practice that, when pressing on the lancet, the liquid which adheres to and between the tips is ejected on either side of the tips so that it is difficult to control the quantity of liquid actually injected under the skin, especially during successive tests. Finally, since the head of the lancet does not have a stop or stopping means, it is difficult to control the depth of penetration of the lancet, which can go beyond the thickness of the epidermis.

[0007] From document FR2535602, a lancet is also known, a head of which comprises a microscarification tip comprising a cavity capable of containing a quantity of liquid. The shoulder at the foot of the tip forms a stop which makes it possible to control the depth of penetration of the tip. However, since the tip of the lancet is blunt, pressing the tip on the skin is not sufficient to break through, so that a 90° rotation of the lancet is necessary in addition to pressing on the skin to break through the skin by mechanical friction before allowing the liquid to penetrate under the epidermis. Furthermore, when the tip penetrates the skin, the liquid contained in the cavity tends to remain in the cavity, so that it is difficult to inject a precise quantity of liquid into the skin, which is homogeneous over several successive tests.

[0008] The invention provides a novel lancet providing a solution to one or more of the technical problems of the known lancets described above.

[0009] The lancet (10) according to the invention extends along a longitudinal axis (X) and comprises a head (11) capable of being connected in a fixed, detachable or single-piece manner to a gripping means (12); said head comprises a base (14) comprising an upper face (14a) forming a stop, said head also comprising at least two tips (13) extending from the surface of the base in the direction of the longitudinal axis; each tip comprises a concave surface (13a) of which one concavity is oriented towards the longitudinal axis; the tips are distributed around the longitudinal axis so that the concave surfaces of the tips together define a volume capable of retaining by capillarity a reproducible quantity of test liquid; the head also comprises, between the tips, a cup (15) hollowed out in the base.

[0010] The tips form blades capable of penetrating the skin. The upper surface of the base forms a stop limiting skin penetration. The concave shape of the tips, oriented towards the longitudinal axis, allows the liquid to be retained between the tips by capillarity when the lancet is immersed in a liquid. The volume between the tips is constant so that the quantity of liquid likely to be loaded onto the lancet is well defined and uniform from one lancet to another. In addition, when the lancet is pressed onto the skin and the tips are pushed into the skin, all of the liquid initially between the tips is actually applied to the skin so that the quantity of liquid administered is reproducible.Finally, when the lancet is pressed against the skin, the liquid contained between the tips and held by capillarity between the tips is pushed towards the cup; the air contained in the cup is compressed under the pressure of the liquid entering the cup and in reaction exerts a pressure on the liquid capable of pushing the liquid towards the ends of the tips of the lancet and the perforations in the skin made by the ends of the tips. The application of the liquid to the skin is thus facilitated.

[0011] The lancet can include three tips for optimal containment of the liquid between the tips.

[0012] According to one embodiment, the cup comprises a side wall extending in the extension of the concave surfaces of the tips. The cup thus forms a blind capillary in the extension of the tips.

[0013] The upper face (14a) of the base may be convex, for example cone-shaped. Excess liquid which is not between the tips but on the upper face forming stops is thus expelled more easily when the lancet is pressed against the skin. The tips may be distributed so that the concavities of the tips together define a substantially tubular volume of circular section (C) and extending along the longitudinal axis. The pressure exerted by the liquid is thus distributed as well as possible on the concave surfaces of the tips and the retention of the liquid by capillarity between the tips is optimal.

[0014] According to one embodiment of the lancet, an edge (13b) of a concave surface of a tip (13) is sharp. The tip of the lancet thus penetrates the skin by incising and not by tearing, as is the case with a blunt tool. The pressure to be applied is thus less and the effect on the skin is less aggressive. In addition, it is not necessary to turn the lancet while pressing to make the tips penetrate the skin. The user's action is thus easier and less traumatic for the skin and for the patient. Finally, when the skin is broken, the mast cells are thus activated only in reaction to the injected liquid, and not in reaction to irritation by friction. The risk of a false positive result is thus limited.

[0015] The edge (13b) of a concave surface is preferably curved. A curved edge further facilitates the penetration of the tip into the skin.

[0016] The tips may have a generally conical shape with a pointed end to further facilitate penetration of the tip into the skin, without rotation of the lancet.

[0017] Brief

[0018] The invention will be better understood, and other characteristics and advantages of the invention will appear in the light of the following description of examples of implementations of the invention. These examples are given without limitation. The description should be read in relation to the appended drawings in which:

[0019] - figure 1 shows a perspective view of an exemplary embodiment of a lancet according to the invention,

[0020] - figure 2 shows a front view of the lancet of figure 1,

[0021] - Figure 3 shows a detailed view of the head of the lancet of Figure 1.

[0022] Throughout the description of this patent application, the following concepts and expressions are used:

[0023] - by "longitudinal" axis, we mean an axis extending substantially along a large length of the lancet (axis X shown in the figures).

[0024] Finally, the dimensions and more broadly all the numerical values ​​in the description are orders of magnitude given purely for information purposes; they do not limit the scope of the invention and are naturally to be adapted according to the embodiments and applications envisaged. Detailed description of embodiments of the invention

[0025] As previously stated, the invention relates to a lancet (10). Developed in particular for allergy tests, it can also be used for other medical practices, in particular any type of skin test, for vaccinations, etc.

[0026] The lancet extends along a longitudinal axis (X) and comprises a head (11) connected to a gripping means 12; in the figures, the head is made in one piece with the gripping means; alternatively, the head can be connected to the gripping means in a fixed or detachable manner. For purely indicative purposes, and for the example shown in the figures, the gripping means has a great length of the order of 15 to 35 mm; the head has a substantially cylindrical or frustoconical shape, with a diameter of the order of 2 to 5 mm and a height of the order of 3 to 6 mm.

[0027] According to the invention, the head 11 comprises a base (14) comprising an upper face (14a) forming a stop; the head also comprises at least two points (13) extending from the upper face of the base in the direction of the longitudinal axis X; each point comprises a concave surface (13a) of which a concavity is oriented towards the longitudinal axis and the points are distributed around the longitudinal axis so that the concave surfaces of the points together define a volume capable of retaining by capillarity a quantity of test liquid.

[0028] Tests show that the capillary effect is effective when two tips are present. However, for a better distribution of the liquid pressure forces on the tip surfaces, a design with three tips is preferred.

[0029] On the lancet shown in the figures, the tips 13 are distributed so that the concave surfaces of the tips, facing the longitudinal axis, together define a substantially tubular, cylindrical volume, of circular section C and extending along the longitudinal axis. The pressure of the liquid exerted on the concave surfaces 13a is thus uniformly distributed between the tips.

[0030] A diameter of the circular section C is between 1 and 2 mm. It can be chosen in particular according to the dosages of the liquids to be used, the intrinsic properties of the liquids such as viscosity. The diameter of the circular section can also be chosen taking into account a surface condition of the concave surfaces 13a of the tips 13, and more precisely a tendency of the surface condition to promote capillarity. Indeed, a slightly matte or rough surface condition will retain liquids better than a perfectly smooth surface condition; a matte or rough surface condition will thus be preferred for producing lancets suitable for larger quantities of liquids.The diameter of the circular section can be chosen from tests, taking into account Jurin's law, which gives the height of rise or depression of a liquid in a capillary tube as a function of the diameter of the latter, the electrostatic charges linked to the material and the viscosity of the liquid. According to another aspect of the invention, the head (11) of the lancet comprises, between the tips, a cup (15) hollowed out in the base of the lancet; the cup follows the capillary made at the junction of the tips.When the lancet is pressed against the skin, the liquid contained between the points is pushed towards the cup, the air contained in the cup is compressed by the liquid and, in return, exerts an increasingly strong pressure on the liquid as the points penetrate the skin; the liquid, channeled by the points, is thus pushed towards the skin and penetrates it in a reproducible manner for the same pressure exerted by the practitioner's hand. The cup thus forms a pressure chamber.

[0031] In the example shown, the cup comprises a side wall extending in line with the concave surfaces of the tips which meet at their base. The cup thus forms a blind capillary in line with the tips, which facilitates the rise of liquid in the cup when the lancet is pressed on the skin. The cup is of course closed to retain the air. A depth of the cup can be adjusted according to the desired pressure effect.

[0032] According to another aspect of the invention, an edge 13b of a concave surface of a tip 13 is sharp. And preferably, all edges of all the tips are sharp. The presence of sharp edges at the edge of the concave surfaces further improves the retention of the liquid. In addition, the sharp effect of the edges facilitates the sectioning of the skin and the penetration of the tips under the epidermis, without unnecessary irritation by friction.

[0033] The edge 13b of a concave surface 13 may be curved to further facilitate penetration of the tip under the skin.

[0034] In one example (not shown), the tips have a substantially three-sided pyramidal shape, with two substantially planar external surfaces and the surface 13a facing the longitudinal axis X; the section of a tip in a plane perpendicular to the longitudinal axis thus has a triangular shape. Alternatively, as shown in the figures, the tips can be made with a substantially conical shape, with a partial conical external surface connected to the concave surface 13a; the section of a tip in a plane perpendicular to the longitudinal axis thus has a crescent moon shape. Other shapes can still be envisaged, the essential being the presence of a concave surface 13a facing the longitudinal axis to retain the liquid. Also, the end of the tips is preferably pointed, and not blunt, to facilitate the penetration of the tips into the skin. A dimension of a base of the tips is of the order of 0.2 to 0.8 mm.In the specific context of the allergy test known as the "prick test", the points have a height of around 0.8 to 1.6 mm, and the end face of the head serves as a stop preventing the points from penetrating too deeply into the dermis.

[0035] The means 12 for gripping the lancet is, in the example shown in the figures, made in one piece with the head 11. It is here flat and formed of a hollow frame allowing the pads of the fingers to come into contact and thus improve the gripping of the lancet and its handling. The gripping means must have sufficient mechanical resistance to pressure along its longitudinal axis, but does not need significant torsional resistance in a transverse plane since the lancet is used without rotation. The shape of the gripping means is optimized taking into account in particular these aspects of mechanical resistance and effective gripping.

[0036] In yet another aspect, the lancet according to the invention is made of plastic, a material which is less impressive to patients, especially young patients. It can be produced by molding, for large-scale production with precise dimensions and low disparity.

[0037] Preferably, for environmental reasons, it can be made of bioplastic.

[0038] The lancet according to the invention can be used according to several techniques. According to a first technique, used mainly in Europe, a drop of allergen solution is placed on the skin and the lancet is used to pass through the drop and prick the skin. According to a second technique, more used in Anglo-Saxon countries, the lancet is dipped in a liquid, a predefined quantity of liquid is thus loaded into the predefined volume by the tips of the lancet, the liquid being lodged and pressed against the concave surfaces; the lancet loaded with liquid is then applied to the skin. According to a third technique, a native food is placed on the skin with the tip. In all cases, when the lancet loaded with liquid or food is pressed against the skin, the liquid or food is pressed against the concave shapes of the surfaces 13a of the tips which retain it by capillarity.

[0039] The lancet according to the invention is used only in translation; its optimized structure makes rotation of the lancet unnecessary to penetrate the liquid into the skin.

Claims

DEMANDS 1. Lancet (10), particularly for allergy tests, said lancet extending along a longitudinal axis (X) and comprising a head (11) capable of being fixedly, detachably or as a single unit connected to a grasping means (12), said head comprising a base (14) comprising an upper face (14a) forming a stop, said head also comprising at least two points (13) extending from the upper face of the base in the direction of the longitudinal axis, each point comprising a concave surface (13a) of which a concavity is oriented towards the longitudinal axis, the points being distributed around the longitudinal axis so that the concave surfaces of the points together define a volume capable of retaining by capillary action a quantity of test liquid, the head also comprising, between the points, a cup (15) hollowed out in the base.

2. Lancet according to claim 1 in which the cup comprises a lateral wall extending in the continuation of the concave surfaces of the points.

3. Lancet according to any one of claims 1 to 2 wherein the upper face (14a) of the base is convex.

4. Lancet according to any one of claims 1 to 3 wherein the head comprises three points.

5. Lancet according to any one of the preceding claims wherein the points are distributed so that the concave surfaces (13a) of the points together define a substantially tubular volume of circular cross-section (C) and extending along the longitudinal axis.

6. Lancet according to claim 5 wherein the diameter of the circular section is a function of a quality of capillarity of a surface condition of the surfaces (13a) of the tips (13).

7. Lancet according to any one of the preceding claims wherein an edge (13b) of a concave surface of a point (13) is sharp.

8. Lancet according to any one of the preceding claims wherein the edge (13b) of a concave surface is curved.

9. Lancet according to any one of the preceding claims, wherein the points have a general conical or pyramidal shape, with a pointed end.

10. Lancet according to one of the preceding claims made of bioplastic.

11. Lancet according to any one of the preceding claims in which the gripping means is flat.

Images