GB2493176A - Microneedle device - Google Patents

Abstract

The device for perforation of the skin or other biological barrier comprises a number of plates 31 with microneedles on one edge with skin contact elements 33 adjacent to the plates. In use each plate is driven repeatedly up and down at high speed, either all together or in a sequence such as a wave pattern. The drive means may be an electric motor attached to a cam 35 which either passes through or touches the tops of the plates. The microneedle array may be formed by etching. The skin contact elements may be formed from a block or may be spring loaded or mechanically driven to produce a downward force on the skin.

Description

Device for penetration of skin Microneedles are an emerging method for drug delivery, but have also found a use in aesthetic treatment of the skin. The major product in use for skin treatment is the microneedle roller, a device that has around 200 needles arranged on a cylinder or disk that creates holes in the skin to a variable depth.

There are several problems with this device for the aesthetic practitioner and the patient. Firstly it is practically impossible to achieve either a reproducible depth of penetration or number of holes per cm2. Secondly, the process is time consuming and physically tiring for the practitioner. Thirdly, the rotational component of the penetration of the needles on the disk tends to cause a lot of damage to the skin on entry and exit. Fourthly, in order the withstand the shear forces on the roller, the needles must be thicker than microneedles used in drug delivery, and must be very long because of the deformation of the skin away from the needles.

From the patient's point of view, the long and thick needles cause pain, and being able to see the needles causes some distress, together with a disconcerting popping feel and noise as the needles break through the skin.

As mentioned above, the sort of high density microneedle arrays, their attendant materials and methodologies, used in drug delivery applications have not been transferred to the aesthetic sphere, because of the need to get much deeper penetration to stimulate collagen synthesis, and the need to repeatedly use the needles across the whole face or other area of the body. Microneedle stamps have been used, both manually and using an automated piston. These have typically involved relatively few lancet type needles embedded in a single solid mass such as a resin, with the needles spaced out to a large degree to overcome the bed of nails effect.

In the sphere of Drug delivery, microneedle devices have been described that attempt to stretch the skin or hold it in place during penetration, in order to increase reproducibility, but these have either been a perforated layer through which the needles poke, which is difficult to manufacture and assemble, or these skin holding and stretching means have been limited to the outside of the array, leading to good penetration on the outside, but poor penetration in the centre of the array.

The invention described herein solves the various problems of getting reproducible depth of penetration, production of a high density, accurate array of holes, reduction of pain and forces perceived by the patient, using true microneedles of a smaller profile than those previously used in aesthetic treatment.

It is understood that in this text the word microneedle or microneedles is used, but this could equally refer to microblades, spikes or any other sharp and penetrating shape.

Although the application refers to penetration of skin, it is understood that this device can be used for any biological barrier.

In a first aspect of the device, there is provided a device comprising: A plurality of independent thin plates or sheets with microneedles on at least one edge A means of driving these plates rapidly up and down so as to penetrate the skin A means of holding the skin in position whilst the needle arrays are approximated to the skin and then lowered thereon, such means being located close to each individual microneedle holding plate.

In one embodiment of the device, the thin plates are metal, and the microneedles are formed from it using an etching process to remove material, leaving sharp spikes.

In another embodiment, the thin plates are driven up and down by a cam, either passing through the plates or touching the top of the plates.

In another embodiment, the skin holding means are also plates or strips that are located between the microneedle plates, which we have found advantageous for enabling good penetration. Preferably) these are spring loaded to push onto the skin. In another embodiment, these can also be driven by an external motor means to push down the skin, and in one embodiment this movement can be in opposition to the direction of the needles.

In a preferred embodiment, the microneedle plates are actuated sequentially, so that at any point, some of the needle arrays are exiting the skin whilst others are entering, reducing the net force on the body. We have found that this enhances penetration of the needles. In one embodiment, this actuation is such that adjacent needle plates are moving in opposition, or a wave movement can be produced, for instance where movement proceeds from one side of the device to the other.

We have found that high speed is greatly advantageous to penetration, with speeds of 50-600Hz being effective to achieve reproducible and the deep skin damage required for aesthetic treatment.

In another embodiment, the plates are fitted into a block of material with slots cut into it, so that the skin contact part comprises the block of material. This material may be a low friction material such as PTFE or can be any other material including but not limited to metals, polymers and ceramics.

Drawings Figure 1 shows an example of a microneedle plate (1) with microneedles on one edge [2]. There is also a space for a cam at the opposite edge. Figure 2 shows a skin contact plate (3) with arms that can be attached to a spring. Figure 3 shows alternating rows of skin contact plates (33] and microneedle plates (31). A drive element (34] passes through the plates, with a cam (35) to push the plate up and down.