Drive means for pen-shaped microneedle device

Abstract

Drive means for a microneedle device (21) in pen form, comprising a rotary drive (1) with a rotational axis (1a), an eccentric (2) connected thereto, a needle shaft (10) and a pivoting element (5) which is rotatably mounted on a pivot axis (4), which is connected to the needle shaft (10) and which, during operation, is set into a pivoting movement (7a, 7b) rotating about the pivot axis (4) via an operative connection with the eccentric (2), so that the pivoting movement (7a, 7b) of the pivoting element (5) sets the needle shaft (10) in a lifting movement (9a, 9b) along the rotational axis (1a), characterized in that the operative connection is designed such that the pivoting element (5) and the eccentric (2) are designed and arranged to engage one another, wherein the engagement in both pivoting directions (7a, 7b) forms a positive-locking stop (8a, 8b) which, during operation, ensures a secure Stop (8a, 8b) in both swivel directions (7a, 7b) is ensured.

Description

[0001] The invention relates to drive means for a pen-shaped microneedle device.

[0002] Microneedling devices are used for physical skin treatment. Fine needles with a diameter of 0.1 to approximately 0.5 mm are inserted into the upper layer of the skin (epidermis) to create tiny injuries so small that they do not leave scars. This stimulates skin regeneration, which improves the appearance of scars, pigmentation disorders, wrinkles, and similar skin problems. The micro-injuries created release the skin's own growth factors, stimulate the formation of new collagen fibers and blood vessels, and initiate the influx of fibroblasts. Needle rollers and needle stamps are known for creating these micro-injuries; these allow a large number of needles to be manually inserted into and onto the skin over large areas. Microneedling devices can also be designed like tattooing devices, as these also serve to insert needles into the skin.However, a dye is simultaneously injected into the skin. If injected into the dermis beneath the epidermis, it creates a permanent tattoo. If injected only into the epidermis, it creates permanent makeup that fades over time. In microneedling, the needles are also inserted only into the epidermis, with the insertion depth determining whether the treatment is cosmetic (up to 0.5 mm) or medical (over 0.5 mm).

[0003] One problem with microneedling is that it is painful. The faster the insertion, the less pain. Skin thickness varies in different areas of the body; for example, the skin on the face and hands is generally thinner. It can also vary in firmness, as in scar tissue, which offers more resistance than the surrounding intact skin. Therefore, optimizing the working parameters of microneedling devices, such as precision, freedom from interference, insertion depth, and insertion speed, is a challenge.

[0004] Drive means for a microneedle device are described, for example, in WO 2012 / 077 943 A2. The rotational movement from a transverse drive is converted into a reciprocating movement for the needle shaft via an eccentric running on the drive shaft, which results in the classic L-shape of the microneedle device. However, if the microneedle device is to be designed in a pen shape, the rotational movement must be implemented in the orientation of the drive axis.

[0005] DE 20 2006 013 148 U1 discloses drive means for a pin-shaped microneedle device in which the linear power transmission from rotational to reciprocating motion is achieved by means of a swash plate. This swash plate is connected to an unbalanced bushing rotating with the drive axis, but is decoupled from the rotational movement by a ball bearing. Thus, a connecting rod engaging in a recess in the swash plate is set into a reciprocating motion during the rotational movement of the unbalanced bushing, driving the needle shaft. The stroke is adjusted by adjusting the connecting rod engagement.

[0006] Drive means for a pen-shaped eyebrow tattooing device are known from CN 2 02 236 855 U. Fig. 3 discloses that an eccentric engages an element that can be moved at right angles to the rotational axis. The movable element, in turn, engages a pivoting element that is pivotally mounted and connected via a joint to an angled end of a needle shaft in such a way that, when the eccentric moves the movable element back and forth during operation, the sliding movement causes the pivoting element to pivot about its pivot axis, causing the needle shaft to reciprocate. The design of this operative connection is complex to manufacture due to the large number of components, and the sliding movement causes high friction during operation. Friction results in energy and material wear, which increases the susceptibility to failure.

[0007] The object of the present invention is therefore to provide drive means for a microneedle device in pen form which is easier to manufacture and less wear-resistant in operation.

[0008] This is achieved for drive means of a microneedle device according to the aforementioned prior art in that the operative connection is designed such that the pivoting element and the eccentric are designed and arranged to engage with one another, wherein the engagement in both pivoting directions forms a positive stop which ensures a secure stop in both pivoting directions at all times during operation.

[0009] It makes no difference whether the eccentric engages the pivoting element as a "male" part or the pivoting element as a "male" part in the eccentric. The only decisive factor is that the engagement is designed in such a way that a secure stop is guaranteed at all times in every pivoting direction. This means that the rotational movement during operation is transferred directly from the rotating eccentric to the pivoting element connected to the needle shaft. Compared to the prior art, this design requires one fewer element and generates significantly less friction during the movement sequence because the back and forth movement of a sliding element with corresponding friction surfaces is eliminated. Here, the force is transmitted exclusively through rotational and pivoting movements. This results in a controlled, trouble-free movement sequence that can be converted into a precise lifting movement in both directions.

[0010] An advantageous embodiment provides for the pivoting element and needle shaft to be connected via a connecting rod, with the connections to the connecting rod being designed as pivot joints, so that the needle shaft can be guided linearly during operation during the stroke movement. The pivot joints ensure that the deflection of the pivoting element does not reach the needle shaft, thus achieving a smooth linear movement for the needle shaft that can be easily guided through the surrounding housing.

[0011] An advantageous design of the engagement provides for the eccentric to engage with the pivoting element. This is particularly easy to implement because eccentrics are usually designed as solid bodies. The pivoting element is then advantageously designed to be essentially U-shaped, into which the eccentric engages as a radially symmetrical cylinder. The stops are formed by the U-legs, which are arranged in the pivoting direction. The distance between the U-legs corresponds to the diameter of the eccentric, so that a secure engagement is ensured at all times and in each of the pivoting directions, which correspond to the two stroke movement directions. This ensures precise needle movement in both directions.

[0012] An alternative embodiment provides that the pivoting element engages in the eccentric, wherein the eccentric is expediently designed as a hollow cylinder in order to ensure a secure stop at all times.

[0013] Advantageously, the contact surfaces of the eccentric and pivoting element in the area of ​​the stops are designed as a sliding pair, minimizing frictional forces and thus disruptions in the movement sequence as well as wear. A sliding pair is achieved by using materials with self-lubricating properties for the corresponding contact surfaces. Examples of materials that can be used for this purpose include plastics, metals, or ceramics.

[0014] A preferred arrangement provides for the pivot axis to be spaced apart from the extension of the rotation axis. This allows the needle shaft or the connecting rod connected to the needle shaft to be guided in an extension of the rotation axis. This facilitates the guidance of the stroke movement and ensures a particularly advantageous distribution of forces.

[0015] An alternative arrangement provides for the pivot axis to be positioned as an extension of the rotation axis. This guides the connecting rod laterally.

[0016] An advantageous further development provides for the control of the supply voltage for the drive using pulse width modulation (PWM). This involves sending a voltage pulse with a variable, i.e. controllable, pulse width at a constant frequency and amplitude. Each transmitted voltage pulse is immediately converted into drive power according to its pulse width, which results in excellent controllability of the motor speed and thus the stitch frequency. This allows for particularly precise regulation of the motor speed and thus also particularly fine gradation in the control system. Since the applied voltage is completely converted into rotary motion, energy consumption is also reduced, because the device does not have to constantly regulate down a constantly applied input voltage; instead, only as much voltage is applied as is actually required for the drive and converted into power.

[0017] An advantageous embodiment provides that a control module for pulse width modulation can be connected to the drive, by means of which the setpoint for the motor speed can be determined, and that a sensor for detecting the actual speed of the drive is provided, which sensor is designed and configured such that it continuously transmits the actual speed to the control module during operation, and that the control module has a control module which is designed and configured such that it continuously compares the actual speed with the setpoint during operation and keeps the motor speed constant at the setpoint by adjusting the pulse width of the voltage pulses transmitted to the drive. The sensor continuously detects the actual speed during operation and transmits it to the control module, which compares the value with the entered setpoint.Depending on a determined difference, the control module then adjusts the pulse width of the voltage pulses transmitted to the drive so that a reduced or increased speed compared to the setpoint is brought back to the setpoint. Due to the immediate effect of this pulse adjustment on the drive power, the motor is kept at a constant speed even with varying skin resistance, thus achieving a consistent puncture frequency, regardless of the thickness and / or density of the skin area being treated.

[0018] The invention is explained in more detail with reference to the drawing. Fig. 1a, Fig. 1b, Fig. 1c the inventive principle at a glance based on a variant, Fig. 2a, Fig. 2b different designs in detail, Fig. 3a, Fig. 3b further forms of design in detail and Fig. 4 a schematic diagram for control using pulse width modulation

[0019] The Fig. 1a, Fig. 1b, Fig. 1c illustrates the inventive principle based on the embodiment in which the eccentric 2 engages a U-shaped pivoting element 5. The rotary drive 1, with a rotational axis 1a, is connected on one side to a sensor 12. On the other side, an eccentric 2 is connected to the drive shaft. The pivoting element 5 is mounted on a stationary pivot axis 4 and arranged such that the eccentric 2 engages the pivoting element 5 and the two U-shaped legs form stops 8a and 8b for the eccentric in both pivoting directions 7a, 7b. In this embodiment, the pivoting element 5 is connected to the connecting rod 3 via a pivot joint 6, which in turn is connected to the needle shaft 10 via a pivot joint 11. The needle shaft 10 serves to accommodate the needle module (not shown), which is a disposable item for hygienic reasons and is therefore detachably connected to the needle shaft so that it can be replaced after each use.The secure engagement of the eccentric 2 in the pivoting element 5 is ensured by ensuring that the diameter of the eccentric 2 corresponds to the distance between the U-shaped legs, at least in the area of ​​the stops 8a, 8b. Other designs of the pivoting element are of course possible; it is only important that secure stops 8a, 8b are provided for the eccentric 2 in both pivoting directions 7a, 7b.

[0020] In Fig. 1a, the eccentric 2 is in the position in which the eccentric part of the eccentric 2 points straight in the viewing direction, so that the pivoting element 5 is in its middle position between the two pivoting directions 7a and 7b.

[0021] In Fig. 1b, the eccentric 2 directs the pivoting element 5 around the pivot axis 4 in the pivoting direction 7a, whereby the connecting rod 3 and, together with it, the needle shaft 10 are moved in the direction of the eccentric 2. This corresponds to the stroke movement direction 9a, with which the needle (not shown) is pulled out of the skin on the needle shaft 10.

[0022] In Fig. 1c, the pivoting element 5 is deflected by the eccentric 2 in the other pivoting direction 7b, whereby the connecting rod 3 and, with it, the needle shaft 10 are moved away from the eccentric 2, which corresponds to the stroke direction 9b with which the needle (not shown) is pierced into the skin on the needle shaft 10. Due to the pivoting of the pivoting element 5, the connecting rod 3 is slightly deflected in the pivoting directions 7a, 7b during the stroke movement exerted on it in the directions 9a, 9b. This deflection is absorbed by the pivot joint 11, with which the connecting rod is connected to the needle shaft 10, so that the needle shaft can be guided linearly in the housing (not shown) without any deflection.

[0023] Fig. 2a, Fig. 2b show two variants of the embodiment, in which the pivot axis 4 is arranged at a distance from the extended rotation axis 1a. In this embodiment, the pivot element 5 is connected via a pivot joint 6 to a connecting rod 3, which is arranged as an extension of the rotation axis 1a. In this embodiment, it would also be possible to connect the needle shaft 10 directly to the pivot element 5 via the pivot joint 6; however, the connection via a connecting rod is advantageous in order to enable uninterrupted linear movement of the needle shaft. Fig. 2a, the eccentric is designed as a “male”, which means that it engages with the pivoting element 5. In Fig. 2b, the eccentric 2 is designed as a “female” so that the pivoting element 5 engages in the eccentric 2.

[0024] Particularly advantageous for this purpose is the design of the eccentric 2 as a hollow cylinder, as indicated in the figure, but other designs are also conceivable which ensure that the engagement is reliably guaranteed in every position.

[0025] Fig. 3a, Fig. 3b show two variants of another embodiment, in which the pivot axis 4 is arranged in extension of the rotation axis 1a. In Fig. 3a is, as in Fig. 2a, the eccentric 2 is designed as a “male” which engages in the pivoting element 5, while in Fig. 3b, the eccentric 2 is designed as a "female" one. In this embodiment, the arrangement of a connecting rod 3 between the pivoting element 5 and the needle shaft 10 is necessary to achieve good linear guidance of the needle shaft 10 (not shown here). The needle shaft (not shown here) is guided by the housing (not shown), which completely surrounds the needle shaft 10.

[0026] Fig. Figure 4 shows a schematic diagram of the control by means of pulse width modulation of the control voltage. It shows a microneedle device 21, indicating the Fig.1a to 1c, wherein a connection 24, indicated here as a cable, exists between the sensor 12 and a control module 22, so that on the one hand the target values ​​for the speed specified in the control module 22 are transmitted to the drive 1, and on the other hand the actual speed values ​​determined by the sensor 12 can be transmitted by the sensor 12 to the control module 22. A controller 23 is arranged in the control module 22, which compares the target value with the actual value and can either display determined values ​​and / or deviations or convert them into automatic control. Only the needles (not shown) emerge from the needle outlet opening 21a, which are connected to the needle shaft as a needle module. The projection of the needles beyond the needle outlet opening 21a in the stroke direction represents the piercing depth or the piercing stroke.

[0027] All illustrated embodiments serve merely to illustrate the inventive principle and are not intended to be limited to the examples shown. Further embodiments within the scope of the claimed subject matter are, of course, also encompassed by the inventive concept. List of reference symbols 1 rotary drive 1a Rotation axis 2 eccentrics 3 connecting rods 4 swivel axis 5 Swivel element 6 Swivel joint 7a, 7b Arrows: Panning directions 8a, 8b stops 9a, 9b Arrows: stroke movement directions 10 needle shaft 11 Swivel joint 12 Sensor 21 Microneedle device 21a Needle exit opening 22 Control module 23 Control module 24 Connection (cable)

Claims

[1] Drive means for a microneedle device (21) in pen form, comprising a rotary drive (1) with a rotation axis (1a), an eccentric (2) connected thereto, a needle shaft (10) and a pivoting element (5) which is rotatably mounted on a pivot axis (4), which is connected to the needle shaft (10) and which, during operation, is set into a pivoting movement (7a, 7b) rotating about the pivot axis (4) via an operative connection with the eccentric (2), so that the pivoting movement (7a, 7b) of the pivoting element (5) sets the needle shaft (10) in a lifting movement (9a, 9b) along the rotation axis (1a), characterized by that the operative connection is designed such that the pivoting element (5) and eccentric (2) are designed and arranged to engage one another, the engagement in both pivoting directions (7a, 7b) forming a positive-locking stop (8a, 8b) which ensures a secure stop (8a, 8b) in both pivoting directions (7a, 7b) at all times during operation. [2] Drive means according to claim 1, characterized by that the pivoting element (5) and needle shaft (10) are connected via a connecting rod (3), wherein the connections to the connecting rod (3) are designed as pivot joints (6, 11), so that in operation the needle shaft (10) can be guided linearly during the lifting movement (9a, 9b). [3] Drive means according to one of the preceding claims, characterized by that the eccentric (2) engages in the swivel element (5). [4] Drive means according to claim 3, characterized by that the swivel element (5) has U-legs. [5] Drive means according to one of claims 1 or 2, characterized by that the pivoting element (5) engages in the eccentric (2), wherein the eccentric (2) is designed as a hollow cylinder. [6] Drive means according to one of the preceding claims, characterized by that the contact surfaces of the eccentric (2) and the pivoting element (5) in the area of ​​the stops (8a, 8b) are designed as a sliding pair. [7] Drive means according to one of the preceding claims, characterized by that the pivot axis (4) is arranged at a distance from the extended rotation axis (1a). [8] Drive means according to one of the preceding claims, characterized by that the pivot axis (4) is arranged in extension of the rotation axis (1a). [9] Drive means according to one of the preceding claims, characterized by that the supply voltage for the drive (1) is controlled by pulse width modulation. [10] Drive means according to claim 9, characterized bythat a control module (22) for pulse width modulation can be connected to the drive (1), by means of which the target value of the motor speed can be determined, and that a sensor (12) for detecting the actual speed of the drive (1) is provided, which sensor is designed and set up such that it continuously transmits the actual speed to the control module (22) during operation, and that the control module (22) has a control module (23) which is designed and set up such that it continuously compares the actual speed with the target value during operation and keeps the motor speed constant at the target value by adjusting the pulse width of the voltage pulses transmitted to the drive (1).

Images