NL2020030B1

NL2020030B1 - Needle module for puncturing skin

Info

Publication number: NL2020030B1
Application number: NL2020030A
Authority: NL
Inventors: Werner François Kortenhorst Roland
Original assignee: Medical Prec B V
Priority date: 2017-12-06
Filing date: 2017-12-06
Publication date: 2019-06-18

Abstract

Needle module for puncturing skin in a reciprocal manner, wherein the needle module comprises a needle unit, a housing and a biasing mechanism, wherein the needle unit comprises a needle, 5 wherein said needle unit is movable with respect to said housing between an extended position wherein a distal end of the needle extends from a distal end of said housing and a retracted position wherein the distal end of the needle is positioned within the housing, wherein the biasing mechanism is arranged for urging the needle unit towards the retracted position, wherein the needle module further comprises a limiting mechanism, wherein the limiting mechanism is arranged for 10 limiting the relative movement of the needle unit out of the distal end of the housing to a maximum extension distance when moving towards the extended position, wherein said maximum extension distance is 1,5 mm or less.

Description

Needle module for puncturing skin

The present invention relates to a needle module for puncturing skin. The invention further relates to a method for introducing ink in the human skin.

In radiation therapy, or simply radiotherapy, a patient is typically locally subjected to a radiation beam to control or kill malignant cells. It is important that these beams are directed as accurately as possible onto the target to on the one hand ensure optimal therapy of these malignant cells and to on the other hand minimize damage lo surrounding tissue upon exposure to the radiation beam.

To properly direct the radiation beams to the tissue as pre-operatively planned, it is known to apply small skin marks on the patient which can be used to automatically direct and align the beams as planned, for instance based on CT-scans of the patient. As radiation therapy typically involves subjecting the target to radiation beams repeatedly over time, sometimes several months, these marks need to remain during the course of therapy to ensure continued proper alignment. It is therefore known to introduce ink into the skin of the patient as skin mark.

Typically, for applying these marks, a small knife or scalpel is used. This knife is dipped in ink and subsequently introduced into the patient’s skin. This can be a painful process, in particular in regions on the patient with superficial bone structures such as the thorax. Further, dipping the ink takes time and may result in accidental drips of ink, while at the same time accidental punctures due to the exposed knife are a risk.

Device for introducing ink in skin, for instance needle modules for puncturing skin in a reciprocal motion in accordance with the preamble of claim 1, are as such known from the field of tattooing or permanent makeup. Permanent marks are typically however not preferred by patients.

It is a goal of the present invention, next to other goals, to provide an improved and/or more efficient needle module for puncturing a skin wherein at least one of the above mentioned problems is at least partially alleviated.

This goal, amongst other goals, is met by a method according to appended claim 1. More specifically, this goal, amongst other goals, is met by a needle module for puncturing skin in a reciprocal manner, wherein the needle module comprises a needle unit, a housing and a biasing mechanism, wherein the needle unit comprises a needle, wherein said needle unit is movable with respect to said housing between an extended position wherein a distal end of the needle extends from a distal end of said housing and a retracted position wherein the distal end of the needle is positioned within the housing, wherein the biasing mechanism is arranged for urging the needle unit towards the retracted position, wherein the needle module further comprises a limiting mechanism, wherein the limiting mechanism is arranged for limiting the relative movement of the needle unit out of the distal end of the housing to a maximum extension distance when moving towards the extended position, wherein said maximum extension distance is 1,5 mm or less.

According to the invention, the needle unit is prevented to extend further from the housing than the maximum extension distance. This limits the insertion depth of the needle unit, more specifically the sharp distal end thereof, in the patient’s skin to the maximum extension distance. The maximum extension distance may thus be defined as the maximum distance between the distal end of the needle unit and the distal end of the housing, from which the distal end preferably extends

Preferably, the maximum extension distance is set to such a distance, that the needle unit, and therewith any ink, is only introduced in the epidermis of the patient’s skin. Other than for instance in the field of tattooing, where the ink is introduced in the tissue underlying the epidermis, this will result in a non-permanent mark. It was however found that the superficial marks as applied using the needle module of the current invention remain sufficiently long to allow continued proper alignment during the course of radiotherapy.

The thickness of the layers of skin may vary between patients. Preferably, said maximum extension distance is 1,5 mm or less, even more preferably 1,2 mm or less, even more preferably 1,0 mm or less. The lower limit is defined such that the ink is introduced sufficiently deep in the skin and may for instance be 0,1 mm, preferably 0,2 mm. A preferred working range is between approximately 0,2 mm and approximately 0,8 mm.

Limiting the maximum extension further improves the safety of the needle module in use, which is, other than for instance in the field of tattooing and permanent makeup, of paramount importance in view of safety and conformity to medical safety standards.

According to a preferred embodiment, the limiting mechanism comprises mutually cooperating stop surfaces for limiting the relative movement of the needle unit and the housing. This provides efficient blocking of any further movement of the needle unit from the housing beyond the maximum extension distance. An efficient limiting mechanism is obtained if interior of the housing is arranged with protrusions and /or recesses for cooperating with protrusions arranged on the exterior of the needle unit.

Typically, a needle module of the kind according to the invention is coupled to a driving device which is provided with a driving rod which is driven, for instance by a suitable motor, in a reciprocal manner back and forth. Such a driving rod then engages the needle unit, thereby pushing the needle unit towards an extended position such that it extends from the housing. To urge the needle unit back upon withdrawal of the driving rod, the biasing mechanism then moves the needle unit back into the housing, i.e. towards the retracted position.

The needle unit is preferably arranged to move only along the longitudinal axis with respect to the housing. A rectilinear, reciprocal movement of the needle unit reduces any pain upon insertion of the needle unit in the patient’s skin. To guide the needle unit in its rectilinear movement, it is preferred if a stop surface is substantially ring-shaped. For instance a ring-shaped stop surface may be arranged in the housing, through the opening of which the needle unit may be movable. The needle unit may then be provided with a cooperating stop surface, abutting the annular stop surface of the housing, thereby defining the maximum extension distance. These stop surfaces, or limiting mechanism more generally, then guide the needle unit with respect to the housing for ensuring in a rectilinear movement between the extended position and retracted position

The biasing mechanism, for instance in the form of a spring or other elastic element, is preferably arranged to urge the needle unit back in the housing, for instance towards the retracted position.

The biasing mechanism may be arranged between the needle unit and the housing to induce such a biasing force. In the case of a spring as biasing mechanism for instance, such a spring may be arranged between suitable protrusions arranged in the housing and the needle unit. As an alternative, an elastic element, for instance an elastic tubular member, may be fixed between the needle unit and the housing, wherein upon movement of the needle unit towards the extended position, the elastic member is elongated, thereby urging the needle unit backwardly when moving towards the retracted position.

According to a further preferred embodiment, the biasing mechanism engages the needle unit at a first location and wherein the needle unit is provided with a stop surface at a location at a distance from said first location. This separates the biasing means and the limiting mechanism, ensuring in a proper working of both of the mechanisms separately.

Preferably, the limiting mechanism is arranged to limit the movement of the needle unit with respect to the housing to such a distance, in which the biasing mechanism is not yet at its maximum relative movement. The biasing mechanism may for instance comprise a spring, against which the driving rod of a driving element works for moving the needle unit out of the housing.

The limiting mechanism is then preferably arranged such that the biasing mechanism has not yet reached its end limit. For the case of the spring for instance, there may still be room between the windings of the spring. For the example of another elastic element, said elastic element may not yet be extended up to its final limits.

As an alternative, the maximum extension distance may be determined by the working range of the biasing means. Thus, according to a further preferred embodiment, the limiting mechanism is at least partially formed by the biasing mechanism, wherein the biasing mechanism is arranged for limiting the relative movement of the needle unit out of the distal end of the housing to said maximum extension distance. In this alternative, the maximum extension distance is determined by the biasing mechanism, i.e. the biasing mechanism limits the extension of the needle unit from the housing to the maximum extension distance. In other words, the biasing mechanism comprises, or forms, the limiting mechanism, such that, in the extended position, the biasing mechanism is at an end position.

According to a further preferred embodiment, the housing comprises a main housing part and a removable distal housing part. Such a module is easier to manufacture. Preferably, the main housing part and the distal housing part can be interconnected using a suitable removable interconnection, for instance a snap fit connection. It is hereby preferred if the limiting mechanism is at least partially arranged in the main housing part. This prevents accidental loosening of the distal housing part.

In order to improve the guiding action as already described above, it is then preferred if the main housing comprises a stop surface at or near the distal end. This improves the guiding action of the limiting mechanism as explained above as guiding the needle unit at the most distal part reduces any deflections of the more distal end of the needle unit.

As mentioned above, in particular the field of medical devices, safety plays an important role. In medical devices such as the needle module according to the invention, any risk to the use must be minimized. Therefore, according to a further aspect of the present invention, in the retracted position, the proximal end of the needle extends in the housing. As mentioned above, the proximal end of the needle unit is in use typically engaged by a driving rod of a driving device for pushing the distal end of the needle unit out of the housing. By providing a needle module wherein said proximal end is retained in the housing, and is preferably not accessible by hand from the outside of the housing, any accidental movement of distal end the needle unit out of the housing is prevented. This improves the safety in the resting or retracted position, that is when the device is not in use.

Preferably, the housing is substantially cylindrical, wherein the needle unit is moveable within said cylindrical housing. The housing preferably has a length larger than the length of the needle unit, such that the needle unit can be completely received in said housing. Only upon coupling for instance a driving device, which is provided with a suitable driving rod which can be received in the proximal opening of the housing, the needle unit can be moved out of the housing.

By limiting on the one hand the maximum extension of the distal end of the needle unit and on the other hand preventing accidental punctures by ensuring that, in the retracted position, the proximal end of the needle extends in the housing, a needle unit which is safe to use is obtained. It should however be mentioned that the retention of the proximal end of the needle unit in the housing may also be applied to needle modules without a limiting mechanism as mentioned above or whereby the limiting mechanism allows for larger displacements than as mentioned before.

According to a preferred embodiment, the limiting mechanism is further arranged for limiting, in the retracted position, a displacement of the proximal end of the needle, such that the proximal end of the needle is retained in the housing. Suitable cooperating protrusions may again be provided to prevent any proximal movement of the needle unit from the housing. Also here, movement in the distal direction may be limited by the biasing means. The biasing mechanism may hereto be further arranged for retaining the proximal end of the needle in the housing.

Applying the skin marks using for instance the knife as described above takes time, as dipping the knife in a suitable coloring agent such as ink takes time. Ink in excess on the knife may further result in ink stains. In needle modules which are used in the field of tattooing or permanent makeup, the needle unit may comprise a plurality of needles in the needle unit. Although the risk of dripping is reduced using such a configuration, dipping the needle module, particularly the distal end of the needle unit, in the coloring agent still takes time.

Therefore, in a further improved needle module according to the invention, the housing is provided with a reservoir containing a coloring agent, such as ink, for introduction in said skin. As the coloring agent to be used is already available within the needle module, dipping said needle module in ink is no longer required. This further improves the process for applying a skin mark.

The coloring agent, or simply ink, is an agent which is suitable to be introduced in the human or animal skin. Preferably, the coloring agent is non-toxic and/or dermatologic neutral.

Preferably, the reservoir contains less than 0,3 ml of coloring agent, more preferably less than 0,1 ml. Other than for instance in the field of tattooing or permanent makeup, this is sufficient to apply the needed skin marks.

The reservoir is arranged for cooperation with the needle unit, in particular the distal end thereof, such that the coloring agent can be introduced in the patient’s skin. To this end, it is preferred if the reservoir is arranged at or near the distal end of the housing. In case a two-piece housing for the needle module is used, comprising a proximal main housing part and a removable distal housing part, it is preferred if the distal housing part is provided with the reservoir. The distal housing part with reservoir can then be manufactured efficiently or even replaced if required.

With a reservoir extending at or near the distal end of the housing the coloring agent can be efficiently transferred to the distal end of the needle unit, for instance through capillary forces. To improve the transfer of coloring agent to the distal end of the needle unit, it is preferred if, according to a further preferred embodiment, the distal end of the needle unit is reciprocally movable between a position near and away of the reservoir when moving between the retracted and extended position. In the position near the reservoir, coloring agent can be transferred, for instance by capillary forces, to the distal end, wherein in the position away or in the extended position, said ink can be transferred to the skin. Coloring agent transfer is further improved if the distal end of the needle unit is reciprocally movable in and out of the reservoir when moving between the retracted and extended position. In use, when driven by a suitable driving device, the distal end is thus moved between a position within the reservoir, allowing efficient ink take-up, to the position wherein the distal end extends from the housing, for introducing said ink in the patient’s skin.

According to a further preferred embodiment, the distal end of the needle unit extends at a proximal distance from the reservoir in the retracted position. The needle unit is then at a distance form the reservoir, preventing any spillage of the coloring agent.

Upon use of the needle module, said module is typically coupled to a driving device having a reciprocally movable driving rod. According to a further preferred embodiment, upon coupling the needle module to a driving device, the needle unit is movable to an intermediate position, said intermediate position being located between the extended and retracted position and wherein the needle unit extends within the reservoir. Upon coupling the needle module, the needle unit. preferably the distal end thereof, is moved distally and is received within the reservoir. Coloring agent can thus be transferred to the needle unit prior to use. In use, the needle unit is then moved between the intermediate position and the extended position.

Preferably, the reservoir is retained by the housing. The reservoir may for instance be formed by two films for holding there between the coloring agent. The films may be pierced by the distal end of the needle unit prior to use. Preferably, the housing further comprising a first film arranged near the distal end of the housing and a second film arranged further from the distal end and wherein the reservoir is positioned between the first and second film.

It is noted that although the use of a reservoir in the housing has advantages in terms of safety, after all, separate dipping of the ink is no longer required, and thus also helps in improved the safety of the device, as do the aspects of the limiting mechanism and the proximal end of the needle unit in the housing, the aspect of the reservoir in the housing can also be applied in a needle module as such, for instance as specified by the preamble.

The invention further relates to a device for puncturing skin, comprising a driving device and a needle module according to the invention, wherein the driving device comprises a motor for reciprocally driving a driving rod for reciprocally moving the needle unit. The driving device is preferably arranged to engage the proximal end of the needle unit, which may be retained in the housing as mentioned above. The driving device is thus shaped accordingly.

If an ink reservoir is arranged in the housing of the needle module, in particular a distal end thereof, it is preferred if the needle module is arranged such that, upon mounting of the needle module onto the driving device, the distal end of the needle is moved to the intermediate position. More preferably, the needle module is arranged to move the distal end of the needle in a range between the intermediate position and the extended position. As mentioned above, this allows and efficient ink take-up from the reservoir. A further preferred embodiment of the device according to the invention further comprises a spacer for setting the extended position of the needle unit, wherein the spacer is arranged between the driving device and the needle unit for adjusting the relative position of the housing and the driving rod of the driving device. This allows fine-tuning the extended position of maximum extension of the distal end of the needle unit from the housing. Preferably however, this maximum extension is limited by the limiting mechanism as mentioned above. The spacer then allows further limitation of the maximum extension distance by introducing a separate part, i.e. the spacer, between the needle module and the driving device. This will change the relative position of the driving device and the needle module and therefore also the reciprocal working stroke of the driving rod.

The invention further relates to a kit of parts comprising the device, the needle module and a plurality of spacers for setting different predetermined distances as mentioned above, wherein the respective spacers are arranged to define varying respective extended positions. Preferably, the spacers have varying lengths, for instance with respective difference of at least 0,1 mm, preferably at least 0,2 nun, more preferably at least 0,5 nun. The respective extended positions then preferably mutually vary at least 0,5 mm.

The invention further relates to a method for introducing ink in the human skin, in particular for applying a skin mark on a patient, comprising the steps of: providing a device as described above; providing a coloring agent; and driving the needle in a reciprocating manner for puncturing the human skin and depositing the coloring agent using the needle in an upper layer of the skin.

The present invention is further illustrated by the following Figures, which show a preferred embodiment of the device and method according to the invention, and are not intended to limit the scope of the invention in any way, wherein:

Figure 1 schematically shows a needle module in perspective;

Figures 2a and b show an embodiment of the needle module in cross-section with the needle unit in retracted and extended position;

Figures 3a-c show another embodiment of the needle module in cross-section with the needle unit in different positions; and

Figures 4a-d show another embodiment of the needle module.

In figure I, a needle module 1 for coupling to a driving device (not shown) such as a tattooing gun or permanent makeup device is shown. The needle module 1 comprises a housing 10, which is in this example substantially cylindrical. The housing 10 comprises an open proximal end 10b (see also the cross-sections of figures 2a and b) and an open distal end 10a. The proximal end 1-b is arranged to couple with the driving device (as will be explained in in relation to figures 3a-c) and is thereto in this example provided with a area 13 of reduced diameter. The step 13a may function as stop surface and determines the relative position of a coupled driving device and the needle module 1. The housing 10 in this example is further formed by two separate housing parts 11 and 12. The distal housing part 12 is provided with a tapering distal end 10a and can be coupled to the proximal main housing part 11 through a snap-fit connection, generally indicated with 12a.

Through the distal end 10b of the housing 10, a needle unit 2 may be extended. The needle unit 2 (see figure 2a) comprises a needle base 23, in this example of a rigid plastic, and a needle 21 at its distal end. The distal end 22 of the needle 21 is sharp. In this example, the needle unit 2 is provided with a single needle 21. It is however also possible to provide a plurality of needles 21, see for instance the embodiment of figures 4a-d. The needle module 1 is arranged such that the needle unit 2 is reciprocally movable along its longitudinal direction L with respect to the housing 10 between a retrac ted position wherein the distal end 22 of the needle unit 2 extends in the housing 10 (see figure 2a) and an extended position wherein the distal end 22 of the needle unit 2 extends from the distal end 10a of the housing (see figure 1 and 2b).

The movement of the needle unit 2 out of the housing 10 in the distal direction D is induced by the movement of a driving rod 32 (see for instance figure 3b) of a driving device 3. Said driving device 3 is arranged to reciprocally move the driving rod 32 with a predetermined amplitude along the longitudinal direction Lb. The movement of the needle unit 2 back into the housing 10 is induced a biasing mechanism 4 which comprises a spring 41 in this example. The biasing mechanism 4 extends between the housing 10 and the needle unit for urging the needle unit 2 towards the retracted position. In this example, the spring 41 is arranged between a stop surface 1 la of the housing 10, formed on the inner surface thereof in this example, and a stop surface of the needle unit 2, in the example the base 23 thereof. The spring 41 will urge the needle unit 2 proximally in the direction P with respect to the housing, i.e. towards the retracted position.

In the distal direction D, the relative movement between the needle unit 2 and the housing 10 is limited by a limiting mechanism, in this example in the form of cooperating protrusions 1 lc, 23b of the housing 10, respectively the needle unit 2. The protrusion He and 23b are abutting in the position as shown in figure 2b. In this example, the protrusion 1 lc is arranged on the inner wall of the housing 10, more specifically the most distal part of the main housing part 11. The protrusion 1 lc further serves to guide the needle unit 2 to only move in the longitudinal direction and is thereto preferably ring or annular shaped. The protrusion 23b of the needle unit 2 is arranged on the relative rigid base part 23. The limiting mechanism limits the extension of the needle unit 2 from the housing 10 to a maximum extension, schematically indicated with the distance d in the detail of figure 2b. The distance d is the distance between the distal end 22 of the needle unit 2 and the distal end 10a of the housing 10. In this example, the maximum extension is defined as 1,2 mm. This ensures that in use, the needle point 22 will only be inserted into the epidermis of the patient.

From figure 2b, which shows the needle unit 2 in the most distal position possible, it can be seen that the spring 41 is not in its complete compressed position. The relative movement between the needle unit 2 and the housing 10 is thus not limited by the biasing mechanism. As an alternative, the biasing mechanism may also form the limiting mechanism in the sense that the final position of the biasing mechanism (for instance the spring in completely compressed situation) limit the maximum extension, in this example set at 1,2 mm as mentioned above.

In the example shown, the protrusion 23b of the limiting mechanism formed on the needle unit 2 extends at a distance from the protrusion 23a operating with the biasing mechanism. The biasing mechanism thus engages the needle unit 2 at a first location and wherein the needle unit 2 is provided with a stop surface 23b at a location at a distance from said first location.

The movement in proximal direction P of the needle unit 2 with respect to the housing 10 is limited by a stop surface 1 lb, in this example formed by a separate plastic or rubber ring shaped element 1 lb. The ring 1 lb further serves to guide the needle unit 2 to only move in the longitudinal direction. In the retracted position as shown in figure 2a, the needle unit 2, in this example the same protrusion 23a operating with the spring 41, abuts the protrusion 1 l b of the housing 10. From figure 2a, which shows the needle unit 2 in the most proximal position with respect to the housing 10, it is clear that also in this retracted position, the proximal end 24 of the needle unit 2 is completely retained or received in the housing 10. In this example, the proximal end 24 extends at a distance from the proximal end 10b of the housing 10. As the proximal end 24 extends in the housing 10, the proximal end 24 cannot be accidentally, for instance due to manual operation, moved to extended position.

The embodiment as shown in figures 2a-b can be used for applying a skin mark to a patient by dipping the distal end 22 of the needle unit 2 in an ink reservoir (not shown) and to subsequently apply the device to the patient. In the embodiment as shown in figures 3a-c however, the needle module 1 is provided with an ink reservoir 5 near the distal end 10a thereof. In this example, the ink reservoir 5 is arranged near the distal end 10a of the distal housing part 12. The reservoir 5 is formed by two films 51, 52 arranged at a mutual distance, between which suitable ink 53 is arranged to be applied on the patient’s skin.

In the retracted position as shown in figure 3a, the distal end 22 of the needle unit 2 extends at a distance proximally from the reservoir. The needle unit 2 does not extend in the reservoir 5 as can be seen. Only when the needle module 1 is coupled to a driving device 3, the needle unit 2 will be moved distally such that the needle unit 2 will extend in the reservoir 5. This is visible in figure 3b. Ink 53 from the reservoir will be transferred to the needle unit 2, in particular the distal end 22 thereof. In this example, the distal end 22 extends distally from the most distal end of the reservoir (in this example formed by the film 52) as can be seen in the detail of figure 3b. It is however also possible that in this position, the distal end 22 of the needle unit 2 extends in the reservoir for efficient ink take-up.

It is hereby noted that driving device 3 is provided with reciprocally movable driving rod 32, which is movable between an inner position (figure 3b) and an outer position (3c). Upon coupling of the driving device 3, the needle unit 2 will be moved from the retracted position (figure 3a) to an intermediate position (figure 3b). In this position, the needle module 1 is ready for use. In use, the driving rod 32 will be reciprocally driven between the inner (figure 3b) and outer positions (figure 3c). In the outer position of the driving rod 32, the needle unit 2 will be urged distally such that the distal end 22 of the needle unit 2 protrudes from the distal end 10a of the housing 10. With reference to figure 3c, it can be seen that the limiting mechanism is not yet operative, i.e. the protrusions 11c and 23b are not yet in contact. The extension d2 of the distal end 22 of the needle unit 2 from the distal end 10a of the housing 10 is in this example determined by the outer position of the driving rod 32, i.e. the amplitude thereof. The distance d2 is smaller than the distance d as shown in figure 2b. The limiting mechanism in figure 3c here functions as safeguard to ensure that the maximum extension is not exceeded.

The distance d2 is determined by the relative position of the needle module 1 and the driving device 3. This relative position can be adjusted by exchanging a spacer 6 with a different space 6 having a different length e. Ring shaped spacer 6 abuts the step 13a provided in the housing 10 to ensure a proper relative potion of the needle module 1 and the spacer 6. It will be appreciated that by arranging a larger spacer 6 (in terms of length e), the distance d2 will decrease.

As an alternative to the spring 41 as biasing mechanism, the embodiment of figures 4a-d is provided with an elastic element 42 for urging the needle unit 2 back to the retracted position as shown in figure 4a. Also in this position, the proximal end 24 of the needle unit 2 is retained in the housing 10.

The elastic element 42 is in the form of an elastic tube, which is connected to the housing 10, in this example at the interconnection between the distal housing part 12 and the proximal housing part 11. The other end of the elastic element 42 is connected to the needle unit 2 at the distal location, in this example at the distal end of the base 23. It will be appreciated that the elastic properties of the element 42 will urge the needle unit 2 back from the position as shown in figure 4b to the position as shown in figure 4a.

Also in this embodiment, a limiting mechanism in the form of cooperating protrusions 23a and 1 lc is provided to limit the extension of the needle unit 2 from the distal end of the housing 10 to a maximum extension d (see the detail of figure 4b).

With reference to figures 4c and 4d, it will again be appreciated that upon mounting the needle module 1 to a combination of a driving device 3 and spacer 6, the needle unit 2 will he urged into the ink reservoir 5. Driving the driving rod 32 will reciprocally move the distal end 22 of the needle unit 2, which is provided with a plurality of needles 21, between the intermediate position (figure 4c) and the extended position (figure 4d). Again, in figure 4d the protrusions 1 lc, 23a of the limiting mechanism are not yet in abutment, such that the extension distance d2 is again smaller than the maximum distance d. The distance d2 is again determined by the length of the spacer 6.

The present invention is not limited to the embodiment shown, but extends also to other embodiments falling within the scope of the appended claims.

Claims

A needle module for piercing skin in a reciprocal manner, wherein the needle module comprises a needle unit, a housing and a biasing mechanism, the needle unit comprising a needle, the needle unit being movable relative to the housing between an extended position, a the distal end of the needle extends from a distal end of the housing, and a retracted position wherein the distal end of the needle is positioned in the housing, the biasing mechanism being adapted to force the needle unit to the retracted position, characterized the needle module further comprising a limiting mechanism, the limiting mechanism being adapted to limit the relative movement of the needle unit from the distal end of the housing to a maximum extension distance upon moving to the extended position, said maximum extension distance being 1.5 mm or less.

The needle module according to claim 1, wherein the limiting mechanism comprises mutually cooperating stop surfaces for limiting the relative movement of the needle unit and the housing.

The needle module according to claim 2, wherein an interior of the housing is provided with protrusions and / or recesses for cooperation with protrusions arranged on the outside of the needle unit.

A needle module according to claim 2 or 3, wherein a stop surface is substantially annular.

The needle module according to at least one of the preceding claims, wherein the biasing mechanism engages the needle unit at a first location and wherein the needle unit is provided with a stop surface at a location remote from the first location.

The needle module according to at least one of the preceding claims 1 to 4, wherein the limiting mechanism is at least partially formed by the biasing mechanism, wherein the biasing mechanism is adapted to limit the relative movement of the needle unit from the distal end of the housing on said maximum extension distance.

7. Needle module according to at least one of the preceding claims, wherein the housing comprises a main housing part and a removable dislaal housing part, wherein the limiting mechanism is arranged at least partially in the main housing part.

The needle module according to at least claims 2 and 7, wherein the main housing part comprises a stop surface at or near the distal end.

The needle module of at least one of the preceding claims, wherein, in the retracted position, the proximal end of the needle extends into the housing.

The needle module of claim 9, wherein the limiting mechanism is further adapted to limit, in the retracted position, a displacement of the proximal end of the needle such that the proximal end of the needle is held in the housing.

The needle module of claim 8 or 9, wherein the biasing mechanism is further adapted to hold the proximal end of the needle in the housing.

A needle module according to at least one of the preceding claims, wherein the housing is provided with a reservoir containing a colorant, such as ink, for insertion into said skin.

The needle module of claim 12, wherein the reservoir is disposed at or near the distal end of the housing.

A needle module according to claim 12 or 13, wherein the reservoir contains less than 0.3 ml of dye.

The needle module according to claim 12, 13 or 14, wherein the distal end of the needle unit is reciprocating into the reservoir as it moves between the retracted and extended position.

A needle module according to at least one of the preceding claims 12-15, wherein in the retracted position the distal end of the needle unit extends at a proximal distance from the reservoir.

The needle module of claim 16, wherein, after coupling the needle module to a drive device, the needle unit is movable to an intermediate position, said intermediate position being located between the extended and retracted position and wherein the needle unit extends within the reservoir.

The needle module of claim 17, wherein the distal end of the needle unit extends into the reservoir in the intermediate position.

The needle module according to at least one of the preceding claims 12-18, wherein the housing further comprises a first film disposed near the distal end of the housing, and a second film further disposed from the distal end, and wherein the reservoir is positioned between the first and second film.

A skin piercing device, comprising a drive device and a needle module according to at least one of the preceding claims, wherein the drive device comprises a motor for reciprocally moving a drive rod for reciprocally moving the needle unit.

Device as claimed in at least claims 17 and 20, wherein the needle module is arranged such that when mounting the needle module on the drive device, the distal end of the needle is moved to the intermediate position.

The device of claim 20 or 21, wherein the needle module is adapted to move the distal end of the needle in a range between the intermediate position and the extended position.

Device according to at least one of the preceding claims 20 - 22, further comprising a spacer for adjusting the extended position of the needle unit, the spacer being arranged between the drive device and the needle unit for adjusting the relative position of the needle unit housing and the drive rod of the drive mechanism.

A set of parts comprising the device, the needle module, and a plurality of spacers for setting different predetermined distances, according to at least claim 23, wherein the respective spacers are configured to define respective varying extended positions.

The set of parts according to claim 24, wherein the respective extended positions vary from each other by at least 1.2 mm.

A method for introducing ink into human skin, comprising the steps of: - providing a device according to at least one of the preceding claims 20-23; and - providing a colorant; and - driving the needle for piercing human skin in a reciprocal manner and applying the dye in an upper layer of the skin with the aid of the needle.