Lancet device for puncturing the skin

A lancet device for puncturing the skin of mammals, especially humans, has a bushing with a grip portion and opposite the grip portion a free end defining a plane. An insert is axially slidably connected within the bushing. The insert has a first and a second end, with the first end having a grip element and the second end having a projecting lancet with a tip for puncturing the skin. The grip element comprises a diaphragm with a preset pressure point, and upon surpassing the pressure point of the diaphragm with an axially directed force in the direction toward the free end of the bushing, the lancet is released with a preset impulse via the insert and penetrates the plane defined by the free end to puncture the skin.

BACKGROUND OF THE INVENTION 
The present invention relates to a lancet device for puncturing the skin of 
mammals, especially of humans, and comprises an insert with a grip element 
as well as a bushing with a grip portion, the bushing receiving the insert 
in an axially slidable manner, whereby the insert at its free end remote 
from the grip element is provided with a lancet having a tip for 
puncturing the skin. 
Lancet devices for puncturing the skin, especially of humans, are known and 
are successfully being used in various embodiments in ambulatory 
facilities, in hospitals, in physicians practices, in red cross facilities 
as well as in emergency facilities, etc. in order to draw small amounts of 
blood for blood testing. An essential requirement for such lancet devices 
is that they must be producible at extremely low cost because they are 
used in great numbers in the aforementioned institutions and must be 
provided in great numbers at these facilities. A further essential 
requirement for these lancet devices that at least the portion of the 
lancet device that directly penetrates the skin of a human, i.e., that is 
directly in contact with the tissue beneath the skin and the blood stream 
of the human, must be maintained in sterile conditions until they are 
being used. In general, the portions of the lancet device which penetrate 
the tissue to a predetermined depth in order to connect with blood vessels 
for collecting the blood emerging from the penetration opening, are 
so-called lancets which have a substantially circular cross-section and 
are comprised of a steel body having a pointed end for puncturing the 
skin. 
In general, such lancet device, after being used once for the designated 
puncturing function are not being reused because a subsequent 
sterilization of the lancet device is much more expensive than the 
manufacture of such a lancet device. Thus, the aforementioned lancet 
devices are usually single use devices. 
From German Patent 31 11 737 a lancet device of the aforementioned kind is 
known. This lancet device is comprised of a bushing and an insert whereby 
the insert is provided with a lancet having a pointed end for the 
puncturing the skin at a free end of the insert remote from a 
corresponding grip element. The insert is provided with a radially 
extending peripheral bead portion which is arranged at the shaft-like 
insert at a predetermined distance to a pressure plate. The end of the 
insert remote from the peripheral bead portion which is also embodied as a 
shaft is arranged in the bushing which has an interior corresponding to 
the shaft cross-section of the insert. From the free end of the shaft of 
the insert the pointed end of the lancet projects. For performing the 
designated puncturing function with the known lancet device, the insert is 
in general axially displaced by the thumb of the operator via the grip 
element whereby the peripheral bead portion is pressed over corresponding 
radially inwardly extending bead provided at the interior of the bushing 
and projecting into the travel path of the insert; whereby the two beads 
are elastically deformed for overcoming their resistance relative to one 
another. After the resistance has been overcome the bead portion of the 
insert glides over the bead portion of the bushing and the lancet tip can 
puncture in the predetermined manner the skin, respectively, the tissue of 
the human, to a predetermined depth. 
The known lancet device has substantial disadvantages. On the one hand, 
already during insertion of the insert element into the bushing the lancet 
tip can lose its sterility when, for example, the operator inserting the 
insert into bushing touches with the lancet tip the grip element at the 
inlet opening of the bushing element or touches his own skin. In 
summarizing the above, it can be said that during the introduction of the 
insert into the bushing a plurality of possibilities for desterilizing the 
lancet are present which is of special concern with respect to the 
treatment of HIV patients. 
Even though in the known device the lancet tip is embedded within the 
material of the bushing, i.e., the insert and the bushing are manufactured 
in one step in the form of a single part by injection molding so that the 
sterility of the lancet tip in so far is completely guaranteed, in any 
case must the insert be removed from the bushing for the use of the lancet 
tip in order to be inserted into the bushing in the aforedescribed manner, 
whereby due to the required separation the lancet tip is freed and thus 
exposed to microbiological bacteria and viruses and other contaminants. 
A further important disadvantage of the lancet device is that the release 
mechanism, depending on the manufacture and sensitivity of the operator 
using the lancet device is released with different velocities and thus 
applied with varying success so that the puncturing is not carried out in 
the required manner at all times, i.e., resulting in the required blood 
flow from the opening that has been made in the skin of the human. 
It is furthermore disadvantageous that this known lancet device can only be 
manufactured in a very complicated and thus very costly process due to the 
absolute sterility requirements for at least the lancet tip. 
It is therefore an object of the present invention to provide a lancet 
device of the aforementioned kind which is simple in its construction and 
thus less expensive to manufacture than the known lancet devices, which 
furthermore remains absolutely sterile until immediately before its use 
for puncturing the skin of a human, which consistently provides for a 
uniform puncturing function of the lancet tip for penetrating the skin of 
a human independent of the individual characteristics of the operator, and 
which furthermore after its use ensures that the lancet tip is protected 
so that no accidental injuries and resulting infections by the blood 
sticking to the lancet tip can occur.

SUMMARY OF THE INVENTION 
The lancet device of the present invention for puncturing the skin of 
mammals is primarily characterized by: 
A bushing having a grip portion and opposite the grip portion a free end 
defining a plane; 
An insert axially slidably connected within the bushing, the insert having 
a first and a second end, the first end having a grip element and the 
second end having a projecting lancet with a tip for puncturing the skin; 
and 
The grip element comprising a diaphragm with a preset pressure point, 
wherein, upon surpassing the pressure point of the diaphragm with an 
axially directed force in the direction toward the free end of the 
bushing, the lancet is released via the insert with a preset impulse and 
penetrates the plane defined by the free end to puncture the skin. 
According to the present invention the grip element of the insert is at 
least partially embodied as a spring-elastic body in the form of a 
diaphragm which releases the lancet via the insert with a predetermined 
impulse after surpassing a pressure point determined by the diaphragm by 
applying an axially directed force in the direction to the free end of the 
bushing so that the lancet penetrates the plane defined by the free ends 
of the bushing and punctures the skin. 
The advantage of the inventive lancet device lies essentially in the fact 
that the insert is continuously, i.e., also in its rest position, in which 
the lancet device does not perform its function, is located in the 
interior of the bushing and surrounded by the bushing so that an 
accidental contact of the lancet tip and thus a contamination with 
microbiological bacteria or viruses or other contaminants is impossible. 
Furthermore, it is an essential advantage that the actuation of the 
puncturing process is substantially free of individual characteristics of 
the operator using the lancet device, i.e., the operator must only apply 
enough pressure for surpassing the pressure point of the spring-elastic 
diaphragm and after surpassing the pressure point the spring constant of 
the diaphragm determines the impulse at which the lancet tip within the 
insert is released and penetrates the skin of the human to the 
predetermined depth. Furthermore, it is advantageous that the inventive 
lancet device can be manufactured in a simple manner as two separate parts 
which subsequently can be easily assembled. This avoids expensive 
manufacturing tools and expensive or complicated manufacturing processes. 
In a preferred embodiment of the lancet device the diaphragm is a 
plate-shaped body having a concave cross-section. The outer convex 
curvature of the diaphragm in the initial state of the lancet device is 
embodied axially outwardly with respect to the bushing. In general, it is 
possible to embody the diaphragm in any desired and suitable manner; 
however, it is advantageous, because the manufacturing cost of the lancet 
device can be reduced, to embody the diaphragm and the shaft-like insert 
as a unitary part so that in principle the lancet device is comprised only 
of the insert with diaphragm and the bushing into which the insert is 
introduced. 
In a further embodiment of the present invention the insert has a shaft 
with first projections and the bushing has an interior with second 
projections, whereby the first projections interlock with the second 
projections upon insertion of the insert into the bushing. After insertion 
of the insert into the bushing the insert cannot be removed without 
destroying the two components which is advantageous because both 
components form an operative unit which can be easily stored and can be 
easily handled for performing the desired puncturing function. 
In another advantageous embodiment of the present invention, the insert 
further comprises a cover element connected to the second end for 
enclosing the lancet in a sterile manner. It is, of course, possible to 
sterilize in a suitable manner the lancet device without this cover 
element, respectively, the individual parts of the lancet device, after 
manufacture and to enclose the components in an air-tight envelope so that 
for using the lancet device only the envelope must be cut open and the 
lancet device removed. However, it has been proven advantageous for cost 
considerations as well as for reasons of a simpler handling to simply 
provide a cover element in the aforedescribed manner so that the lancet 
tip is covered in a sterile manner and the cover element must be removed 
from the lancet tip immediately before using the lancet device. 
Preferably, the insert and the cover element form a unitary part. This is 
advantageous because the insert and cover element can be manufactured in 
one step resulting in a more economical manufacturing process. 
In order to be able to remove in a simple and fast manner the cover element 
from the lancet device for the puncturing step and to thereby free the 
lancet tip, the cover element has a transition into the second end of the 
insert, whereby the transition has a designated breakage zone. This 
designated breakage zone allows for a fast removal of the cover element, 
especially when the designated breakage zone is advantageously formed by a 
radial recess within the transition so that the cover element can simply 
be slightly rotated relative to the insert about its axis to thereby break 
the connection between the insert and the cover element, i.e., the 
transition breaks at the recess. 
Preferably, the cover element has a segment projecting from the bushing 
when the shaft with the first projections is interlocked with second 
projections of the bushing, whereby the segment forms a grip. By providing 
this grip it is ensured that the removal of the cover element from the 
insert is possible without actuating the spring-elastic diaphragm, i.e., 
the removal of the cover element is possible without first activating the 
lancet device. Preferably, the grip has a substantially oval 
cross-section. 
The grip portion of the bushing is preferably a plate-shaped body 
supporting the grip element of the insert when the shaft with the first 
projections is interlocked with the second projections of the bushing. 
With this embodiment the grip element and the grip portion together form a 
unit which can be easily handled when compared to the known lancet 
devices. 
In general, the bushing can have a body that is formed in any suitable 
manner, for example, with a circular cross-section. However, it has been 
proven advantageous that the body of the bushing have an essentially oval 
cross-section and that the interior of the body of the bushing also have 
an oval cross-section. A body of the bushing designed as aforedescribed 
easily allows for the penetration of the insert with the integral grip 
preferably having also an oval cross-section, i.e., the grip essentially 
comprises two wing-like parts which allow for a simple removal of the 
cover element for freeing the lancet tip. 
In general it would be possible to use the lancet device multiple times due 
to its construction because due to the suitable counter position of the 
lancet tip on a resistance-providing support the diaphragm, after 
surpassing its predetermined pressure point, can be displaced into its 
initial position. This could, for example, be useful when for the same 
patient, due to the lack of readily accessible blood vessels, not enough 
blood for blood tests can be drawn in the first attempt. 
However, in other embodiments of the lancet device for single use, it is 
advantageous to provide the insert with first blocking elements and the 
bushing with second blocking elements whereby the first blocking elements 
engage the second blocking elements such that a further release of the 
lancet after the lancet has been used once is impossible. 
DESCRIPTION OF PREFERRED EMBODIMENTS 
The present invention will now be described in detail with the aid of 
several specific embodiments utilizing FIGS. 1 through 6. 
The lancet device 10 is essentially comprised of an insert 12 and a bushing 
14 which in the assembled state together with the lancet 18 form the 
complete lancet device. The insert 12 has a substantially cylindrical 
shaft 23 into which the lancet 18 is embedded essentially axially relative 
to the axis 16 of the insert. The lancet 18 is generally comprised of a 
biocompatible stainless steel. Furthermore, the insert is provided with 
radially extending projections 24, 25 at its shaft 23. The projections 24, 
25 cooperate with projections 26, 27 that are arranged in the interior 28 
of the bushing 14. This will be described in detail in the following. At 
the free end 17 of the insert 12, see especially FIG. 6, the lancet tip 19 
projects from the insert 12 during the designated puncturing function. 
Before carrying out the puncturing function a cover element 29 which is 
directly connected to the free end 17 of the insert 12 must be removed. In 
the embodiment represented in the drawings the cover element 17 and the 
insert 12 are a unitary part of the lancet device 10. With this cover 
element 29 the lancet tip is enclosed in a sterile manner. 
In contrast to the known lancets of the prior art, the lancet 18 does not 
have a rotational securing device, for example, in the form of a 
flattening of certain portions of the lancet 18. In the present invention, 
for the manufacture of the insert 12 the frictional force resulting after 
the manufacturing step due to the shrinking of the material used is 
dimensioned such that after completion of shrinking no rotation of the 
lancet 18 is possible. This results in a considerably simplified and less 
expensive solution in comparison to the known lancet devices. 
The transition 30 between the insert 12 and the cover element 29, see 
especially FIGS. 3 and 4, is provided with a designated breakage zone 31 
that is formed by a radial recess in the transition 30. The segment of the 
cover element 29 which in the interlocked state of the bushing 14 and the 
insert 12 extends past the bushing body 33, compare FIG. 1, forms a grip 
32 which in cross-section is oval, respectively, double winged. By 
rotating the grip 32 relative to the shaft 23 of the insert 12 the 
designated breakage zone 31, which is formed by the radial recess within 
the transition 30, is broken and the cover element 29 can be removed from 
the lancet tip 19. 
The grip element 13 of the insert 12 which is formed at the end of the 
shaft 23 remote from the lancet tip 19 is in the form of a spring-elastic 
membrane 20. The membrane 20 is an essentially plate-shaped body which in 
cross-section is concavely curved. In the rest position the highest point 
of the outer convex curvature of the diaphragm points away from the shaft 
23, compare FIGS. 1 to 5. The bushing 14 also comprises a grip portion 15 
which is also essentially a plate-shaped body. The grip portion 15 is 
provided with a peripheral recess which is designed such that the grip 
element 13 of the insert 12 with its peripheral lateral edge rests within 
this recess, compare FIGS. 1 and 5. The body 33 of the bushing 14 has an 
inner and an outer contour of a substantially oval cross-section, i.e., 
the interior 28 of the bushing 14, see FIG. 2, has also an oval 
cross-section. As mentioned before, the interior 28 is provided with 
projections 26, 27 which after insertion of the insert 12, compare FIG. 5, 
interlock with the projections 24, 25 of the shaft 23 of the insert 12. 
For the designated use of the lancet device 10 for performing a puncturing 
of the human skin 11 the insert 12 is first introduced into the interior 
28 of the bushing 14 so that the projections 24, 25 interlock with the 
projections 26, 27. This step must still be considered a manufacturing 
step. Due to the elastic prestress of the spring-elastic diaphragm 20 
which is essentially formed by the grip element 13, the insert 12 is 
immobile in the direction of the axis 16. After removal of the cover 
element 29 from the lancet tip 19, as described before, the lancet tip 19 
is freed within the interior 28 of the bushing 14 without at this point 
penetrating the plane 22 defined by the free end 21 of the bushing 14. 
When an operator exerts a force in the direction of arrow 34 which is 
sufficient to overcome the pressure point in the axial direction toward 
the free end of the bushing 21 (arrow 34), the spring-elastic body 
(diaphragm 20) applies a predetermined impulse to the insert 12 and thus 
to the embedded lancet 18 which then penetrates the plane 22 due to this 
impulse and punctures the skin 21 of a human, compare FIG. 6, to the 
predetermined depth. The predetermined depth of penetration of the lancet 
tip 19 into the skin 21 is determined by the constructive embodiment of 
the axial displacement of the diaphragm 20. The inventively used material 
is preferably polyethylene, polypropylene, or any other plastic material 
suitable for injection molding that is furthermore biocompatible and safe 
with respect to human health. 
The present invention is, of course, in no way restricted to the specific 
disclosure of the specification and drawings, but also encompasses any 
modifications within the scope of the appended claims.