The invention relates to a lancet having a flat shaft ( 1 ) which has an upper side ( 1 c ) and a lower side ( 1 b ), the shaft ( 1 ) forming at a front end ( 2 ) a cutter ( 1 a ) which ends in a point ( 2 ), the cutter ( 1 a ) having on the underside ( 1 b ) two cutting edges ( 4 ), which run together at the point ( 2 ), and the shaft ( 1 ) having at least one depression ( 3 ) on its underside ( 1 b ) to receive a sample. The invention provides for the shaft, on its upper side ( 1 c ), to merge into the cutter ( 1 a ) at two edges ( 5 ) which run together at a vertex ( 6 ), and for the upper side ( 1 c ) of the cutter ( 1 a ) between the vertex ( 6 ) and the front end ( 2 ) to be curved convexly, as seen in cross section.
1. A lancet comprising a flat shank having a top side and a bottom side, the shank forming a blade at a forward end, the blade terminating in a point, the blade having two cutting edges at the bottom side, the cutting edges converging in the point, and
the shank having on its bottom side at least one recess for receiving a sample, characterized in that
the shank turns into the blade on its top side at two edges which converge in a vertex, and that the top side of the blade is curved convexly between the vertex and the forward end, as seen in cross-section.
2. The lancet according to claim 1 , characterized in that the blade is formed concavely along a line running from the vertex to the forward end.
3. The lancet according to claim 1 , characterized in that the top side has an undercut at the vertex.
4. The lancet according to claim 1 , characterized in that the blade has concave lateral surfaces between the vertex and the rear end of the cutting edges.
5. The lancet according to claim 1 , characterized in that both edges, which delimit the blade on the top side, run parallel to the cutting edges.
6. The lancet according to claim 1 , characterized in that the vertex is arranged behind the point by more than the thickness of the shank.
7. The lancet according to claim 1 , characterized in that the two edges, which delimited the blade on the top side, enclose an acute angle.
8. The lancet according to claim 1 , characterized in that the cutting edges have a cutting angle that decreases towards the forward end.
9. The lancet according to claim 1 , characterized in that the bottom side of the blade is plane at least in a marginal region along the cutting edges.
10. The lancet according to claim 1 , characterized in that the bottom side of the shank is plane exclusive of the recess for receiving a sample.
11. The lancet according to claim 1 , characterized in that the upper edges extend further back than the cutting edges.
12. The lancet according to claim 1 , characterized in that the recess is a groove which extends beyond the vertex and has a section arranged between the cutting edges, in said section the area of a cross-section of the groove decreases towards the forward end.
13. The lancet according to claim 1 , characterized in that
the shank has a bending stiffness of less than 0.1 kNmm 2 .
14. A puncturing system comprising a lancet according to claim 1 and a puncturing device that, during a puncture, causes a forward motion of the lancet and subsequently a retracting motion, wherein the retracting motion is slower than the forward motion.
15. The lancet according to claim 13 , wherein the bending stiffness of the shank is less than 0.05 kNmm 2 .
16. The lancet according to claim 13 , wherein the bending stiffness of the shank is less than 0.03 to 0.01 kNmm 2 .
17. The lancet according to claim 1 , wherein the at least one recess includes two grooves extending parallel to one another for receiving the sample.
18. The lancet according to claim 17 , wherein the groove has a section arranged between the cutting edges, wherein the area of cross-section of the groove decreases in that section towards the forward end.
19. A lancet comprising a flat shank having a top side and a bottom side,
the shank forming a blade at a forward end, the blade terminating in a point,
the blade having cutting edges on the bottom side, the cutting edges converging in the point, and
the shank having on the bottom side at least one groove for receiving a sample, characterized in that
the groove has a section arranged between the cutting edges,
wherein the area of cross-section of the groove decreases in that section towards the forward end, wherein the groove has a depth, wherein the depth of the groove decreases towards the forward end, wherein the shank turns into the blade on its top side at two edges which converge in a vertex and the groove extends beyond the vertex.
20. The lancet according to claim 19 , wherein the at least one groove includes two grooves extending parallel to one another for receiving the sample.
21. The lancet according to claim 19 , wherein the thickness of the blade is less than two thirds of the thickness of the shank at the forward end of the groove.