Lancet actuator with retractable mechanism

The present invention provides an actuator mechanism for sequentially advancing and retracting a lancet needle and includes a drive carriage for advancing and retracting the lancet needle and a hinge structure operatively connected to displace the drive carriage. The hinge structure includes first and second coupled leaf members relatively pivotal between a first position thereof in which the drive carriage is advanced to project and thrust the lancet needle into a tissue penetration position, and the second pivotal position of the leaf members in which the drive carriage is retracted to withdraw the lancet needle from the penetration position. The leaf members can also be pivotal to a third position in which the drive carriage is retracted prior to initiating the advancement so that the first position of the leaf members is pivotally intermediate between the second and third relative positions thereof. The drive carriage is thus advanced and thereafter retracted for thrusting and then withdrawing the lancet needle in continuous reversal motions thereof. The drive carriage is guided so that the advancement and retraction motions are along a highly accurate linear path.

BACKGROUND OF THE INVENTION 
This invention relates to lancet devices for use by physicians and 
technicians to extract a patient's blood sample, and more particularly 
relates to a mechanism for effecting the initial puncture and thereafter 
retracting the lancet needle following the skin puncturing procedure. 
In order to reduce trauma to the patient during blood sampling procedures, 
automated finger lancet devices have been developed which eliminate the 
patient's view of both skin puncture and the lancet needle or blade 
itself. As described for example in U.S. Pat. No. 4,892,097, the lancet 
needle can be housed within a small device which provides a spring-driven 
mechanism for thrusting and retracting the needle. While such devices 
obstruct the patient's view, considerable patient discomfort has been 
experienced when all lateral motion of the lancet needle is not prevented. 
This disadvantage is eliminated by the lancet actuator in accordance with 
the present invention which provides improved patient comfort in that 
initial puncture and withdrawal of the lancet needle is effected in a 
continuous, smooth motion, and this is done rapidly, so that little or no 
lateral movement can take place. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, an actuator mechanism for 
sequentially advancing and retracting a lancet needle includes a drive 
carriage for advancing and retracting the lancet needle and a hinge 
structure operatively connected to displace the drive carriage. The hinge 
structure includes first and second coupled leaf members relatively 
pivotal between a first position thereof in which the drive carriage is 
advanced to project and thrust the lancet needle into a tissue penetration 
position, and the second pivotal position of the leaf members in which the 
drive carriage is retracted to withdraw the lancet needle from the 
penetration position. The leaf members can also be pivotal to a third 
position in which the drive carriage is retracted prior to initiating the 
advancement so that the first position of the leaf members is pivotally 
intermediate between the second and third relative positions thereof. The 
drive carriage is thus advanced and thereafter retracted for thrusting and 
then withdrawing the lancet needle in continuous reversal motions thereof. 
The drive carriage is guided so that the advancement and retraction 
motions are long a highly accurate linear path. 
In a preferred embodiment, the drive carriage is integrally molded with a 
double hinge structure to form a transmission linkage including two 
"living hinge" portions which convert the radial motion of the leaf 
members into the linear motions of the drive carriage and lancet needle. 
The smoothly guided and highly accurate linear motions of the lancet 
needle reduce the user discomfort. The drive carriage accepts removable 
lancet needle units so that the actuator is reusable with successive 
lancet needles. The actuator includes trigger and rearming structures 
which tension and release a torsion spring bearing against one of the leaf 
members to drive the transmission linkage and actuator operation. 
A second preferred embodiment of the actuator is designed for single-use 
disposability, in which the lancet needle is insert molded within the 
drive carriage, and accordingly reuse of the unit by rearming or resetting 
of the structure is precluded.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
Referring to FIG. 1, an embodiment of a lancet actuator in accordance with 
the present invention is generally designated by reference character 10. 
The actuator 10 accommodates the use of conventional, disposable lancet 
needle-and-support-body units A. The units A comprise a metal needle 11 
carried by a plastic body 15. A lancet unit A is inserted into a lancet 
holder or carriage means 12 within the actuator 10, as more fully 
described hereinafter, prior to operation of the actuator 10 to puncture 
tissue in a blood sample extraction procedure, after which the lancet unit 
A is removed from the holder or carriage 12 for disposal. In the actuator 
10 of the first embodiment, a split housing 14 has an access and operation 
aperture 16 formed at one end, through which the disposable lancet unit A 
is inserted and removed. The actuator 10 also has a cap 18 which is 
snap-fitted to the housing 14 to cover the aperture 16 and the inserted 
lancet unit A during the blood extraction procedure, and therefore the cap 
18 will be exposed to the blood sample and will consequently be disposable 
with the used lancet unit A. The cap 18 includes an opening 18a through 
which the needle 11 of lancet A can project. The extension of the cap 18 
determines the length of the projection of the needle portion 11 
therefrom, and therefore also determines the puncture depth when the cap 
18 is seated on the donor's skin. FIG. 1 illustrates the mechanism of the 
actuator 10 preparatory to insertion of the lancet unit A and before the 
actuating mechanism has been cocked to prepare the actuator for operation. 
As can be appreciated, this condition of the actuator 10 also corresponds 
to that as would occur after completion of a prior procedure. Thus, the 
lancet unit A is positioned within the carriage or holder 12 and the cap 
18 is snapped into place. The actuator is then cocked to arrive at the 
position shown in FIG. 2, as explained more fully hereinafter, and is thus 
ready for operation. 
In operation of the actuator 10, the lancet holder 12 carries the lancet 
unit A from the retracted position shown in FIG. 2 to the linearly 
advanced position shown in FIG. 3 in which the lancet needle 11 projects 
from the clearance hole 18a to puncture the tissue, and then immediately 
retracts the lancet unit A into the position shown in FIG. 4. FIGS. 1 and 
4 illustrate the same retracted position of the holder 12, although FIG. 1 
also shows the cap 18 and lancet unit A prior to assembly. 
The holder or carriage 12 is integrally molded and connected with a double 
hinge linkage structure 13 including first and second hinge leaf members 
20 and 22 respectively, which form a transmission linkage to convert the 
radial motion of the leaf members 20 and 22 into linear motion of the 
holder or carriage 12 and the associated lancet unit A. The second leaf 22 
is directly coupled to the rear wall of the carriage 12 by a first 
integrally attenuated, flexible pivot portion 24 forming a "living hinge" 
at the forward end of the second leaf member 22. A second integrally 
attenuated flexible portion 26 forms a "living hinge" joining the rear end 
of the second leaf 22 to the forward end of the first leaf 20 enabling 
relative pivot of the two leaves 20 and 22. A rotatable hub 28 is 
integrally molded at the rear end of the first leaf member 20. The first 
leaf 20 pivots with the rotation of the hub 28, as indicated by arrow 29, 
FIG. 3, which hub 28 is journaled on a stationary pivot bearing pin 30 
which projects inwardly from the housing half 14. The hub 30 has a 
radially projecting boss 32 which seats the movable end 34 of a torsion 
spring 36 which is wound around the hub 30 and drives the hub rotation in 
the lancet displacement operation. The generally anchored end 38 of the 
torsion spring 36 is seated against a spring seat portion 40 of a pivoted 
trigger member, generally designated by reference character 42. The 
trigger member 42 has an integral pivot bearing pin 44 which is pivotally 
supported on an arcuate journal bearing 46 which projects inwardly from 
the housing half 14. The interior end of the trigger 42 is formed as a 
latch portion 48 which releasably engages a retainer cam 50 projecting 
from the hub 28 as shown in FIG. 2. The releasable trigger latching of the 
cam 50 retains the tension in the torsion spring 36 which maintains force 
against both the boss 32 and the trigger seat 40 in the cocked or armed 
condition of the actuator 10 shown in FIG. 2. 
In order to arm the actuator 10 from the released condition of the spring 
36 or previously fired position as shown in FIG. 1 in which the latch 48 
is disengaged from the cam 50, a displaceable cocking member 52 is 
slidably mounted as shown for rearward movement into engagement with a 
laterally projecting foot portion 54 formed on the end of the boss 32. The 
cocking, counter-rotation of the foot 54 and hub 28 continue until the cam 
50 reaches the latch 48, which is under tension from the spring 36. The 
element or cam 50 will pivot the latch position 48 of trigger 42 upwardly, 
until said latch portion engages over the cam 50, to attain the armed or 
cocked position as shown in FIG. 2. 
The rearward cocking motion of the cocking member 52 also compresses an 
attached, biasing coil spring 58 within a blind guide bore 60 formed in 
the housing 14. When this cocking motion is completed, manual 
disengagement from the cocking member 52 will permit the biasing spring 58 
to return the cocking member 52 to a neutral position (FIGS. 1, 3 and 4) 
in which the biasing spring 58 is in expanded condition. Comparison of 
FIGS. 1 and 2 illustrates that the counterclockwise cocking motion of the 
hub 28 pivots the first leaf member 20 and the second hinge portion 26 
downwardly as indicated by the motion arrows in FIG. 2. 
At the other end of the integral linkage structure 13, as best shown in 
FIG. 6, the holder or carriage 12 has a laterally projecting and 
longitudinally extending guide flange 62 and an upwardly projecting and 
similarly longitudinally extended guide flange 64 which has a modified 
dove-tail or similarly convoluted cross-sectional configuration; the two 
guide flanges 62 and 64 are slidably displaceable through corresponding, 
mating receiving slots formed in the housing halves 14 and 15. FIG. 7 also 
illustrates that the slot 68 is vertically split between the housing 
halves 14 and 15. The guide flanges 62 and 64 insure that the holder 12 
and lancet unit A are displaceable only in a smooth and accurately linear 
longitudinal path during advancement and retraction, without any lateral 
motion so that the lancet needle 11 enters and withdraws from the skin at 
a highly focused point of penetration, which eliminates any side-to-side 
motion of the lancet needle and the resulting penetration trauma and user 
discomfort experienced with prior actuator devices. 
Since the holder or carriage 12 is constrained to an accurately linear 
longitudinal path of the advancement and retraction, the first hinge 
portion 24 adjacent the rear wall of the holder 12 is similarly limited to 
the highly linear motion of the holder displacement; therefor the 
downwardly pivotal motion of the second hinge portion 26 about the pin 30 
pulls the rear end of the leaf 22 downwardly to induce a combined pivot 
and rearward translation of the leaf 22 which also pulls the rearward 
retraction of the holder 12 and lancet unit A through the highly linear 
path constrained by the guide flanges 62 and 64. FIG. 2 illustrates the 
pivotal position of the leaf members 20 and 22 which retracts the holder 
12 into its "armed position" prepared for advancement, in which the hinge 
portion 24 is a distance D from the surface of the rotatable hub 28, which 
is determined in general by the lengths B and C of the respective leaf 
members 20 and 22 and the angle of relative pivot therebetween. 
Referring again to FIG. 3, when the surface of the cap 18 is placed against 
the donor's arm, and the trigger surface 56 is manually depressed the 
latch 48 is disengaged from the cam 50 and the hub 28 rotates in a 
clockwise direction, as indicated by arrow 29, under the influence of 
spring 36 to begin the lancet needle and skin puncture procedure. As hub 
28 rotates, the leaf member 20 is pivotally driven upwardly and clockwise 
as indicated by the direction of the arrow P. Correspondingly, the leaf 22 
will pivot in a counterclockwise direction from the position shown in FIG. 
2 to the intermediate position of FIG. 3. The resulting pivotal movement 
of the coupled leaf member 22 produces the linear advancement of the 
holder or carriage 12 and lancet needle 11 which reaches its maximum 
projection from the cap aperture 18a (corresponding to the maximum skin 
puncture depth) when the leaf members 20 and 22 are linearly aligned, as 
shown in FIG. 3, corresponding to the position of hinge portion 24 at 
maximum distance E from the surface of the hub 28. Thus, the advancing 
displacement of the holder 12 and lancet needle 11 can be expressed by the 
difference between the distance E and the distance D. In addition, 
however, the torsion spring 36 continues to drive the hub 28, which 
produces continued upward, clockwise pivotal movement of the leaf member 
20 so that the resulting pivot of the leaf member 22, in which hinge 
portion 26 becomes elevated relative to the hinge portion 24, produces a 
smooth reversal in the advancement of the holder or carriage 12 and lancet 
needle 11 and their linear withdrawal to the maximum position of 
retraction shown in FIG. 4 which is indicated by the position of the hinge 
portion 24 at minimum distance F from the surface of the hub 28. This 
reverse stroke of the holder and lancet needle can be expressed by the 
difference between the distance E and the distance F. 
The operation of the actuator 10 from the armed position in FIG. 2 through 
the intermediate, skin puncturing position in FIG. 3 and continuously to 
the needle withdrawal, retracted position in FIG. 4 can thus be measured 
by the displacements of the hinge portion 24 from the initially retracted 
distance D to the maximally advanced distance E and then retracted to the 
distance F in the smooth and highly linear displacement reversals as the 
leaf member 20 is pivotally driven clockwise by the tensioned torsion 
spring 36. 
When the actuator operation and lancet puncture procedure are completed as 
reflected in the actuator position shown in FIG. 4, the used lancet unit A 
is ejected from the holder 12 by sliding the cocking member 52 forward 
from its neutral position as shown in FIG. 4 into the forward position 
shown in FIG. 5; in this position the ejector portion 70, on the upper 
part of the cocking member 52 enters and passes through the slot 72 formed 
through the rear end of the holder so that the ejector portion 70 engages 
and displaces the lancet unit A from the aperture 16 of the holder 12. The 
cocking member 52 is then manually retracted to the neutral position shown 
in FIG. 4 so that the ejector portion 70 is withdrawn from the slot 72. A 
new lancet unit A can then be inserted into the holder 12 which is 
maintained in the fully retracted position of FIG. 4 during the 
friction-fit insertion of the lancet unit A by a stop member 74, depending 
from the housing 14. The stop member 74 engages the rear end of the guide 
flange 64 to arrest further retraction of the holder 12. After installing 
the new lancet unit A, the actuator 10 can then be armed to the position 
shown in FIG. 2 in the cocking operation described hereinabove with 
reference thereto. 
Referring now to FIGS. 8, 9 and 10, a second embodiment of the actuator in 
accordance with this invention is generally designated by reference 
character 100. The entire actuator 100 can be employed for single-use 
disposability, and therefore the double hinged linkage structure generally 
designated by reference character 102 is similar to the double hinge 
linkage structure 13 in the first embodiment of the actuator 10, with the 
exception that a lancet needle 104 is insert molded within the integrally 
molded holder or carriage 106. 
In operation, the lancet needle 104 is driven forwardly from the retracted 
position shown in FIG. 8 to project from the operation aperture 108 at the 
forward end of the split housing 110 as shown in FIG. 9; the continued 
pivot of the first and second leaf members 112 and 114 of the linkage 
structure 102 produces the immediately sequential retraction of the lancet 
needle 104 and holder 106 to the safely withdrawn position shown in FIG. 
10. The operation of the actuator is driven by a flat or leaf spring 116 
which is anchored at one end 118 within the housing 110 and is initially 
flexed as shown in FIG. 8 by engagement of the opposite end 120 against a 
spring seat 122 formed at the rear end of a manual trigger member 124. The 
trigger member 124 is maintained in the armed condition of the actuator 
100 and spring 116 by wedged engagement with a safety tab 126 which is 
integrally secured to the housing 110 by a small detachable web 128. 
When the actuator 100 is employed to puncture the intended tissue, the web 
128 is fractured to detach the safety tab 126. After removal of the safety 
tab 126, the trigger member 124 can be manually depressed in a downward 
direction as shown in FIG. 9, thus pivoting the trigger member about the 
pivot bearing 130 so that the spring end 120 becomes unseated from the 
trigger spring seat 122 and a retaining pin 132 on the trigger becomes 
unseated from a retaining notch 134 formed in a retaining cam 136 
extending from the first leaf member 112. The released spring end 120 
unflexes leftwardly, as shown in FIG. 9, so that it engages against a 
bearing cam 138 formed on the first leaf member 112 so that the entire 
leaf member 112 is driven to pivot in a clockwise direction about the 
integrally formed pivot bearing 140 which is journaled in the housing 110. 
Resulting relative pivotal motion of the hinge members 112 and 114 brings 
the hinge members to the intermediate position of full extension as shown 
in FIG. 9 which advances the integrally hinged holder or carriage 106 
slidably through the extended guide bore 142 formed in the housing 110. 
The bore 142 opens into the operating aperture 108 from which the advanced 
lancet needle 104 is extended to achieve the tissue puncture. Thereafter 
as shown in FIG. 10 the continuous clockwise rotation of the first leaf 
member 112 under action of the spring end 120 also drives the smoothly 
continuous relative pivot of the second leaf member 114 which pulls the 
immediately sequential and highly accurate linear retraction of the holder 
106 through the guide bore 142 as shown in FIG. 10 so that the lancet 
needle is safely withdrawn from the aperture 108. Since the second 
actuator embodiment 100 has a simplified design for single-use 
disposability, a rearming mechanism for repeated use is unnecessary but 
could be provided. 
In light of the foregoing description of the embodied lancet actuators, 
modifications will be evident to those skilled in the design of such 
mechanisms and are within the broad scope of the appended claims and 
equivalents thereof.