Retractable finger lancet

A two-piece, single-use, disposable lancet assembly includes a housing containing a lancet formed from a spring wire integrally formed with a sharpened, skin-piercing probe end section. The spring lancet is mounted within the housing and is secured in a retracted, pre-tensioned or cocked position. A lever-like bar hingedly secured to the housing serves both as a closure for the access opening in the housing and as a lever for dislodging and for releasing the tensioned spring wire to actuate the skin-piercing probe to pulse functionally through a base port in the housing and then automatically to retract irretrievably into the housing.

FIELD OF THE INVENTION 
The present invention relates to a retractable finger lancet assembly 
including a lancet for penetrating the skin of a patient to obtain blood 
samples for medical examination and testing. More particularly, the 
invention is directed to a lancet, a housing in which the lancet is stored 
and restrained in a tensioned configuration, and from which the lancet may 
be functionally projected, and including a mechanism by which the probe of 
the lancet is promptly and automatically retracted into the protective 
housing. 
BACKGROUND OF THE INVENTION 
Spring-energized or driven lancets of many and varied structual 
arrangements have been employed extensively to replace needles and 
hand-carried needle-like probes for piercing the skin, particularly the 
finger, to provide blood samples for examination and clinical testing. 
While these "automated" lancets have provided some inprovement and an 
enhanced degree of control in the procedures involved, the mechanisms 
themselves have disadvantages and objectionable features. 
The relative complexity of some devices has contributed to these 
difficulties and has made the devices expensive in manufacture as well as 
unreliable in use. Excessive numbers of springs, plunger elements and 
other interrelated operating components have rendered many of the 
automated lancet assembles unduly complex. Others of prior art lancets are 
foreboding in their visual appearance and give rise to undue concern on 
the part of the patient. 
It is, accordingly, a principal aim of the present invention to provide an 
automatic lancet having minimum physical components, and which is 
relatively simple in construction, uninhibiting in appearance, and which 
exhibits an enhanced simplicity and is reliable in use. The lancet of the 
present invention obviates many of the shortcomings and objectionable 
features of prior art devices. 
SUMMARY OF THE INVENTION 
The retractable finger lancet of the present invention is advantageously 
characterized in that it is exceedingly simple in construction. The lancet 
assembly consists of only two physical components--a housing of plastic 
composition and a spring having a sharpened end portion which constitutes 
the needle-like probe of the lancet. 
It is a feature of the retractable finger lancet assembly of the invention 
that it includes an actuating spring which is secured and restrained 
within the housing in a pretensioned, cocked configuration, with the 
skin-piercing probe retracted so that it is protected and out of sight. 
Another feature of the invention is that the housing is formed with a top 
access opening and that a lever-like bar is hingedly attached to the 
housing as a pivotally positionable closure therefor. 
It is a related feature of the invention that digital pressure applied to 
the housing closure bar when the latter is in a housing-closing attitude 
is effective further to depress the bar and to release and to actuate the 
lancet spring, thereby causing the spring forcibly to elongate and project 
and to present its sharpened probe end functionally through a port formed 
in a base of the housing. 
It is a further feature of the invention that upon actuation of the 
pretensioned and secured lancet spring by digitally effected dislodging 
displacement, the spring itself automatically traverses a series of 
uninterrupted sequential movements in which a skin-piercing end of the 
spring is extended to project, through a port, out from the housing and, 
thereupon, is promptly retracted into the housing to assume a withdrawn, 
inoperative and sequestered disposition. 
A related feature of the invention is that the housing of the assembly is 
formed interiorly thereof with spaced guide walls delineating a path of 
travel of a central coiled body portion of the spring during execution of 
the sequence of movement thereof initiated upon release of the spring from 
its initial, retracted, pretensioned mode. 
Yet another feature of the retractable lancet of the invention is a locking 
notch formed in a sidewall of the housing for releasably securing an end 
arm of the lancet spring there within to restrain the spring in a 
pretensioned, protected, stand-by mode. 
A related feature of the invention is the provision in a sidewall of the 
assembly housing of a transverse, generally horizontal slot communicating 
with the spring arm locking notch, the slot defining a path of lateral 
travel of the spring arm therewithin when the latter is forcibly dislodged 
an released from the locking notch. Upon its release from the locked 
position, the spring arm snaps to travel across the lateral expanse of the 
housing and to effect concurrent lineal reciprocal movement of a probe end 
of the lancet spring downwardly and outwardly of the housing. Finally, 
without any interruption in the motion of the spring assembly, the probe 
end is automatically retracted inwardly into the housing. 
Yet another feature of the invention is that an upper edge of the sidewall 
bounding the slot formed in the housing is vaulted upwardly to define a 
controlled, arcuate guide path to be traversed by the spring arm as the 
latter bears there against in its travel across the housing. 
Another feature of the invention is the provision of cooperating 
interlocking elements at a free end of the lever-like, housing-closing bar 
and at a corresponding upper edge of the housing for retaining the closing 
bar in a position to overlie and to close a top opening in the housing. 
Still another feature of the invention is that the spring lancet uses only 
a single spring element. The spring comprises a wire having a circularly 
looped or coiled center sector unitary with a pair of arms extending in a 
wing-like attitude from the center sector and tangentially thereof. 
It is a structual feature of the lancet assembly of the invention that the 
housing is generally triangular or funnel shaped as viewed in front 
elevation, with a wide upwardly-opening upper section tapering to a narrow 
base formed with a restricted orifice through which the probe end of the 
lancet is forcibly projected during functional operation of the lancet. 
The probe end then automatically retracts to within the body of the 
housing.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT 
The aims and objects of the invention are accomplished by providing in a 
retractable lancet assembly a simplified mechanical structure with a 
reduced number of functional physical components. The illustrated 
embodiment of the invention includes a plastic housing of unitary 
construction in combination with a wire spring element, the latter serving 
both as the lancing probe and as the means for functionally driving the 
skin-piercing probe. The spring utilized is preferably in the form of a 
resilient stainless steel wire having straight end sections projecting in 
generally opposed directions from a looped or coiled central body. The 
housing is formed internally with spring guide walls and with a spring 
securement notch in which an upper end portion of the spring is retained 
to restrain and hold the spring in a pretensioned mode. A digitally 
depressible lever integrally formed with the housing serves also as a bar 
for displacing the secured end of the tensioned spring to release the 
spring to permit the latter to pulse, causing its probe end to extend 
through a base orifice in the housing and then automatically to retract to 
a relaxed and spent mode, interiorly of the housing. 
Referring now to the drawings, in a preferred embodiment of the retractable 
lancet of the invention, shown for illustrative purposes only and not to 
be construed in any limiting sense, the lancet assembly 20 is depicted 
(FIG. 1) as including hollow housing 22 of plastic material and having a 
generally funnel shaped configuration. The housing 22 includes spaced 
front and rear walls 24 and 26 joined by side walls 30 and 32. The housing 
22 is illustratively shown as integrally molded in a unitary form 
corresponding generally to its final physical configuration. 
Alternatively, the housing may be molded in a spread or "opened" attitude 
in which the opposed side walls are initially disposed as opposed pages of 
an open book, and joined at inner edges thereof along a connecting live 
hinge, the latter being integrally formed with the sides of the housing, 
during the molding process. 
As shown, the rear wall 26 of the lancet assembly includes at its upper end 
a rearwardly displaced, laterally extending section 34 (FIGS. 1 and 6) and 
with an elongate slot 36 extending transversly through the rear wall 26 
along substantially a full lateral expanse thereof. 
As indicated in FIG. 1, the housing 22 is formed with an upwardly directed 
top opening 38 providing access into the body cavity 42 or interior of the 
housing 22. A pivotally manipulatable lever-like bar 46 is hingedly 
fastened to the housing 22 at an upper end edge 48 thereof by means of a 
integrally formed web or live hinge 52. The bar 46 serves the dual 
function of a closure for the top opening 38 in the housing 22 and as an 
actuator for releasing a tensioned lancet spring 56 mounted within the 
cavity 42 of the housing 22 (FIGS. 2 through 6). At its lower end 58 the 
housing 22 is formed with a port or aperture 60 through which a lower or 
distal, sharpened skin-piercing terminal or probe end 62 of the spring 56 
is directed forcibly to pulse and to project, and then automatically to 
retract during the use cycle of the lancet of the invention. 
FIGS. 2-6 show in somewhat greater detail additional structual features of 
the automatically retractable lancet assembly 20 of the invention and 
depict the successive orientations assumed by the lancet spring 56 during 
sequential operational modes of the assembly 20. In the illustrated 
embodiment of the invention, as best shown in FIG. 2, the lancet spring 56 
is a wire having lineal, generally upwardly extending and downwardly 
extending opposed end sections 66 and 68 which are joined to, extend 
taugentially from and which are integrally formed with an immediately 
positioned looped or coiled section 70. The downwardly directed lower 
section 68 of the spring 56 terminates in the sharpened, skin piercing 
probe end 62. The upper lineal section 66 of the spring 56 is bent to 
provide an arm 74 (FIG. 6) extending normally of a plane defined by the 
looped spring section 70. 
The arm 74 of the spring 56 is releasably restrained in a locking notch or 
socket 78 so as to secure the spring 56 in a tensioned mode. The notch 78 
is formed in an upper zone of the rear wall 24 of the housing and opens 
downwardly to communicate with the horizontally extending guide slot 36 so 
that, upon downward displacement of the locking arm 74 and dislodgement of 
the arm 74 from the notch or socket 78, the pretensioned spring 56 is 
released so that the upper end section 66 of the spring 56 traverses an 
arcuate path across the width of the housing 22 with the arm 74 of the 
spring riding in the slot 36 and bearing against a downwardly presented 
edge 80 of the rear wall 24 of the housing 22 bounding a 
laterally-extending upper limit of the slot 36. 
In the specific embodiment of the invention illustrated, the edge 80 is 
formed to include a section 84 executing an arcuate path vaulted upwardly. 
An adjacent, substantially horizontally extending connected section 86 
provides, with the arcuate section 84, a cam surface defining a guide path 
for regulating movement of the spring arm 74 upon its release from 
restraint. That is, upon release of the spring 56 from its pretensioned 
mode, the spring arm 74 will bear against and travel along the wall edge 
80 as the probe end 62 of the spring 56 pulses out through the aperture 60 
and then automatically retracts to recede into the housing 22. In the 
illustrated embodiment, these surfaces 84 and 86 are also partially formed 
on an adjacent undersurface of the trigger bar 46. 
As shown in FIGS. 2 through 5, the front wall 24 of the housing 22 is 
formed with a pair of generally parallel, laterally-spaced, vertically 
directed ribs 88 and 90 which diverge slightly in an upward direction and 
which are integrally formed with and extend along the front wall 24 and 
inwardly thereof, within the cavity 42 of the housing 22. The ribs 88 and 
90 are aligned at lower ends thereof with corresponding lower end wall 
sections 94 and 96 of the housing 22, establishing the ribs as upwardly 
projecting, in-line extensions of the wall sections 94 and 96. This 
internal structure within the housing 22 delineates a vertically-extending 
guide channel 100 in which the looped section 70 of the spring 56 is 
restricted reciprocally to ride during execution of its functional 
movement when released from its initial, pre-tensioned mode. 
Referring further to FIG. 2, the spring lancet 56 is shown in its initial 
pre-tensioned mode, the locking arm 74 being seated in the notch 78 and 
secured in place to immobilize the spring 56. The spring actuating bar 46 
is shown in a housing-closing attitude, but not in a fully depressed 
position. The bar 46 carries on its undersurface a downwardly projecting 
elongate wall-like flange 104 (FIG. 6) which functions as a guide for an 
upper portion 108 of the spring section 66 of the spring 56 thereagainst 
when the bar 46 is fully depressed to release the spring 56. The upper 
section 66 of the spring 56 then moves rapidly across the width of the 
housing 22, interiorly thereof. 
It will be understood that the spring 56 is released from its secured, 
tensioned mode by dislodging the arm 74 of the spring 56 from the locking 
notch 78. In the embodiment of the invention shown, this dislodgement is 
effected by application of digital pressure downwardly on the free end 110 
of the bar 46 to bring an under-shoulder 112 of the actuating bar 46 to 
bear downwardly upon the arm 74 of the spring 56 and forcibly to displace 
the arm 74 from its seat in the locking notch 78. FIG. 2 shows the 
actuator bar 46 in a housing-closing mode, but in a standby position, and 
the spring 56 restrained and under tension, with the holding arm 74 locked 
in the notch 78. 
FIG. 3 depicts the spring 56 at the instant of dislodgement of the spring 
locking arm 74 from the retaining notch 78, the arm 46 having been urged 
downwardly and having dislodged the holding arm 74, thereby initiating the 
skin-piercing cycle. A wedge-like projection 116 on a forward end face of 
the bar 46 keys in cooperating opening 118 formed adjacent the top of the 
opposed side wall 26 to latch the bar 46 in a cavity-closing disposition 
in which the bar overlies the spring arm 74. The arrangement described 
permits digitally effected downward displacement of the bar 46 to dislodge 
and release the spring arm 74. 
Referring also to FIG. 4, there is indicated schematically in FIG. 4 the 
orientation of the automatically retractable spring lancet 56 shortly 
after release of the locking arm 74. In FIG. 4, the spring section 66, 
being under tension from an initial distortion of the looped section 70, 
begins its swing laterally across the housing 22 with the arm riding along 
the camming guide edge 84. During this movement of the upper section 66 of 
the spring 56, and as shown in FIG. 4, the upper spring arm 66 assumes a 
transitory position in-line with the lower spring arm 68, the result being 
to establish a lengthened effective vertical expanse and reach of the 
spring 56 as the looped central section 70 and the lower section 68 of the 
spring 56 are urged downwardly in the guide channel 100. At the same 
instant, the sharpened probe end 62 of the lancet 56 is momentarily and 
forcibly advanced through the base aperture 60 in a manner to pierce the 
skin, should the lancet assembly be then supported in place, for example 
on the finger of a patient. 
FIG. 4 illustrates an intermediate, transitory position and configuration 
of the spring section 66 when the probe end 62 of the lancet 56 extends at 
a maximum piercing travel distance through the orifice 60 and outwardly of 
the housing 22. 
The continuing and uninterrupted steps in the travel sequence of the lancet 
spring 56 as it completes its reciprocal, probe-advancing and retracting 
cycle are shown in FIG. 5. As the upper section 66 of the spring lancet 56 
continues its lateral travel beyond the point (FIG. 4) at which the upper 
section 66 is an in-line extension of the lower spring section 68, the 
over-all effective length of the spring 56 is foreshortened. When the 
spring 56 finally assumes a neutral end position and configuration in 
which the upper spring arm 66 abuts an upper angled portion 122 of the 
side wall 32 of the housing 22, as depicted in FIG. 5, the looped or 
coiled central section 70 is elevated within the channel 100 and, 
simultaneously, the probe end 62 is irreversibly and irretrievably 
retracted into and sequestered within the interior of the housing 22. The 
end 74 is visible through a top end opening 114 in the wall 34. 
In assembling the automatically retractable lancet device of the invention, 
the spring 56, in its at-rest, untensioned configuration, is inserted into 
the housing 22 through the top opening 38, the closure bar 46 being 
hingedly pivoted to an open position as indicated in broken lines in FIG. 
4. The lancet spring 56 assumes generally the position shown in FIG. 5. 
To cock the spring 56 and set it at a tensioned mode, a machine finger or 
other suitable tool (not shown) is introduced into the housing 22 through 
the top opening to engage the spring section 66 adjacent the arm 74 and to 
displace the upper part 66 of the spring 56 laterally against its biasing 
force, thereby to seat the locking arm 74 in the spring-restraining 
locking socket 78. The closure bar 46 is then pivoted to assume the 
position indicated in FIGS. 1 and 2. 
Alternatively, the bar 46 may be pivoted to a housing closing position 
immediately after insertion of the spring lancet 56. A machine finger may 
then be inserted into the horizontal slot 36 and moved laterally to pull 
back and cock the spring 56, locking the spring arm 74 in the retaining 
notch 78. 
The device may conveniently be sterilized, after assembly, through the use 
of a sterilizing gas such as ethylene oxide Any other suitable 
sterilization technique may be employed. 
While the structure of the automatically retractable lancet of the 
invention has been described with reference to certain structual 
materials, this fact should not be construed as limiting the invention in 
any sense. For example, the housing 22 may be molded from any preferred 
plastic, for example polypropylene or a copolymer of acrylonitrile, 
butadiene and styrene (ABS). The lancet spring is conveniently fabricated 
from stainless steel wire. The openings 36 and 114 in the housing are 
useful to show the location of the wire spring so that one may readily 
discern whether the unit has or has not been used. 
While particular embodiments of the invention have been shown and described 
in detail, it will be obvious to those skilled in the art that changes and 
modifications of the present invention, in its various aspects, may be 
made without departing from the invention in its broader aspects, some of 
which changes and modifications being matters of routine engineering or 
design, and others being apparent only after study. As such, the scope of 
the invention should not be limnited by the particular embodiment and 
specific construction described herein but should be definded by the 
appended claims and equivalents thereof. Accordingly, the aim in the 
appended claims is to cover all such changes and modifications as fall 
within the true spirit and scope of the invention.