Patent Application
20050070819
The present invention is directed to devices, constructions and techniques for effectively obtaining a sample of body fluid in a reliable, minimally-invasive and/or substantially pain-free manner.
A survey of the prior art reveals an abundance of techniques and devices for obtaining a sample of body fluid.
According to the present invention, the state of the art has been advanced through the provision of devices and techniques, such as those described further herein, for obtaining a sample of body fluid in a manner which is reliable, minimally-invasive and/or substantially pain free.
According to one aspect, the present invention provides a device operable to extract a sample of body fluid, the device comprising: at least one skin-penetration member; an actuator for extending and/or retracting the at least one skin-penetration member; a controller for controlling the actuator; and a housing for mounting the at least one skin-penetration member and the actuator.
According to a further aspect, the present invention provides a device for extracting body fluid, the device comprising: at least one needle having an inner bore and an outer diameter; and at least one axially moveable hollow tubular member disposed in the inner bore.
According to an additional aspect, the present invention provides a body fluid sampling device comprising: at least one skin-penetration member; an actuator for extending and/or retracting the at least one skin-penetration member; a controller for controlling the actuator; a housing for mounting the at least one skin-penetration member and the actuator, the housing allowing the at least one skin-penetration member to be extended from the device; and a skin sensor measuring electrical parameters transmitted through the at least one skin-penetration member.
According to yet another aspect, the present invention provides a method of extracting a sample of body fluid, the method comprising: (i) inserting at least one skin-penetration member a predetermined distance into the skin at a sampling site; (ii) at least partially retracting the at least one skin-penetration member back from the predetermined distance; and (iii) withdrawing a sample of body fluid form the sampling site.
Exemplary arrangements and techniques for obtaining a sample of body fluid will now be described by reference to the accompanying drawing figures.
As used herein, the term “body fluid” is intended to encompass blood, interstitial fluid, and combinations thereof. While the principles of the present invention have been developed primarily with the goal of obtaining samples of body fluid from humans, it is envisioned that the arrangements and techniques described herein could also find application in obtaining samples of body fluids from other animals as well.
According to one aspect, the present invention provides arrangements and techniques for automating and precisely controlling the body-fluid sampling procedure.
The term “automation” as used herein, is intended to encompass arrangements and techniques whereby a sample of body fluid may be obtained with little or no active intervention. However, it should also be understood that the arrangements and techniques described herein as being “automated” are also intended to encompass arrangements and techniques that can be initiated, manipulated, and terminated by the subject whose body fluid is being sampled, or a third party such as a caregiver, etc.
Arrangements and techniques according to the present invention allow for the precise control of numerous body-fluid sampling parameters, such as the penetration depth of a skin-penetration member, the speed at which the skin-penetration member is inserted, the frequency at which the skin-penetration member is inserted, the dwell time of the skin-penetration member within the body of the subject, as well as longitudinal (i.e.—axial), rotational, and/or angular articulation and manipulation of the skin-penetration member.
Illustrative embodiments of arrangements constructed according to the principles of the present invention are illustrated in
Arrangements representing embodiments of the above are illustrated in
A suitable arrangement constructed according to the principles of the present invention may be provided with numerous other details and features. Some of these details and features are illustrated in
As illustrated in
The skin-penetration member 6 can be provided with any suitable construction. For example, the skin-penetration member 6 can comprise one, a plurality, or a combination of at least the following types of elements: a needle or a lancet.
The skin-penetration member 6 can be mounted within the larger device in any suitable manner. In the illustrated embodiment, the skin-penetration member 6 is carried by, and through, a guide member 7 which is disposed within the base 2. The guide member 7 accurately controls the travel of the skin-penetration member 6 therethrough. According to the one alternative embodiment of the present invention, the skin-penetration member 6 comprises a very small diameter, or gage, needle or lancet. Such small diameter penetration members can provide an advantage in terms of creating a smaller wound and thus reducing the pain associated with penetration into the skin S. A tradeoff involved with the use of such small diameter members is that they lack structural integrity. Thus, when a skin-penetration member of a very small diameter is inserted into the skin S, buckling or other distortions of the skin-penetration member are frequently observed. The guide member 7, when utilized, acts to counteract the above-described tendency to buckle or otherwise to deform small diameter skin-penetration members.
According to the illustrated embodiment, a mounting block 8 is also provided, which carries and locates the guide member 7 within the base 2.
According to one aspect of the present invention, an arrangement, such as the illustrated arrangement 1, is ambulatory or wearable by the subject whose body fluid is being sampled. The principles of the present invention are seen as being potentially useful when incorporated in the context of wearable devices, and in particular, in wearable glucose monitoring devices. Benefits provided to such wearable devices by the constructions, arrangements and techniques of the present invention include: the reliable acquisition of body fluid, the ability to autonomously obtain samples of body fluid, and the minimization of pain associated with obtaining samples of body fluid.
Thus, an arrangement constructed according to the principles of the present invention may include means which permits the device to be worn by the subject whose body fluid is being sampled. For example, in the illustrated embodiment, the arrangement 1 may be provided with a securing strap 9 which may be fitted over the base 2 and loops around a limb of the wearer, such as an arm, leg, etc. The securing strap 9 can take any suitable form, such as a Velcro strap. Further, an adhesive 10 may be used to secure a sampling device to the body of a wearer. The adhesive 10 may be provided as a substitute for, or in addition to, a securing strap 9.
According to an alternative embodiment, an arrangement, similar to that illustrated in
As noted above, an arrangement constructed according to one embodiment of the present invention allows for the insertion of the skin-penetration member at either a 90° angle, or a non-orthogonal angle α, relative to the surface of the skin S. One suitable construction for providing this function is illustrated in
According to one aspect of the present invention, the skin-penetration member 6 is operatively associated with the actuator 4, as well as a mechanism for the collection of the sample of body fluid, by any suitable arrangement. In the arrangement 1 illustrated in
As further illustrated in
According to a further aspect of the present invention, a suitable arrangement can be provided with an actuator 4. The specific details of such an actuator 4 can vary greatly. For example, as illustrated in
One of the benefits of an arrangement provided consistent with the principles of the present invention is to control actuation of the skin-penetration member in a precise, and possibly autonomous manner. In this regard, one or more connections 22 can be provided which communicate with a suitable controller (e.g.—5,
The actuator 4 can also be operatively associated with a device for providing a motive force thereto, such as a motor M. Any suitable motor or motive-force producing element can be utilized. According to a non-limited example, the motor M comprises an electrical stepper-motor. Whatever the mechanism utilized to drive the actuator 4, it is within the scope of the present invention to provide the skin-penetration member not only with pure longitudinal travel, but with rotational and/or angular articulation as well. Further, it is within the scope of the present invention to also provide the skin-penetration member with vibration and/or heat.
The controller 5 can be operatively associated with the motor M to provide the above-mentioned functionality.
According to a further aspect, an arrangement constructed according to the principles of the present invention may further be provided for facilitating collection of a sample of body fluid produced by actuation of the skin-penetration member 6 into the surface of the skin S. According to the example illustrated in
In the discussion that follows, various additional constructions, arrangements, and techniques will be described. While it is entirely possible that the following constructions, arrangements and techniques may be utilized in connection with an arrangements as described above, it should be understood that the present invention is not so limited. In other words, the constructions, arrangements and techniques described below may clearly be utilized independently from some or all of the previously described aspects of the present invention, as well as being incorporable therein.
Another aspect of the present invention involves the manipulation of the skin and/or wound either before, during, or subsequent to insertion of a skin-penetration member into the surface of the skin. Such manipulation can increase the reliability of obtaining a sample of body fluid, as well as decreases the invasiveness and pain associated with obtaining an adequate sample of body fluid in a reliable and repeatable manner. According to the present invention, mechanical, vacuum-assisted, thermal and/or chemical stimulation is comprehended.
According to one example, an arrangement 30 can be utilized to provide mechanical stimulation of the skin prior to, during, or subsequent to the insertion of a skin-penetration member. The arrangement 30, as illustrated in
As previously noted, the above-described arrangement 30 can be utilized to pinch the skin S prior to insertion of a skin-penetration member. By doing so, blood and other body fluids may rush to the site which corresponds to the site which the skin-penetration member is to penetrate the skin S. This profusion effect increases the likelihood of obtaining an appropriate sample of body fluid.
Alternatively, the arrangement 30 may be utilized, for example, once a wound has been created by insertion of the skin-penetration member. In this regard, the pinching action illustrated in
According to another aspect, the present invention utilizes devices and/or techniques which involve the thermal stimulation of the skin at the site where the skin-penetration member is to be inserted, either prior to insertion, during insertion or subsequent to insertion. Numerous devices and techniques for accomplishing this thermal stimulation are clearly possible. For example, as illustrated in
The application of thermal stimulation to the skin prior to insertion of the skin-penetration member also causes profusion of blood to the stimulated area, thereby increasing the likelihood of obtaining an adequate sample of body fluid upon insertion of the skin-penetration member. When applied during insertion, the same basic effect can be utilized in order to prevent coagulation, and increase profusion of body fluid to the wound site. When thermal stimulation is provided subsequent to withdrawal of the skin-penetration member, the same effect can be utilized to create profusion of body fluid to the wound site, prevention of coagulation, etc.
According to another aspect, the present invention involves devices, constructions and techniques for utilizing a vacuum to stimulate the skin at the area in which the skin-penetration member is to be inserted and/or at the wound site itself within the skin. Generally speaking, this aspect of the present invention involves vacuum assisted manipulation in which a pulsed vacuum can be applied to repeatedly draw-up and release the skin at the area around the wound site. The use of such a pulsed vacuum can be utilized to work the skin and produce a warming effect which is similar to that produced by mechanical stimulation, or rubbing. This stimulation results in profusion of body fluid to the site in which the skin-penetration member is to be inserted, thus increasing the possibility of obtaining an adequate sample of body fluid therefrom. The application of such a pulsed vacuum to the skin around the wound subsequent to insertion of the skin-penetration member enhances the ability to draw the bodily fluid from the skin and increases the volume of body fluid available for sampling. Thus, it is evident that the use of the above-described pulsed vacuum, by maximizing the amount of body fluid that can be drawn from insertion of the skin-penetration member, thereby permits the use of smaller diameter needles or lancets to produce an adequate sample size, thus resulting in lower pain levels to the user of the device. Further, the use of the above-described pulsed vacuum eliminates the necessity of relatively bulky mechanical components and drive mechanisms, thereby facilitating a more compact design. The application of a vacuum which can be used for skin manipulation, can also serve the dual purpose of drawing and transporting the sample of body fluid from the wound site.
Illustrative embodiments of this aspect of the present invention are set forth in
The block 42 is provided with an interior annular cavity 44. This cavity 44 is in communication with a vacuum port 46. A central post 48 is also provided which is also constructed for contact with the surface of the skin. A central port 50 may also be provided through the central post 48, the central port 50 being in fluid communication with the surface of the skin. The vacuum port may be connected to a pulsed vacuum source in any suitable manner, such as an appropriate fluid connection 52.
According to the present invention, the central post member 48 may be modified so that, for example, a concave or convex or otherwise advantageously configured bottom can be provided such that when contact is made with the surface of the skin, the advantageous benefits described above can be more readily achieved. The central port 50 may be utilized to collect and transport body fluid to a remote location. Further, the central post 48 can be constructed with a modified length from that of the illustrated embodiment to provide effects similar to that described above.
It should be noted, however, that the use of a vacuum may optionally be provided to assist with the collection and transport of body fluid from the wound site to a remote location. However, the use of a vacuum is not necessary. In this regard, a separate hollow capillary tube or other similarly constructed member may be inserted through the central port 50 to transport a sample of body fluid via capillary action. According to a further alternative, a skin piercing element in the form of a hollow needle may be inserted through the central port 50 which is then utilized to pierce the skin S and create a wound and which may also subsequently be used to collect and transport a sample of body fluid from the wound site to a remote location with or without the assistance of a vacuum and/or capillary action.
It is contemplated that many factors can and do affect the magnitude of the pulsed vacuum which may be applied to the wound site. One suitable, but non-limiting example of possible vacuum level is approximately 3.5 psi. One of ordinary skill in the art could determine that other optimal vacuum conditions exist under the particular set of circumstances under which the body fluid sample is being collected.
Any suitable means of providing the desired pulsed vacuum pressure may be utilized. Illustrative, and non-limiting examples are depicted in
An alternative construction for providing a suitable source of pulsed vacuum pressure is illustrated by the arrangement 66 contained in
An additional aspect of the present invention involves constructions and techniques associated with the skin-penetration members.
As previously noted, a skin-penetration member formed consistent with the principles of the present invention may take any suitable form, such as a hollow needle, or a solid lancet.
According to one embodiment of the present invention, a skin-penetration member can be formed which includes one or more of the features illustrated in
As noted above, the skin-penetration member 500 is in the form of a hollow needle, thus, the skin-penetration member 500 includes both an outside diameter OD as well as an inside diameter ID, defining an inner bore (see, e.g.—
According to one embodiment, the skin-penetration member 500 is in the form of a so-called “microneedle.” As the name implies, microneedles are characterizable by their relatively small outer diameters. For example, a microneedle, as the term is utilized herein, may encompass a skin-penetration member having an outside diameter which is on the order of 40-200 μm. The inside diameter can vary, for example, having an inside diameter on the order of 25-160 μm. Needles are also characterizable in the art by reference to the “gage.” By way of illustration, and consistent with the above description, microneedles having a gage ranging from 26-36 are clearly comprehended by the present invention. Certain advantages may be gleaned from the use of such microneedles as the skin-penetration member. In particular, due to their small size, the size of the wound left upon entry into the skin is relatively small, thereby minimizing the pain associated with such needle insertions and allowing for a quicker healing process.
A skin penetration member according to the present invention can be formed by any suitable material. Such materials include polymers, metals, ceramics, glass, etc. According to one embodiment, a skin penetration member formed according to the principles of the present invention is constructed of drawn metallic tubing.
According to a further aspect, a skin-penetration member formed according to the principles of the present invention may be provided, on its outside and/or inside diameters with a suitable coating. A number of different coatings are possible. For example, the skin-penetration member can be provided with a anti-friction coating which facilitates entry into the skin upon insertion. By reducing friction with the skin upon insertion, pain-reduction benefits may be achieved. Any number of suitable anti-friction coatings are comprehended. For example, the anti-friction coating may comprise a polymer-based coating material. One such material is in the form of a hydrophilic/hydrophobic polymer matrix. One example of such a coating material is commercially available under the trade name “SLIP-COAT®” which may be obtained commercially from STS Biopolymers, Inc.
Another exemplary coating material includes a drug or therapeutic agent. For example, one suitable coating material includes an anti-coagulant which acts to prevent clotting of the blood which pools inside the wound, thereby facilitating extraction of a sample of body fluid from a newly-created wound caused by insertion of the skin-penetration member. By way of example, one such suitable coating is generally in the form of a hydrogel layer which contains the therapeutic agent therein. One such coating is commercially available under the tradename “MEDI-COAT®” which is commercially available from STS Biopolymers, Inc.
A skin-penetration member constructed and utilized in accordance with the present invention may be formed as illustrated in
According to the present invention, numerous other features and modifications may be provided to a skin-penetration member. Various modifications to the leading end of a skin-penetration member are illustrated in
As illustrated in
Another modified form of a skin-penetration member 700′ is illustrated in
According to another possible embodiment, a skin-penetration member 700″ can be provided in the form of a generally cylindrical member having a serrated or corrugated generally-cylindrical end 702″ which may function as a rotary cutting device upon insertion into the skin thereby forming a wound for the collection of an adequate sample of body fluid. Thus, according to this particular embodiment, the skin-penetration member 700″ can be rotated upon insertion into the skin. The leading or serrated cutting end 702″ is rotated, thereby producing a cutting action which forms a wound which allows for the collection of a sample of body fluid therefrom.
As previously noted, the skin-penetration members 700, 700′ and 700″ can be formed from any suitable material, can be provided with a suitable coating on its inner and/or outer surfaces, and/or may be sized such that they are in the form of “microneedles,” as previously described.
Additional features associated with a skin-penetration member formed according to the principles of the present invention are illustrated in
The second component 810 is an actuator of any suitable construction. By way of example, the actuator 810 can be in the form of a solid rod-like member which is sized such that it may freely travel within the inner diameter of the member 802. The first needle-like member 802 is preferably provided with an inner diameter ID which includes a narrowed or necked-down portion 812 near the leading end thereof. The necked-down inner diameter 812 acts as a ramping-type surface in cooperation with the second component 810 when it is slid toward the leading end of the skin-penetration member 800. As the actuation member 810 contacts the narrowed or necked-down portion 812, a radially outward force is generated at the leading end of the first component 802 such that a splitting-type action occurs, most likely along the weakened areas or cuts 806, 808 thereby causing the leading end of the first component 802 to spread, as illustrated in
The skin-penetration member 800 can be formed from any suitable material, may optionally be provided with a suitable coating material, and may be sized appropriately, as previously disclosed.
An alternative skin-penetration member construction is illustrated in
The skin-penetration member 900 can be formed from any suitable material, provided with any suitable coating, and can be sized such that skin-penetration member 900 is in the form of a “microneedle.”
A skin-penetration member formed according to the principles of the present invention may also include various axial features. Examples of such features are illustrated in
One embodiment of a skin-penetration member formed consistent with the principles of the present invention is set forth in
According to an alternative embodiment, a skin-penetration member 1100 may be constructed as illustrated in
Yet another alternative skin-penetration member construction is illustrated in
A further alternative construction for a skin-penetration member constructed according to the principles of the present invention is illustrated in
As with the previously described embodiments, the skin-penetration members illustrated in
Another aspect of the present invention can be described generally as arrangements and techniques which provide a fluid path for the transport of a sample of body fluid which is separate from the device that causes the wound itself. Three illustrative examples appear in
Devices, arrangements, and techniques constructed or performed according to this aspect of the present invention may provide certain advantages. First, as previously noted, when a skin-penetration member is inserted into the skin, the body often reacts by attempting to form a seal around the penetrating member in order to prevent loss of blood from the body. This sealing effect can inhibit the ability of the device to collect and transport a sample of body fluid from the wound site. Thus, this aspect of the present invention provides a solution for this problem in that at least one of the concentric members can be manipulated in a manner such that the above-described sealing effect does not adversely effect the ability of the device to collect and transport a sample of body fluid. In addition, the use of separate members for wound creation and sample transport also provide opportunities in terms of optimizing the properties of the materials of the members according to their desired function. For example, a body fluid transport member can be constructed of a material, such as an engineered plastic, which promotes capillary action, thereby being more effective in the transport of the sample of body fluid than the member which creates the wound. The material which is utilized in the member which creates the wound can be optimized with respect to the properties which are important to perform this function. Namely, structural integrity, low coefficient of friction, etc. Moreover, multiple fluid pathways can be provided according to this aspect of the present invention. Thus, for example, a gas could be introduced at a positive pressure through one of the fluid passageways into the wound site, thereby expanding the wound site and promoting the pooling of a sample of body fluid for collection and transport. Simultaneously, or subsequent thereto, a vacuum may be applied to another separate fluid passageway, thereby facilitating the collection and transport of a sample of body fluid from the wound site.
Specific illustrative examples will now be described.
One such multi-component skin-penetration member 1400 is illustrated in
As noted above, the components 1402 and 1410 can be constructed of any suitable material. By way of example only, the first member 1402 can be in the form of a needle which has a size on the order of 26 gage, and can be formed from a drawn metallic tubing material. The second component 1410 can be formed from a suitable polymeric material, such as a polyetherimide (PEI) material in the form of a tube sized such that it may freely travel within the inner bore of the first component 1402. For example, the tubular component 1410 can have an outer diameter on the order of 0.008 inches.
The skin-penetration arrangement 1400 can provide certain advantages. For example, the outer needle-like member 1402 can be utilized to create a wound in the skin. Subsequent to insertion in the skin, the inner tubular member 1410 can be translated within the axial bore 1406 and extended beyond the end of the needle-like member 1402, thereby breaking any seal formed between the end of the needle-like member 1402 and the tissue of the body at the wound site. Extension of the tubular member 1410 also creates a greater space at the end of the needle-like member 1402, thereby creating a greater opportunity for the pooling of blood or body fluid at the wound site. A sample of body fluid can be collected by the tubular member 1410 through the inner bore 1412. When present, axial features, such as the passages 1416 facilitate the collection of body fluid from the wound site. As noted above, the tubular member 1410 can be constructed of a material which provides advantageous properties to carry out the functions thereof. For example, the tubular member 1410 can be made from a material, or coated with such a material, that enhances capillary action of a fluid flowing through the inner bore 1412. Vacuum pressure may also be applied to the inner bore 1406 and/or 1412 in order to enhance the ability of the device to collect and transport a sample of body fluid. Further, a gas under positive pressure may be introduced to the wound site via the inner bore 1406 and/or 1412, and passages 1416, if present, thereby expanding the wound site and providing a greater opportunity for the pooling of blood or body fluid. A sample can be collected solely by capillary action, or with the assistance of a vacuum pressure.
According to another illustrative example, a skin-penetration arrangement 1500 is illustrated in
The arrangement 1500 can be utilized in a manner similar to that described above in connection with the arrangement 1400 of
In addition, since the inner member 1510 is in the form of a hollow needle, it is possible to utilize the arrangement 1500 in a manner such that the inner needle-like member 1510 is responsible for creation of the wound site, and the outer needle-like member 1502 is responsible for collecting and transporting the sample of body fluid from the wound site, preferably after retraction of the inner needle-like member 1510. Of course, it is also possible to insert the outer needle-like member 1502 in order to create the wound, then extend the inner needle-like member 1510 from the end thereof in order to break any seal formed over the end of the outer needle-like member 1502, to increase the area of the wound, thereby facilitating the pooling of a sample of blood or body fluid. Further, as previously described, the inner needle-like member 1510 can be extended from the end of the outer needle-like member 1502, and can then be utilized to collect a sample of body fluid from the wound site by capillary action, with vacuum assistance, or a combination of the two. It is also possible to further manipulate the inner and/or outer members 1502, 1510. For example, the inner member 1510 can be rotated to promote cutting action upon wound creation and manipulation.
Yet another illustrative example appears as arrangement 1600 in
A further aspect of the present invention involves providing a skin-penetration member with a cross-section which can provide certain advantages, such as an increased probability of producing a collectable sample of body fluid upon insertion into the skin. One embodiment of this aspect of the present invention is illustrated in
The illustrative embodiment is in the form of a needle-like member 1700 which includes an outer cylindrical surface 1702, an inner bore 1704, and a beveled or angled leading surface 1706. The skin-penetration member 1700 can generally be described as a “flat” needle. As best illustrated in
The cross-section of the flat needle described above, increases the probability of cutting through a body fluid producing element contained under the surface of the skin, such as the capillaries when such a flat needle is inserted into the skin.
As discussed above, in connection with previous embodiments, the skin-penetration member 1700 can be formed from any suitable material, be provided with one or more suitable coatings, and can be appropriately sized. According to one illustrative, but non-limiting example, the skin-penetration member 1700 can be initially provided in the form of a 34 gage hypodermic needle which is then flattened by a suitable process, such as rolling, such that its width dimension W is 2 to 3 times greater than its thickness dimension T.
An additional aspect of the present invention involves techniques for the manipulation of a skin-penetration member with regard to wound creation and wound manipulation. Techniques performed according to the principles of the present invention are believed to be beneficial at least with respect to the areas of reliable and effective acquisition of body fluid, minimization of invasiveness, and/or pain reduction.
One exemplary embodiment of a technique performed consistent with the principles of the present invention is illustrated in
According to the exemplary embodiment, a skin-penetration member 1800 is inserted into the surface of the skin 1802 thereby forming a wound W. There are various skin-penetration member parameters which may be adjusted according to the present invention. For instance, an arrangement, such as the one previously described herein, can be utilized to control the speed, depth, and timing of one or more insertions of a skin-penetration member.
With regard to speed, conventional skin-penetration members, such as lancets, are typically driven into the surface of the skin at a very high rate of speed. While such speeds are possible, it is also comprehended by the present invention that a skin-penetration member, such as a hollow needle, may be inserted into the surface of the skin 1802 at a speed which is far less than that typically utilized when driving lancets into the surface of the skin. By way of example, as previously discussed herein, a skin-penetration member in the form of a hollow needle can be driven into the skin at a travel rate of approximately 1.0-1.5 mm/sec. With regard to timing, it is possible to control, possibly in an automated fashion, when one or more skin-penetration members are inserted into the surface of the skin. When utilized in the context of obtaining a sample of body fluid for analysis to determine concentration levels of glucose, a skin-penetration member can be automatically inserted into the surface of the skin at predetermined intervals. These intervals may be uniform or standard, such as every 2 to 3 hours. Alternatively, the timing of needle insertions can be calculated based on prior test results so that more frequent sampling be carried out when it is determined that the probability that glucose levels present in the body may fall outside of an acceptable range.
The depth at which the skin-penetration member is driven into the surface of the skin 1802 can also be controlled. For example, when attempting to obtain a sample of blood, a penetration depth that is too shallow often results in the situation where capillaries which provide a rich source of blood, are not cut, thereby resulting in a failure to obtain an adequate sample of blood. When the penetration depth is too deep, a problem that has been experienced involves the body's natural tendency to form a seal around an object which penetrates the skin. Thus, this self-sealing problem is frequently encountered at greater penetration depths.
Thus, according to the principles of the present invention, a skin-penetration member 1800 is inserted into the surface of the skin 1802 to a depth such that it penetrates the capillary bed 1804 thereof. By penetrating the capillary bed 1804, an adequate number of capillaries are cut or ruptured to produce an adequate sample of body fluid, such as blood. This step is clearly illustrated in
Further, in order to avoid the above-described self-sealing problem, the skin-penetration member 1800 can be withdrawn, at least partially, from its initial penetration depth, as illustrated in
This pooled body fluid BF can then be collected by any suitable member or technique. When the skin-penetration member 1800 is in the form of a hollow needle, the body fluid BF can be withdrawn through the inner bore thereof. The body fluid can be drawn through the inner bore by either capillary action, a vacuum, or a combination thereof.
Alternatively, a separate member, such as a concentric hollow tubular member (see, e.g.—
According to the present invention, the skin-penetration member 1800 can be manipulated in a number of different ways in order to provide the desired results. The skin-penetration member can be manipulated either during insertion, or subsequent to the initial wound formation.
As illustrated in
An additional embodiment of a technique performed according to the principles of the present invention is illustrated in
Preferably, the skin-penetration member 1900 is inserted to a depth which is sufficient to penetrate into the capillary bed 1904 contained under the surface of the skin 1902.
Subsequently, the skin-penetration member 1900 is completely withdrawn from the wound W, as illustrated in
Subsequently, body fluid BF which has been allowed to pool within the wound W is then collected. A number of different possibilities are possible for this stage of the technique. According to a first option, as illustrated in
Alternatively, as illustrated in
Further, it should be recognized, that a number of different possibilities exist for collection of the sample of body fluid BF once pooling has been allowed to occur.
For example, an arrangement such as that illustrated in
As previously described herein, one aspect of the present invention is the ability to control, and possibly automate, a number of, if not all, of the skin-penetration member insertion and manipulation parameters. In this regard, according to a further aspect of the present invention, a skin sensor arrangement can be utilized in order to facilitate the aforementioned control, manipulation and/or automation of the body fluid sampling arrangements and techniques.
One possible skin-sensing arrangement 2000 formed according to the principles of the present invention is illustrated in
A high gain or trans-impedance amplifier 2006 is provided which is electrically connected to the skin-penetration member 2002, grounded at 2008, and can also be connected to an optional resistive device 2010. According to one embodiment, the amplifier 2006 is driven by a power source in order to facilitate amplification of the output. For purposes of illustration only, the amplifier 2006 can be driven by a 5-volt power source. The amplifier 2006 is capable of detecting very small changes in electrical current which is communicated to it via the electrically-conductive skin-penetration member 2002. According to the present invention, currents, or changes in current, on the order of 10−10 Amps are measurable.
These currents, flowing through the skin-penetration member 2002, are picked up by the amplifier 2006, then outputted to the remainder of the circuit. Several alternative constructions for the remainder of the circuit are envisioned. For example, the signal outputted by the amplifier 2006 can be routed to signal conditioning software and circuitry (not shown) for further processing. Similarly, the signal outputted by the amplifier 2006 may also be routed, either independently, or sequentially, to a microprocessor (not shown) which interprets data, generates information, and may produce a desirable output.
Thus, as apparent from the above, slight changes in currents which occur at the skin-penetration member 2002 are detectable, amplified, and outputted to generate a signal 2012 which is indicative thereof.
When a skin-penetration member 2002 comes into contact with a surface of the skin 2004, a detectable change in current level occurs, and is transmitted to the amplifier 2006. The amplifier then produces an output in response thereto, which, after optional additional processing, generates a signal 2012 which can be interrupted as being indicative of contact of the skin-penetration member 2002 with the surface of the skin 2004.
Numerous uses and applications of the above-described arrangement 2000, and the resulting output signal 2012, are envisioned.
One such technique which utilizes the above-described concepts, is described as follows. A device or arrangement is provided which is capable of inserting a skin-penetration member into the surface of the skin. The device is programmed such that once the surface of the skin is sensed, the device causes the skin-penetration member to be inserted into the skin a predetermined given distance. Subsequent to its insertion, the device may then be programmed to retract or withdraw the skin-penetration member partially, or fully, to a point outside the skin. Further, the device and/or arrangement could also be programmed to re-approach the skin and sense the surface again. Once the surface of the skin has been sensed, a program could be executed to either stop advancement of the skin-penetration member, or re-enter the skin with the skin-penetration member. A device or arrangement to sense the presence of blood may also be incorporated. Thus, as the skin-penetration member reapproaches and senses the surface of the skin, a blood sensing device could be utilized to sense the presence of body fluid, then execute a body fluid collection routine depending upon the results of this inquiry. Thus, if blood was sensed on the surface of the skin, the skin-penetration member would not advance any further, and a sample of body fluid could be collected from the surface of the skin. In the event that body fluid is not sensed on the surface of the skin, the skin-penetration member, or a distinct body fluid collection member, could be reinserted into the skin for the purpose of reopening the wound, improving body fluid pooling action, and/or collection of the sample of body fluid from within the wound.
As a possible modification, it should be evident that an arrangement such as the one illustrated in
The above-described arrangements and techniques are clearly illustrative, and numerous modifications should be apparent to those of ordinary skill in the art using the fundamental concepts of the present invention.
The described embodiments of the present invention are intended to be illustrative rather than restrictive, and are not intended to represent every possible embodiment of the present invention. Various modifications can be made to the disclosed embodiments without departing from the spirit or scope of the invention as set forth in the following claims, both literally and in equivalents recognized in law.
