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ANALYTICAL DEVICE WITH LANCET AND
TEST ELEMENT
The invention concerns an analytical device which contains a lancet and an analytical test element. The invention 5 also concerns a process for manufacturing such an analytical device.
The examination of blood samples in clinical diagnostics enables the early and reliable recognition of pathological states as well as a specific and well-founded monitoring of 10 physical conditions. Medical blood diagnostics always requires the collection of a blood sample from the individual to be examined. Whereas in hospitals and in doctor's offices several millilitres of blood are usually collected by venepuncture from a person to be examined for analysis in order to 15 carry out many laboratory tests, individual analyses which are directed towards one parameter nowadays often only require blood quantities ranging from a few microlitres down to less than one microlitre. Such small quantities of blood do not require a laborious and painful venepuncture. Instead it is 20 sufficient to push a sterile sharp lancet into a finger pad or earlobe of the person to be examined to collect blood through the skin and thus to obtain a few microlitres of blood or less for analysis. This method is particularly suitable when it is possible to carry out the analysis of the blood sample imme- 25 diately after blood collection.
Lancets and suitable instruments for them (so-called blood withdrawal instruments, blood lancet devices or—as they are referred to in the following—lancing aids) which enable 3Q blood collection that is as painfree and reproducible as possible are available especially for so-called home monitoring i.e. where medical laymen carry out simple analyses of the blood by themselves and are used in particular by diabetics to collect blood regularly and several times daily to monitor the 35 blood glucose concentration. Furthermore the use of lancets with lancing aids is intended to reduce the psychological barrier associated with piercing one's own body which is particularly important for children that suffer from diabetes and need regular blood glucose tests. The commercially avail- 4Q able instruments (lancing aids) and lancets Glucolet® from Bayer AG and Softclix® from Roche Diagnostics GmbH are mentioned as examples of lancets and lancing aids. Such lancets and instruments (lancing aids) are for example the subject matter of WO-A 98/48695, EP-AO 565 970, U.S. Pat. No. 4,442,836 or U.S. Pat. No. 5,554,166.
Personal blood sugar determination (so-called home monitoring) is today a world-wide method in diabetes monitoring. Blood sugar instruments of the prior art such as the AccuChek Sensor (from Roche Diagnostics) are composed of a 50 measuring instrument into which a test element (test strip, sensor) is inserted. The test strip is contacted with a drop of blood which has previously been collected from the finger pad by means of a lancing aid. The numerous system components (lancet, lancing aid, test strip and measuring instru- 55 ment) need a lot of space and require a relatively complex handling. There are now also systems with a high degree of integration which are thus more simple to operate. These for example include the AccuCheck Compact (from Roche Diagnostics), the Glucometer Dex (from Bayer Diagnostics) and 60 the Soft-Sense (from Medisense). In the two former systems the test strips are stored in the measuring instrument in magazines and are available for the measurement.
A next step in miniaturization is for example to integrate several functions or functional elements into a single analyti- 65 cal device (disposable). For example the operating process can be considerably simplified by a suitable combination of
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the lancing process and sensory analyte concentration detection on a test strip. There are the following examples of this in the prior art:
EP-B 0 199 484 (Audio Bionics) describes an analytical device ("disposable"; abbreviated dispo) containing an integrated lancet which is actuated by the instrument (see FIG. 9 for example). The lancet is retracted again after the puncture by means of a specific spring mounting ("spring-mounted lance means"). The dispo contains a so-called "wick means" through which the sample liquid is passed from the body surface to the analytical area which is an optically analysable test field.
A method is described in U.S. Pat. No. 6,143,164 (E. Heller & Comp.) in which a body opening (for example a small puncture or incision through the skin) is made and subsequently body fluid is transported into a sensor and examined there for the presence of an analyte. Forthis purpose U.S. Pat. No. 6,143,164 discloses an analytical device in which a lancing device is attached to a sensor test strip. The sample liquid is transported from the body opening to the actual detection element of the sensor for example again by means of a wick or a capillary gap/channel.
WO 99/26539 (Mercury Diagnostics), U.S. Pat. No. 5,951, 492 (Mercury Diagnostics) and U.S. Pat. No. 6,056,701 (Amira Medical) describe, inter alia, collection devices for body fluids comprising an elongate handle; a test field being attached to its head region.
U.S. Pat. No. 6,032,059 (Abbott) and U.S. Pat. No. 6,014, 577 (Abbott) describe a disposable containing a needle which is used to pierce the skin. Body fluid which is previously sucked into the needle by capillary action is analysed by a sensor integrated into the needle.
U.S. Pat. No. 5,801,057 (Smart et al.) describes a disposable made of silicon containing an integrated hollow needle. A collection chamber for aspirated body fluid is located at one end of this hollow needle. The concentration of a blood component can be determined in the body fluid by a suitable reaction chemistry.
U.S. Pat. No. 5,035,704 (Lambert et al.) discloses a system for collecting blood containing a magazine for disposables. It is possible to integrate a lancet element into the dispos. A blood drop is transferred to the test field by direct skin contact and can be increased by applying a vacuum.
U.S. Pat. No. 6,132,449 (Agilent Technologies) discloses an integrated dispo with a puncturing and measuring function. The puncturing element is activated perpendicular to the dispo plane whereby it passes through the dispo. The wound opening is in direct contact with several capillary structures which transport the emerging blood into a separate analytical part of the dispo.
A key problem in collecting blood using a so-called "integrated disposable" (in which the lancet and test element are connected together or form a single unit) is the fact that, after puncture, the capillary blood usually does not automatically emerge from the wound. This adverse effect is increased by directly contacting a disposable with the wound opening. After a puncture the blood drop must be actively conveyed to the skin surface by for example mechanically opening the wound and/or applying gentle pressure to the tissue around the wound area (for example by simple "finger milking"). Application of a vacuum can assist this process.
Experiments in the laboratory have shown that it is advantageous to keep the wound open during the period of blood collection. However, this fact results in a complicated movement process of the dispo since a very rapid piercing motion and a slow blood withdrawal movement can only be achieved
