Surgery – Diagnostic testing – Liquid collection
Reexamination Certificate
2002-07-22
2004-12-14
Marmor, Charles (Department: 3736)
Surgery
Diagnostic testing
Liquid collection
C600S347000, C600S372000, C606S181000, C204S403010
Reexamination Certificate
active
06830551
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a body fluid measuring apparatus for measuring the concentration of a specific component contained in body fluid such as glucose contained in blood, and to a body fluid sampler for the apparatus.
BACKGROUND ART
For diabetes treatment, it is necessary to maintain, in a normal range, the concentration of glucose (hereinafter “blood glucose level”) contained in the blood of a diabetes patient. An important treatment is the blood glucose level management by the patient. Particularly for treatment of insulin-dependent diabetes, the patient should inject insulin to keep the blood glucose level in a normal range. Therefore, measurement of the blood glucose level is essential for the patient.
A portable apparatus usable by a diabetes patient by himself or herself for measuring the blood glucose level is commercially available. For example, JP-B-8-20412 discloses such a blood glucose level measuring apparatus. The blood glucose level measuring apparatus comprises a main unit and a disposable test piece to be mounted on the main unit. An enzyme electrode is formed on the test piece. With this measuring apparatus, when the tip of the test piece contacts blood, a portion of the blood is sucked in by a reacting portion of the test piece by capillary phenomenon to cause an enzyme reaction and an electrochemical reaction in the reacting portion. As a result, an anode current flows to the electrode of the test piece. The anode current is converted to a blood glucose level in an arithmetic circuit in the main unit of the apparatus, and the result is represented on a display.
In order to bring an analyte such as blood into contact with a test piece in the measuring apparatus, a tool named “lancet” is commonly used, as disclosed in JPA-9-266898 for example. The lancet is a tool used for making a small hole or cut in the skin of a finger tip, for example, of a patient. Upon bleeding from the hole or cut, blood is brought into contact with a predetermined site of the test piece for further supply of blood used for measurement of the blood glucose level.
However, with the conventional common self-measurement of the blood glucose level, the lancet for sampling blood is separate from the measuring apparatus, so that the two tools need to be carried by the patient. Moreover, it is necessary to separately perform the steps of injuring the skin with the lancet and of bringing the bleeding blood into contact with the test piece, thus making measurement still complex. In particular, when bringing the blood into contact with the test piece, since a predetermined amount of blood needs to be brought into contact with a predetermined portion of the test piece, it is difficult for an untrained or weak-sighted patient to perform this step quickly and properly.
In addition, the above-described conventional blood glucose level measuring apparatus is designed to suck blood from a hole at the tip of the test piece onto a planar enzyme electrode in the reacting portion by capillary phenomenon. Therefore, at least 3 to 5 &mgr;l of blood needs to be brought into contact with the test piece to ensure that a necessary amount of blood reaches the reacting portion. If the amount of blood is insufficient or if a sufficient amount of blood is not deposited appropriately on a small area surrounding the tip hole of the test piece, the apparatus may suffer erroneous measurements. In particular, such a case is more likely to occur with respect to patients such as infants and the elderly who tend to suffer insufficient bleeding of blood from a cut.
JP-A-9-94231, JP-2616331, and JP-A-9-89885 disclose a measuring apparatus which comprises a lancet and an enzyme electrode for providing the dual functions of blood extraction and measurement.
However, use of the apparatus of JP-A-9-94231 requires the sucking of blood by piercing the skin with a needle-like lancet during blood glucose level measurement, which causes continual pain. Further, since disposability of the blood sampling unit is not intended, problems therefore arise with regard to hygienic management and utility for repeated use. The apparatus of JP-2616331 also necessitates the sucking of blood with a needle-like lancet held stabbed into the skin and disposability of the blood sampling unit is not intended. On the other band, the apparatus of JP-A-9-8985 is designed to instantaneously complete a skin injuring operation with a lancet However, this apparatus is equipped with two pairs of electrodes in addition to the lancet and thereby a process for manufacturing the apparatus becomes complex with a resultant increase of the manufacturing cost. Moreover, with this apparatus, no ideas have been put forward concerning alleviation of pain in blood sampling by reducing the amount of blood for measurement.
DISCLOSURE OF THE INVENTION
An object of the present invention is to eliminate or relieve the above described problems. Specifically, the object of the present invention is to simplify the patient's action needed for measurement. A further object of the present invention is to provide a body fluid measuring apparatus and a body fluid sampler therefor, which require a significantly decreased amount of analyte for measurement with a high reliability to thereby relieve the pain attendant therewith.
According to a first aspect of the present invention, there is provided a body fluid measuring apparatus comprising a main body and a body fluid sampler fitted to the main body. The body fluid sampler comprises a fixed member fixed to the main body and a movable member guided by the fixed member. The fixed member is formed with a body fluid-sucking chamber open at a tip of the fixed member and a through-hole communicating therewith. The movable member comprises a lancet acting as a first electrode and is reciprocatively movable for bringing the tip of the lancet into and out of the tip of the fixed member. The body fluid-sucking chamber is provided with a second electrode and a reactive layer containing a reactive reagent necessary for measurement. The main body comprises an electronic circuit for providing a measurement on the basis of an electrical signal from the lancet as the first electrode and a second electrode, and a drive mechanism for driving the movable member for causing the tip of the lancet to project from the tip of the fixed member.
Preferably, the fixed member comprises a cylindrical electrode acting as the second electrode and an insulator for electrically separating the cylindrical electrode from the lancet. The cylindrical electrode and the lancet are concentrically arranged.
Preferably, a surface of the insulator facing the lancet is hydrophobically treated.
Preferably, the reactive layer is provided over an entire wall surface defining the fluid-sucking chamber in the cylindrical electrode.
Preferably, the drive mechanism comprises an automatic drive mechanism for driving the movable member to first cause the tip of the lancet to project from the tip of the fixed member and to subsequently cause the tip of the lancet to retreat from the tip of the fixed member.
Preferably, the main body has a fixed terminal connected to the electronic circuit, and the movable member of the body fluid sampler comprises a contact portion in slidable contact with the fixed terminal for electrically connecting the lancet to the fixed terminal.
Preferably, the main body has an annular spring terminal for electrically connecting the second electrode to the electronic circuit, and the fixed member of the body fluid sampler is detachably fixed to the main body under urging of the annular spring terminal.
Preferably, the fixed member is provided with an air-vent hole for enabling the fluid-sucking chamber to communicate with an external space.
Preferably, the inner diameter of the cylindrical electrode is 0.4-1.2 mm, and more preferably 0.5-0.8 mm.
Preferably, the tip of the lancet is pointed like a needle, and the outer diameter thereof is 0.2-0.4 mm.
Preferably, each of the first electrode and the second electrode is formed from carb
Ishida Kohei
Matsuoka Shiro
Uchigaki Takatoshi
Arkray Inc.
Marmor Charles
Merchant & Gould P.C.
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