Small volume in vitro analyte sensor
DC CAFCFirst Claim
1. A method for determining a concentration of an analyte in body fluid, comprising the steps of:
- collecting a sample of body fluid of about 500 nL or less;
filling a measurement zone of an electrochemical sensor with at least a portion of the sample;
holding the sample within the measurement zone in a non-flowing manner; and
determining the concentration of the analyte in the sample using a coulometric technique.
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Abstract
A sensor designed to determine the amount and concentration of analyte in a sample having a volume of less than about 1 μL. The sensor has a working electrode coated with a non-leachable redox mediator. The redox mediator acts as an electron transfer agent between the analyte and the electrode. In addition, a second electron transfer agent, such as an enzyme, can be added to facilitate the electrooxidation or electroreduction of the analyte. The redox mediator is typically a redox compound bound to a polymer. The preferred redox mediators are air-oxidizable.
The amount of analyte can be determined by coulometry. One particular coulometric technique includes the measurement of the current between the working electrode and a counter or reference electrode at two or more times. The charge passed by this current to or from the analyte is correlated with the amount of analyte in the sample. Other electrochemical detection methods, such as amperometric, voltammetric, and potentiometric techniques, can also be used.
The invention can be used to determine the concentration of a biomolecule, such as glucose or lactate, in a biological fluid, such as blood or serum. An enzyme capable of catalyzing the electrooxidation or electroreduction of the biomolecule is provided as a second electron transfer agent.
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Citations
71 Claims
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1. A method for determining a concentration of an analyte in body fluid, comprising the steps of:
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collecting a sample of body fluid of about 500 nL or less; filling a measurement zone of an electrochemical sensor with at least a portion of the sample; holding the sample within the measurement zone in a non-flowing manner; and determining the concentration of the analyte in the sample using a coulometric technique. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for determining a concentration of an analyte in a body fluid of a patient, comprising the steps of:
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creating an unassisted flow of a body fluid from the patient; transporting a portion of the body fluid into an analyte sensor configured and arranged to determine the concentration of the analyte from 500 nL or less of body fluid; holding the sample in a non-flowing manner within a sample chamber of the analyte sensor; and determining the concentration of the analyte in the body fluid from the portion of the body fluid transported into the analyte sensor. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. An apparatus for determining the concentration of an analyte in a body fluid of a patient, the apparatus comprising:
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a piercing member configured and arranged to pierce a site on the patient and then withdraw from the site to cause a flow of body fluid from the site; and an analyte sensor adjacent a tip of the piercing member, the analyte sensor comprising a sample chamber and an opening for transport of the body fluid into the sample chamber, the analyte sensor being configured and arranged to determine the concentration of the analyte in the body fluid using an undiluted sample of less than 1 μ
L of the body fluid disposed in the sample chamber;wherein, when the patient is pierced with the piercing member, body fluid flows from the pierced site into the sample chamber without displacement of the analyte sensor. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62)
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63. A method for determining a concentration of an analyte in a body fluid of an animal, comprising:
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piercing a site on the animal to cause a flow of body fluid from the site using a piercing member having a tip adjacent to an analyte sensor, the piercing member withdrawing after piercing the site; and collecting at least a portion of the body fluid in the analyte sensor without displacement of the analyte sensor, the analyte sensor being configured and arranged to determine the concentration of the analyte in the body fluid using an undiluted sample of less than 1 μ
L of the body fluid disposed in the analyte sensor. - View Dependent Claims (64, 65, 66, 67, 68, 69, 70, 71)
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Specification