WO2009125930A1

WO2009125930A1 - Bio-sensor

Info

Publication number: WO2009125930A1
Application number: PCT/KR2009/001466
Authority: WO
Inventors: Yon Chan Ahn; Jun Oh Ryu
Original assignee: All Medicus Co.,Ltd.
Priority date: 2008-04-08
Filing date: 2009-03-23
Publication date: 2009-10-15

Abstract

Disclosed herein is a biosensor, in which an enzyme reaction layer (13) and an upper cover(10)are stacked on a substrate (15) on which a plurality of electrodes (16a, 16b) are formed, a blood supply layer (11 ) is inserted between the enzyme reaction layer (13) and the upper cover (10) such that a constant amount of blood is uniformed introduced through a blood injection groove (12) formed on the blood supply layer (11 ) in the longitudinal direction to easily and accurately measure blood glucose, and the enzyme reaction layer (13) is arranged in the width direction such that a plurality of reaction layers are continuously formed in the width direction at a time in a state where a plurality of sensors are arranged in the longitudinal direction.

Description

BIO-SENSOR

The present invention relates to a biosensor and, more particularly, to a biosensor which can easily and accurately measure blood glucose.

Recently, the necessity of periodically measuring the amount of glucose (sugar) in blood in diagnosing and treating diabetes has increased. The measurement of blood glucose is easily performed using a blood glucose meter.

In the case of an insulin-dependent diabetic who should measure blood glucose two to three times a day, he or she takes a drop of blood by pricking a fingertip with a lancet to measure blood glucose. At this time, the blood glucose meter is used to measure blood glucose level from an electrical signal generated by an electrochemical reaction between a chemical substance in a strip-type biosensor and a sample (blood) taken from a diabetic.

The operation principle and structure of the biosensor and the blood glucose meter using the biosensor have been developed in various ways.

The biosensor typically includes an electrode system having a plurality of electrodes formed on an insulating substrate by screen printing, for example, and an enzyme reaction layer formed on the electrode system and including a hydrophilic polymer, an oxidoreductase and an electron acceptor.

When a sample containing a substrate (glucose) is dropped onto the enzyme reaction layer through a sample injection port of the biosensor, the enzyme reaction layer dissolves the sample, the substrate in the sample reacts with an enzyme and is oxidized, and thus the electron acceptor is reduced.

At this time, an oxidation current obtained when the electron acceptor is electrochemically oxidized is measured with a measuring device, thereby obtaining the concentration of the substrate contained in the sample.

Conventionally, a biosensor including a porous enzyme reaction layer formed on an electrode system, a fixing frame for fixing the same, and a cover is provided. The biosensor having the above structure measures blood glucose by dropping blood on the reaction layer.

However, in the case of the above biosensor, the amount of the blood sample introduced into the reaction layer is changed according to the volume of the dropped blood, and thus there is a measurement error according to the amount of blood during the measurement of blood glucose.

Moreover, there is provided a method of measuring blood glucose in an absorbing manner in which a sample is injected into a blood injection groove; however, a reagent is dropped to form a reagent layer during manufacturing of the sensor, and thus there is an error in fixation of the reagent layer.

Furthermore, with existing manufacturing methods, it is impossible to construct a structure, in which a plurality of reagent layers for measuring a plurality of analytes are independently fixed on a single sensor and the measurement is made through a single sample inlet.

Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a biosensor, in which an enzyme reaction layer and an upper cover are stacked on a substrate on which a plurality of electrodes are formed, a blood supply layer is inserted between the enzyme reaction layer and the upper cover such that a constant amount of blood is uniformly introduced through a blood injection groove formed on the blood supply layer in the longitudinal direction to easily and accurately measure blood glucose, and the enzyme reaction layer is arranged in the width direction such that a plurality of reaction layers are continuously formed in the width direction at a time in a state where a plurality of sensors are arranged in the longitudinal direction.

Moreover, another object of the present invention is to provide a biosensor, in which a plurality of electrodes are formed on a lower surface of a substrate to determine whether or not a sensor is inserted, a different code is assigned to each sensor according to the shape of each electrode when a code recognition electrode is inserted into an insertion space of a blood glucose meter such that a corresponding code is determined according to an error in the measured value of blood glucose, and thus the blood glucose meter recognizes a correction value corresponding to the assigned code to correct the error, thereby minimizing the measurement error.

To accomplish the above objects of the present invention, there is provided a biosensor including: a substrate on which a plurality of electrodes are formed in parallel with each other; a main reaction layer formed on the electrodes of the substrate in the width direction; a blood supply layer having a blood injection groove formed in the longitudinal direction to supply blood to the main reaction layer; and an upper cover covering the top of the blood injection groove, wherein the main reaction layer, the blood supply layer, and the upper cover are sequentially stacked on the substrate, and the biosensor measures the amount of current generated by a reaction between blood injected through the blood injection groove and the main reaction layer.

The biosensor may further include at least one expanded reaction layer formed in parallel with the main reaction layer at the rear of the main reaction layer at regular intervals and capable of measuring a plurality of analytes in blood, wherein the blood injection groove is connected to the main reaction layer and the expanded reaction layer.

The number of electrodes may increase proportionally to the types of analytes to be measured using blood.

The electrodes may include a first reference electrode and a first working electrode to measure the amount of current generated by the reaction between the blood and the main reaction layer.

The electrodes may further include a second working electrode having a length shorter than that of the first working electrode at a position corresponding to the expanded reaction layer to measure the amount of current generated by a reaction between the blood and the expanded reaction layer, wherein the first reference electrode is used in common, the amount of current generated by the reaction between the blood and the main reaction layer is measured by subtracting the amount of current measured by the first reference electrode and the second working electrode from the amount of current measured by the first reference electrode and the first working electrode, and the amount of current generated by the reaction between the blood and the expanded reaction layer is measured by the first reference electrode and the second working electrode.

The electrodes may further include: a second working electrode having a length shorter than that of the first working electrode and formed at a position corresponding to the expanded reaction layer to measure the amount of current generated by a reaction between the blood and the expanded reaction layer; and a first insulating layer formed on the first reference electrode at a position corresponding to the expanded reaction layer to insulate the first working electrode from the expanded reaction layer, wherein the first reference electrode is used in common, the amount of current generated by the reaction between the blood and the main reaction layer is measured by the first reference electrode and the first working electrode, and the amount of current generated by the reaction between the blood and the expanded reaction layer is measured by the first reference electrode and the second working electrode.

The electrodes may further include: a second reference electrode and a second working electrode each having a length shorter than that of the first reference electrode and the first working electrode and formed at a position corresponding to the expanded reaction layer to measure the amount of current generated by a reaction between the blood and the expanded reaction layer; and a second insulating layer formed on the first reference electrode and the first working electrode at a position corresponding to the expanded reaction layer to insulate the first reference electrode and the first working electrode from the expanded reaction layer, wherein the amount of current generated by the reaction between the blood and the main reaction layer is measured by the first reference electrode and the first working electrode, and the amount of current generated by the reaction between the blood and the expanded reaction layer is measured by the second reference electrode and the second working electrode.

The main reaction layer may be a fist enzyme reaction layer containing a glucose oxidase and an electron acceptor to measure blood glucose in blood, and a blood glucose level may be obtained by measuring the amount of current generated by a reaction between the blood glucose and the glucose oxidase.

The expanded reaction layer may be a second enzyme reaction layer containing a cholesterol oxidase to measure cholesterol in blood.

A notch may be formed at a front end of the upper cover and the blood supply layer to prevent an inlet of the blood injection groove from being clogged by a body region being in contact with the blood injection groove.

A plurality of electrodes each having a different shape according to each sensor s properties may be formed on a lower surface of the substrate to determine whether or not the sensor is inserted, and a different code is assigned to each sensor according to the shape of each electrode.

The sensors may include a plurality of code recognition electrodes each having a different shape according to an error in a measured value of blood glucose such that a different code may be assigned to each sensor and a correction value predetermined according to each code may be assigned to each sensor to correct the error in the measured value.

The shape of the electrodes may be patterned and the substrate may be punched to correspond to the shape of the patterned electrodes.

The upper cover may include a blood injection hole through which blood is injected.

According to the biosensor of the present invention, since the blood injection groove is formed at one end of the blood supply layer in the longitudinal direction, a subject can easily apply blood to one end of a sensor while the other end of the sensor is inserted into a blood glucose meter in the longitudinal direction, thus facilitating the supply of blood.

Moreover, the enzyme reaction layer is formed at the bottom of the blood supply layer in the width direction to be connected to the blood injection groove of the blood supply layer such that a plurality of enzyme reaction layers are formed at a time in a state where the plurality of sensors are arranged in the longitudinal direction, thus reducing manufacturing cost and time.

Furthermore, the measurement errors for the respective sensors are determined, and the plurality of electrodes having different shapes according to the errors are formed on the lower surface of the substrate such that a code is determined according to the shape of each electrode and a correction value is assigned according to the corresponding code. As a result, when the sensors to which different codes are assigned are inserted into the blood glucose meter to measure blood glucose, the blood glucose meter recognizes the codes corresponding to the sensors and corrects the errors in the measured values with the correction values corresponding to the codes, thus accurately measuring the blood glucose.

FIG. 1 is an exploded view showing a biosensor in accordance with a preferred embodiment of the present invention.

FIG. 2 is an assembled view of FIG. 1.

FIGS. 3A to 3C are exploded views showing biosensors in accordance with various preferred embodiments of the present invention.

FIGS. 4A to 4C are assembled views of FIGS. 3A to 3C.

FIG. 5 is an exploded view showing a biosensor in accordance with still yet another preferred embodiment of the present invention.

FIG. 6 is an assembled view of FIG. 5.

FIGS. 7 to 9 are diagrams showing states where code recognition electrodes and substrates are formed in various shapes in accordance with the present invention.

FIGS. 10 to 12 are diagrams showing states where only the code recognition electrodes are patterned in accordance with the present invention.

FIG. 13 is an exploded view showing a biosensor in accordance with a further preferred embodiment of the present invention.

FIG. 14 is an assembled view of FIG. 13.

FIGS. 15A to 15C are exploded views showing electrodes formed on a substrate in accordance with various embodiments of the present invention.

FIGS. 16A to 16C are assembled views of FIGS. 15A to 15C.

10, 20, 30, 40, 150: upper cover

11, 21, 31, 41, 151: blood supply layer

12, 22, 32, 42, 152: blood injection groove

13, 43: enzyme reaction layer

23a, 153a: first enzyme reaction layer

23b, 153b: second enzyme reaction layer

14a, 24a, 154a: first insulating layer

14b, 24b, 154b: second insulating layer

24c, 154c: third insulating layer

15: substrate

16a: first working electrode

16a´: second working electrode

16b: first reference electrode

16b´: second reference electrode

17: air discharge passage

18a: first terminal

18b: second terminal

18c: third terminal

19a: first insulating layer

19b: second insulating layer

33: notch

40a, 150a: blood injection hole

50~52: first sensor ~ third sensor

53~55: electrode

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an exploded view showing a biosensor in accordance with a preferred embodiment of the present invention, and FIG. 2 is an assembled view of FIG. 1.

A biosensor in according wifth a preferred embodiment of the present invention includes a substrate 15 on which

electrodes

16a and 16b are formed, an enzyme reaction layer 13 formed on the substrate 15, a blood supply layer 11 having a blood injection groove 12 formed at one end thereof, and an upper cover 10. The enzyme reaction layer 13 in this embodiment is to measure glucose in blood.

The substrate 15 is a base substrate for forming sensors on the upper surface thereof and is formed of a non-conductive polymer resin.

The

electrodes

16a and 16b formed on the substrate 15 include a working electrode 16a and a reference electrode 16b, which detect an electrical signal generated by an enzyme reaction with blood glucose in a sample in the enzyme reaction layer 13.

Ends of the

electrodes

16a and 16b are disposed adjacent to the corner of the upper surface of the substrate 15 and are inserted into an insertion space of a blood glucose meter to be electrically connected thereto.

The

electrodes

16a and 16b may be formed of platinum (Pt), gold (Au), silver (Ag), a mixed paste of silver (Ag) and chloride (AgCl), or a conductive carbon paste by a general method such as etching, screen printing, or sputtering.

The kind of the enzyme reaction layer 13 may be changed according to an analyte to be measured. When measuring cholesterol, alcohol, and lactate in blood, a cholesterol oxidase, an alcohol dehydrogenase, and a lactate dehydrogenase are applied to the enzyme reaction layer 13. Besides, an oxidoreductase that oxidizes/reduces an analyte is applied to the enzyme reaction layer 13 to quantitate the analyte in blood.

The enzyme reaction layer 13 is located between a first insulating layer 14a having a shorter length and a second insulating layer 14b having a longer length. The first and second insulating

layers

14a and 14b are formed at the top of the

electrodes

16a and 16b to insulate the

adjacent electrodes

16a and 16b from each other.

An air discharge passage 17 is formed between the enzyme reaction layer 13 and the blood supply layer 11, that is, the height of the enzyme reaction layer 13 is lower than that of the first and second insulating

layers

14a and 14b, so as to discharge internal air contained in the blood injection groove 12, which will be described later, to the outside through the air discharge passage 17 when blood is supplied to the blood supply layer 11, thus easily absorbing the blood taken from a subject through the blood injection groove 12.

The first and second insulating

layers

14a and 14b may be formed of an insulating material such as a polymer film by stacking the insulating materials or by a general method such as screen printing.

Here, according to the present invention, a plurality of sensors are arranged in the longitudinal direction and a reagent containing a glucose oxidase and an electron acceptor is applied onto the substrate 15 in the width direction such that a plurality of enzyme reaction layers 13 may be formed at a time, thus reducing manufacturing cost and time.

The enzyme reaction layer 13 is formed on the upper surface of the substrate 15 and includes the glucose oxidase and the electron acceptor for electron transfer. In detail, the enzyme reaction layer 13 may be formed by coating a predetermined amount of a solution, prepared by mixing a water-soluble polymer, a glucose oxidase, a stabilizer, and an electron acceptor in an electrolyte solution in a predetermined ratio, between the first and second insulating

layers

14a and 14b and drying the coated solution.

Moreover, the present invention provides the blood supply layer 11 stacked between the enzyme reaction layer 13 and the upper cover 10. The blood injection groove 12 through which blood is supplied is formed at one end of the blood supply layer 11.

In this case, the blood supply layer 11 has a very small thickness such that the blood is absorbed by a capillary phenomenon as soon as it is in contact with the blood injection groove 12. The blood injection groove 12 is connected to the top of the enzyme reaction layer 13 such that the blood reacts with the enzyme reaction layer 13. Moreover, the upper cover 10 is stacked on the upper surface of the blood supply layer 11 to cover the blood injection groove 12 of the blood supply layer 11.

The measurement method and principle of the biosensor in accordance with a preferred embodiment having the above-described structure will be described below.

A drop of blood taken from a subject s fingertip is injected through the blood injection groove 12 and is then diffused into the enzyme reaction layer 13 by the capillary phenomenon at the blood injection groove 12. At this time, the enzyme reaction layer 13 dissolves the blood such that the glucose in blood is oxidized by the glucose oxidase contained in the enzyme reaction layer 13, and the glucose oxidase is reduced.

Subsequently, the reduced glucose oxidase is oxidized by the oxidation-reduction reaction with the electron acceptor, and the electron acceptor is reduced. The reduced electron acceptor migrates to the surface of the

electrodes

16a and 16b. At this time, the current generated by applying an oxidation potential to the reduced electron acceptor is measured. Since the concentration of glucose in blood is proportional to the amount of current generated during the oxidation of the electron acceptor, it is possible to measure blood glucose by measuring the amount of current.

The blood glucose meter converts the current generated by the oxidation-reduction reaction between the glucose in blood and the glucose oxidase and the electron acceptor and received through the

electrodes

16a and 16b into a concentration value and, then, quantitatively calculates the concentration of glucose present in blood, i.e., the blood glucose level.

FIGS. 3A to 3C are exploded views showing biosensors in accordance with various preferred embodiments of the present invention, and FIGS. 4A to 4C are assembled views of FIGS. 3A to 3C.

Another preferred embodiment of the present invention provides a biosensor capable of measuring at least two analytes in blood simultaneously. For example, the biosensor includes a first enzyme reaction layer 23a for measuring blood glucose and a second enzyme reaction layer 23b for measuring cholesterol in blood.

The biosensor in this embodiment includes a substrate 15 on which

electrodes

16a and 16b are formed, the first enzyme reaction layer 23a for measuring blood glucose and the second enzyme reaction layer 23b for measuring cholesterol, which are disposed on the upper surface of the substrate 15, a blood supply layer 21 disposed on the reaction layers 23a and 23b, and an upper cover 20 disposed thereon.

In this case, a blood injection groove 22 formed on the blood supply layer 21 extends from one end of the blood supply layer 21 to the top of the second enzyme reaction layer 23b for measuring cholesterol in the longitudinal direction. Moreover, the first enzyme reaction layer 23a is located between a first insulating layer 24a and a second insulating layer 24b, and the second enzyme reaction layer 23b is located between the second insulating layer 24b and a third insulating layer 24c.

As shown in FIG. 3A, the substrate 15 in accordance with another preferred embodiment of the present invention includes a first reference electrode 16b used in common, a first working electrode 16a, and a second working electrode 16a . The upper surface of the first working electrode 16a is formed to cover both the first enzyme reaction layer 23a and the second enzyme reaction layer 23b, and the upper surface of the second working electrode 16a is formed to cover only the second enzyme reaction layer 23b.

The amount of current generated by a reaction between the blood and the first enzyme reaction layer 23a for measuring blood glucose is transmitted to a blood glucose meter through the first working electrode 16a and the first reference electrode 16b, and the amount of current generated by a reaction between the blood and the second enzyme reaction layer 23b for measuring cholesterol is transmitted to a cholesterol meter through the second working electrode 16a and the first reference electrode 16b.

At this time, since the first reference electrode 16b is used in common, the voltage applied to the first working electrode 16a is the same as the voltage applied to the second working electrode 16a . Moreover, since the first working electrode 16a is formed to cover both the first enzyme reaction layer 23a and the second enzyme reaction layer 23b, the blood glucose meter may measure the amount of current generated by the reaction between the blood and the first enzyme reaction layer 23a from a value obtained by subtracting the amount of current transmitted through the second working electrode 16a and the first reference electrode 16b from the amount of current transmitted through the first working electrode 16a and the first reference electrode 16b, thus obtaining a blood glucose level.

(The amount of current generated by the reaction between the blood and the first enzyme reaction layer 23a) = (The amount of current transmitted through the first working electrode 16a and the first reference electrode 16b) - (The amount of current transmitted through the second working electrode 16a and the first reference electrode 16b)

Moreover, the cholesterol meter may measure the amount of current generated by the reaction between the blood and the second enzyme reaction layer 23b by receiving the amount of current through the second working electrode 16a and the first reference electrode 16b, thus obtaining a cholesterol level.

In this case, the number of the electrodes increases proportionally to the types of analytes.

As shown in FIG. 3B, a first reference electrode 16b used in common, a first working electrode 16a, and a second working electrode 16a are formed on a substrate 15 in accordance with still another embodiment of the present invention. Here, the upper surface of the first working electrode 16a is formed to cover both the first enzyme reaction layer 23a and the second enzyme reaction layer 23b, and the upper surface of the second working electrode 16a is formed to cover only the second enzyme reaction layer 23b.

However, a first insulating layer 19a is formed on the first working electrode 16a on the substrate 15 shown in FIG. 3B, and thus the current generated by the reaction between the blood and the second enzyme reaction layer 23b is blocked by the first insulating layer 19a and does not flow to the first working electrode 16a.

Accordingly, the blood glucose meter may measure the amount of current generated by the reaction between the blood and the first enzyme reaction layer 23a by receiving only the amount of current through the first working electrode 16a and the first reference electrode 16b, thus obtaining a blood glucose level. Moreover, the cholesterol meter may measure the amount of current generated by the reaction between the blood and the second enzyme reaction layer 23b by receiving the amount of current through the second working electrode 16a and the first reference electrode 16b, thus obtaining a cholesterol level.

As shown in FIG. 3C, a first reference electrode 16b, a first working electrode 16a, a second reference electrode 16b , and a second working electrode 16a are formed on a substrate 15 in accordance with yet another preferred embodiment of the present invention. Here, the upper surfaces of the first reference electrode 16b and the first working electrode 16a are formed to cover both the first enzyme reaction layer 23a and the second enzyme reaction layer 23b, and the upper surfaces of the second reference electrode 16b and the second working electrode 16a are formed to cover only the second enzyme reaction layer 23b.

However, a second insulating layer 19b is formed on the first reference electrode 16b and the first working electrode 16a on the substrate 15 shown in FIG. 3C, and thus the current generated by the reaction between the blood and the second enzyme reaction layer 23b is blocked by the second insulating layer 19b and does not flow to the first reference electrode 16b and the first working electrode 16a.

Accordingly, the blood glucose meter may measure the amount of current generated by the reaction between the blood and the first enzyme reaction layer 23a by receiving the amount of current through the first reference electrode 16b and the first working electrode 16a, thus obtaining a blood glucose level. Moreover, the cholesterol meter may measure the amount of current generated by the reaction between the blood and the second enzyme reaction layer 23b by receiving the amount of current through the second working electrode 16a and the second reference electrode 16b , thus obtaining a cholesterol level.

Here, since the substrates 15 shown in FIGS. 3A and 3B use the same first reference electrode 16b, it can be used in the case where the reaction conditions and time for measuring blood glucose are the same as those for measuring cholesterol. Moreover, since the substrate 15 shown in FIG. 3C uses the first and

second reference electrodes

16b and 16b corresponding to the number of analytes, it can be used even in the case where the reaction conditions and time for measuring blood glucose are different from those for measuring cholesterol.

FIG. 5 is an exploded view showing a biosensor in accordance with still yet another preferred embodiment of the present invention, and FIG. 6 is an assembled view of FIG. 5.

Still yet another preferred embodiment of the present invention provides a biosensor including a notch 33 formed around an inlet of a blood injection groove 32 so as to prevent the inlet from being clogged by a body region, e.g., a fingertip being in contact with the blood injection groove 32 when blood is introduced through the blood injection groove 32.

FIGS. 7 to 9 are diagrams showing states where code recognition electrodes and substrates are formed in various shapes in accordance with the present invention, and FIGS. 10 to 12 are diagrams showing states where only the code recognition electrodes are patterned in accordance with the present invention.

Meanwhile, during manufacturing process of the biosensor, it is determined for each of sensors 50 to 52 whether the measurement of blood glucose is accurate or how large the measurement error is. Accordingly, the present invention provides electrodes 53 to 55 formed on a lower surface of the substrate 15 to assign a code to each sensor such that correction values are given to correct the errors.

For example, in the case where a blood glucose reference value is 100, if the measured value of the first sensor 50 is 100, code A is assigned. If the measured value of the second sensor 51 is 90, code B is assigned to add a correction value of 10, thus making 100. If the measured value of the third sensor 52 is 110, code C is assigned to subtract 10 from 110, thus making 100.

As such, to assign a different code to each of the sensors 50 to 52, the shapes of the electrodes 53 to 55 corresponding to the respective codes are determined and the corresponding electrodes 53 to 55 are formed on the lower surface of the substrate 15. The shapes of the electrodes 53 to 55 may be different according to the codes and the correction values.

Moreover, when the sensors 50 to 52 to which the electrodes 53 to 55 having different shapes are attached are inserted into a socket connected to the blood glucose meter, a plurality of terminals 18a to 18c installed in the socket recognize the electrodes 53 to 55 having different shapes based on the codes such that the blood glucose meter corrects the errors in the measured values with the correction values corresponding to the respective codes.

In this case, numbers are assigned to the plurality of terminals 18a to 18c, and the

terminals

18a and 18c are turned on and off according to the shape of each of the

electrodes

53 and 55.

For example, in the case of the first sensor 50 to which code A is assigned, an OFF signal is transmitted to the first terminal 18a, and an ON signal is transmitted to the second and

third terminals

18b and 18c.

In the case of the second sensor 51 to which code B is assigned, an ON signal is transmitted to the first and

second terminals

18a and 18b, and an OFF signal is transmitted to the third terminal 18c.

In the case of the third sensor 52 to which code C is assigned, an ON signal is transmitted to the first and

third terminals

18a and 18c, and an OFF signal is transmitted to the second terminal 18b.

When the sensors 50 to 52 to which different codes are assigned are inserted into an inlet port of the blood glucose meter, the blood glucose meter assigns a predetermined correction value to each of the sensors 50 to 52 according to each code such that each of the sensors 50 to 52 corrects the error in the measured value, thus accurately measuring the blood glucose level.

In this case, the electrodes 53 to 55 may be formed in various shapes according to the number of the terminals and, for example, the terminals 18a to 18c or the electrodes 53 to 55 may be formed in a linear pattern (FIGS. 7 to 9) or in a zigzag pattern.

Moreover, the substrate 15 may be punched to correspond to the

electrodes

53 and 55 and the electrode shapes for the code recognition of each of the sensors 50 to 52 (FIGS. 7 to 9), or only the electrodes 53 to 55 may be patterned to correspond to the shapes of the electrodes 53 to 55 (FIGS. 10 to 12) such that the blood glucose meter may assign correction values according to the properties of the sensors 50 to 52 (errors in the measured values of blood glucose) through the plurality of terminals (e.g., three or four terminals), thus accurately measuring the blood glucose level.

FIG. 13 is an exploded view showing a biosensor in accordance with a further preferred embodiment of the present invention, and FIG. 14 is an assembled view of FIG. 13.

A blood injection hole 40a is formed on an upper cover 40 in accordance with a further preferred embodiment of the present invention. As mentioned above, a drop of blood is taken by pricking a subject s fingertip with a lancet to measure blood glucose. In the case where the blood is injected through the blood injection groove 12 as shown in FIG. 1, it is not easy to inject the blood by bringing the fingertip, from which a small amount of blood is drawn, into contact with an end of the blood injection groove 12.

The reason is that the blood drawn from the fingertip may flow down by gravity when the blood of the subject is injected through the blood injection groove 12 while the biosensor is maintained horizontal. Moreover, in the case where the blood of the subject is injected while the fingertip is turned over such that the drop of blood faces upward in order for the blood on the fingertip not to flow down by gravity, when the blood injection groove 12 of the biosensor is inclined toward the blood, it is not easy for the blood to flow to the inside of the blood injection groove 12 which is inclined upwardly. Furthermore, it is not easy to bring the fingertip into contact with the blood injection groove 12 while the biosensor is maintained horizontal to prevent the blood from flowing.

However, according to the present invention, the blood injection hole 40a is formed on the upper cover 40 to facilitate the injection of blood. The blood injection hole 40a is formed in an end portion of the upper cover 40, and a blood injection groove 42 is formed adjacent to an end portion of a blood supply layer 41 in the longitudinal direction. Accordingly, when the subject pricks his or her fingertip with a lancet while the palm faces upward and, then, turns down the finger from which blood is drawn to be brought into the blood injection hole 40a formed on the upper cover 40, it is possible to easily inject the blood into the blood injection hole 40a.

FIGS. 15A to 15C are exploded views showing electrodes formed on a substrate in accordance with various embodiments of the present invention, and FIGS. 16A to 16C are assembled views of FIGS. 15A to 15C.

A first reference electrode 16b used in common, a first working electrode 16a, and a second working electrode 16a are formed on a substrate 15 shown in FIG. 15A, which are substantially the same as the configuration and operation of the electrodes in FIG. 3A. However, a blood injection hole 150a is formed in the middle of an upper cover 150 of FIG. 15A, and a blood injection groove 152 is slightly spaced from an end portion of a blood supply layer 151 such that blood is supplied to first and second enzyme reaction layers 153a and 153b, which are different from those of FIG. 3A. Here, since the blood injection hole 150a is formed in the middle of the upper cover 150 in FIG. 15A, it is possible to more easily inject the blood through the blood injection hole 150a.

A first reference electrode 16b, a first working electrode 16a, and a second working electrode 16a are formed on a substrate 15 shown in FIG. 15B, and a first insulating layer 19a is formed on the first working electrode 16a, which are substantially the same as the configuration and operation of the electrodes in FIG. 3B. However, a blood injection hole 150a is formed in the middle of an upper cover 150 of FIG. 15B, and a blood injection groove 152 is slightly spaced from an end portion of a blood supply layer 151 such that blood is supplied to first and second enzyme reaction layers 153a and 153b, which are different from those of FIG. 3B. Here, since the blood injection hole 150a is formed in the middle of the upper cover 150 in FIG. 15B, it is possible to more easily inject the blood through the blood injection hole 150a.

A first reference electrode 16b, a second reference electrode 16b , a first working electrode 16a, and a second working electrode 16a are formed on a substrate 15 shown in FIG. 15C, and a second insulating layer 19b is formed on the first reference electrode 16b and the first working electrode 16a, which are substantially the same as the configuration and operation of the electrodes in FIG. 3C. However, a blood injection hole 150a is formed in the middle of an upper cover 150 of FIG. 15C, and a blood injection groove 152 is slightly spaced from an end portion of a blood supply layer 151 such that blood is supplied to first and second enzyme reaction layers 153a and 153b, which are different from those of FIG. 3C. Here, since the blood injection hole 150a is formed in the middle of the upper cover 150 in FIG. 15C, it is possible to more easily inject the blood through the blood injection hole 150a.

The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

A biosensor comprising:

a substrate on which a plurality of electrodes are formed in parallel with each other;

a main reaction layer formed on the electrodes of the substrate in the width direction;

a blood supply layer including a blood injection groove formed in the longitudinal direction to supply blood to the main reaction layer; and

an upper cover covering the top of the blood injection groove,

wherein the main reaction layer, the blood supply layer, and the upper cover are sequentially stacked on the substrate, and the biosensor measures the amount of current generated by a reaction between blood injected through the blood injection groove and the main reaction layer.
The biosensor of claim 1, further comprising:

at least one expanded reaction layer formed in parallel with the main reaction layer at the rear of the main reaction layer at regular intervals and capable of measuring a plurality of analytes in blood,

wherein the blood injection groove is connected to the main reaction layer and the expanded reaction layer.
The biosensor of claim 1, wherein the number of electrodes increases proportionally to the types of analytes to be measured using blood.
The biosensor of claim 1, wherein the electrodes comprise:

a first reference electrode and a first working electrode to measure the amount of current generated by the reaction between the blood and the main reaction layer.
The biosensor of claim 4, wherein the electrodes further comprise:

a second working electrode having a length shorter than that of the first working electrode at a position corresponding to the expanded reaction layer to measure the amount of current generated by a reaction between the blood and the expanded reaction layer,

wherein the first reference electrode is used in common, the amount of current generated by the reaction between the blood and the main reaction layer is measured by subtracting the amount of current measured by the first reference electrode and the second working electrode from the amount of current measured by the first reference electrode and the first working electrode, and the amount of current generated by the reaction between the blood and the expanded reaction layer is measured by the first reference electrode and the second working electrode.
The biosensor of claim 4, wherein the electrodes further comprise:

a second working electrode having a length shorter than that of the first working electrode and formed at a position corresponding to the expanded reaction layer to measure the amount of current generated by a reaction between the blood and the expanded reaction layer; and

a first insulating layer formed on the first working electrode at a position corresponding to the expanded reaction layer to insulate the first working electrode from the expanded reaction layer,

wherein the first reference electrode is used in common, the amount of current generated by the reaction between the blood and the main reaction layer is measured by the first reference electrode and the first working electrode, and the amount of current generated by the reaction between the blood and the expanded reaction layer is measured by the first reference electrode and the second working electrode.
The biosensor of claim 4, wherein the electrodes further comprise:

a second reference electrode and a second working electrode each having a length shorter than that of the first reference electrode and the first working electrode and formed at a position corresponding to the expanded reaction layer to measure the amount of current generated by a reaction between the blood and the expanded reaction layer; and

a second insulating layer formed on the first reference electrode and the first working electrode at a position corresponding to the expanded reaction layer to insulate the first reference electrode and the first working electrode from the expanded reaction layer,

wherein the amount of current generated by the reaction between the blood and the main reaction layer is measured by the first reference electrode and the first working electrode, and the amount of current generated by the reaction between the blood and the expanded reaction layer is measured by the second reference electrode and the second working electrode.
The biosensor of any one of claims 1 to 7, wherein the main reaction layer is a fist enzyme reaction layer containing a glucose oxidase and an electron acceptor to measure blood glucose in blood, and a blood glucose level is obtained by measuring the amount of current generated by a reaction between the blood glucose and the glucose oxidase.
The biosensor of any one of claims 2 and 5 to 7, wherein the expanded reaction layer is a second enzyme reaction layer containing a cholesterol oxidase to measure cholesterol in blood.
The biosensor of claim 1, wherein a notch is formed at a front end of the upper cover and the blood supply layer to prevent an inlet of the blood injection groove from being clogged by a body region being in contact with the blood injection groove.
The biosensor of claim 1, wherein a plurality of electrodes each having a different shape according to each sensor s properties are formed on a lower surface of the substrate to determine whether or not the sensor is inserted, and a different code is assigned to each sensor according to the shape of each electrode.
The biosensor of claim 1, wherein the sensors comprise a plurality of code recognition electrodes each having a different shape according to an error in a measured value of blood glucose such that a different code is assigned to each sensor and a correction value predetermined according to each code is assigned to each sensor to correct the error in the measured value.
The biosensor of claim 11, wherein the shape of the electrodes is patterned and the substrate is punched to correspond to the shape of the patterned electrodes.
The biosensor of claim 1, wherein the upper cover comprises a blood injection hole through which blood is injected.