JPH0994231A - Skin insertion type biosensing device using microneedle enzyme electrode and voice response device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure blood glucose value, etc., and to make the results respond with voice by using a device which is made of microinjection needle provided with a microelectrode immobilizing a biological functional substance and is made for naturally aspirating blood and measuring blood glucose and by measuring a current by a nonsteady state method using this device. SOLUTION: A biologically functional substance is immobilized on a microelectrode of platinum black 2, the microelectrode is disposed in a microinjection needle of a styringe 5 together with a counter electrode 3 and a reference electrode 4, the opposing side of the syringe is opened so that blood should be aspirated into the syringe by capillary phenomena. A subjective substance in the blood is unsteadily and electrically measured and the output is informed as a voicing result through a device responding by sound, thus the device is readily used for self-care administration by a blind man or the aged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro needle-shaped skin insertion electrode composed of a micro bio-functional electrode for measuring a bio substance by utilizing the molecular identification function of the biofunctional substance. In particular, the present invention relates to an unsteady measuring device using a microelectrode produced by immobilizing a biofunctional substance on a porous electrode, an unsteady measuring method using the device, and a method of notifying a measured value. In this case, the biofunctional substance is an enzyme, an antibody, and a biopolymer including a binding protein.

[0002]

2. Description of the Related Art Many methods have been proposed for measuring biochemical test items such as blood glucose level. The present inventors have already found that a biofunctional substance can be comprehensively immobilized on a platinum black surface, succeeded in producing an immobilized biofunctional electrode using this, and applied for a patent (1994). Publication number 6-75054 and 1988 publication number 63-22
2256). Furthermore, we developed and applied for a patent for an analysis system that can measure a stationary trace sample using this immobilized electrode and an analysis method based on an electrochemical unsteady method that uses this (Patent No. 2-38854 of 1991). ).

This method greatly expands the applicability of the biosensor in that it is not necessary to define the amount of sample solution to be taken, and is characterized by the measurement of a small amount of static sample and undiluted measurement. . However, when the electrochemically stationary method is applied to the immobilized enzyme electrode, its response current does not become 0 with respect to the blank solution, but to solve this, after applying a preliminary potentiostatic pulse, He found that the problem can be solved by applying a main measurement pulse after maintaining a constant open circuit state, and applied for a patent (1990 application number 2-9399).
1).

[0004]

In the present measurement of blood glucose level and the like, a method is adopted in which a needle is used to bleed from the skin, and then the sensor electrode is sucked and displayed on a liquid crystal display after a predetermined time. This two-step procedure is complicated for those who can see it, but blind persons suffering from diabetic retinopathy and Behcet's disease require considerable education and training.

Therefore, the present invention shows that a small amount of blood can be inhaled just by inserting it into the skin, and then the above-mentioned unsteady measurement method can be applied, whereby metabolism-related substances in blood can be measured rapidly and easily. . It is shown that it is possible to make a measuring device that can be used by blind people based on the present invention, and also to make a device that can announce the measured value by voice.

[0006]

In order to solve the above-mentioned problems, the present invention incorporates a microenzyme electrode inside an injection needle, sucks blood when the injection needle is pierced subcutaneously, and Provided are an electrode for measuring the amount of glucose by a non-steady method, a method for measuring the electrode, and a method for notifying the measurement result.

The micro-biologically functional electrode and the analysis system used in the present invention are the analysis systems using the unsteady response described in the patent application (published No. 2-383854 of 1991). That is, 1994 publication number 6
-75054 and 1988 publication number 63-222
As described in No. 256, an electrode having a structure having a fine particle layer in which a biofunctional substance such as an enzyme is entrapped and immobilized on the surface of a fine electrode composed of fine particles such as platinum is used as a working electrode, and silver / silver chloride is used. 1 is an electrochemical system having a reference electrode and three electrodes including a counter electrode, and an example of the structure is shown in FIG. In FIG. 1, the working electrode 2 is a minute platinum black electrode 9 entrapping and immobilizing a biological functional substance (eg glucose oxidase), and has a diameter of, for example, about 1 μm to 5 μm.
It is a microelectrode in the range of 00 μm. A sensor element is composed of a counter electrode 3 of a platinum wire whose side surface is coated with Teflon 10 and a silver / silver chloride reference electrode 4. The above three electrodes, that is, the microimmobilized enzyme electrode 2, the counter electrode 3, and the reference electrode 4 are inserted into the microinjection needle 5. Since such a needle sensor 6 has a structure in which only three thin metal wires are inserted, if fine processing technology is used,
It is also possible to configure all of these into a very small sensor.

If this sensor element is used, for example, several μl
It is possible to measure even a small amount of sample. That is, a substance in a trace sample can be detected by a method in which a potential is applied after sucking a trace sample and the current value generated at this time is detected by a transient response method. Further, this current value can be announced to the blind as voice.

Using the analysis system described above, the sensor response is obtained by recording the unsteady current response to a constant potential pulse, but the response to a simple pulse is ignored even for a solution containing no substance to be measured. Faraday currents that are impossible to observe are observed. Traditionally, blank measurements were required because this current had to be subtracted.
It has already been shown that this problem can be solved by pre-oxidation of contaminants, accumulation of an electrode active material by an enzymatic reaction in an open circuit state, and detection of oxidation by this pulse (1990 application number 2-93991).

As shown in FIG. 1, the present invention utilizes the above principle to measure the concentration of a substance to be measured simply by inserting it into the skin, and by notifying by voice, a device that enables the blind to manage their own health It is the one we are trying to provide.

[0011]

In general, the sensor response to a blood sample or serum sample is the sum of the response to easily oxidizable impurities contained in the sample solution and the response to the substance to be measured.
In the following description and examples, the case where glucose in a standard glucose solution and blood or serum is used as a measurement target will be described as an example. In this case, glucose is oxidized by the glucose oxidase immobilized on the electrode, and the hydrogen peroxide generated at this time is electrochemically pulse-oxidized, and the glucose can be measured by detecting the output current. If this output current is read and information processing is performed, it can be converted to voice. Therefore, in the following description, it is clarified that a microneedle containing a microenzyme electrode or the like is inserted into serum or blood, and a current corresponding to the glucose concentration can be detected, and the output signal is converted into voice. After demonstrating the above, it is clarified that it can be used as a skin-insertion type glucose sensor, and that it can be provided as a voice notification type glucose sensing device for the visually impaired.

[0012]

Example 1 Production of Insertion Needle Type Sensing Device The device shown in FIG. 1 was produced by the following procedure.
A capillary tube was produced by slowly pulling while heating one end of the minute soda glass tube 1. An enzyme electrode 2 immobilized on fine platinum black, a counter electrode 3 whose side portion was coated with a Teflon tube, and a silver / silver chloride reference electrode 4 on which silver was deposited, which was also coated with a Teflon tube 10, were inserted therein. When applied to blood or serum, the microenzyme-immobilized platinum black electrode or all three electrodes are reinforced with a glass tube 6 having a diameter of 2 to 3 mm to protect the capillary tube 1 if necessary, and polyvinylpyrrolidone or It was coated with a thin film 8 of Nafion. In addition, the capillary tube is replaced with a micro injection needle 5.
The sample was aspirated by capillarity with the other end opened. The oxidation current as the measurement result is measured by using a measuring instrument, or directly taken into the voicing device of the second embodiment so that the voicing can be output. That is, when a sample such as blood or a buffer solution is sucked into the device of Example 1, an oxidation current flows between the enzyme electrode and the counter electrode, so that the sample may be sucked into the device of Example 1 by the computer. Be recognized. From this moment, the device of Example 1 is put in a pre-oxidized state by keeping the potentiostat in the potential fixing mode for a predetermined time, for example, 10 seconds. Further, immediately after the pre-oxidized state, the potentiostat was kept in the open circuit mode for a predetermined time, for example, 10 seconds, so that Example 1
The device is placed in an open circuit condition. Then, the potentiostat is again set to the fixed voltage mode, and the device of Example 1 is placed in the reoxidized state.
Furthermore, after entering the reoxidation state, a predetermined time, for example, 4
After 0 milliseconds, the current flowing between the enzyme electrode and the counter electrode is read by the computer. Using the injection needle type sensing device manufactured in this way, measurement and voicing relating to the present invention were performed.

[0013]

Example 2 Method of Processing Signals from Device and Production of Audio Device A glucose concentration in a sample such as blood or a buffer solution was measured from the current flowing in the enzyme electrode by driving the device of Example 1 and further measuring this value. FIG. 2 shows a configuration example of a device for notifying by voice.

The micro-immobilized biofunctional electrode, the reference electrode and the counter electrode of the device 11 of Example 1 are connected to the potentiostat 12 which is a part of the present apparatus. The potentiostat has two modes, an open circuit mode and a fixed potential mode, and these modes are switched by a signal output from a computer connected to the potentiostat. When the potentiostat is in open circuit mode, the connection between the device of Example 1 and the potentiostat is circuitically broken. Further, when the potentiostat is in the potential fixing mode, a voltage set to, for example, 0.6 V by the potential setting circuit is applied to the micro-immobilized biological function electrode with the reference electrode as a reference. The voltage applied between the counter electrode and the reference electrode is controlled by a potentiostat so that it does not flow. In the potential fixing mode, the current flowing from the micro-immobilized biological function electrode to the counter electrode is converted into a voltage by the potentiostat and is output. This voltage signal is converted into a digital signal by the analog-digital converter 13 to be converted into a computer signal. 14 is input. The computer has a digital-to-analog converter 15 and an amplifier 16
The speaker 17 is connected via the device, and the digital signal output from the computer is output as sound via these devices.

The apparatus thus constructed measures the glucose concentration contained in the sample such as blood or buffer solution sucked into the device of Example 1, and outputs the value as voice. The potentiostat, which is a part of this device, is in a potential fixing mode when the power is turned on, and in this state, no current flows between the microelectrode on which glucose oxidase is immobilized as a biofunctional substance and the counter electrode. Example 1
As for the output current of the device, the glucose concentration will be calculated by the correspondence table or the calculation formula of the current value and the glucose concentration stored in the computer in advance, and the computer will convert the calculated value of the glucose concentration into voice data. . That is, in the memory circuit of the computer, voice data corresponding to each word necessary for notifying the blood glucose level, for example, voice data corresponding to a numerical value of 0 to 9 is recorded, converted into a digital value, and stored. The voice data corresponding to each digit of the glucose concentration is selected and connected in order. This composite audio data is converted into an analog signal by a digital-analog converter connected to a computer, and is output as an audio signal from a speaker via an amplifier.

[0016]

Example 3 Response Characteristics of Device Response in Glucose Standard Solution This transient response (non-steady response) was made to the glucose standard solution prepared by the biosensing device of Example 1 and adjusted with a phosphate buffer solution. Was signal processed, and the measurement result was announced by voice. The relationship between the measured value and the glucose concentration at this time is shown in FIG. In this case, the electrode system does not necessarily have to be coated with polyvinylpyrrolidone or Nafion.

[0017]

Example 4 Dependence of Device Response on Blood Glucose Concentration With respect to blood collected using the skin-insertion type biosensing device of Example 1, the previous patent (1990 application number 2-
No. 93991), a constant potential (0.6V against silver / silver chloride reference electrode) preliminary pulse was applied for 10 seconds, then an open circuit state was maintained for 10 seconds, and finally a measurement pulse of 0.6V was generated. The oxidation current is measured. The current signal is converted into a voice by a voice device (Example 2) to announce the glucose value. In this case, the microenzyme electrode was coated with polyvinylpyrrolidone and Nafion.

FIG. 4 shows the result of comparison between the glucose concentration obtained by this method and the glucose concentration obtained by clinical chemistry analysis using glucose kinase and glucose-6-phosphate dehydrogenase. Here, the measurement notification values of the blood sample and the glucose standard sample are plotted, but it is shown that both are on the same measurement curve.

[0019]

EFFECTS OF THE INVENTION When a skin-insertion type biosensing device in which a micro biofunction electrode is attached to a microinjection needle is applied to the measurement of blood glucose, a predetermined amount of blood can be sucked and pretreated just by inserting it into the skin. It was revealed that when an open circuit state was maintained and a predetermined potential (0.6 V) was set after application of a preliminary pulse for use, an oxidation current corresponding to the glucose concentration was generated. This overcomes the greatest difficulty that the conventional sensing device, which is premised on collecting a predetermined amount of blood, is extremely difficult for blind people to use. Furthermore, by adopting the transient response method, extremely quick measurement is possible. This device provides a sensing device that enables a blind person to manage his blood glucose level without being dependent on others by integrating it with a device that announces the measurement result by voice.

In summary, the technical effect of the present invention is that by providing a device that informs the visually impaired person of the blood glucose level simply by inserting it into the skin, the self-control of the blood glucose level becomes extremely easy. . It goes without saying that such a device can be used not only for the blind but also for the elderly and people suffering from adult diseases such as diabetes.

[Brief description of drawings]

FIG. 1 is a structural example of a microneedle type sensing device which constitutes the present invention.

FIG. 2 is a schematic diagram of an audio device used in the present invention.

FIG. 3 is a response characteristic in a glucose standard solution by a skin-insertion type biosensing device using a microneedle-shaped enzyme electrode and a voice announcement device used in the present invention.

FIG. 4 Correlation between blood glucose measurements obtained using the devices of Examples 1 and 2 and glucose values obtained by clinical biochemical methods.

[Explanation of symbols]

 1 glass capillary tube 2 working electrode (microenzyme-immobilized platinum black electrode) 3 platinum counter electrode 4 silver / silver chloride reference electrode 5 microinjection needle 6 reinforcing glass tube 7 glass capillary tube (same as 1) 8 coating film 9 Enzyme-immobilized platinum black 10 Teflon coating agent 11 Micro needle type sensing device 12 Potentiostat 13 Analog-digital converter 14 Computer 15 Digital-analog converter 16 Amplifier 17 Speaker

Claims (4)

[Claims] 1. A microneedle having a microenzyme electrode, a counter electrode, and a reference electrode held therein is simply inserted into the skin,
A biosensing device of the type in which blood is sucked into a microneedle and a specific component in the blood is measured. 2. The device according to claim 1, wherein the measurement data is displayed or Braille or voice is announced. 3. The unsteady measurement method using the electrode according to claim 1. 4. The method for notifying a measurement result according to claim 2.