WO2013141414A1

WO2013141414A1 - Method for compensating output signal of optical biosensor and optical biosensor using the same

Info

Publication number: WO2013141414A1
Application number: PCT/KR2012/001950
Authority: WO
Inventors: Younjae Lee; Gyoungsoo KIM; Taehyung LEE; Yonghyun Kim; Gueisam Lim
Original assignee: Lg Electronics Inc.
Priority date: 2012-03-19
Filing date: 2012-03-19
Publication date: 2013-09-26

Abstract

Disclosed herein are a method for compensating the output signal of an optical biosensor and an optical biosensor using the same. The optical biosensor includes: a cartridge for supporting a marker substance; a light-emitting diode (LED) for radiating an optical signal to the marker substance; a photodiode (PD) serving to measure a signal reflected from the marker substance after the optical signal radiated from the LED was absorbed by the marker substance; an LED driving unit serving to convert the type of the optical signal irradiated to the marker substance such that the radiated optical signal is distinguished from a noise component; and a micom serving to measure the concentration of the marker substance based on the signal measured by the PD. The disclosed method removes an external noise component, thus achieving more accurate diagnosis.

Description

METHOD FOR COMPENSATING OUTPUT SIGNAL OF OPTICAL BIOSENSOR AND OPTICAL BIOSENSOR USING THE SAME

The present invention relates to a method for compensating the output signal of an optical biosensor and an optical biosensor using the same, and more particularly to a method for compensating the output signal of an optical biosensor, which can remove an external noise component to provide more accurate sensing, and to an optical biosensor using the same.

In general, the health condition of a patient is diagnosed by analyzing the body fluids of the patient and measuring the amount or concentration of a substance related to the patient’s health condition (hereinafter referred to as the marker substance), such as disease or pregnancy, in the body fluids. Herein, measurement of the marker substance is performed by collecting a body fluid from the patient and performing an antibody-antigen reaction with the marker substance present in the body fluid.

In the prior art, this diagnosis was performed using reagents or systems requiring professional knowledge, and thus was expensive and time-consuming. In addition, for this diagnosis, the patient had the inconvenience of visiting a hospital.

In a recent attempt to overcome the shortcomings of this diagnosis method, a point-of-care test (POCT) has received attention. The POCT is a test of diagnosing the patient within a short time by performing the collection and analysis of body fluid directly at the point where the patient is located. The POCT has various advantages in that it allows patients to diagnose themselves in a simple manner and can save additional cost and time. Due to these advantages, the POCT is being widely used.

A biosensor which is used in the POCT system frequently uses an electrochemical or optical method and comprises a light-emitting diode and a photodiode. The optical biosensor mainly uses an enzymatic luminescent reaction, and in this case, a light-emitting diode (LED) with a suitable wavelength is selected depending on a luminescent dye to be used and irradiates light to a substance to be measured. The reflected light is absorbed and the light intensity is measured by a photodiode, whereby the concentration of the substance can be measured.

However, in the case of this biosensor comprising the light-emitting diode or the photodiode, an external noise exists. Specifically, the output signal of the photodiode can contain noises, including an external light component, an electrical signal offset component, etc. If the output signal of the photodiode is used as it is, particularly, if it contains a large amount of an external optical signal, there is a problem in that undesired signal components contained therein cause measurement errors.

The present invention has been made in view of the above-described problems, and it is an object of the present invention to a method for compensating the output signal of an optical biosensor for optically diagnosing a marker substance, the method being capable of removing an external noise component in the optical biosensor to achieve more accurate diagnosis, and a biosensor using the same.

To achieve the above objects, in accordance with one aspect of the present invention, there is provided an optical biosensor comprising: a cartridge for supporting a marker substance; a light-emitting diode (LED) for radiating an optical signal to the marker substance; a photodiode (PD) serving to measure a signal reflected from the marker substance after the optical signal radiated from the LED was absorbed by the marker substance; an LED driving unit serving to convert the type of the optical signal irradiated to the marker substance such that the radiated optical signal is distinguished from a noise component; and a micom serving to measure the concentration of the marker substance based on the signal measured by the PD.

Preferably, the LED driving unit may control the on/off state of the LED such that the optical signal radiated from the LED may be converted to a pulse type signal.

Preferably, the micom may determine that a portion of the reflected signal measured by the PD, which corresponds to a signal measured when the LED is in the “off” state, is a noise signal.

Preferably, the micom may measure the concentration of the marker substance based on a signal obtained by subtracting the noise signal from the reflected signal measured by the PD, which corresponds to a signal measured when the LED is in the “on” state.

Preferably, the noise signal may comprise at least one of an external optical signal and an electrical signal offset.

Preferably, the LED driving unit may control the on/off state of the LED to convert the optical signal, radiated from the LED, to a ramp-type signal.

Preferably, the micom may determine that the reflected signal measured by the PD, which corresponds to a signal measured when the LED is in the “off” state, is a noise signal.

In accordance with another aspect of the present invention, there is provided a method for compensating the output signal of an optical biosensor, the method comprising the steps of: radiating an optical signal to a marker substance; measuring a signal reflected from the marker substance after the radiated optical signal was absorbed by the marker substance; measuring the concentration of the marker substance based on the measured reflected signal; and analyzing the marker substance based on the measured concentration of the marker substance, wherein the optical signal radiated in the step of radiating the optical signal is a pulse-type or ramp-type signal.

Preferably, the method of the present invention may further comprise, before the step of radiating the optical signal, a step of controlling the on/off state of a LED (light-emitting diode) to produce a pulse-type or ramp-type optical signal.

Preferably, the step of measuring the concentration of the marker substance may be performed based on a determination that the reflected signal, which corresponds to an optical signal measured when the LED is in the “off” state, is a noise signal.

Preferably, the step of measuring the concentration of the marker substance may be performed based on a signal obtained by subtracting the noise signal from the reflected signal which corresponds to an optical signal measured when the LED is in the “on” state.

According to the above-described method for compensating the output signal of the optical biosensor and the biosensor using the same, an external noise component in the optical biosensor can be removed, thereby achieving more accurate diagnosis.

FIG. 1 illustrates the optical structure of an optical biosensor according to one embodiment of the present invention.

FIG. 2 illustrates the configuration of an optical biosensor according to one embodiment of the present invention.

FIG. 3 is a graph showing a general LED signal that is used in conventional biosensors.

FIG. 4 is a graph showing a PD output signal measured when a pulse-type optical signal is radiated in an optical biosensor according to one embodiment of the present invention.

FIG. 5 is a graph showing a PD output signal measured when a ramp-type optical signal is radiated in an optical biosensor according to one embodiment of the present invention.

FIG. 6 is a flow chart showing a method for compensating the output signal of an optical biosensor according to one embodiment of the present invention.

Although the present invention can be modified variously and have several embodiments, exemplary embodiments are illustrated in the accompanying drawings and will be described in detail in the detailed description. However, the present invention is not limited to the specific embodiments and should be construed as including all the changes, equivalents and substitutions included in the spirit and scope of the present invention.

The terms "first", "second", etc., may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing a component from other components.

It is to be understood that, when an element is referred to as being “connected” or “coupled” to another element, it can be connected or coupled directly to the other element or intervening elements may be present. Terms used in this specification are used only to describe a specific embodiment and are not intended to limit the scope of the present invention. Singular expressions include plural expressions unless specified otherwise in the context thereof. In this specification, the terms "comprise", "have", etc., are intended to denote the existence of mentioned characteristics, numbers, steps, operations, components, parts, or combinations thereof, but do not exclude the probability of existence or addition of one or more other characteristics, numbers, steps, operations, components, parts, or combinations thereof.

In the following description with reference to the accompanying drawings, like components are denoted by like reference numerals, and the descriptions of the components will not be repeated. In the following description, the detailed description of related known technology will be omitted when it may obscure the subject matter of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 illustrates the optical structure of an optical biosensor according to one embodiment of the present invention.

As shown in FIG. 1, the optical structure of an optical biosensor according to one embodiment of the present invention comprises a light-emitting diode (LED) 140, a photodiode (PD) 150, a substrate 180 for supporting the LED 140 and PD 150, and a cartridge 20 for supporting a marker substance 10.

The marker substance 10 refers to a substance serving to diagnose the health condition of a patient and related to the health state of the patient. The health condition of the patient can be diagnosed by measuring the amount or concentration of the marker substance 10. Specifically, the optical biosensor according to one embodiment of the present invention uses mainly an enzymatic color-developing reaction and measures the absorption of radiated light depending on a color-developing dye used, thereby determining the concentration of the marker substance.

The LED 140 functions to radiate an optical signal of a specific wavelength to the marker substance. Meanwhile, only light remaining after the optical signal radiated to the marker substance 10 was absorbed by the marker substance 10 is reflected, and the PD 150 functions to measure the reflected signal.

These functions of the LED 140 and the PD 150 enable measurement of light absorbed by the marker substance 10, thereby determining the concentration of the marker substance 10.

The cartridge 20 for supporting the marker substance 10 can be constructed so as to be attachable to and detachable from the optical biosensor according to one embodiment of the present invention.

FIG. 2 shows the configuration of an optical biosensor according to one embodiment of the present invention. As shown in FIG. 2, an optical biosensor 100 according to one embodiment of the present invention comprises a micom 110, a digital-to-analog converter (DAC) 120, an LED driving unit 130, an LED 140, a PD 150, an amplifying/filtering unit 160 and an AD 170.

The micom 110 performs the general control of the optical biosensor 100 according to one embodiment of the present invention. Particularly, the main function of the micom 110 is either to derive the LED driving unit 130 so as to cause the LED 140 to produce a pulse signal or a ramp signal or to cause the PD 150 to analyze the received reflected signal so as to analyze the marker substance 10.

The DAC (digital-to-analog converter) 120 functions to convert a digital signal to an analog signal. The micom 110 controls the DAC 120 so as to cause the LED driving unit 130 to supply or block power to the LED 140, whereby the optical signal produced in the LED 140 is controlled to a pulse or ramp signal.

The LED driving unit 130 functions to directly drive the LED 140 and controls the on/off state of the LED 140 by control f the micom 110.

The LED 140 can be embodied as a general light-emitting unit and functions to radiate an optical signal to the marker substance 10 as described above.

The PD 150 functions to receive a signal reflected from the marker substance 10 after the LED 140 radiated an optical signal to the marker substance 10. The absorption of the optical signal radiated from the LED varies depending on the concentration of the marker substance 10, and the light intensity thereof decreases. Thus, the reflected signal contains a signal having a light intensity lower than the radiated optical signal. Based on the reduced light intensity, the concentration of the marker substance 10 can be detected, and based on the detected concentration, the health condition of the patient can be diagnosed.

The amplifying/filtering unit 160 functions to receive the reflected signal from the PD 150, remove a noise from the reflected signal and amplify the signal.

The AD 170 functions to convert an analog signal to a digital signal. Specifically, it converts a signal, transmitted from the amplifying/filtering unit 160, to a digital signal, and transmits the converted signal to the micom 110.

The micom 110 analyzes the marker substance 10 based on the received signal, thereby diagnosing the health condition of the patient. Hereinafter, a method of analyzing the marker substance 10 by the micom 110 based on the transmitted signal will be described in detail.

FIG. 3 is a graph showing a general LED signal that is used in conventional biosensors. In the prior art, the LED was maintained in the “on” state after it was switched to the “on” state, and the PD received the reflected signal and used the received signal intact. For this reason, there was a problem in that the signal output from the PD contains not only the LED optical signal, but also an external optical signal and an electrical signal offset, etc., and thus a measurement error occurs where a large amount of external light exists.

FIGS. 4 and 5 show a signal output from the PD 150 in the optical biosensor according to the embodiment of the present invention. Specifically, FIG. 4 shows a signal output from the PD 150 when the LED 140 radiated a pulse-type optical signal, and FIG. 5 shows a signal output from the PD 150 when the LED 140 radiated a ramp-type optical signal.

As shown in FIG. 4, because the LED driving unit 130 controls the LED 140 so as to cause the LED 140 to produce a pulse-type signal, the PD output signal is also produced as a pulse-type signal. The pulse-type signal can produce this optical signal when the LED 140 is maintained in the “on” state, switched to the “off” state after a given point of time and then switched again to the “on” state.

Analysis of the PD output signal indicates that the PD output signal detected during which the LED 140 is maintained in the “off” state has a magnitude corresponding to (b). Because this PD output signal in the “off” state does not contain the LED optical signal, it corresponds to a value containing only an external optical signal and an electrical signal offset.

Then, the PD output signal detected during the LED 140 is maintained in the “on” state increases by (a). Herein, the signal corresponding to (a) means the LED optical signal only. Thus, a pure LED optical signal can be detected by subtracting the signal, detected when the LED 140 is in the “off” state, from the signal when the LED 140 is in the “on” state.

In FIG. 5, because the LED driving unit 130 controls the LED 140 so as to produce a ramp-type signal, the PD output signal is also produced as a ramp-type signal. The ramp-type optical signal as shown in FIG. 5 can be produced by maintaining the LED 140 in the “off” state, applying voltage thereto after a given point of time to slowly increase the light intensity of the LED 140 and then switching-off the LED 140 again after a given point of time.

The analysis of the PD output signal indicates that the PD output signal detected during which the LED 140 is maintained in the “off” state has a magnitude corresponding (d). This signal in the “off’ state does not contain the LED optical signal, and thus corresponds to a value including only an external optical signal and an electrical offset signal.

Then, the PD output signal detected during which the light intensity of the LED 140 increases slowly increases by (c). Herein, the signal corresponding to (c) means the LED optical signal only. Thus, a pure LED optical signal can be detected by subtracting the PD output signal, detected when the LED 140 is in the “off” state, from the peak PD output signal.

In the pulse mode, an instantaneous change in a noise signal when the LED 140 is in the “on” state can have a somewhat change on the result value, but when a ramp-type optical signal is used, there is an advantage in that even an instantaneous change in a noise signal can be removed.

FIG. 6 is a flow chart showing a method for compensating for the measurement error of an optical biosensor according to one embodiment of the present invention.

Referring to FIG. 6, the LED 140 is first controlled to produce a pulse-type or ramp-type optical signal (S200). The produced optical signal is radiated to the marker substance 10 (S210), and the signal from the marker substance 10 is measured by the PD 150 (S220).

The micom 110 receives the measured signal from the PD 150, separates a pure LED optical signal from the received signal, and measures the concentration of the marker substance 10 (S230). In addition, the marker substance 10 is analyzed based on the concentration of the marker substance 10 (S240) thereby diagnosing the health condition of the patient.

When the above-described method is used, an external noise component in the optical biosensor can be removed, thereby achieving more accurate diagnosis.

The mixing and matching of features, elements and/or functions between various embodiments may be expressly contemplated herein. Although the preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

An optical biosensor comprising:

a cartridge for supporting a marker substance;

a light-emitting diode (LED) for radiating an optical signal to the marker substance;

a photodiode (PD) serving to measure a signal reflected from the marker substance after the optical signal radiated from the LED was absorbed by the marker substance;

an LED driving unit serving to convert the type of the optical signal irradiated to the marker substance such that the radiated optical signal is distinguished from a noise component; and

a micom serving to measure the concentration of the marker substance based on the signal measured by the PD.　　　
The optical biosensor of claim 1, wherein the LED driving unit controls the on/off state of the LED such that the optical signal radiated from the LED is converted to a pulse type signal.
The optical biosensor of claim 2, wherein the micom determines that a portion of the reflected signal measured by the PD, which corresponds to a signal measured when the LED is in an “off” state, is a noise signal.
The optical biosensor of claim 3, wherein the micom measures the concentration of the marker substance based on a signal obtained by subtracting the noise signal from the reflected signal measured by the PD, which corresponds to a signal measured when the LED is in an “on” state.
The optical biosensor of claim 2, wherein the noise signal comprises at least one of an external optical signal and an electrical signal offset.
The optical biosensor of claim 1, wherein the LED driving unit controls the on/off state of the LED to convert the optical signal, radiated from the LED, to a ramp-type signal.
The optical biosensor of claim 6, wherein the micom determines that a portion of the reflected signal measured by the PD, which corresponds to a signal measured when the LED is in an “off” state, is a noise signal.
The optical biosensor of claim 7, wherein the micom measures the concentration of the marker substance based on a signal obtained by subtracting the noise signal from the reflected signal measured by the PD, which corresponds to a signal measured when the LED is in an “on” state.
A method for compensating the output signal of an optical biosensor, the method comprising the steps of:

radiating an optical signal to a marker substance;

measuring a signal reflected from the marker substance after the radiated optical signal was absorbed by the marker substance;

measuring the concentration of the marker substance based on the measured reflected signal; and

　　　analyzing the marker substance based on the measured concentration of the marker substance, wherein the optical signal radiated in the step of radiating the optical signal is a pulse-type or ramp-type signal.
The method of claim 9, further comprising, before the step of radiating the optical signal, a step of controlling the on/off state of a LED (light-emitting diode) to produce a pulse-type or ramp-type optical signal.　　　
The method of claim 9, wherein the step of measuring the concentration of the marker substance is performed based on a determination that a portion of the reflected signal, which corresponds to an optical signal measured when the LED is in an “off” state, is a noise signal.　　　
The method of claim 11, wherein the step of measuring the concentration of the marker substance is performed based on a signal obtained by subtracting the noise signal from the reflected signal which corresponds to an optical signal measured when the LED is in an “on” state.　　　
The method of claim 12, wherein the noise signal comprises at least one of an external optical signal and an electrical signal offset.