WO2012053851A1

WO2012053851A1 - System for signal detection of specimen using magneto resistance sensor

Info

Publication number: WO2012053851A1
Application number: PCT/KR2011/007870
Authority: WO
Inventors: Man Hue Choi; Goo Sam Kang; Jeong Ryul Kim
Original assignee: Lg Innotek Co., Ltd.
Priority date: 2010-10-21
Filing date: 2011-10-21
Publication date: 2012-04-26
Also published as: KR101239863B1; KR20120041576A

Abstract

Provided is a detection system using a magneto resistance sensor. In particular, the magneto resistance sensor includes an amplification driver amplifying a detection signal supplied from a detection device including a magneto resistance sensor and sensing only a magnetic signal during the application of magnetic field, wherein the amplification driver includes an AC amplification circuit having at least one capacitor disposed at an back end of an input of the magneto resistance sensor to which the detection signal is input.

Description

SYSTEM FOR SIGNAL DETECTION OF SPECIMEN USING MAGNETO RESISTANCE SENSOR

The present invention relates to a detection system using a magneto resistance sensor capable of increasing detection efficiency.

A bio sensor uses a magnetic particle detection apparatus using a magneto resistance sensor (Hall sensor) for sensing materials. The magnetic particle detection apparatus needs to use a complex power supply of an alternating and direct power supply.

In addition, since some of the magneto resistance sensors have poor sensitivity, there is a need to drive the magneto resistance sensors by applying a strong magnetic field in a vertical direction. Further, since the magneto resistance sensor uses an input signal of the alternating waveform, the magneto resistance sensor is sensitive to the external noise and has a difficulty in transforming a reference voltage using a variable resistor.

Further, a configuration of a system is complicated so as to drive the Hall sensor, which consumes a large amount of power and increases costs. Therefore, the configuration of the system is complicated so as to drive the magneto resistance sensor (Hall sensor), which is sensitive to external noises, consumes a large amount of power, and increases costs. In addition, a system of detecting detection signals sensed by the above-mentioned Hall sensor is configured to include an amplifier amplifying the detection signal and a lock-in stage oscilloscope detecting signals passing through the amplifier.

That is, the magnetic particle detection apparatus using the magneto resistance sensor (Hall sensor) according to the related art needs to use the complex power supply of the alternating and direct power supply. In addition, since the magneto resistance sensor has poor sensitivity, there is a need to drive the magneto resistance sensor by applying a strong magnetic field in a vertical direction. Further, since the magneto resistance sensor uses the input signal having the alternating waveform, the magneto resistance sensor is sensitive to the external noises and performs the signal processing using the lock-in stage oscilloscope. Therefore, the configuration of the system is complicated so as to drive the Hall sensor, which is sensitive to the external noise, consumes a large amount of power, and increases costs.

An aspect of the present invention is directed to a system for efficiently and reliably detecting a signal including an AC amplifier amplifying only AC component of a signal of an input terminal to which a detection signal generated from a magneto resistance sensor is input so as to exclude a phenomenon that the signal of the input terminal is amplified up to unnecessary DC voltage, thereby increasing a gain of differential amplification and improving a signal to noise ratio.

According to an embodiment of the present invention, there is provided a detection system using a magneto resistance sensor, including: an amplification driver amplifying a detection signal supplied from a detection device including a magneto resistance sensor and sensing only a magnetic signal during the application of magnetic field, wherein the amplification driver includes an AC amplification circuit having at least one capacitor disposed at an back end of an input of the magneto resistance sensor to which the detection signal is input.

As set forth above, the exemplary embodiment of the present invention can efficiently and reliably detect the signal including the AC amplifier amplifying only the AC component of the signal of the input terminal to which the detection signal generated from the magneto resistance sensor is input so as to exclude the phenomenon that the signal of the input terminal is amplified up to the unnecessary DC voltage, thereby increasing the gain of the differential amplification and improving the signal to noise ratio.

In particular, the exemplary embodiments of the present invention can use the giant magneto resistance sensor to efficiently detect the magnetic particles with the excellent MR ratio and the sensitivity, reduce costs by using a small amount of power, and further simplify the circuit than the existing amplification circuit.

The above and other aspects, features and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a conceptual diagram for describing a sensing principle of a giant magneto resistance sensor (GMR) according to an exemplary embodiment of the present invention;

FIG. 2 is a diagram showing an entire configuration of a detection system according to the exemplary embodiment using the magneto resistance sensor (GMR sensor);

FIG. 3 is an image showing a GMR bare chip implementing a measurement kit as a magneto resistance sensor according to the exemplary embodiment of the present invention;

FIG. 4 is a conceptual diagram showing an example of a method scanning a detection signal using the GMR bare chip implemented by a measurement kit as the magneto resistor sensor described in FIG. 3;

FIG. 5 shows a configuration diagram of a general amplification circuit and FIG. 6 is a configuration diagram showing an amplification driver according to the exemplary embodiment of the present invention;

FIG. 7 is a diagram showing an image implementing a structure of an amplification driver according to the exemplary embodiment of the present invention by an actual circuit of FIG. 6; and

FIG. 8 is a diagram showing a signal waveform detecting a low-concentration magnetic particle of a GMR signal through the amplification driver according to the exemplary embodiment of the present invention.

Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Wherever possible, the same reference numerals will be used to refer to the same elements throughout the specification, and a duplicated description thereof will be omitted. It will be understood that although the terms first, second , etc. are used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element.

The gist of the exemplary embodiment of the present invention is to provide a detection system capable of improving a signal to noise ratio of a signal output from a magneto resistance sensor by adding an AC amplification circuit to an amplification driver amplifying an input detection signal.

The exemplary embodiment of the present invention may use a various types of the magneto resistance (MR) sensor. An example of the magneto (MR) sensor may include any one of an ortrinary magneto resistance (OMR) sensor, an anisotropic magneto resistance (AMR) sensor, a giant magneto resistance (GMR) sensor, a colossal magneto resistance (TMR) sensor, and a magnetic tunneling junction (MJT) sensor. In particular, the giant magneto resistance (GMR) sensor may be used. Therefore, a detection system using a giant magneto resistance sensor among the magneto resistance sensors according to the exemplary embodiments of the present invention will be described as an example for describing an effect of the present invention.

Referring to FIG. 1, FIG. 1 is a conceptual diagram for describing a sensing principle of a giant magneto resistance sensor (GMR) according to an exemplary embodiment of the present invention.

The detection system using the giant magnetic sensor according to the exemplary embodiment of the present invention includes a bio sensor in which at least one of a giant magneto resistance device, a switching device, and a giant magneto resistance (hereinafter, referred to as GMR) sensor made of a magnetic material, or analyzes electrical component of peripheral materials by sensing different magnetic susceptibility according to component of a material having different characteristics by forming at least one giant magneto resistance (GMR) sensor in a measurement device, loading the measurement kit in the measurement kit, and applying magnetic force thereto.

In this case, the GMR sensor may use the GMR device of a spin-valve type. The sensing principle of the GMR device of the spin valve type is disposed between two ferroelectric metal layers and a non-magnetic metal layer as shown in FIG. 1. The sensing principle uses a principle of fixing a magnetic force of any one of two ferroelectric metal layers and variably controlling magnetic force of the other of two ferroelectric metal layers to pass only spin-oriented electrons through the conductor in a specific direction when the magnetic force of two layers is parallel with each other. That is, a difference in the electric resistance or a potential difference induced from the inside of the material according to an alignment of a magnetization direction of two ferroelectric layers is generated, which are recognized as digital signals.

FIG. 2 is a diagram showing an entire configuration of a detection system (hereinafter, referred to as the present system ) according to the exemplary embodiment using the magneto resistance sensor (GMR sensor).

Referring to FIG. 2, the present system according to the present invention is configured to include a sample to be detected, a sample fixing unit 120 fixing the sample, an external magnetic field application device 110 applying magnetic field to the sample from the outside, and a magneto resistance sensor 130. By using the fundamental structure, the sample is mounted on the sample fixing unit 120, the external magnetic field is applied from the external magnetic field application device 110, and the magnetic signal (MR signal) for the sample coupled with the magnetic component is sensed in the magneto resistance sensor 130 to separate into the electrical component and to be analyzed.

In this case, the detection system according to the exemplary embodiment of the present invention includes an amplification driver A amplifying a detection signal 131 supplied from a detection device including the magneto resistance sensor 130 and sensing only a magnetic signal during the application of magnetic field, wherein the amplification driver A may be configured to include an AC amplification circuit having at least one capacitor disposed at an back end of an input of the magneto resistance sensor to which the detection signal is input. The amplification driver A including the AC amplification circuit prevents a phenomenon that unnecessary DC voltage is amplified together by not directly connecting (capacitor connection) the input back end of the magneto resistance sensor, thereby improving the signal to noise ratio and efficiently detecting the signal.

In other words, the amplification driver is designed in the AC amplification method that amplifies only the AC component of the signal of the input terminal of the magneto resistance sensor to prevent the unnecessary bias DC voltage together to increase the gain of the differential amplification, thereby effectively detecting the signal and accurately confirm the signal corresponding to the low-density magnetic particle.

The magnetic particle may include a magnetization value of 10 to 100 emu/g. In this case, a characteristic of the magnetic particle is superparamagnetism or paramagnetism.

The external magnetic field application device basically applies first and second directional external magnetic field of the magneto resistance sensor 130. The above-mentioned first direction and second direction may include a first application unit applying a magnetic field to the magneto resistance sensor in a horizontal direction (Y axis) and a second application unit applying a magnetic field to the magneto resistance sensor in a vertical direction (Z axis). Further, the above-mentioned horizontal direction and vertical direction does not mean that it is necessarily vertical to the vertical surface of the magneto resistance sensor but has a concept that includes flowability of a predetermined incident direction.

Therefore, the first application unit may be configured to apply the fixing magnetic field by configuring a magnetic field generation unit in any one or plurality of a solenoid coil, a Helmholtz coil, an electromagnetic yoke, and a permanent magnet.

Therefore, the second application unit 112 may be configured to apply the fixing magnetic field by configuring a magnetic field generation unit in any one or plurality of a solenoid coil, a Helmholtz coil, an electromagnetic yoke, and a permanent magnet.

In the present invention, the range of the magnetic field applied to the first application unit may be 2 to 30 Gauss and the range in which the giant magneto resistance sensor (GMR) can react may be 2 to 300 Gauss. Further, the magnetic field applied to the second application unit may be applied in a range of 1200 to 1800 Gauss.

The reason why the biaxial magnetic field is applied is that the GMR sensor is strongly affected only by the magnetic field in the right direction (Y axis) to the sensor and is weakly affected by the direction (X axis) parallel with the sensor but is not affected by the magnetic field in the direction (Z axis) vertical to the sensor. In addition, the Y-axial magnetic field may be biased within the unique linear range.

Therefore, the system design for implementing the maximum performance of the GMR sensor saturation-magnetizes the superparamagnetic magnetic particle by applying DC magnetic field in a Z-axis direction and needs to bias so that the sensitivity performance of the sensor is maximum by applying the magnetic field in the Y-axis direction. In this case, the application of magnetic field in a Y-axis direction is made by using an induced magnetic field generated through the DC current, which is very efficient to improve the signal to noise ratio. In addition, it is the most preferable that the magnetic particle locally accumulated in the side flowable membrane may be transferred through the scanning in the same direction and the induced magnetic field in the Y-axis direction.

As described above, various types of the magneto resistance sensor 130 may be used. However, the exemplary embodiment of the present invention will describe, by way of example, the case in which the sensor using the giant magneto resistance (GMR) device is configured.

FIG. 3 is an image showing a GMR bare chip implementing a measurement kit as a magneto resistance sensor according to the exemplary embodiment of the present invention.

The magneto resistance sensor is implemented as the structure in which the electrode pattern is formed by installing one or a plurality of GMRs for a bio sensor within the measurement kit that is an image shown as the exemplary embodiment applied to the present system. In this case, the used GMR device has a standard having a volume of (0.2 mm, 0.5 mm, 1.0 mm) and (0.25 mm, 1.0 mm, 1.5 mm). The GMR device of which the saturation field is 3 to 150 Gauss and the sensitivity is a minimum of 0.9 to a maximum of 18 (mV/V-Oe) is used.

In addition, the interface of the GMR device applies several v to several tens V by using a Wheatstone bridge. In this case, a sensing element measured at about several to several M is used.

FIG. 4 is a conceptual diagram showing an example of a method scanning a detection signal using the GMR bare chip implemented by a measurement kit as the magneto resistor sensor described in FIG. 3.

That is, in order to measure a magnetic particle band of a sample using the giant magneto resistance, a scan method for measuring the magnetization value of the magnetic particle that is change over time is used.

The sample 121 formed by the magnetic particle band is seated in the measurement kit of the sample fixing unit 120 and the measurement kit may be configured to move forward and backward by a motor scanner (SC). The top of the support 131 spaced apart by a predetermined distance from the measurement kit is mounted with the magneto resistance sensor (GMR) 130 to sense the change in the temporal magnetization value of the magnetic particle in the sample moving at the scan speed.

FIG. 5 shows a configuration diagram of a general amplification circuit and FIG. 6 is a configuration diagram showing an amplification driver according to the exemplary embodiment of the present invention.

Describing in more detail, the magneto resistance sensor has a system structrue in which the back end of the sensor input unit 131 receiving the detection signal at the magnetic particle is directly connected 132 with the amplification unit 133. That is, the application circuit configuration (DC Topology: a method directly connecting the back end of the sensor input) may be made. However, when the signal detection system is configured as described above, the unnecessary bias DC voltage is amplified together, the gain of the differential amplification may not be increased, such that it is difficult to obtain an accurate signal and it is difficult to accurately confirm the signal corresponding to the low-density magnetic particle. In addition, there is a need to dispose a DC offset control circuit (there is a need to control offset by changing the DC reference value by the amplification due to the configuration of the DC type), which should be controlled at the time of detecting the signal.

FIG. 6 shows an amplification driver according to the exemplary embodiment of the present invention, which has a structure implemented by a method of connecting the capacitor between the sensor input unit 131 and the amplifier 133. That is, the method (AC Topology: a method of non-direct connecting the back end of the sensor input (capacitor connection)) of connecting the AC amplification circuit between the back end of the sensor input unit and the amplifier is implemented to prevent the phenomenon that the unnecessary bias DC voltage is amplified together, thereby improving the signal to noise ratio and efficiently detecting the signal.

In other words, the amplification driver is designed in the AC amplification method that amplifies only the AC component of the signal of the input terminal of the sensor input terminal to prevent the unnecessary bias DC voltage together to increase the gain of the differential amplification, thereby effectively detecting the signal and accurately confirm the signal corresponding to the low-density magnetic particle. In addition, the DC offset control circuit needs not to be disposed at the back end (there is no need to perform the offset control since the DC reference value is not changed due to the AC type configuration), such that the circuit has an automatic correction function, thereby simplifying the circuit.

FIG. 7 is a diagram showing an image implementing a structure of an amplification driver according to the exemplary embodiment of the present invention by an actual circuit of FIG. 6. That is, the circuit diagram of the type in which the back end of the AC topology sensor input applied to the giant magneto resistance sensor is not connected (capacitor connection) is shown.

In FIG. 8A, the signal detected by the general circuit configuration as shown in FIG. 5 is shown and in FIG. 8B, the actual measurement data detecting the signal by configuring the AC Topology type according to the exemplary embodiment of the present invention is shown. As can be configured in the shown image, the signal of the AC Topology type according to the exemplary embodiment of the present invention is more excellent in the signal to noise ration than the general type, thereby increasing the gain of the differential amplification and effectively detecting the signal.

A circuit unit AC amplification circuit (hardware control method: AC topology type) forming the amplification driver is disposed to prevent the phenomenon that the unnecessary bias DC voltage of the output signal is amplified together, thereby improving the signal to noise ratio and more simplifying the circuit than the existing amplification circuit. As a result, various applications may be made.

In addition, the magnetic particle may be effectively detected by using the giant magneto resistance having the most excellent MR ratio and the sensitivity among the magneto resistance sensors and the giant magneto resistance sensor consumes a smaller amount of power than the magneto resistance Hall sensor since it uses only the DC power supply voltage at the time of driving the system, thereby reducing the costs.

While the invention has been shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.

Claims

A detection system using a magneto resistance sensor, comprising:

an amplification driver amplifying a detection signal supplied from a detection device including a magneto resistance sensor and sensing only a magnetic signal during the application of magnetic field,

wherein the amplification driver includes an AC amplification circuit having at least one capacitor disposed at a back end of an input of the magneto resistance sensor to which the detection signal is input.
The detection system of claim 1, wherein the detection signal is driven using DC power supply voltage.
The detection system of claim 2, wherein the detection device includes:

a sample fixing unit fixing the sample;

a magneto resistance sensor sensing magnetic component of the sample coupled with magnetic particles; and

an external magnetic field application device applying external magnetic field to the magneto resistance sensor.
The detection system of claim 3, wherein the external magnetic field application device includes:

a first application unit horizontally applying magnetic field to the magneto resistance sensor; and

a second application unit vertically applying magnetic field to the magneto resistance sensor.
The detection system of claim 4, wherein the magneto resistance sensor is a giant magneto resistance (GMR) sensor.
The detection system of claim 5, wherein the sample fixing unit including the sample is a measurement cartridge or a membrane to which a bio material including antigen is fixed.
The detection system of claim 4, wherein the first application unit applies the fixing magnetic field by configuring a magnetic field generation unit in any one or plurality of a solenoid coil, a Helmholtz coil, an electromagnetic yoke, and a permanent magnet.
The detection system of claim 4, wherein the second application unit applies the variable magnetic field by configuring a magnetic field generation unit in any one or plurality of a solenoid coil, a Helmholtz coil, an electromagnetic yoke, and a permanent magnet.
The detection system of claim 4, wherein the magnetic filed applied by the second application unit is formed by DC current.
The detection system of claim 5, wherein the magnetic particle includes a magnetization value of 10 to 100 emu/g.
The detection system of claim 10, wherein a characteristic of the magnetic particle is superparamagnetism or paramagnetism.
The detection system of claim 10, wherein the external magnetic field application device sets a range of a horizontal (Y axis) magnetic field or a range in which the magneto resistance sensor (MR) reacts to be 2 to 30 Gauss.
The detection system of claim 12, wherein the external magnetic field application device sets the magnetic field applied to the vertical direction (Z axis) to be a range of 1200 to 1800 Gauss.
The detection system of claim 6, further comprising a motor scanner (SC) moving the measurement kit forward and backward, wherein the sample fixing unit is seated in a measurement kit.