Optical analysis circuit for molecular diagnostic device

Abstract

The utility model discloses an optical analysis circuit for molecular diagnosis equipment, which belongs to the field of medical molecular diagnosis equipment, and a light-emitting circuit of the optical analysis circuit is good in consistency due to the fact that current amplification is carried out in an operational amplifier; the detection circuit reads the reference voltage before the DAC1 works each time, so that the influence caused by natural light, circuit noise and operational amplifier drift can be effectively eliminated, and the depth of stripes can be effectively read. The circuit mainly comprises a light-emitting circuit and a detection circuit, the detection circuit comprises an operational amplifier U3 and a voltage follower circuit, the negative input end of the operational amplifier U3 is connected with a photosensitive diode PD, and the output end of the voltage follower circuit is connected with the positive input end of an operational amplifier U4. The output end of the operational amplifier U3 is connected with the negative input end of the operational amplifier U4 through a resistor R18. The utility model is mainly used for optical analysis of molecular diagnosis equipment.

Description

Technical Field

[0001] This utility model relates to the field of medical molecular diagnostic equipment, and more specifically, to an optical analysis circuit for molecular diagnostic equipment. Background Technology

[0002] The optical analysis circuit of molecular diagnostic equipment primarily operates on the principle of fluorescence reflectance comparison. The essence of fluorescence reflectance comparison is that the light-emitting circuit drives an LED light source to emit stable light. When the LED light source shines on a sample, different samples will reflect light with varying intensities. The detection circuit can read the corresponding current changes caused by the changes in the intensity of the reflected light received by the photocell. LED light sources and photocells vary in model, and stable light-emitting and detection circuits are existing technical challenges requiring further research. For example, a testing device for photosensitive circuit boards (publication number CN202393876U) judges the quality of the circuit board by visually observing changes in the brightness of the LED light. However, given the varying light intensities reflected by different samples when illuminated by an LED light source, current technology lacks a device to detect these changes in reflected light intensity and read the corresponding current changes. Utility Model Content

[0003] The purpose of this invention is to provide an optical analysis circuit for molecular diagnostic equipment. Since the current amplification of the light-emitting circuit is performed inside the operational amplifier, the consistency is better. The detection circuit reads the reference voltage before each operation through DAC1, which can effectively eliminate the influence of natural light, circuit noise and operational amplifier drift, and thus effectively read the depth of the stripes.

[0004] This utility model is achieved through the following technical solution:

[0005] An optical analysis circuit for a molecular diagnostic device includes a light-emitting circuit and a detection circuit. The detection circuit includes an operational amplifier U3 and a voltage follower circuit. The negative input terminal of the operational amplifier U3 is connected to a photodiode PD. The output terminal of the voltage follower circuit is connected to the positive input terminal of the operational amplifier U4 through a resistor R12. The output terminal of the operational amplifier U3 is connected to the negative input terminal of the operational amplifier U4 through a resistor R18. A resistor R15 is connected between the negative input terminal and the output terminal of the operational amplifier U4. Resistors R12, R18, R15, and the operational amplifier U4 form a subtraction circuit.

[0006] Furthermore, the light-emitting circuit includes an operational amplifier U1. The positive input terminal of the operational amplifier U1 is connected to V_DAC2 through a resistor R9. Resistors R10 and R13 and a filter capacitor C23 are also connected between the positive input terminal of the operational amplifier U1 and the resistor R9. The output terminal of the operational amplifier U1 is connected to a light-emitting diode (LED). The negative input terminal of the operational amplifier U1 is connected to the negative terminal of the LED through a feedback resistor R6. The feedback resistor R6 and the negative terminal of the LED are connected to a current sampling resistor R1.

[0007] Furthermore, the voltage follower circuit includes an operational amplifier U2. The positive input terminal of the operational amplifier U2 is connected to V_DAC1 through a resistor R5. A filter capacitor C13 is connected between the resistor R5 and the positive input terminal of the operational amplifier U2. The negative input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U2. The output terminal of the operational amplifier U2 is connected to a resistor R12.

[0008] Furthermore, the output terminal of the operational amplifier U2 is connected to the filter capacitor C15 and the resistor R12 respectively, and the output terminal of the operational amplifier U2 is connected to the positive input terminal of the operational amplifier U4 through the resistor R12.

[0009] Furthermore, the photodiode PD is connected to the negative input terminal of the operational amplifier U3 through a resistor R20. A resistor R11 and a filter capacitor C16 are connected in parallel between the negative input terminal and the positive input terminal of the operational amplifier U3. The output terminal of the operational amplifier U3 is connected to a resistor R18 through a low-pass filter circuit.

[0010] Furthermore, the output terminal of the operational amplifier U4 is connected to a resistor R21, and the resistor R21 is connected to a filter capacitor C20.

[0011] Compared with the prior art, the beneficial effects of this utility model are:

[0012] 1. The light-emitting circuit has good consistency because the current amplification is all performed inside the operational amplifier. Compared with the traditional constant current source circuit, this circuit has superior performance, simple structure, high sensitivity, wide linear range, and significantly reduced cost and failure rate. The detection circuit reads the reference voltage before each operation of DAC1, which can effectively eliminate the influence of natural light, circuit noise and operational amplifier drift, and thus effectively read the depth of the stripes.

[0013] 2. It has a reliable, convenient, and simple structure, excellent performance, high sensitivity, wide linear range, and low cost, making it easy to use in the optical analysis circuits of molecular diagnostic equipment. Attached Figure Description

[0014] Figure 1 This is the circuit diagram of the detection circuit of this utility model;

[0015] Figure 2 This is the circuit diagram of the light-emitting circuit of this utility model. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] like Figure 1 – Figure 2 As shown in Example 1, an optical analysis circuit for a molecular diagnostic device includes a light-emitting circuit and a detection circuit. The detection circuit includes an operational amplifier U3 and a voltage follower circuit. The negative input terminal of the operational amplifier U3 is connected to a photodiode PD (photocell). The output terminal of the voltage follower circuit is connected to the positive input terminal of the operational amplifier U4 through a resistor R12. The output terminal of the operational amplifier U3 is connected to the negative input terminal of the operational amplifier U4 through a resistor R18. A resistor R15 is connected between the negative input terminal and the output terminal of the operational amplifier U4. Resistors R12, R18, R15, and the operational amplifier U4 form a subtraction circuit.

[0018] Example 2: An optical analysis circuit for a molecular diagnostic device, wherein the light-emitting circuit includes an operational amplifier U1. The positive input terminal of operational amplifier U1 is connected to V_DAC2 through resistor R9. Resistors R10 and R13 and a filter capacitor C23 are also connected between the positive input terminal of operational amplifier U1 and resistor R9 (the other ends of resistors R10, R13 and filter capacitor C23 are grounded). The output terminal of operational amplifier U1 is connected to a light-emitting diode (LED). The negative input terminal of operational amplifier U1 is connected to the negative terminal of LED through feedback resistor R6. Feedback resistor R6 and the negative terminal of LED are connected to a current sampling resistor R1. The voltage follower circuit includes an operational amplifier U2. The positive input terminal of operational amplifier U2 is connected to V_DAC1 through resistor R5. A filter capacitor C13 is connected between resistor R5 and the positive input terminal of operational amplifier U2 (the reference voltage V_DAC1 passes through a low-pass filter formed by resistor R5 and filter capacitor C13 and is connected to the positive input terminal of operational amplifier U2). The negative input terminal of operational amplifier U2 is connected to the output terminal of operational amplifier U2. The output terminal of operational amplifier U2 is connected to resistor R12; the output terminal of operational amplifier U2 is connected to filter capacitor C15 and resistor R12 respectively; the output terminal of operational amplifier U2 (operational amplifier U2 is a voltage follower) is connected to the positive input terminal of operational amplifier U4 through resistor R12; the photodiode PD is connected to the negative input terminal of operational amplifier U3 through resistor R20; a resistor R11 and filter capacitor C16 are connected in parallel between the negative input terminal and the positive input terminal of operational amplifier U3 (resistors R20, resistor R11 and...). The filter capacitor C16 forms a low-pass filter (the filter capacitor C16 is a Miller capacitor). The operational amplifier U3, resistor R20, resistor R11, and filter capacitor C16 form a current amplification circuit. The output terminal of the operational amplifier U3 is connected to resistor R18 through a low-pass filter circuit (this low-pass filter circuit is composed of resistor R23 and filter capacitor C22). The output terminal of the operational amplifier U4 is connected to resistor R21, and resistor R21 is connected to filter capacitor C20 (resistor R21 and filter capacitor C20 form a low-pass filter). The rest is the same as in embodiment 1.

[0019] Working principle of the LED circuit: The voltage V_DAC2 is connected to pin 1 of operational amplifier U1 through voltage divider resistor R10. The voltage across sampling resistor R1 is the voltage across pin 1 of operational amplifier U1. By selecting an appropriate sampling resistor R1, the required current can be obtained. During normal use, the output current can be adjusted by controlling the V_DAC2 voltage. By adjusting the value of sampling resistor R1, the saturation effect of the operational amplifier can be used to limit the output current of the LED, achieving current limiting protection for the LED. Current amplification occurs internally within the operational amplifier, resulting in good consistency. Compared to traditional constant current source circuits, this circuit offers superior performance, a simpler structure, significantly reduced costs, and a lower failure rate. The corresponding operational amplifier calculation formula is:

[0020] V_DAC2_A=V_DAC2*((R10*R13 / (R10+R13)) / (R9+(R10*R13 / (R10+R13))))=V_DAC2 / 3,

[0021] According to the virtual short principle of op-amps: V_DAC2_A=V_DAC2_B=V_DAC2_C,

[0022] Therefore, the current flowing through the sampling resistor R1 is I_R1=V_DAC2_C / R1=V_DAC2_A / R1=V_DAC2_A / (3*R1).

[0023] Therefore, the current flowing through the light-emitting diode LED is I_LED1=I_R1=V_DAC2_A / (3*R1).

[0024] The detection circuit works as follows: The current signal generated by the photovoltaic cell is amplified into a voltage signal V2 by a current amplifier (composed of operational amplifier U3, etc.); the voltage generated by V_DAC1 is amplified into V1 by a voltage follower composed of operational amplifier U2; the voltages V1 and V2 are amplified into VOUT by a subtraction circuit composed of operational amplifier U4, and the amplifier output is: VOUT = K*(V1-V2).

[0025] V_DAC1 can be adjusted on a white background, which in turn adjusts V1, setting VOUT to 0. V_DAC1 can then be fixed as a reference voltage for the white background. Different V2 values ​​are generated when passing through stripes of varying shades, causing VOUT to change with the stripe depth, thus allowing the reading of the stripe depth. This circuit effectively eliminates the effects of natural light, circuit noise, and op-amp drift by reading the reference voltage before each operation of V_DAC1, thus effectively reading the stripe depth. Based on the op-amp virtual short principle: V1 = V_DAC1 = V_DAC1_A = V_DAC1_B, V_SEN_A = V_SEN_B = 0V, and the photovoltaic cell current is I_SEN = V_SEN / R20; due to the virtual open principle: V2 = |I_SEN|*R11 = V_SEN*R11 / R20;

[0026] VOUT=V1*(R18+R15) / R18-V2*R15 / R18=V1+R15*(V1-V2) / R18=V1+12*(V1-V2)=13*V1-12*V2.

Claims

1. An optical analysis circuit for a molecular diagnostic device, comprising a light emitting circuit and a detection circuit, characterized in that: The detection circuit includes operational amplifier U3 and voltage follower circuit, the negative input terminal of operational amplifier U3 is connected with photosensitive diode PD, the output terminal of voltage follower circuit is connected with the positive input terminal of operational amplifier U4 through resistance R12, the output terminal of operational amplifier U3 is connected with the negative input terminal of operational amplifier U4 through resistance R18, resistance R15 is connected between the negative input terminal of operational amplifier U4 and the output terminal of operational amplifier U4.

2. The optical analysis circuit for a molecular diagnostic device according to claim 1, characterized in that: The light-emitting circuit includes operational amplifier U1, the positive input terminal of operational amplifier U1 is connected with V_DAC2 through resistance R9, resistance R10, resistance R13 and filter capacitor C23 are further connected between the positive input terminal of operational amplifier U1 and resistance R9, the output terminal of operational amplifier U1 is connected with light-emitting diode LED, the negative input terminal of operational amplifier U1 is connected with the negative pole of light-emitting diode LED through feedback resistance R6, and current sampling resistance R1 is connected between feedback resistance R6 and the negative pole of light-emitting diode LED.

3. The optical analysis circuit for a molecular diagnostic device of claim 1, wherein: The voltage follower circuit includes operational amplifier U2, the positive input terminal of operational amplifier U2 is connected with V_DAC1 through resistance R5, filter capacitor C13 is connected between resistance R5 and the positive input terminal of operational amplifier U2, the negative input terminal of operational amplifier U2 is connected with the output terminal of operational amplifier U2, and the output terminal of operational amplifier U2 is connected with resistance R12.

4. The optical analysis circuit for a molecular diagnostic device of claim 1, wherein: The photosensitive diode PD is connected with the negative input terminal of operational amplifier U3 through resistance R20, and resistance R11 and filter capacitor C16 are further connected in parallel between the negative input terminal of operational amplifier U3 and the positive input terminal of operational amplifier U3, and the output terminal of operational amplifier U3 is connected with resistance R18 through low-pass filter circuit.

5. The optical analysis circuit for a molecular diagnostic device of claim 1, wherein: The output terminal of operational amplifier U4 is connected with resistance R21, and filter capacitor C20 is connected with resistance R21.

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