Biochemical acquisition and detection circuit and biochemical analyzer

Abstract

The utility model discloses a biochemical acquisition and detection circuit and a biochemical analyzer. The biochemical acquisition and detection circuit comprises a photodiode, a primary amplification circuit, a bias current matching circuit, a secondary amplification circuit, a filter circuit and an acquisition circuit, the photodiode is used for converting the optical signal into a current signal; the primary amplification circuit is used for converting the current signal into a first voltage signal; the bias current matching circuit is arranged between the primary amplifying circuit and the secondary amplifying circuit and is used for matching the bias current of the primary amplifying circuit; the secondary amplification circuit is used for amplifying the first voltage signal to obtain a second voltage signal, and the amplification factor of the secondary amplification circuit is adjustable; the filter circuit is used for filtering the second voltage signal to obtain an output voltage signal; the acquisition circuit is used for acquiring the output voltage signal. The detection circuit is suitable for reagents with high absorbance and is suitable for the condition of weak light intensity, and the output voltage signal is greatly improved by the two-time amplification circuit, so that the output voltage signal is easy to detect.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of detection circuit, specifically relates to a biochemical collection detection circuit and biochemical analyzer. BACKGROUND

[0002] The biochemical analyzer is based on photoelectric colorimetry, a light source forms monochromatic light with a certain bandwidth through a two-mirror and a filter, a plurality of vertical monochromatic lights irradiate a colored liquid in a colorimetric cup, the absorption of light energy of a sample is measured, and a photoelectric signal is collected.

[0003] Figure 1 The collection detection circuit provided by the prior art is used for irradiating a light beam on a photodiode 01, the photodiode 01 converts a light signal into a current signal, a first amplification circuit 02 is used for converting the photoelectric current into a voltage, a bias current matching circuit 03 is used for matching the bias current of the first amplification circuit 02, an analog signal output circuit 04 is used for outputting an analog signal, and a signal is received by an external device.

[0004] The inventor of the present application found the following defects in the prior art during research.

[0005] 1. The design directly leads out the multi-channel analog signal, which is easy to be disturbed and radiated, so that the front-end power supply needs to be well isolated, the subsequent adapter wire harness needs to be well shielded, and the cost of the whole machine is increased.

[0006] 2. The installation requirement is high, the circuit needs to be far away from an inductive load, and the difficulty of the whole circuit system design is greatly increased.

[0007] 3. In the application of small light intensity, the light intensity of the PD (photo-diode, photodiode) after the light source device such as the filter is greatly weakened, and the resistance of the first amplification circuit is completely insufficient, in the experiment, the output voltage of the rear end is close to 0, and the noise value is close to 0, so that data analysis cannot be performed. UTILITY MODEL CONTENTS

[0008] The present application provides a biochemical collection detection circuit and a biochemical analyzer to solve the problem that the prior art is not applicable to small light intensity.

[0009] The first aspect of the application provides a biochemical acquisition and detection circuit, comprising a photoelectric diode, a first amplification circuit, a bias current matching circuit, a second amplification circuit, a filter circuit and an acquisition circuit connected in sequence; the photoelectric diode is used for converting an optical signal into a current signal; the first amplification circuit is used for converting the current signal into a first voltage signal; the bias current matching circuit is arranged between the first amplification circuit and the second amplification circuit and is used for matching a bias current of the first amplification circuit; the second amplification circuit is used for amplifying the first voltage signal to obtain a second voltage signal, and the amplification multiple of the second amplification circuit is adjustable; the filter circuit is used for filtering the second voltage signal to obtain an output voltage signal; and the acquisition circuit is used for acquiring the output voltage signal.

[0010] Optionally, the biochemical acquisition and detection circuit further comprises an MCU control circuit, the MCU control circuit is connected with the second amplification circuit and the acquisition circuit respectively, and the MCU control circuit is used for controlling the amplification multiple of the second amplification circuit and receiving the output voltage signal acquired by the acquisition circuit.

[0011] Optionally, the second amplification circuit comprises a digital potentiometer and an operational amplifier; the operational amplifier comprises a third input end, a fourth input end and a first output end; the third input end is connected with an output end of the first amplification circuit through the bias current matching circuit; the fourth input end is connected with a sliding end of the digital potentiometer, and a second resistor is arranged between the fourth input end and the sliding end; a fourth resistor is connected in series between the first output end and the fourth input end, and the fourth resistor is connected in parallel with a second capacitor.

[0012] Optionally, the bias current matching circuit comprises a first resistor.

[0013] Optionally, the filter circuit comprises a third resistor and a third capacitor; a first end of the third resistor is connected with the first output end, and a second end of the third resistor is connected with an input end of the acquisition circuit; one end of the third capacitor is connected with the second end of the third resistor, and the other end of the third capacitor is grounded.

[0014] Optionally, the MCU control circuit is connected with the sliding end of the digital potentiometer, and the digital potentiometer is used for providing a variable resistor under the adjustment of the MCU control circuit.

[0015] Optionally, the amplification multiple of the second amplification circuit is 2-4 times.

[0016] The second aspect of the application provides a biochemical analyzer, comprising the biochemical acquisition and detection circuit provided in any one of the implementation manners of the first aspect.

[0017] From the above technical solutions, the present application provides a biochemical light path acquisition part circuit suitable for different biochemical item light path systems; gives a solution when the dark value is high or susceptible to external interference, suitable for reagents with high absorbance; this circuit is suitable for weak light intensity, and the two amplification circuits greatly improve the output voltage signal; this circuit only needs to write programs and digital voltage power supply, and has low performance requirements for installation, power supply, wiring harness and the like outside the circuit. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A circuit structure schematic diagram provided by the prior art;

[0019] Figure 2 A biochemical acquisition detection circuit circuit structure schematic diagram provided by the present application embodiment;

[0020] Figure 3 A two-stage amplification circuit circuit structure schematic diagram provided by the present application embodiment.

[0021] Reference signs: 01-photodiode; 02-first-stage amplification circuit; 03-bias current matching circuit; 04-analog signal output circuit; 1-photodiode; 2-first-stage amplification circuit; 3-bias current matching circuit; 4-two-stage amplification circuit; 5-filtering circuit; 6-acquisition circuit; 7-MCU control circuit; 41-digital potentiometer; 42-operational amplifier; 421-first output end; 422-ground terminal; 423-third input end; 424-fourth input end; 425-power terminal. DETAILED DESCRIPTION

[0022] The technical solutions in the present application embodiments will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0023] In order to adapt to various light intensity light path modules and eliminate dark values in light path acquisition and external circuit interference on biochemical acquisition circuit, the present application embodiment provides a biochemical acquisition detection circuit, referring to the circuit schematic diagram shown in Figure 2 The biochemical acquisition detection circuit includes a photodiode 1, a first-stage amplification circuit 2, a bias current matching circuit 3, a two-stage amplification circuit 4, a filtering circuit 5 and an acquisition circuit 6 connected in sequence.

[0024] The halogen lamp or LED lamp bead emits light, and then the optical device converts the light to form a certain bandwidth of monochromatic light. Different wavebands can select light-sensitive photodiodes, and combination can reduce noise. The photodiode is a semiconductor device that converts optical signals into current signals. When it is exposed to light, it will generate a current proportional to the light intensity. In this embodiment, the photodiode 1 is used to convert the optical signal into a current signal.

[0025] In this embodiment, the first-stage amplification circuit 2 uses a combination of PD and TIA to convert the current signal into a first voltage signal. In optical fiber communication, the combination of PD and TIA is used to recover the electrical signal from the received optical signal.

[0026] In PD signal collection, a transimpedance amplifier (TIA) is often used, which mainly converts input current into output voltage. This circuit structure can efficiently convert and amplify the weak current signal of the PD. The design of the transimpedance amplifier needs to consider factors such as bandwidth, input bias current, noise performance, etc. to ensure accurate signal reading.

[0027] The bias current matching circuit is arranged between the first-stage amplification circuit and the second-stage amplification circuit, and is used to match the bias current of the first-stage amplification circuit. In this embodiment, a first resistor R1 110kΩ is placed between the second-stage amplification circuit and the first-stage amplification circuit to match the bias current of the operational amplifier.

[0028] In this embodiment, the second-stage amplification circuit is a proportional amplifier composed of a digital potentiometer and an operational amplifier, and the second-stage amplification circuit is used to amplify the first voltage signal to obtain a second voltage signal, and the amplification multiple is adjustable; the filter circuit is used to filter the second voltage signal to obtain an output voltage signal.

[0029] An operational amplifier is a high-gain electronic voltage amplifier with differential input and usually single-ended output. As a core device for signal amplification and processing, it has wide application in analog circuit design. In photodiode detection, the operational amplifier is often used to amplify the small photocurrent signal generated by the PD into a usable voltage signal for further processing.

[0030] In this embodiment, the operational amplifier with small offset voltage and bias current is selected to reduce noise. When the dark value is large after the later stage collection, the amplification transimpedance resistance value of the first-stage amplification circuit can be increased, and the resistance with high precision is selected. The relationship between the first-stage amplification and the second-stage amplification is balanced, and the output voltage should not exceed the maximum range of the ADC (analog to digital converter) collection.

[0031] In this embodiment, the acquisition circuit is an ADC, which is used to acquire the output voltage signal. The application uses an ADC acquisition chip to convert the front-end analog signal into a digital signal output. The ADC acquisition circuit and the front-end amplification circuit are designed on one PCBA or are designed not too far away, otherwise they are easily disturbed.

[0032] From the above technical solutions, the application provides a biochemical light path acquisition circuit suitable for different biochemical project light path systems, gives a solution when the dark value is high or easily disturbed by the outside world, and is suitable for reagents with high absorbance. The circuit is suitable for weak light intensity, and the two amplification circuits greatly improve the output voltage signal. The circuit only needs to write programs and digital voltage power supply, and has low performance requirements for installation, power supply and wiring harness outside the circuit.

[0033] The biochemical acquisition and detection circuit provided in this embodiment further includes an MCU control circuit 7, which is connected with the secondary amplification circuit 4 and the acquisition circuit 6 respectively. The MCU control circuit is used to control the amplification multiple of the secondary amplification circuit and receive the output voltage signal acquired by the acquisition circuit. Further, the secondary amplification circuit adjustment control is controlled by the SPI / I2C of the MCU.

[0034] Referring to Figure 3 The secondary amplification circuit 4 includes a digital potentiometer 41 and an operational amplifier 42. The operational amplifier 42 includes a first output end 421, a ground end 422, a third input end 423, a fourth input end 424 and a power supply end 425. The third input end 423 is connected with the output end of the primary amplification circuit 2 through the bias current matching circuit 3. The fourth input end 424 is connected with the sliding end of the digital potentiometer 41, and a second resistor R2 is arranged between the fourth input end 424 and the sliding end. A fourth resistor R4 is connected in series between the first output end 421 and the fourth input end 424, and the fourth resistor R4 is connected in parallel with a second capacitor C2. R4 is the transimpedance of the operational amplifier, and C2 is the feedback capacitor, which prevents self-oscillation and improves the stability of the circuit. Figure 3 C1 and C4 are filter capacitors of the power supply.

[0035] The digital potentiometer is also called a digital programmable resistor, which replaces the traditional mechanical potentiometer. The digital potentiometer is controlled by digital input to generate an analog output. When the digital potentiometer is used as a variable resistor, the sliding end is represented by RW.

[0036] Referring to Figure 3The circuit structure schematic diagram shows that the embodiment uses R3 and C3 to build a filter circuit according to a required response time setting. The filter circuit 5 comprises a third resistor R3 and a third capacitor C3. A first end of the third resistor R3 is connected with the first output end 421, and a second end of the third resistor R3 is connected with an input end of the acquisition circuit 6. One end of the third capacitor C3 is connected with the second end of the third resistor R3, and the other end is grounded.

[0037] In the embodiment, the MCU control circuit is connected with a sliding end of the digital potentiometer, and the digital potentiometer is used to provide a variable resistor under the adjustment of the MCU control circuit. The output voltage signal acquired by the acquisition circuit is calculated according to the following formula:

[0038]

[0039] In the formula, v out is the output voltage signal acquired by the acquisition circuit, v in is a first voltage signal output by the first amplification circuit, R4 is the fourth resistor, and R w is a variable resistor obtained by the MCU control circuit by adjusting the sliding end of the digital potentiometer.

[0040] In the embodiment, the proportional amplification resistor is replaced by a digital potentiometer, so that the digital potentiometer can be controlled by the MCU control circuit, thereby controlling the second amplification multiple, and realizing an adjustable second amplification circuit. R2 functions as a current limiting resistor and is selected as 100Ω. In the calculation, R2 can be ignored. The second amplification circuit provided in the embodiment has an amplification multiple of 2-4. When the digital potentiometer has a value that is not enough and the amplification multiple is not within the requirement, R2 and R4 can be used for adjustment.

[0041] The entire circuit design in the application is installed in a module, so that the entire acquisition system can be less affected by external interference. The entire circuit is affected by temperature, and is installed in a position that is not affected by heat.

[0042] The application also provides a biochemical analyzer comprising the biochemical acquisition and detection circuit provided in any of the implementation manners.

[0043] The above is only an embodiment of the application and is not used to limit the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application is included in the claim range of the application.

Claims

1. A biochemical collection detection circuit, characterized by, The biochemical acquisition detection circuit comprises, in sequence, a photodiode, a first amplification circuit, a bias current matching circuit, a second amplification circuit, a filter circuit and an acquisition circuit. The photodiode is configured to convert an optical signal into a current signal; the first amplification circuit is configured to convert the current signal into a first voltage signal; the bias current matching circuit is arranged between the first amplification circuit and the second amplification circuit and is configured to match a bias current of the first amplification circuit; the second amplification circuit is configured to amplify the first voltage signal to obtain a second voltage signal, and an amplification multiple of the second amplification circuit is adjustable. The filter circuit is configured to filter the second voltage signal to obtain an output voltage signal. The acquisition circuit is configured to acquire the output voltage signal.

2. The biochemical collection and detection circuit of claim 1, wherein, The biochemical acquisition detection circuit further comprises an MCU control circuit, which is connected to the second amplification circuit and the acquisition circuit respectively, and is configured to adjust the amplification multiple of the second amplification circuit and to receive the output voltage signal acquired by the acquisition circuit.

3. The biochemical collection and detection circuit of claim 2, wherein, The second amplification circuit comprises a digital potentiometer and an operational amplifier. The operational amplifier comprises a third input end, a fourth input end and a first output end; the third input end is connected to an output end of the first amplification circuit through the bias current matching circuit; the fourth input end is connected to a sliding end of the digital potentiometer, and a second resistor is arranged between the fourth input end and the sliding end; a fourth resistor is connected in series between the first output end and the fourth input end, and the fourth resistor is connected in parallel with a second capacitor.

4. The biochemical collection detection circuit of claim 3, wherein, The bias current matching circuit comprises a first resistor.

5. The biochemical collection detection circuit of claim 3, wherein, The filter circuit comprises a third resistor and a third capacitor; a first end of the third resistor is connected to the first output end, and a second end of the third resistor is connected to an input end of the acquisition circuit; one end of the third capacitor is connected to the second end of the third resistor, and the other end of the third capacitor is grounded.

6. The biochemical collection detection circuit of claim 3, wherein, The MCU control circuit is connected to the sliding end of the digital potentiometer, and the digital potentiometer is configured to provide a variable resistor under adjustment of the MCU control circuit.

7. The biochemical collection detection circuit of claim 6, wherein, The amplification multiple of the second amplification circuit is 2-4 times.

8. A biochemical analyzer characterized by comprising: The biochemical acquisition detection circuit comprises the biochemical acquisition detection circuit according to any one of claims 1-7. The biochemical acquisition detection circuit comprises the biochemical acquisition detection circuit according to any one of claims 1-7.

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