Programmable fluorescence spectrophotometer

Abstract

The invention discloses a programmable fluorescence spectrophotometer, relates to the technical field of optical detection and analysis, and aims to solve the technical problems that an existing spectrophotometer is insufficient in wavelength scanning precision, low in detection sensitivity, low in data processing efficiency and difficult to realize automatic control of a complex experimental process. The gain control module is used for realizing high-precision gain control of signals; the phosphorescence and fluorescence test switching circuit is used for switching phosphorescence and fluorescence test modes; the low-noise amplification circuit and the integrating circuit are used for signal noise reduction processing; the analog switch controls circuit switching and is used for controlling on-off of the circuit; and the microcontroller is used for sending a gain gear and a mode switching instruction. The programmable gain amplification circuit and the phosphorescence / fluorescence test switching circuit are integrated, so that the problems of poor signal stability and loud noise caused by fixed gain and extensive switching of a traditional circuit are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of optical detection and analysis technology, and more specifically, to a programmable fluorescence spectrophotometer. Background Technology

[0002] Fluorescence spectrophotometers are important analytical instruments in fields such as medicine, agriculture, and environmental science, primarily used to analyze the components of substances that fluoresce after excitation by a light source or after chemical treatment. However, traditional fluorescence spectrophotometers face key technical bottlenecks in practical applications: due to the use of fixed-gain amplifier circuits and the lack of precise mode switching mechanisms, the signal is easily affected by noise during gain control and phosphorescence / fluorescence mode switching, resulting in problems such as low data acquisition accuracy and unstable output data. Especially in weak signal detection scenarios, noise amplification and signal drift significantly reduce the measurement signal-to-noise ratio, making it difficult to meet the requirements of high-precision analysis. Therefore, we propose a programmable fluorescence spectrophotometer. Summary of the Invention

[0003] The purpose of this invention is to provide a programmable fluorescence spectrophotometer to solve the technical problems of existing spectrophotometers, such as insufficient wavelength scanning accuracy, low detection sensitivity, slow data processing efficiency, and difficulty in automating complex experimental procedures.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a programmable fluorescence spectrophotometer, comprising: Programmable gain amplifier circuit, used to achieve high-precision gain control of signals; A phosphorescence and fluorescence test switching circuit is used to switch between phosphorescence and fluorescence test modes. A low-noise amplifier circuit and an integrator circuit are connected to the switching circuit and the programmable gain amplifier circuit for signal noise reduction processing. The analog switch control circuit is connected to the signal input terminal of the programmable gain amplifier circuit and is used to control the circuit's on / off state. The microcontroller is connected to the control terminal of the programmable gain amplifier circuit and is used to send gain level and mode switching commands.

[0005] Preferably, the programmable gain amplifier circuit uses a PGA281 chip as the core amplifier device, and its control terminals G0-G3 are connected to the I / O ports of the microcontroller. It achieves four gain levels of 1x, 4x, 32x, and 128x through 12 level combinations, and the G4 terminal is set to low level.

[0006] Preferably, the programmable gain amplifier circuit is externally connected to an ADR421ARZ chip to provide a +2.5V reference voltage.

[0007] Preferably, the phosphorescence and fluorescence test switching circuit includes a 4-channel analog switch ADG211AKRZ and an 8-bit serial input / parallel output shift register 74HC595PW. The microcontroller controls the 8-bit parallel output status of the 74HC595PW, of which 4 bits control the on / off state of ADG211AKRZ. One channel of ADG211AKRZ controls the selection of either the phosphorescence fixed gain amplifier circuit or the fluorescence integrator circuit.

[0008] Preferably, the phosphorescent fixed-gain amplifier circuit is composed of dual operational amplifiers AD8512 forming an inverting amplifier circuit with a fixed gain of 1; the fluorescence integrator circuit is controlled by a pulse wave with a frequency of 2KHz to realize signal charging, holding and discharging, and smoothing processing.

[0009] Preferably, the microcontroller uses an STM32F407ZGT6 chip, whose ADC module acquires the amplified signal and removes abnormal data points with deviations exceeding 2-3 LSBs through an outlier filtering algorithm.

[0010] Preferably, the system further includes a power supply system for powering the circuit, the power supply voltage of which includes ±15V for powering the programmable gain amplifier circuit and the low noise amplifier circuit, +5V for powering the 4-channel analog switch and the shift register, +3.3V for powering the microcontroller via an AMS1117 voltage regulator chip, and +2.5V provided by an ADR421ARZ chip as a reference voltage for the programmable gain amplifier circuit.

[0011] Preferably, the data signal after switching by the analog switch control circuit is amplified twice by the programmable gain amplifier circuit, processed by the microcontroller, and then output to the host computer.

[0012] Preferably, in the fluorescence mode, the integrating circuit controls the noise to within 0.5 LSB, and the signal-to-noise ratio is improved by more than 30%; the range switching delay of the programmable gain amplifier circuit is ≤10μs, and the signal drift is <1 LSB after 8 hours of continuous operation.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention integrates a programmable gain amplifier circuit (using a PGA281 chip to achieve precise four-level gain switching of 1 / 4 / 32 / 128 times) and a phosphorescence / fluorescence test switching circuit (using a 4-channel analog switch ADG211AKRZ and an 8-bit serial input / parallel output shift register 74HC595PW to coordinate mode selection), thereby achieving dynamic and precise gain adjustment and low-noise mode switching at the hardware level. This effectively solves the problems of poor signal stability and high noise caused by fixed gain and coarse switching in traditional circuits, controlling the noise in fluorescence mode to within 0.5 LSB and improving the signal-to-noise ratio by more than 30%.

[0014] 2. This invention also constructs a multi-stage noise reduction system by combining a low-noise amplifier circuit, an RC filter network, and a 2kHz pulse-controlled fluorescence integrator circuit. The integrator circuit smooths high-frequency noise in real time through time-domain accumulation effects, and, combined with the ≤10μs level switching delay characteristic of the programmable gain amplifier circuit, further suppresses transient noise during dynamic switching, achieving a signal drift of <1LSB after 8 hours of continuous operation, a drift reduction of over 80% compared to traditional solutions.

[0015] 3. This invention also employs a multi-voltage power supply architecture of ±15V, +5V, +3.3V, and +2.5V (such as ADR421ARZ providing a +2.5V reference voltage), combined with the outlier filtering algorithm of the STM32F407ZGT6 microcontroller (eliminating abnormal data with deviations exceeding 2-3 LSB), thus ensuring system reliability from both power supply stability and data processing perspectives. This solves the gain accuracy drift problem caused by traditional single-voltage power supply, enabling deep integration of hardware circuits and software algorithms, and improving measurement accuracy to 1 LSB = 0.152mV. Attached Figure Description

[0016] Figure 1 The present invention provides a switching circuit for fluorescence mode and phosphorescence mode, and a charge-hold-discharge circuit for fluorescence mode. Figure 2 This is a circuit diagram of a programmable gain amplifier based on PGA281 according to the present invention. Detailed Implementation

[0017] like Figures 1 to 2 As shown, the present invention relates to a programmable fluorescence spectrophotometer, comprising: Programmable gain amplifier circuit, used to achieve high-precision gain control of signals; The programmable gain amplifier circuit uses the PGA281 chip as the core amplifier device. Its control terminals G0-G3 are connected to the I / O ports of the microcontroller. G0-G3 control 16 levels of gain, of which 1x, 4x, 32x, and 128x are used. The four levels of gain are switched through 12 combinations of levels. The G4 terminal is set to low level. When the G4 terminal is set to low level, the chip enters the programmable gain mode to ensure the flexibility and accuracy of gain switching. The programmable gain amplifier circuit is externally connected to an ADR421ARZ chip to provide a +2.5V reference voltage, which avoids the impact of voltage fluctuations on gain accuracy, ensures stable operation of the circuit, further purifies the amplified signal, and reduces noise levels.

[0018] A phosphorescence and fluorescence test switching circuit is used to switch between phosphorescence and fluorescence test modes. The phosphorescence and fluorescence test switching circuit includes a 4-channel analog switch ADG211AKRZ and an 8-bit serial input / parallel output shift register 74HC595PW. The microcontroller controls the 8-bit parallel output status of the 74HC595PW, of which 4 bits control the on / off state of ADG211AKRZ. One channel of ADG211AKRZ controls the selection of either the phosphorescence fixed gain amplifier circuit or the fluorescence integrator circuit. The host computer software provides a human-machine interface, allowing users to select either the "phosphorescence" or "fluorescence" test mode. Instructions are transmitted to the STM32F407ZGT6 microcontroller via serial port.

[0019] Phosphorescent mode: The ADG211AKRZ selects the inverting amplifier circuit composed of dual op-amps AD8512, with a fixed gain of 1x. It is suitable for stable amplification of long-persistence signals and avoids signal distortion caused by excessive gain.

[0020] Fluorescence mode: ADG211AKRZ gating integrator circuit, which is controlled by a 2KHz pulse wave. It smooths high-frequency noise through time-domain accumulation effect and improves the signal-to-noise ratio of weak fluorescence signals.

[0021] In the fluorescence mode, the control circuit pulses at 2kHz, controlling the charging, holding, and discharging processes of its integrating circuit, and collecting data during the holding time of the circuit.

[0022] The phosphorescent fixed-gain amplifier circuit is composed of dual operational amplifiers AD8512 forming an inverting amplifier circuit with a fixed gain of 1; the fluorescence integrator circuit is controlled by a pulse wave with a frequency of 2KHz to achieve real-time signal smoothing.

[0023] In fluorescence mode, the integrating circuit periodically charges and discharges the input signal (controlled by a 2kHz pulse) to average out random noise, achieving a "real-time smoothing" effect. Experimental data shows that this circuit can control the noise level to within 0.5 LSB, improve the signal-to-noise ratio by more than 30%, and significantly improve the detection accuracy of the fluorescence signal.

[0024] A low-noise amplifier circuit and an integrator circuit are connected to the switching circuit and the programmable gain amplifier circuit for signal noise reduction processing. The analog switch control circuit is connected to the signal input terminal of the programmable gain amplifier circuit and is used to control the circuit's on / off state. The data signal after switching by the analog switch control circuit is amplified twice by the programmable gain amplifier circuit, processed by the microcontroller, and then transmitted to the host computer.

[0025] The microcontroller is connected to the control terminal of the programmable gain amplifier circuit and is used to send gain level and mode switching commands.

[0026] The microcontroller uses an STM32F407ZGT6 chip, which acquires the amplified signal through an internal ADC module, achieving a sampling accuracy of 1LSB=0.152mV. The collected data is processed using an "outlier filtering" algorithm: outlier data points with deviations exceeding 2-3 LSBs are automatically removed, while the majority of valid data are retained, thus improving data reliability. Circuit stability tests show that the signal drift is 4.97 LSB (0.76 mV) during two hours of continuous operation, which meets the requirements for long-term high-precision measurement.

[0027] It also includes a power supply system for powering the circuit, the power supply voltage of which includes ±15V for powering the programmable gain amplifier circuit and the low noise amplifier circuit, +5V for powering the 4-channel analog switch and the shift register, +3.3V for powering the microcontroller via an AMS1117 voltage regulator chip, and +2.5V provided by an ADR421ARZ chip as a reference voltage for the programmable gain amplifier circuit; Multi-voltage power supply solutions: ±15V voltage supplies power to operational amplifier chips such as PGA281 and AD8512, ensuring linear operating range during high-gain amplification and avoiding nonlinear distortion.

[0028] The +5V voltage powers logic devices such as the 4-channel analog switch ADG211AKRZ and the 74HC595PW shift register, ensuring reliable transmission of digital signals.

[0029] The +3.3V voltage is supplied to the STM32F407ZGT6 microcontroller through the AMS1117 voltage regulator chip, which meets its low power consumption requirements and ensures the stable operation of the digital circuit.

[0030] The +2.5V reference voltage is provided by the ADR421ARZ chip as the reference level for the PGA281, ensuring the accuracy and stability of gain control.

[0031] Working principle: This embodiment provides a programmable fluorescence spectrophotometer. When in use, the lower computer (STM32F407ZGT6) receives instructions from the upper computer, first configures the gain level of PGA281 and the switch status of ADG211AKRZ, and completes the test mode initialization.

[0032] After the optical signal is converted into an electrical signal by the sensor, it enters the corresponding amplification circuit through a 4-channel analog switch: the phosphorescent signal enters the fixed gain amplification circuit, and the fluorescence signal enters the integration circuit for noise reduction.

[0033] After the processed signal is amplified twice by the PGA281, it is acquired by the STM32F407ZGT6 and a denoising algorithm is executed. Finally, the processed data is transmitted to the host computer for display, storage or further analysis.

[0034] This implementation utilizes an innovative collaborative design between the PGA281 programmable gain chip and the ADG211AKRZ4 channel analog switch, combined with a multi-voltage power supply architecture and multi-stage filtering circuits, to achieve low-noise switching and high-precision signal amplification for fluorescence / phosphorescence testing modes. The deep integration of hardware design and software algorithms effectively solves the technical problems of high noise and poor stability in traditional spectrophotometers, providing a reliable instrument solution for high-precision fluorescence detection in various fields. The structural design of this invention combines flexibility and scalability, allowing for parameter adjustments and functional upgrades to meet different detection needs, and has broad market application prospects.

[0035] The embodiments disclosed in this invention are preferred embodiments, but are not limited thereto. Those skilled in the art can easily understand the spirit of this invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of this invention, they are all within the protection scope of this invention.

Claims

1. A programmable fluorescence spectrophotometer, characterized in that, include: Programmable gain amplifier circuit, used to achieve high-precision gain control of signals; A phosphorescence and fluorescence test switching circuit is used to switch between phosphorescence and fluorescence test modes. A low-noise amplifier circuit and an integrator circuit are connected to the switching circuit and the programmable gain amplifier circuit for signal noise reduction processing. The analog switch control circuit is connected to the signal input terminal of the programmable gain amplifier circuit and is used to control the circuit's on / off state. The microcontroller is connected to the control terminal of the programmable gain amplifier circuit and is used to send gain level and mode switching commands.

2. The programmable fluorescence spectrophotometer according to claim 1, characterized in that, The programmable gain amplifier circuit uses the PGA281 chip as the core amplifier device. Its control terminals G0-G3 are connected to the I / O ports of the microcontroller. It achieves four gain levels of 1x, 4x, 32x, and 128x through 12 level combinations, and the G4 terminal is set to low level.

3. A programmable fluorescence spectrophotometer according to claim 2, characterized in that, The programmable gain amplifier circuit is externally connected to an ADR421ARZ chip to provide a +2.5V reference voltage.

4. A programmable fluorescence spectrophotometer according to claim 3, characterized in that, The phosphorescence and fluorescence test switching circuit includes a 4-channel analog switch ADG211AKRZ and an 8-bit serial input / parallel output shift register 74HC595PW. The microcontroller controls the 8-bit parallel output status of the 74HC595PW, of which 4 bits control the on / off state of ADG211AKRZ. One channel of ADG211AKRZ controls the selection of either the phosphorescence fixed gain amplifier circuit or the fluorescence integrator circuit.

5. A programmable fluorescence spectrophotometer according to claim 4, characterized in that, The phosphorescent fixed-gain amplifier circuit is composed of dual operational amplifiers AD8512 forming an inverting amplifier circuit with a fixed gain of 1; the fluorescence integrator circuit is controlled by a 2KHz pulse wave to realize signal charging, holding and discharging, and smoothing.

6. A programmable fluorescence spectrophotometer according to claim 5, characterized in that, The microcontroller uses an STM32F407ZGT6 chip, whose ADC module acquires the amplified signal and uses an outlier filtering algorithm to remove outlier data points with deviations exceeding 2-3 LSB.

7. A programmable fluorescence spectrophotometer according to claim 6, characterized in that, It also includes a power supply system for powering the circuit, the power supply voltage of which includes ±15V for powering the programmable gain amplifier circuit and the low noise amplifier circuit, +5V for powering the 4-channel analog switch and the shift register, +3.3V for powering the microcontroller via an AMS1117 voltage regulator chip, and +2.5V provided by an ADR421ARZ chip as a reference voltage for the programmable gain amplifier circuit.

8. A programmable fluorescence spectrophotometer according to any one of claims 1-7, characterized in that, The data signal after switching by the analog switch control circuit is amplified twice by the programmable gain amplifier circuit, processed by the microcontroller, and then transmitted to the host computer.

9. A programmable fluorescence spectrophotometer according to claim 1, characterized in that, In the fluorescence mode, the integrating circuit controls the noise to within 0.5 LSB, and improves the signal-to-noise ratio by more than 30%; the range switching delay of the programmable gain amplifier circuit is ≤10μs, and the signal drift is <1 LSB after 8 hours of continuous operation.

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