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Issue 6 ， 2019
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High-throughput digital capillary microarray
Abstract：A digital Polymerase Chain Reaction (PCR) system sample segmentation chip was developed for the "division" method for samples of a digital PCR system, and a capillary microarray was used for trace biological sample detection. First, arrayed silicon substrates were fabricated using Micro-electron-mechanical Systems(MEMS) technology, subsequently silicon wafers were thinned by the process of high-efficiency, low-damage, and ultra-precision grinding and then combined through chemical modification methods. A ca Keywords：microarray;high-throughput;capillary;digitization;chemical modification;hydrophilic and hydrophobic- 168
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Published：2020-08-13 -
Development and performance evaluation of flow cytometry for rapid quantitative detection of bacteria
Abstract：To realize rapid quantitative detection of bacteria found in drinking water, a high-throughput quantitative detection system based on flow cytometry was established. The system's signal acquisition system, absolute counting method, and comprehensive performance for bacterial detection were investigated and evaluated. Firstly, according to the fluorescent dyes of typical bacteria found in drinking water and their fluorescence excitation spectra, the working principle and hardware platform of the flow cytomet Keywords：flow cytometry;bacteria;drinking water;microorganisms;tap water;absolute counting- 82
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Published：2020-08-13 -
Integrated FAIMS system using needle-ring ion source
Abstract：A needle-ring ion source structure based on printed circuit board technology was designed to integrate an ion source with a High-field Asymmetric Ion Mobility Spectrometry (FAIMS) structure, which was composed of a needle electrode, loop electrode, air inflow pedestal, and fixed needle pedestal. A stainless steel needle tip with a diameter of 28 μm was used as the cathode, and a copper loop with a diameter of 3 mm and length of 16 mm was used as the anode. A discharge property experiment shows that corona a Keywords：needle-ring ion source;high-field asymmetric waveform ion mobility spectrometry;integration;UV-lamp ion source- 76
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Published：2020-08-13 -
Flexible curvature sensor based on composite substrate
Abstract：To meet the demand for curvature measurements in the fields of intelligent biomedical equipment and soft robotics, among others, a flexible curvature sensor based on a polyvinyl chloride (PVC) and silicone composite substrate was proposed and has been designed. Firstly, a fiber Bragg grating (FBG) sensor was embedded into a silicone film, which was pasted onto the surface of a PVC substrate. Then, calibration experiments were carried out to evaluate the reflection spectrum and wavelength shift of the sensor Keywords：fiber sensing;curvature sensor;Fiber Brag Grating(FBG);sensitivity;repeatability;consistency- 109
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Published：2020-08-13 -
Image brightness adaptive adjustment during skin imaging by reflectance confocal microscopy
Abstract：For quick adjustment of image brightness during skin imaging with reflectance confocal microscopy, an adaptive brightness adjustment method was proposed. The association between laser power control voltage and image brightness was established by experiments. Images can have two types of brightness: extreme and moderate. Using segmental adjustment, brightness of the initial image could be quickly changed from extreme to moderate. Finally, the optimal brightness was obtained using linear compensation. Real-time imaging of skin tissues at different depths and locations can show if the initial image is too bright, too dark, or of moderate brightness. Subsequently, quick adjustment of the brightness can be achieved. The number of iterations is 2-3, and the optimal image brightness is approximately 70. The results show that this method is fast and can effectively meet the needs of skin imaging with reflectance confocal microscopy.Keywords：microscopy;reflectance confocal microscopy;skin;brightness section;linear compensation;image pixels mean value- 72
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Published：2020-08-13 -
Measuring multi-surface shape by Fourier transform
Abstract：To measure transparent parallel plates more easily and accurately, a phase recovery method based on the region growing algorithm and Fourier transform for single three-surface interference fringes was proposed. Through the Fourier transform, the three-surface interference fringe pattern was changed from the spatial to the spectral domain. Because the interference fringes of different surfaces have different positions in the spectral domain, the appropriate regions were extracted by changing the parameters i Keywords：interferometry;Fourier transform;phase recovery;multi-surface interference fringe;parallel plate;region growing- 124
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Published：2020-08-13 -
Design and implementation of optical system for corneal cross-linking device
Abstract：To treat corneal dilatation diseases caused by keratoconus safely and effectively and to reduce manual alignment errors during surgery, an optical system for a corneal cross-linking surgical device was designed in this study. First, based on the requirements of corneal cross-linking surgery related to spot size, uniformity, and working distance, an illumination system was designed based on the principle of uniformation of the compound eye lens array. Second, an infrared lens was designed that was imaged by Keywords：optical system design;corneal cross-linking;complex eye homogenization;uniformity- 95
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Published：2020-08-13 -
Fabrication of microscale axial symmetric three-dimensional curved shell resonators based on silicon isotropic wet etching
Abstract：Axial symmetric curved shell resonators are among the most-widely used resonators because of their high symmetry, robustness, and reliability. However, the fabrication of this kind of resonator is based on newly developed three-dimensional (3D) microelectromechanical system technologies, making it difficult to fabricate. Polysilicon shell resonator is suitable for batch fabrication owing to its compatibility with the materials and fabrication technologies used in the IC industry, which is of high value and Keywords：Micro-electro-mechanical System(MEMS);three-dimensional(3D) fabrication;silicon isotropic wet etching;shell resonators;axial symmetric- 105
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- 12
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Published：2020-08-13 -
Non-invasive blood glucose in vivo detection based on photoacoustic spectroscopy
Abstract：To achieve non-invasive blood glucose in vivo detection, solving common problems such as low measurement sensitivity, large interference of excitation source fluctuation, and serious patient temperature interference is first necessary. In this study, a new method based on temperature compensation for differential photoacoustic measurement was proposed, which can greatly suppress the influence of temperature. Two identical photoacoustic cells were used, one for accommodating the blood to be measured, the oth Keywords：Photoacoustic Spectroscopy (PA);glucose concentration;temperature error compensation;differential PA cell;serum;simulated skin- 127
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- 6
Published：2020-08-13 -
Transient spray cooling system for high-power laser treatment
Abstract：During high-power laser treatment, protection of the epidermis and normal tissues from thermal damage is critical to ensure safety and effectiveness of the process. In this investigation, medical 134a cryogen with high cooling performance was used, and a high-pressure storage tank, an airtight transmission line, a high-speed atomized spray device, and an electronic control system were designed as part of a transient spray cooling system combined with laser therapy for different output timings to cool the sk Keywords：laser treatment;skin protection;cryogen;spray cooling- 150
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- 3
Published：2020-08-13 -
Optical coherence tomography system for measurement of eye axial parameters
Abstract：Biometrics is becoming more and more important in the diagnosis and treatment of ophthalmic diseases. Monitoring the axial length of children and adolescents can help prevent and treat myopia, and the ophthalmic diseases that it causes. The accurate measurement of eye axial parameters is an important factor in visual quality that affects postoperative patients with eye diseases. In order to measure the parameters of the eye axis, the eye axis measurement method based on the time domainlow-coherence techniqu Keywords：eye axis measurement;low-coherence interference;coherent tomography;long coherent interference- 142
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Published：2020-08-13 -
Denoising and implementation of a photoplethysmography signal based on EEMD and wavelet threshold
Abstract：Signals of interest can be affected by various types of noise during the acquisition of photoplethysmography data. To address this problem, a denoising method based on the combination of Ensemble Empirical Mode Decomposition (EEMD) and wavelet threshold was proposed to reduce the noise associated with photoplethysmography signals. In this investigation, this approach was compared with EMD combined with wavelet denoising. Initially, an algorithm applied EEMD to the signal, which was decomposed into a limited Keywords：photoplethysmography;ensemble empirical mode decomposition;wavelet threshold;denoising- 223
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- 11
Published：2020-08-13 -
Design and applied research of dual-mode switching endomicroscopic imaging system
Abstract：Clinical studies have shown that fluorescent molecular imaging technology is extensively utilized in intraoperative navigation, tumor boundary recognition, in vivo microscopic pathology diagnosis, etc. However, identification of tumor boundaries through in vivo biopsy remains a challenging task owing to the slight discrepancy between tumor tissue and surrounding normal tissue in optical imaging. To better distinguish tumor tissue and observe histopathology in clinical examination, a dual-mode switching endo Keywords：tumor;endoscopy;LED;boundary feature recognition;fluorescence imaging- 119
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Published：2020-08-13 -
Multi-walled carbon nanotubes enhanced electrochemical sensor for prothrombin time detection
Abstract：The determination of coagulation parameters is of crucial significance in the guided treatment of anticoagulant drug users and patients with liver diseases. Considering the challenges associated with commercial coagulation detection instruments such as high cost and complex operation, a MWCNT-enhanced screen-printed electrochemical sensor was developed for coagulation measurement. Initially, the measurement of thrombin substrate cleaved by thrombin was used to evaluate the feasibility of prothrombin time (P Keywords：Multi-Walled Carbon Nanotubes(MWCNTs);electrochemical sensor;chronoamperometry;blood coagulation detection;Prothrombin Time(PT)- 109
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Published：2020-08-13 -
Non-contact respiratory rate and heart rate signal acquisition system
Abstract：A non-contact respiratory and heart rate monitoring system was designed to monitor bedridden patients. Initially, according to the mechanical properties of the cardiac ejection contraction process, piezoelectric ceramic sensors with high sensitivity and good stability were selected to acquire ballistocardiography (BCG) signals. The collected signal was then desiccated, filtered and amplified; it was then digitized to obtain a heart impact diagram. A respiratory signal was then extracted from the cardiogram Keywords：non-contact;heart rate detection;respiratory rate detection;bland-altman analysis- 178
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Published：2020-08-13 -
Rapid preparation and medical application of wearable flexible electronics
Abstract：To realize the initial design and experimental verification of wearable flexible electronics, an electronic rapid preparation method based on "cutting and pasting" was proposed. First, a micro-nano patterning process based on laser cutting was presented by a comparison with photolithography and inkjet printing processes. The patterned film structure was then transferred to an elastic substrate by adjusting the adhesion of a polydimethylsiloxane (PDMS) substrate to control the energy release rate. To ensure Keywords：wearable;rapid transfer printing;tunable adhesive force;flexible electronics;Electrocardiogram(ECG)- 134
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Published：2020-08-13 -
Device for automatic pupil center location and alignment
Abstract：To assist unattended fundus examination equipment in automatically performing fundus examinations under different lighting environments, an automatic pupil center location and alignment device was developed and a circle approximation algorithm was proposed to automatically locate the pupil center. First, an image was preprocessed by binarization and contour extraction, and a filling algorithm was used to eliminate the influence of noise and speckle for follow-up processing. The circle approximation algorith Keywords：fundus examination;pupil recognition;circle approximation;automated alignment- 108
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Published：2020-08-13 -
Design of bioaffinity detection system based on optical interference
Abstract：Molecular interaction detection is a hot topic in the fields of food safety detection, clinical cancer pathological screening, and other areas of research. To realize real-time and rapid detection of interactions between biomolecules, a molecular interaction detection system based on a fiber biosensor was designed in this study. The coupling structure of a self-focusing lens and quartz fiber was adopted to improve the coupling efficiency of optical transmission between the light source and interference ligh Keywords：bioaffinity detection;optical interference;fiber biosensor;fiber coupling structure;STM32;immunoglobulin igg- 117
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Published：2020-08-13 -
Graphene sensor for activatied partial thromboplatin time detection
Abstract：Graphene (GR) has excellent physical and chemical properties as a revolutionary material, and its excellent electrical conductivity is critical in developing coagulation electrochemical sensors. Currently, large coagulation testing instruments are complicated to operate and time-consuming, and few point-of-care tests exist for activated partial thromboplastin time (APTT) indicators. To solve this problem, designing and manufacturing a GR-modified electrochemical sensor based on screen-printing technology, w Keywords：graphene;electrochemical sensor;chronoamperometry;blood coagulation detection;Activated Partial Thromboplatin Time(APTT)- 93
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Published：2020-08-13 -
CO2 concentration detection system for seed respiration
Abstract：To address the problem of low detection accuracy in the traditional method of seed-breathing CO2 concentration measurement, a seed-breathing measurement system based on tunable diode laser absorption spectroscopic technology was proposed to meet the needs of seed-breathing CO2 concentration measurements. First, the system was designed to consist of a seed-breathing container, a distributed feedback laser and control circuit, photoelectric conversion and an amplification circuit, a data acquisition circuit, Keywords：CO2;Tunable Diode Laser Absorption Spectroscopy(TDLAS);multiple reflection cell;seed respiration- 125
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Published：2020-08-13 -
Technique of image guided radiotherapy with conventional video cameras
Abstract：Image guidance plays a major role in precision radiotherapy. Because conventional X-ray image guided techniques used in radiotherapy deliver additional doses to patient, an image guided radiation therapy (IGRT) technique using conventional video cameras that does not cause harm to the patient was investigated in this study. Three conventional video cameras were installed in different directions to acquire real-time images. The backgrounds of the images were deleted using an adaptive background removal algor Keywords：image guided radiotherapy;corner point;patient positioning;respiratory motioning- 102
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Published：2020-08-13
Life Science Instrument
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Integrated FAIMS system using needle-ring ion source
Abstract：A needle-ring ion source structure based on printed circuit board technology was designed to integrate an ion source with a High-field Asymmetric Ion Mobility Spectrometry (FAIMS) structure， which was composed of a needle electrode， loop electrode， air inflow pedestal， and fixed needle pedestal. A stainless steel needle tip with a diameter of 28 μm was used as the cathode， and a copper loop with a diameter of 3 mm and length of 16 mm was used as the anode. A discharge property experiment shows that corona and glow discharges are realized through discharge voltages of -2 kV and -2.8 kV， respectively， proving that the stable discharge state could be obtained in ambient air. Comparing the FAIMS system using a UVlamp ion source with the FAIMS system using a needlering ion source， the compensation voltages in the FAIMS spectrum are nearly the same under the conditions of a carrier gas flow rate of 1.5 L/min and a highfield rectangular radio peaktopeak voltage of 300 V. However， the electric currents are 64 pA and 45 pA for the needle-ring and UV-lamp ion sources， respectively. Experimental results thus reveal that the integrated FAIMS using the needle-ring ion source can work stably and that it has a better integration property and stronger signal when compared to a UV-lamp ion source.Keywords：Needle-loop ion source;high-field asymmetric waveform ion mobility spectrometry;integration;UV-lamp ion source- 47
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Published：2020-08-13 -
Flexible curvature sensor based on composite substrate
Abstract：To meet the demand for curvature measurements in the fields of intelligent biomedical equipment and soft robotics， among others， a flexible curvature sensor based on a polyvinyl chloride (PVC) and silicone composite substrate was proposed and has been designed. Firstly， a fiber Bragg grating (FBG) sensor was embedded into a silicone film， which was pasted onto the surface of a PVC substrate. Then， calibration experiments were carried out to evaluate the reflection spectrum and wavelength shift of the sensor. Finally， the sensitivity and repeatability of the sensor based on the composite and silicone substrates were tested experimentally. The experimental results show that the sensitivity and repeatability of the FBG curvature sensor can be improved by using a PVCreinforced substrate. The maximum sensitivity of the FBG sensor with the composite substrate is 245.5 pm/m-1 and its deviation index is less than 3%. The sensor has wide application prospects in the fields of soft robotics and biomedical curvature measurements.Keywords：fiber sensing;curvature sensor;Fiber Brag Grating(FBG);sensitivity;repeatability;consistency- 54
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Published：2020-08-13 -
Non-invasive blood glucose in vivo detection based on photoacoustic spectroscopy
Abstract：To achieve non-invasive blood glucose in vivo detection， solving common problems such as low measurement sensitivity， large interference of excitation source fluctuation， and serious patient temperature interference is first necessary. In this study， a new method based on temperature compensation for differential photoacoustic measurement was proposed， which can greatly suppress the influence of temperature. Two identical photoacoustic cells were used， one for accommodating the blood to be measured， the other for pure water. Measured and reference photoacoustic signals are respectively obtained. First， the temperature coefficient of the two photoacoustic signals is determined by changing the liquid temperature of the two photoacoustic cells. Then， the error of temperature in the two photoacoustic signals are separately compensated and corrected to eliminate the interference of temperature on the experimental results. Finally， the intensity of one photoacoustic signal is divided by that of the other photoacoustic signal to suppress the influence of laser intensity fluctuation. Based on this procedures the study used tissue engineered skin to simulate a human skin environment and explored the skins permeability to laser and photoacoustic signals. The results show that the R2 of linear fitting between glucose photoacoustic signal intensity and glucose concentration under a low concentration was 0.970 6， thereby proving the feasibility of this method for use in practical applications. The results also show that the average transmittance of the simulated skin to laser was 53.88%， and the average transmittance of the simulated skin to the photoacoustic signal was 94.50%. The results of this study can provide a useful reference for the noninvasive detection of blood glucose.Keywords：Photoacoustic signal (PA);glucose concentration;temperature error compensation;differential PA cell;serum;simulated skin- 117
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Published：2020-08-13 -
Transient spray cooling system for highpower laser treatment
Abstract：During high-power laser treatment, how to protect the epidermis and normal tissues from thermal damage is the key technology to ensure the safety and effectiveness. This paper used medical 134a cryogen with high cooling performance, designed a high-pressure storage tank, airtight transmission line, high-speed atomized spray device and electronics control system, and formed a transient spray cooling system combined with laser therapy in different output timing, to cool skin and tissue in real time. By studying the relationship between spraying time, jet distance and temperature changing of materials similar to skin, the cooling effect of device was verified. The experimental results show that the tissue temperature can be reduced 40℃ to 60℃ in 20ms to 50ms. The biological compatibility, pressure resistance, sealing of the cooling system passed the testing of medical device registration. It was combined with high-power 1450nm semiconductor laser to treat facial acne in clinical, and the total effective rate of 189 patients with mild-to-moderate acne patients is 87.3% after treatments of 4 times, without thermal damage. The transient spray cooling system can be combined with various laser device, to improve the safety, effectiveness, scope of existing laser treatment.Keywords：laser treatment;skin protection;cryogen;spray cooling- 39
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Published：2020-08-13 -
Denoising and implementation of photoplethysmography signal based on EEMD and wavelet threshold
Abstract：Signals of interest can be affected by various types of noise during the acquisition of photoplethysmography data. To address this problem， a denoising method based on the combination of Ensemble Empirical Mode Decomposition (EEMD) and wavelet threshold was proposed to reduce the noise associated with photoplethysmography signals. In this investigation， this approach was compared with EMD combined with wavelet denoising. Initially， an algorithm applied EEMD to the signal， which was decomposed into a limited number of Intrinsic Mode Functions (IMF). Then， it performed a correlation calculation on the components， followed by wavelet threshold denoising on the noisecontaining components. Finally， the signal was reconstructed. The original signal was measured using the stm32 platform with a MAX30100 sensor. The experimental results show that the method can effectively remove highfrequency noise and baseline drift in photoplethysmography. After noise reduction， the signalto-noise ratio is 34.09 and the root mean square error is 1.99， which improved the signal quality. This new approach facilitates accurate monitoring of photoelectric volume pulse wave signals.Keywords：photoplethysmography;ensemble empirical mode decomposition;wavelet threshold;denoising- 91
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Published：2020-08-13 -
Design and Applied research of dual-mode switching endomicroscopic imaging system
Abstract：Clinical studies have shown that fluorescent molecular imaging technology is extensively utilized in intraoperative navigation， tumor boundary recognition， in vivo microscopic pathology diagnosis， etc. However， identification of tumor boundaries through in vivo biopsy remains a challenging task owing to the slight discrepancy between tumor tissue and surrounding normal tissue in optical imaging. To better distinguish tumor tissue and observe histopathology in clinical examination， a dualmode switching endomicroscopic system was proposed in this paper， which consisted of widefield imaging for surgical navigation and microscopic imaging for performing tumor boundary recognition. The system employed sodium fluorescein as a fluorescent molecular probe and an inhouse developed blue LED with highbrightness as an excitation source. Fast switching between two modes was an advantageous design for clinical surgery to effectively determine benign and malignant tumors during in vivo microscopic pathology analysis. This paper examined the feasibility of the dualmode imaging system for mouse liver inspection in vivo. The experimental results show that dualmode imaging can identify tissue color and boundary features with a resolution of 4.4 μm. The system can meet the clinical demands of real-time surgical navigation and microscopic pathological diagnosis of in vivo tumors.Keywords：tumor;endoscopy;LED;boundary feature recognition;fluorescence imaging- 42
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Published：2020-08-13 -
Multi-walled Carbon Nanotubes Enhanced Electrochemical Sensor for Prothrombin Time Detection
Abstract：The determination of coagulation parameters is of crucial significance in the guided treatment of anticoagulant drug users and patients with liver diseases. Considering the challenges associated with commercial coagulation detection instruments such as high cost and complex operation， a MWCNTenhanced screenprinted electrochemical sensor was developed for coagulation measurement. Initially， the measurement of thrombin substrate cleaved by thrombin was used to evaluate the feasibility of prothrombin time (PT) detection by chronoamperometry. Then the plasma PT parameters were measured and the results were validated using the SYSMEX CS 5100 optical coagulator. The response intensity of a MWCNT electrochemical sensor in thrombin validation experiments increase by （36±1）% compared with a general electrochemical sensor and the peak time coefficient of variation and peak current coefficients of variation are 2.99% and 3.27% respectively. The testing of PT values of different blood samples clearly shows discrimination. Three groups of blood samples are selected for repeated PT parameter measurements and the coefficients of variation are 2.26%， 322%， and 2.96% respectively. The linear fitting decision coefficient R2 is 0.986 for clinical results. The MWCNT screenprinted electrochemical sensor for PT testing has good repeatability and consistency， is easy to mass produce， reduces the cost of coagulation measurement， and is suitable for measurement in many circumstances. As such， this sensor has great potential in the field of pointofcare testing.Keywords：Multi-Walled Carbon Nanotubes（MWCNTs）;electrochemical sensor;chronoamperometry;blood coagulation detection;Prothrombin Time(PT)- 61
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Published：2020-08-13 -
Rapid preparation and medical application of wearable flexible electronics
Abstract：To realize the initial design and experimental verification of wearable flexible electronics， an electronic rapid preparation method based on “cutting and pasting” was proposed. First， a micro-nano patterning process based on laser cutting was presented by a comparison with photolithography and inkjet printing processes. The patterned film structure was then transferred to an elastic substrate by adjusting the adhesion of a polydimethylsiloxane (PDMS) substrate to control the energy release rate. To ensure a close fit between the metal electrode and the flexible substrate， the overall structure was packaged by PDMS. Finally， a multichannel physiological signal acquisition system was built to enable electrophysiological testing and medical exploration. Compared with the traditional flexible electronic processing technology， the proposed method was more efficient and cheaper. In addition， the flexible electronic sensor was in conformal contact with skin and generated a stable signal. This investigation outlines the preliminary foundation and initial design for flexible electronics and their industrial applications.Keywords：wearable;rapid transfer printing;tunable adhesive force;flexible electronics;ECG- 56
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Published：2020-08-13 -
Graphene sensor for activatied partial thromboplatin time detection
Abstract：Graphene (GR) has excellent physical and chemical properties as a revolutionary material, and its excellent electrical conductivity is extremely important for the development of coagulation electrochemical sensors. At present, large coagulation testing instruments are complicated to operate and take a long time, and there are few POCT tests for activated partial thromboplastin time (APTT) indicators. In order to solve this situation, it is necessary to design and manufacture a GR-modified electrochemical sensor based on screen printing technology, which can be used for APTT index detection. The feasibility of chronoamperometry to detect the time principle of activated partial thromboplastin was verified by thrombin-cleaving thrombin substrate assay. The plasma activated partial thromboplastin time parameter was measured and the measurement results were verified using SYSMEX CS 5100 optical coagulation instrument. Experiments show that the screen-printed GR modified electrode has good consistency, and its impedance test coefficient of variation is 2.71%. In the thrombin experiment, the current response intensity of the GR-modified electrochemical sensor was increased by 16±1% compared with the electrochemical sensor before modification, and the repeated peak time and peak current coefficient of variation were 3.29% and 3.13%, respectively. The APTT values of the three groups of blood samples were selected to clearly show the degree of discrimination, and the peak time variation coefficients of each group of APTT repeat experiments were 3.20%, 3.25% and 2.84%, respectively. The experimental results were linearly fitted with the clinical results of the hospital. R2 is 0.978. The GR modified enhanced electrochemical sensor has shown good repeatability in the APTT test and has the potential for immediate detection in a variety of situations.Keywords：Graphene;electrochemical sensor;chronoamperometry;blood coagulation detection;activated partial thromboplatin time- 63
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Published：2020-08-13 -
CO2 concentration detection system for seed respiration
Abstract：To address the problem of low detection accuracy in the traditional method of seedbreathing CO2 concentration measurement, a seedbreathing measurement system based on tunable diode laser absorption spectroscopic technology was proposed to meet the needs of seedbreathing CO2 concentration measurements. First, the system was designed to consist of a seedbreathing container, a distributed feedback laser and control circuit, photoelectric conversion and an amplification circuit, a data acquisition circuit, and upper computer software. The space volume of the seed breathing container was 1.5 L, the laser source was in the 2 004nm band, and the light path of the multiple reflection cell was 16 m. Then, based on Lamberts law and wavelength modulated absorption spectroscopy, the concentration of CO2 produced during seed respiration could be retrieved in real time using second harmonics. The stable repeatability of the CO2 concentration measurement in seed respiration is 0.033%, the linear fitting degree of CO2 concentration is 0.999 38, and the detection limit of CO2 concentration is 1.7×10-6. The change curve of 20g maize seed respiration is obtained by testing waxy maize seeds. The amount of change in waxy maize seed respiration after 12 h is 2 750.5×10-6, and the respiration rate is 229.2×10-6/h. Experimental results show that the system can solve the inability for continuous measurement of CO2 concentration in seed respiration and the low precision of concentration detection.Keywords：CO2;Tunable Diode Laser Absorption Spectroscopy(TDLAS);Multiple reflex pool;seed respiration- 47
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Published：2020-08-13
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