Abstract:
Abstract: The fungal disease of false smut is research focus, which can spread around within short time and cause much loss of rice yield. However, there hasn't been any effective detection and prediction method. For this reason, we designed a set of sample interface, injection channel, enrichment detection area, electric pumping interface in one of the microfluidic chips. The sample interface is connected to the hose for the collection of fungal spores. The injection channel adopts the simple and gentle straight-through design with a fixed width, in order to achieve the barrier-free movement of the fungal spores in the channel, making it easy to clean the chip, and thus improving the recycle rate of the chip. The enrichment detection area is designed as a circular chamber. This design not only slows the drop rate of the spores, which therefore makes the spores arranged in the enrichment detection area efficiently, but it also matches the circular parallel light spot formed by the fiber output lens. In this way, we can reduce the interference and noise introduced by positioning the light source inaccurately and too large spot diameter. Electric suction interface accesses micro-pump pipeline, and compared to the inflatable design, the pumping design reduces the loss in the pump during the collection of spores. In order to make the fungal spores be arranged in the enrichment detection area correctly, the sample channel width was set in the experiment and the diameter of the enrichment detection area was optimized to meet the needs of fungal spore enrichment speed. The experimental results showed that the enriched detection zone had the best enrichment effect when the diameter was 2 000 μm. Then, a photoelectric detection system based on microfluidic chip was established in this paper. When the spore concentration of microfluidic chip was detected by photoelectric detection method, the system condition parameters mainly included light intensity and wavelength. Therefore, different concentrations of spores were tested by the spectrometer, and the results were analyzed to determine the optimal light source parameters of the detection system. The experiment was performed at the Jiangsu University Laboratory in April 2017, and the spores used in the experiment were obtained in the artificial climate room in Jiangsu Vocational College of Agriculture and Forestry. We used the spectrometer, fiber and other structures to build the experimental platform for light intensity and wavelength optimization. According to the principle of light detection and the characteristics of light attenuation formed by different concentrations of spores in the enrichment area, the detection intensity with high sensitivity was screened. Taking the detection of the sensitivity performance of the spectrum as the target and considering the linearity, the detection wavelength was determined; the best light intensity was at 1.1×104 cd and the best wavelength was 650 nm. Finally, with strawberry grey mold spores as the object, we conducted an automated microfluidic chip enrichment and photoelectric detection experiment, and established a curve of spore concentration and absorbance based on the principle of enrichment and photo-detection. The experimental results showed that the detection method we proposed had a linear correlation coefficient of 0.992 9. The method of photoelectric detection of false smut fungal disease based on microfluidic chip realizes the efficient detection of spores concentration, which provides a theoretical foundation for the development of portable false smut disease detection equipment.