Design And Experimental Study Of A 28.3LPM Dust Particle Counting Sensor

The aim of this study was to develop a highly sensitive dust particle counting sensor to meet the high requirements of modern clean rooms.The characteristics of domestic and foreign particle measurement technologies were analyzed through extensive theoretical calculations,and the proposed solution was implemented in terms of optics,airflow,and circuits.Firstly,an overview of clean room technology and standards was provided,and the significance of monitoring sub-micron particles was introduced.The dust particle counting sensor was designed using the light scattering method based on a comparison of the key characteristics of different particle measurement technologies.The research significance of developing a domestically produced dust particle counter that conforms to the ISO 21501-4 standard was explained based on a comparison of domestic and international development status.Next,starting from the working principle of the dust particle counting sensor,the Mie scattering theory,Rayleigh scattering,and Fraunhofer diffraction were introduced.The Mie scattering theory was programmed and calculated using MATLAB software to obtain the variation patterns of scattering illuminance spatial distribution with respect to scattering angle θ and azimuth angle φ.The article compared the distribution of scattering light intensity caused by factors such as particle size and wavelength.The scattering light flux collected by different scattering light path systems was calculated using the expression for scattering light flux.Finally,the key performance indicators of the particle counter were introduced.By analyzing the spatial distribution patterns of particle scattering illuminance based on the Mie scattering theory and MATLAB software calculations,it was concluded that a right-angle scattering light path system was superior to a forward structure.Then,the design goals of the particle counting sensor were elucidated,and various requirements to consider when designing the sensor were discussed in detail.In-depth analysis and design were conducted for the illumination light path system,scattering light path system,sampling airflow system,and signal processing circuit,combining theoretical analysis,simulation calculations,and experimental verification.The component models were ultimately determined.Based on the design requirements for the photosensitive area of the particle counting sensor,methods using aspherical lenses and cylindrical mirrors to achieve laser collimation and convert the energy distribution of the beam from a Gaussian distribution to a flat-top distribution were explored.With the assistance of ZEMAX software,an illumination light path system suitable for the particle counting sensor was designed to meet its performance specifications.The illumination light path system employed a laser diode,and aspherical and cylindrical mirrors were used to shape the laser,resulting in a spot size in the photosensitive area of approximately 2.0mm × 0.3mm.The intake port utilized a structure similar to a Laval nozzle to reduce airflow diffusion.The ANSYS FLUENT software was used to simulate the flow field distribution and particle trajectories in the sampling airflow system,and the results indicated that the airflow achieved a reduction in particle diffusion.For the right-angle scattering light path system,a spherical reflector with a numerical aperture of 54 mm was employed,and the solid angle range for light collection was 17 to 163 degrees.In terms of the optoelectronic conversion device,an LSSPD-10 model PIN silicon photodiode was used.To eliminate background noise and external electromagnetic interference,a mature bandpass amplification circuit was adopted,which simultaneously achieved DC isolation and filtering.This circuit allowed for nonlinear amplification of weak voltage signals while maintaining the elimination of DC and low-frequency components without introducing new noise.Finally,the performance parameters of the designed particle counting sensor were investigated through experimental calibration to verify if they met the design requirements.Standard PSL particles with sizes of 0.3μm,0.4μm,0.5μm,and0.6μm were used to experimentally calibrate the sensor’s sensitivity and particle size-voltage curve.The sensitivity of the designed particle counting sensor was validated to reach 0.3μm.In the obtained calibration curves,the median voltage for the 0.3μm channel was 80 m V,and for the 0.5μm channel,it was 540 m V.Furthermore,the particle size distribution error and counting efficiency of the sensor were analyzed,and the potential errors in the measurement results were discussed.Through experimental validation,all performance parameters of the sensor met the requirements of relevant standards,achieving the design goals of the dust particle counting sensor.This demonstrates that the research content of this article has practical value and reference significance for enhancing the performance of particle counting sensors in domestic research.