Measurement Of The Volume Scattering Function Of Dual Particle Based On Microfluidic Chip Capture Technology

The volume scattering function(VSF)is an important physical property of particles,which can reflect the particles’ size,shape,internal structure and morphology information,so measuring the VSF of particles has important value in many fields.Present research on dual particle VSF is mainly focused on theoretical analysis,and experimental study on direct measurement is rarely reported.In this thesis,a dual particle VSF measurement system was designed based on the microfluidic capture technology.In order to capture and fixed the particle sample,combined with microfluidic capture technology,and through the comprehensive application of fluid dynamics,finite element analysis tools and SU-8 lithography process,a microfluidic chip with dual particle capture and release capabilities was designed and fabricated.According to the characteristics of the dual particle light scattering obtained by the T-matrix method,a large dynamic range scattering detecting equipment based on the spatial filter and PMT detector was designed.Then use the fabricated microfluidic capture chip and designed PMT detection device,completed the dual particle VSF measurement system,and debugged the concentricity and the flatness of experiment device,and the actual field of view of the PMT detector.Using the built experimental system,and according to the designed experimental processes,completed the precision alignment of the system.By matching the refractive index of the channel and the outer contour in the microfluidic chip after particle trapping,achieved a single refractive index environment around the particle to be measured.Using this method,completed the VSF experimental measurements of individual 23.75μm in diameter and two touched at different orientations polystyrene spherical particles between 1° and 170°.The experimental curves of individual particle was in good agreement with the theory.The dual particle’s experimental data has some difference compare with the theoretical trend,and there was a significant difference when illuminated along a parallel and a perpendicular to the line of the two particles,it is shown that the VSF of the dual particle was closely related to its orientation.The scattering light intensity of the dual particle fluctuates more than the individual,and the fluctuation range of the intensity of the adjacent scattering angles is larger.Repeated measurement results were consistent in trend The experimental results show that this experimental system has reliable stability and effectiveness.