Analysis of nebulization process based on multi-angle polarization scattering measurements

Nebulization therapy is a common treatment for respiratory diseases. The particle size distribution and physicochemical properties of the atomized droplets of different nebulizers have a great impact on the treatment. Droplets larger than 5 microns and less than 10 microns generally can only reach the upper airway, those with 5-10 microns can reach the nasopharynx, those below 5 microns can reach the bronchi, and those smaller than one micron can enter the alveoli. This study provides a polarization measurement system for atomized droplets. In the experimental device, we used a 532 nm laser as the light source. In the incident module, we used a polarizer and a quarter wave plate to form a polarization generator to generate a specific incident polarization state. In the detection module, we measured the polarization scattering signals at four different angles, namely 30°, 60°, 85° and 115°. When the droplet passes through the scattering region, the trigger channel set in the forward direction of 10° first detects the signal, and then triggers the other four channels to complete the detection of the polarization signal. The liquid medicines we used in the experiment were sterile water, acetylcysteine, budesonide and sodium chloride solution. For different liquid medicines, we compared the nebulization effects of two nebulizers, oxygen-driven nebulizer and compressed air nebulizer. The suspended droplets produced by the nebulizer first pass through a pressure-stabilizing box with a built-in fan to realize the uniform dispersion of the atomized droplets, and then use the sheath flow device to realize single droplet detection according to the principle of hydrodynamic focusing. Experiments show that this method can obtain multidimensional polarization information for each measurement and enables fast real-time detection of the polarization scattering signal of liquid droplets.