A Novel Method for Scatterers Type Enumeration in Polydisperse Suspensions through Fiber Trapping and Unsupervised Scattering Analysis

摘要

Colloids and suspensions are part of our daily routines. Even the blood is considered a "naturally" occurringcolloid. However, the majority of colloids are complex and composed by a diversity of nano to microparticles.The characterization of both synthetic and physiological uids in terms of particulate types, size and surfacecharacteristics plays a vital role in products formulation, and in the early diagnosis through the identication ofabnormal scatterers in physiological uids, respectively. Several methods have been proposed for characterizingsuspensions, including imaging, electrical sensing counters, hydrodynamic or eld ow fractionation. However,the Dynamic Light Scattering (DLS) has evolved as the most convenient method from these. Based also onthe scattering signal, we propose a novel, simple and fast method able to determine the number of differentscatterers type present in a suspension, without any previous information about its composition (in terms ofparticle classes). This is achieved by collecting features from a 980 nm laser back-scattered signal acquiredthrough a polymeric lensed optical fiber tip dipped into the solution. Unlike DLS, this technique allows thetrapping of particles whose diameter ≥1 μm. For smaller particles, despite not guaranteeing their immobilization,it is also able to determine the number of different nanoparticles classes in an ensemble. The number of particletypes was correctly determined for suspensions of synthetic particles and yeasts; different bacteria; and 100 nmnanoparticles types, using both Principal Component Analysis and K-means algorithms. This method couldbe a valuable alternative to complex and time-consuming methods for particles separation, such as field owfractionation.