A plug-and-play 3D hydrodynamic focusing Raman platform for label-free and dynamic single microparticle detection

Abstract

The label-free and dynamic single microparticle Raman detection has shown the capability for the chemical and biological heterogeneity investigation of microdroplets, microplastics, and live cells. 3D hydrodynamic focusing of microparticles is essential to this aim. However, current 3D hydrodynamic focusing methods are normally limited by the complex and cleanroom-dependent fabrication as well as the professional operation. Herein, a plug-and-play 3D hydrodynamic focusing Raman platform is developed for label-free and dynamic single microparticle detection. This platform is easily assembled with a coaxial needle for 3D hydrodynamic focusing, a quartz capillary for Raman detection, a 3D printed holder and soft silicone tubes for connection in a plug-and-play manner, which does not need any professional skills and sophisticated conditions. The microparticle 3D hydrodynamic focusing is implemented in the theoretical simulations and experimental validations. Raman intensity of the good focused microparticles is almost 3 times higher than those not focused. The label-free and dynamic single microparticle Raman detection is analyzed by the Poisson distribution. KNN model is established for Raman spectra classification with the accuracy, sensitivity, and specificity up to 100%. R2 is up to 0.916 with average count of microparticles per element from 0.02 to 0.2. This platform can be used to label-free and dynamically detect in mixed samples with two as well as three types of microparticles. It would become a powerful tool for the label-free and dynamic single microparticle detection such as chemical reaction monitoring inside microdroplets, microplastics detection and classification, noninvasive biosensing of live cells and so on.