Table 1.

Particle detection and characterization principles.

	Particle Light Interactions	Microscopy and Imaging	Resistive Pulse Sensing	Suspended Microchannel Resonators	Sedimentation and Centrifugation	Further Separation Approaches
Physical phenomenon	Absorption, diffraction, refraction, scattering, fluorescence, polarization, etc.	Space-resolved imaging of particles coded by colors and intensity	Current blockage of specific intensity and duration	Change in the resonator frequency density and size dependent	Sedimentation velocity, separation	Separation in fractions due to a particle property
Output particle properties (examples)	Size and size distribution, molecular weight, material and structural properties, concentration, interaction parameter	Size and size distribution, shape, optical properties, concentration, etc.	Size and size distribution, shape, concentration, charge, etc.	Size and size distribution, concentration, density, material differentiation, etc.	Size and size distribution, shape, density, equilibrium parameters, etc.	Depending on the investigated property and the used detector
Main advantage(s)	Variable approaches possible	Direct measurement and imaging	Independent of optical/material properties	Differentiation between materials	Variable approaches, no destructive preparation expected	Analysis of separated fractions, advantageous for polydisperse/polymodal samples
Main challenge(s)	Complex physical processes and calculation, polydispersity	Resolution, preparation	Conductivity, polydispersity	Channel blockage due to interactions	Material properties necessary; no concentration determination	Separation conditions
Techniques (examples)	LO, SLS, DLS, turbidimetry, UV/Vis spectroscopy and spectrometry, Raman spectroscopy, flow cytometers, etc.	Various types of microscopes, e.g., optical, REM, TEM, AFM, flow imaging devices, e.g., MFI	Coulter counters and some FACS instruments	Chip-based SMRs, commercial instrument: Archimedes	All types of preparative and analytical centrifuges, e.g., AUC, DISC	Chromatographic methods, e.g., HP-SEC; AF4; SDS-PAGE