Table 1.

Comparison of EV detection techniques

EV Detection Technique	Principle	Potential Advantage	Potential Disadvantage
Nanoparticle Tracking Analysis (NTA)	Dynamic light scattering and Brownian motion	Straight forward operation; Both size variation and concentration information can be collected; Available addon parts for fully automatic operation	Sensitive to vibration; Contamination particles can also be included; High cost for the instrument and addon parts
Electron microscopies.	Electrons as the source of illumination	High-resolution images; Direct illumination for EV morphology	High cost for the instrument; Not appropriate for quantitative analysis; EV morphology may be damaged by the sample preparing steps
Atomic force microscopies	Scanning cantilever over the surface	High-resolution images; Ture 3D image with surface topology determinations	High cost for the instrument; EV morphology may be damaged by the scanning cantilever
High-Resolution Flow Cytometry	Light scattering or fluorescent excitation	Sub-type EV labeling and detection; Principle is applicable in micro/nano-fluidic technology for better sensitivity	Sensitivity limitation for particles size < 200 nm
Resistive pulse sensing (RPS)	Nanopore blockage with changes of current or potential	Higher sampling frequency comparing to optical sensing; Principle is applicable in micro/nano-fluidic technology for better sensitivity	Fabrication with intricate nano-structures, Small sampling efficiency; Calibration is required for each nanopore design