  Efficient transportation and delivery of analytes to the surface of optical
sensors are crucial for overcoming limitations in diffusion-limited transport
and analyte sensing. In this study, we propose a novel approach that combines
metasurface optics with optofluidics-enabled active transport of extracellular
vesicles (EVs). By leveraging this combination, we show that we can rapidly
capture EVs and detect their adsorption through a color change generated by a
specially designed optical metasurface that produces structural colors. Our
results demonstrate that the integration of optofluidics and metasurface optics
enables robust colorimetric read-out for EV concentrations as low as 107
EVs/ml, achieved within a short incubation time of two minutes, while using a
CCD camera or naked eye for the read-out. This approach offers the potential
for rapid sensing without the need for spectrometers and provides a short
response time. Our findings suggest that the synergy between optofluidics and
metasurface platforms can enhance the detection efficiency of low concentration
bioparticle samples by overcoming the diffusion limits.
