Super-Resolution Displacement Spectroscopic Sensing over a Surface“Rainbow”

Subwavelength manipulation of light waves with high precision can enable new and exciting applications in spectroscopy,sensing,and medical imaging.For these applications,miniaturized spectrometers are desirable to enable the on-chip analysis of spectral information.In particular,for imaging-based spectroscopic sensing mechanisms,the key challenge is to determine the spatial-shift information accurately(i.e.,the spatial displacement introduced by wavelength shift or biological or chemical surface binding),which is similar to the challenge presented by super-resolution imaging.Here,we report a unique"rainbow"trapping metasurface for on-chip spectrometers and sensors.Combined with super-resolution image processing,the low-setting 4×optical microscope system resolves a displacement of the resonant position within 35 nm on the plasmonic rainbow trapping metasurface with a tiny area as small as0.002 mm2.This unique feature of the spatial manipulation of efficiently coupled rainbow plasmonic resonances reveals a new platform for miniaturized on-chip spectroscopic analysis with a spectral resolution of 0.032 nm in wavelength shift.Using this low-setting 4×microscope imaging system,we demonstrate a biosensing resolution of 1.92×109exosomes per milliliter for A549-derived exosomes and distinguish between patient samples and healthy controls using exosomal epidermal growth factor receptor(EGFR)expression values,thereby demonstrating a new on-chip sensing system for personalized accurate bio/chemical sensing applications.