摘要
Optical whispering-gallery-mode microsensors are a promising platform for many applications,such as biomedical monitoring,magnetic sensing,and vibration detection.However,like many other micro/nanosensors,they cannot simultaneously have two critical properties–ultrahigh sensitivity and large detection area,which are desired for most sensing applications.Here,we report a novel scanning whispering-gallery-mode microprobe optimized for both features and demonstrate enhanced Raman spectroscopy,providing high-specificity information on molecular fingerprints that are important for numerous sensing applications.Combining the superiorities of whispering-gallery modes and nanoplasmonics,the microprobe exhibits a two-orders-of-magnitude sensitivity improvement over traditional plasmonics-only enhancement;this leads to molecular detection demonstrated with stronger target signals but less optical power required than surface-enhanced-Raman-spectroscopy substrates.Furthermore,the scanning microprobe greatly expands the effective detection area and realizes two-dimensional micron-resolution Raman imaging of molecular distribution.The versatile and ultrasensitive scanning microprobe configuration will thus benefit material characterization,chemical imaging,and quantum-enhanced sensing.
基金
This work was supported by National Institutes of Health under Grant No.NIH-1R21EB03084501A1.The authors acknowledge the Institute of Materials Science and Engineering(IMSE)and Nano Research Facility(NRF)at Washington University in St.Louis for the use of instruments,financial support,and staff assistance.
