Nanophotonic resonators can confine light to deep-subwavelength volumes with highly enhanced near-field intensity and therefore are widely used for surface-enhanced infrared absorption spectroscopy in various molecula...Nanophotonic resonators can confine light to deep-subwavelength volumes with highly enhanced near-field intensity and therefore are widely used for surface-enhanced infrared absorption spectroscopy in various molecular sensing applications.The enhanced signal is mainly contributed by molecules in photonic hot spots,which are regions of a nanophotonic structure with high-field intensity.Therefore,delivery of the majority of,if not all,analyte molecules to hot spots is crucial for fully utilizing the sensing capability of an optical sensor.However,for most optical sensors,simple and straightforward methods of introducing an aqueous analyte to the device,such as applying droplets or spin-coating,cannot achieve targeted delivery of analyte molecules to hot spots.Instead,analyte molecules are usually distributed across the entire device surface,so the majority of the molecules do not experience enhanced field intensity.Here,we present a nanophotonic sensor design with passive molecule trapping functionality.When an analyte solution droplet is introduced to the sensor surface and gradually evaporates,the device structure can effectively trap most precipitated analyte molecules in its hot spots,significantly enhancing the sensor spectral response and sensitivity performance.Specifically,our sensors produce a reflection change of a few percentage points in response to trace amounts of the amino-acid proline or glucose precipitate with a picogram-level mass,which is significantly less than the mass of a molecular monolayer covering the same measurement area.The demonstrated strategy for designing optical sensor structures may also be applied to sensing nano-particles such as exosomes,viruses,and quantum dots.展开更多
基金This work was supported in part by the National Science Foundation(NSF)(award no.ECCS-1748518 and ECCS-1847203)the National Cancer Institute of the National Institutes of Health(NIH)(award no.5R33CA191245 and 5R21CA235305)+1 种基金The content is solely the responsibility of the authors and does not necessarily represent the official views of NIH.The Zeiss LSM 710 confocal microscope at UB North Campus Imaging Facility was funded by the NSF Major Research Instrumentation(award no.DBI-0923133)The authors would also like to thank the Toronto Nanofabrication Center(TNFC)for access to the EBL instrument and Qiaoqiang Gan for access to the FTIR in the Nanooptics&Biophotonics lab at University at Buffalo.
文摘Nanophotonic resonators can confine light to deep-subwavelength volumes with highly enhanced near-field intensity and therefore are widely used for surface-enhanced infrared absorption spectroscopy in various molecular sensing applications.The enhanced signal is mainly contributed by molecules in photonic hot spots,which are regions of a nanophotonic structure with high-field intensity.Therefore,delivery of the majority of,if not all,analyte molecules to hot spots is crucial for fully utilizing the sensing capability of an optical sensor.However,for most optical sensors,simple and straightforward methods of introducing an aqueous analyte to the device,such as applying droplets or spin-coating,cannot achieve targeted delivery of analyte molecules to hot spots.Instead,analyte molecules are usually distributed across the entire device surface,so the majority of the molecules do not experience enhanced field intensity.Here,we present a nanophotonic sensor design with passive molecule trapping functionality.When an analyte solution droplet is introduced to the sensor surface and gradually evaporates,the device structure can effectively trap most precipitated analyte molecules in its hot spots,significantly enhancing the sensor spectral response and sensitivity performance.Specifically,our sensors produce a reflection change of a few percentage points in response to trace amounts of the amino-acid proline or glucose precipitate with a picogram-level mass,which is significantly less than the mass of a molecular monolayer covering the same measurement area.The demonstrated strategy for designing optical sensor structures may also be applied to sensing nano-particles such as exosomes,viruses,and quantum dots.
