Abstract
Optical devices are highly attractive for biosensing as they can not only enable quantitative measurements of analytes but also provide information on molecular structures. Unfortunately, typical refractive index-based optical sensors do not have sufficient sensitivity to probe the binding of low-molecular-weight analytes. Non-optical devices such as field-effect transistors can be more sensitive but do not offer some of the significant features of optical devices, particularly molecular fingerprinting. We present optical conductivity-based mid-infrared (mid-IR) biosensors that allow for sensitive and quantitative measurements of low-molecular-weight analytes as well as the enhancement of spectral fingerprints. The sensors employ a hybrid metasurface consisting of monolayer graphene and metallic nano-antennas and combine individual advantages of plasmonic, electronic and spectroscopic approaches. First, the hybrid metasurface sensors can optically detect target molecule-induced carrier doping to graphene, allowing highly sensitive detection of low-molecular-weight analytes despite their small sizes. Second, the resonance shifts caused by changes in graphene optical conductivity is a well-defined function of graphene carrier density, thereby allowing for quantification of the binding of molecules. Third, the sensor performance is highly stable and consistent thanks to its insensitivity to graphene carrier mobility degradation. Finally, the sensors can also act as substrates for surface-enhanced infrared spectroscopy. We demonstrated the measurement of monolayers of sub-nanometer-sized molecules or particles and affinity binding-based quantitative detection of glucose down to 200 pM (36 pg/mL). We also demonstrated enhanced fingerprinting of minute quantities of glucose and polymer molecules.
Highlights
Optical transducers are one of the most promising candidates for label-free, sensitive, and specific on-chip biosensing.[1,2,3] Optical devices are unique in their ability to detect binding between biochemical molecules and probe their molecular structures[4,5,6,7,8]
The hybrid metasurface consisted of an Au nanorod antenna array covered by monolayer graphene, atop a Pt mirror with a SiO2 spacer layer in between (Figs. 1a, b)
A pair of such dipoles are coupled via near-field interactions and can form a quadrupole to suppress radiation loss in the far field and improve the quality factor of the plasmonic resonance band[38]
Summary
Optical transducers are one of the most promising candidates for label-free, sensitive, and specific on-chip biosensing.[1,2,3] Optical devices are unique in their ability to detect binding between biochemical molecules and probe their molecular structures[4,5,6,7,8]. Non-optical devices such as field effect transistors may provide more sensitive alternatives[11,15,16,17] at the expense of molecular spectroscopic information, convenient wireless communication between optical devices, and other features of optical methods. Use of these devices may face other complexities in biosensing, such as unstable contact, Zhu et al Light: Science & Applications (2018)7:67 a b
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
