Optical conductivity-based ultrasensitive mid-infrared biosensing on a hybrid metasurface

• Published in: Light, science & applications science & applications, 2018-09, Vol.7 (1), p.67-11, Article 67
• Main Authors: Zhu, Yibo, Li, Zhaoyi, Hao, Zhuang, DiMarco, Christopher, Maturavongsadit, Panita, Hao, Yufeng, Lu, Ming, Stein, Aaron, Wang, Qian, Hone, James, Yu, Nanfang, Lin, Qiao
• Format: Article
• Language: English
• Subjects: 142/126; 639/624/1075/1083; 639/624/399/1015; 639/624/399/918/1054; Applied and Technical Physics; Atomic; Biosensors; Classical and Continuum Physics; Fingerprinting; Infrared spectroscopy; Lasers; metamaterials; Molecular; nanofabrication; NANOSCIENCE AND NANOTECHNOLOGY; Optical and Plasma Physics; Optical Devices; Optics; Photonics; Physics; Physics and Astronomy; Sensors
• ISSN: 2047-7538; 2095-5545; 2047-7538
• DOI: 10.1038/s41377-018-0066-1

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. Metasurfaces: mid-infrared biosensors A highly sensitive glucose sensor has been constructed from a functionalized graphene-metallic hybrid metasurface. Pioneered by a US-Chinese collaboration from Columbia University, University of South Carolina, Brookhaven National Laboratory and Nanjing University the device by detecting the changes in graphene optical conductivity, enables ultrasensitive detection of glucose concentrations as small as 200 pM via a small shift in its plasmonic resonant wavelength which is then measured. Importantly, the new sensing principle overcomes the detection limit defined by the molecular weight or the changes in local refractive index, which