Abstract
Better sensitivity of a biosensor could boost up the detection limit of analytes, thus a must in the fields of bio-sensing and bio-detection. To further enhance the sensitivity of a biosensor, in this work, we design an oblique-flat-sheet metamaterial perfect absorber (MPA) to concentrate the hot spots within air between the oblique flat sheet and the continuous ground metal, thus enabling fully interaction between analytes and hot spots. The corresponding field distributions in simulation corroborated our assumption and its sensitivity could be up to 1049 nm/RIU. Then, we fabricated the sample by e-beam lithography process for a seed layer and simply tilting the sample during deposition to obtain oblique flat sheets. When considering the stochastic nature of the deposited multiple oblique flat sheets, we modified the metallic upper resonator of the MPA from the single oblique-flat-sheet into randomly distributed oblique-wire-bundle (OWB) and in simulation, its sensitivity is boosted up to 3319 nm/RIU. In experiments, the measured sensitivity is 1329 nm/RIU under different concentrations of glucose solutions that is four times larger than the 330 nm/RIU of the planar MPA. The higher sensitivity was attributed to that the OWB MPA could provide hot spots within air not only between OWB and grounded metal but also among wires. Moreover, the OWB could also trap and concentrate the analytes locally.
Highlights
Better sensitivity of a biosensor could boost up the detection limit of analytes, a must in the fields of bio-sensing and bio-detection
The sensitivity of the planar metamaterial perfect absorber (MPA) are ranged around 225–1000 nm/ RIU8,23,24; to solve this issue, some researchers proposed three dimensional metamaterials that provide a hot spot within a ir[22,25–31]; alternatively, researchers proposed a micro/nano-fluidic integrated MPA to locate the hots spots within the fluidic channel where analytes could fully interact with hot s pots[32–35]
In this work, we proposed a simple method to enhancing the sensitivity of a metamaterial-based sensor by tilting the substrate to a certain angle to conduct oblique deposition[38–42] with a periodic seed layer fabricated by e-beam lithography process and results in an oblique-flatsheet (OFS) metamaterial perfect absorber
Summary
Better sensitivity of a biosensor could boost up the detection limit of analytes, a must in the fields of bio-sensing and bio-detection. The nanoparticles would suffer from the insufficiencies of random distribution of the particles, resulting in poor stability and repeatability and the gap plasmons showed the disadvantages including small-area hot spots and less interaction between analytes and hot spots It is the metamaterial perfect absorbers, one of the most promising candidates to achieve higher sensitivity. The sensitivities are only a little bit better than or comparable to the planar MPAs, for example, 885/900 nm/RIU in Refs.22 and[27] for 3D metamaterials, 3.5 THz/RIU at the frequency of 6.4 THz and 140 GHz/THz at ~ 0.8 THz in Refs.32 and[33] for micro/nano fluidic MPAs. in this work, we proposed a simple method to enhancing the sensitivity of a metamaterial-based sensor by tilting the substrate to a certain angle to conduct oblique deposition[38–42] with a periodic seed layer fabricated by e-beam lithography process and results in an oblique-flatsheet (OFS) metamaterial perfect absorber. The field would concentrate between the oblique sheet and ground, providing space for analytes to fully interact with the hot spots
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.
