Interacting Metal–Insulator–Metal Resonator by Nanoporous Silver and Silk Protein Nanomembranes and Its Water-Sensing Application

Abstract

Planar and lithography-free metal–insulator–metal (MIM) resonators based on the Fabry–Pérot etalon are attractive for biochemical sensing applications because of their acceptable optical performance and cost-effectiveness. However, injecting analytes into the insulating layer where the optical field is localized (high light–matter interaction) is difficult. Here, planar and lithography-free MIM resonators interacting with their environment are reported. In the MIM, molecules of a liquid can infiltrate the inherent nanopores in the deposited silver nanomembrane and be absorbed into the silk protein hydrogel membrane. The silk layer is swollen when water molecules are absorbed, inducing a large shift in the resonance wavelength. Thus, in this study, the proposed MIM resonator was applied as a highly sensitive water sensor, and a water content as low as 0.008% in organic solvents could be determined by reading the shift in the transmission peak. This limit can be lowered further by using a high-resolution spectrometer and a thicker silk layer. In addition, the area of interaction can be artificially selected by applying an elastomer stamp and a patterned photoresist window.

Functional silk fibroin hydrogels: preparation, properties and applications

“…Narendar Gogurla et al 94 made use of this phenomenon to change the electrical conductivity of the hydrogels and prepared the Au-silk hydrogels with unique negative photoconductive response. In another study, Sara Arif et al 95 developed a hydrogel from the silk fibroin solution by methanol-induced cross-linking. The hydrogel was sandwiched between two silver nano-films deposited by an electron beam evaporation system to prepare a MIM resonator.…”

Multistimuli-Responsive Optical Hydrogel Nanomembranes to Construct Planar Color Display Boards for Detecting Local Environmental Changes

“…Employing a stimuli-responsive hydrogel as the insulating layer enables the MIM resonator to adjust the resonant color dynamically, by changing the physical volume of the insulation layer. , However, the induced interaction between the external stimulus and the hydrogel sandwiched between the two metallic layers must be considered to realize the responsive hydrogel-based MIM resonator. Our previous study proves that the stimuli-responsive hydrogel insulator in the MIM can promptly and locally interact with external stimuli through inherent nanopores in the ultrathin silver (Ag) layer . Construction of a photonic-based thermometer/alcohol sensor using an MIM structure using a thermo- and alcohol-responsive optical hydrogel polymer is compatible with microfabrication of spin-coating, and metal deposition in vacuum is highly required.…”

“…Our previous study proves that the stimuliresponsive hydrogel insulator in the MIM can promptly and locally interact with external stimuli through inherent nano- pores in the ultrathin silver (Ag) layer. 22 Construction of a photonic-based thermometer/alcohol sensor using an MIM structure using a thermo-and alcohol-responsive optical hydrogel polymer is compatible with microfabrication of spin-coating, and metal deposition in vacuum is highly required.…”

Biomimetic Nanomembranes: An Overview

“…They are characterized by large molecules, sometimes very large. These include polysaccharides [19], synthetic lipids [82], synthetic polymers [83], proteins [84], DNA [85] and RNA [86]-based membranes.…”