Black Phosphorus All‐Fiber Sensor for Highly Responsive Humidity Detection

Abstract

Black phosphorus (BP) promises high‐performance humidity sensing, due to its unique electrical, mechanical, and surface properties. Different from traditional transistor‐based BP humidity sensors, herein, an all‐fiber sensing strategy is proposed by integrating BP nanosheets with etched single‐mode fiber (ESMF). The experiments show that transmitted light in the ESMF can be effectively modulated by the coated BP nanosheets as relative humidity varies from 35% to 80%. Due to the combination of unique sensing characteristics of BP materials with a high sensitivity of optical modulation strategy, highly responsive humidity sensing is achieved with the response time as fast as 7 ms. This work demonstrates a BP‐based all‐optical sensing platform not only for high‐performance humidity sensing, but also for opening up new opportunities for many potential vapor/gas sensing applications in the fields of biomedicine and chemistry.

Surface Plasmonic Sensors: Sensing Mechanism and Recent Applications

“…On the other, they can further increase the localized electromagnetic field. Graphene [ 228 , 229 , 230 , 231 , 232 , 233 ], TMDs [ 234 , 235 ] and BP [ 236 ] combined with different types of optical fibers sensors have been successfully demonstrated.…”

Recent Development of Gas Sensing Platforms Based on 2D Atomic Crystals

“…Most MC-based electrical gas sensors are based on the charge transfer mechanism [ 1 , 38 , 56 , 58 – 64 ], while sensing via surface reaction and proton conduction has also been proposed [ 65 – 68 ]. Besides, sensing via gas adsorption-induced change of the refractive index has been explored in MC-functionalized optical sensors [ 20 , 21 ].…”

“…Alternative gas sensing techniques are therefore being developed in parallel for reduced cost and better portability. These gas sensors include electrical sensors, such as electrochemical sensors [ 14 ], chemiresistors [ 15 ], field-effect transistors (FETs) [ 16 ], Schottky diodes [ 17 ], conductometric (or chemiresistive) sensors [ 18 ], and impedance sensors [ 19 ], and optical sensors, such as fiber optic gas sensors [ 20 ] and photonic crystal gas sensors [ 21 ]. Although conventional gas sensing materials such as metal oxides, conducting polymers, and carbon nanotubes have long been developed and applied in commercial gas sensors, they still suffer from problems such as limited selectivity, poor reproducibility, and, in most cases, high operating temperatures [ 22 – 24 ].…”

“…Its main component is a waveguide consisting of a fiber core and the surrounding cladding. The core has a higher refractive index than the cladding, allowing the light to travel along with the fiber core via total reflection; a small portion of the light is transmitted as evanescent waves perpendicular to the fiber axis with intensity reduced exponentially in the cladding [ 20 ]. The adsorption of gas molecules on the cladding changes its refractive index, resulting in the change of the output light signals such as its intensity and wavelength.…”

Excellent humidity sensor based on ultrathin HKUST-1 nanosheets

“…Sensors based on nanomaterials such as graphene and MoS 2 can overcome the above disadvantages, 3,4 but their response time is not satisfactory. Although the improved WS 2 or black phosphorus akes have faster response and recovery time, 5,6 the preparation is complicated and energy consumption is high, which limit the development and wide application of these materials. In recent years, there have been studies reporting new biomaterial-based sensors, but their high cost is also a problem that must be overcome.…”