“…From the slope in the inset, the diffusion coefficient of the etchant in p(DDA- t BVPC53) LB films was determined to be 3.16 × 10 -15 cm 2 /s. In general, diffusion coefficients in polymer cast films yield values ranging between 10 -9 and 10 -8 cm 2 /s. , The D value for p(DDA- t BVPC53) LB films is much lower than values in the literature, indicating that densely packed LB films provide good etching resistance. 5 (a) Reflectivity change at 40.0° as a function of immersion time.…”
“…From the slope in the inset, the diffusion coefficient of the etchant in p(DDA- t BVPC53) LB films was determined to be 3.16 × 10 -15 cm 2 /s. In general, diffusion coefficients in polymer cast films yield values ranging between 10 -9 and 10 -8 cm 2 /s. , The D value for p(DDA- t BVPC53) LB films is much lower than values in the literature, indicating that densely packed LB films provide good etching resistance. 5 (a) Reflectivity change at 40.0° as a function of immersion time.…”
“…crystal. In addition, although not dealing directly with ethanol-methanol mixtures, there are related works on VOC sensors that demonstrate detection of pure ethanol and pure methanol vapors by means of a variety of sensing materials (typically polymers that swell in response to vapor sorption [11][12][13][14][15]) and transduction methods, such as electro-acoustic devices [11][12][13][14], electrical resistors [14,15], and optical fibers [16]. All the aforementioned chemical sensors required the synthesis of specific sensitive materials and/or specially designed transducers, which increases cost and reduces versatility.…”
Section: Methodsmentioning
confidence: 99%
“…Chang et al [10] reported a methanol/ethanol colorimetric sensor based on a cholesteric liquid crystal. In addition, although not dealing directly with ethanol-methanol mixtures, there are related works on VOC sensors that demonstrate detection of pure ethanol and pure methanol vapors by means of a variety Sensors 2019, 19, 5381 2 of 9 of sensing materials (typically polymers that swell in response to vapor sorption [11][12][13][14][15]) and transduction methods, such as electro-acoustic devices [11][12][13][14], electrical resistors [14,15], and optical fibers [16].…”
A simple optical vapor sensor based on conventional Scotch adhesive tape, for analyzing ethanol–methanol mixtures, is proposed and demonstrated. The sensing signal relies on the variation of optical power transmitted through the tape, resulting from the response of the adhesive material to vapor sorption. The optical sensor exhibits high selectivity for ethanol vapor over methanol vapor. When exposed to vapors from ethanol–methanol liquid mixtures, the sensor shows a linear detection range of 0–100 vol%, and detection limits of 8.8 vol% ethanol and 17.6 vol% methanol. Repeatability, reproducibility, reversibility, and sensitivity to other volatile organic compounds are also studied.
“…Highly sensitive sensors are required for the detection of molecules in various fields of application. Evanescent-field-coupled waveguide-mode sensors are effective for this purpose [1][2][3][4][5][6][7]. These sensors use a sensing plate whose geometry is based on a sequence of layers with well-selected optical properties.…”
Section: Introductionmentioning
confidence: 99%
“…In principle, any kind of solid material that reflects light and optically isolates the waveguide from the substrate can be used as the reflecting layer. Silver and gold are typical materials for the reflecting layer, since the use of these metals provides a good sensitivity [3][4][5][6][7]. The reflecting layer and the waveguide layer are usually deposited sequentially on the substrate, so adhesion between the layers and any surface roughness of the layers strongly affect the sensitivity, reliability, and durability of the sensor.…”
We developed a monolithic sensing plate for a waveguide-mode sensor. The plate consists of a SiO(2) glass substrate and a thin silicon layer the surface of which is thermally oxidized to form a SiO(2) glass waveguide. We confirmed that the sensing plate is suitable for high-sensitivity detection of molecular adsorption at the waveguide surface. In addition, a significant enhancement of the sensitivity of the sensor was achieved by perforating the waveguide with holes with diameters of a few tens of nanometers by selective etching of latent tracks created by swift heavy-ion irradiation. Possible strategies for optimizing the plate are discussed.
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