Alcohol intoxication has a dangerous effect on human health and is often associated with a risk of catastrophic injuries and alcohol-related crimes. A demand to address this problem adheres to the design of new sensor systems for the real-time monitoring of exhaled breath. We introduce a new sensor system based on a porous hydrophilic layer of submicron silica particles (SiO 2 SMPs) placed on a onedimensional photonic crystal made of Ta 2 O 5 /SiO 2 dielectric layers whose operation relies on detecting changes in the position of surface wave resonance during capillary condensation in pores. To make the active layer of SiO 2 SMPs, we examine the influence of electrostatic interactions of media, particles, and the surface of the crystal influenced by buoyancy, gravity force, and Stokes drag force in the frame of the dipcoating preparation method. We evaluate the sensing performance toward biomarkers such as acetone, ammonia, ethanol, and isopropanol and test sensor system capabilities for alcohol intoxication assessment. We have found this sensor to respond to all tested analytes in a broad range of concentrations. By processing the sensor signals by principal component analysis, we selectively determined the analytes. We demonstrated the excellent performance of our device for alcohol intoxication assessment in real-time.
Silver triangular nanoplates (AgTNPs) is a promising and still relatively poorly studied colorimetric probe for sensing various organic compounds. In particular, they undergo a change in their morphology when interacting with various catecholamines. This process is accompanied by a hypsochromic shift of the local surface plasmon resonance (LSPR) band of nanoparticles. The greatest spectral changes can be observed in the case of the interaction of AgTNPs with epinephrine which can be the basis for a sensitive method for its detection. It was found that the detection limit of epinephrine under the selected optimal conditions is equal to 3 uM, and the dynamic range is from 9 uM up to 50 uM. Selectivity of the proposed method for the epinephrine determination was evaluated as well. It was shown that the determination does not interfere with a 10-fold excess of vanillylmandelic acid and dopamine, and with a 1000-fold excess of common cations and anions. The proposed approach was successfully applied to the determination of epinephrine in a drug and a sample of artificial urine containing an epinephrine additive.
This study focuses on the synthesis of bi-hierarchical porous Pt microspheres directly on titania nanotube arrays grown on a Ti wire for their application as a one-electrode selective alcohol sensor. We evaluate the synthesis conditions, morphology, structure of the obtained material using scanning, transmission electron microscopy, and electron diffraction. The sensor performance is assessed in a one-electrode configuration, using thermocycling both to heat and acquire a signal that we further process with a machine learning algorithm for selective determination of alcohols. We found that reduction of Pt precursor by formic acid facilitates the appearance of quasi-1D Pt structures without using any surfactant. High excess of formic acid yields the formation of quasi-dendritic Pt structures with the overall morphology of a sphere and channels whose diameter remains one of the TiO2 nanotubes. Our data suggest the growth of Pt spheres to be diffusion-controlled with constant or decreasing nucleation rate that should include assembling of Pt nanorods. The fabricated sensors based on the synthesized structures show a chemiresistive response to methanol, ethanol, and isopropanol vapors in the mixture with air, which we selectively determine using only one sensor.
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