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This paper describes the process of producing chemosensors based on hybrid nanostructures obtained from Al2O3, as well as ZnO ceramic nanotubes and the following conducting polymers: poly(3-hexylthiophene), polyaniline emeraldine-base (PANI-EB), and poly(3, 4-ethylenedioxythiophene)-polystyrene sulfonate. The process for creating ceramic nanotubes involves three steps: creating polymer fiber nets using poly(methyl methacrylate), depositing ceramic films onto the nanofiber nets using magnetron deposition, and heating the nanotubes to 600 °C to burn off the polymer support completely. The technology for obtaining hybrid nanostructures from ceramic nanotubes and conducting polymers is drop-casting. AFM analysis emphasized a higher roughness, mainly in the case of PANI-EB, for both nanotube types, with a much larger grain size dimension of over 5 μm. The values of the parameter Rku were close or slightly above 3, indicating, in all cases, the formation of layers predominantly characterized by peaks and not by depressions, with a Gaussian distribution. An ink-jet printer was used to generate chemiresistors from ceramic nanotubes and PANI-EB structures, and the metallization was made with commercial copper ink for printed electronics. Calibration curves were experimentally generated for both sensing structures across a wider range of NH3 concentrations in air, reaching up to 5 ppm. A 0.5 ppm detection limit was established. The curve for the ZnO:PANI-EB structure presented high linearity and lower resistance values. The sensor could be used in medical diagnosis for the analysis of breath ammonia and biomarkers for predicting CKD in stages higher than 1. The threshold value of 1 ppm represents a feasible value for the presented sensor, which can be defined as a simple, low-value and robust device for individual use, beneficial at the patient level. [ABSTRACT FROM AUTHOR]

This paper describes the process to obtain ceramic nanotubes from titanium dioxide, alumina and yttrium oxide by a feasible, replicable and reliable technology, including three stages, starting from an electrospinning process of poly(methyl methacrylate) solutions. A minimum diameter of 0.3 μm was considered optimal for PMMA nanofibers in order to maintain the structural stability of covered fibers, which, after ceramic film deposition, leads to a fiber diameter of 0.5–0.6 μm. After a chemical and physical analysis of the stages of obtaining ceramic nanotubes, in all cases, uniform deposition of a ceramic film on PMMA fibers and, finally, a uniform structure of ceramic nanotubes were noted. The technological purpose was to use such nanotubes as ingredients in screen-printing inks for electrochemical sensors, because no study directly targeted the subject of ceramic nanotube applications for printed electronics to date. The printing technology was analyzed in terms of the ink deposition process, printed electrode roughness vs. type of ceramic nanotubes, derived inks, thermal curing of the electrodes and the conductivity of electrodes on different support (rigid and flexible) at different curing temperatures. The experimental inks containing ceramic nanotubes can be considered feasible for printed electronics, because they offer fast curing at low temperatures, reasonable conductivity vs. electrode length, good printability on both ceramic or plastic (flexible) supports and good adhesion to surface after curing. [ABSTRACT FROM AUTHOR]