Ex vivo performance evaluation of a transdermal gold injectable microneedle for tyrosinase sensing

Here, the semi-invasive direct electrochemical detection of melanoma biomarkers in non-treated skin has been envisaged. The enzyme tyrosinase (TYR) was to be addressed with a microneedle electrochemical sensor. The microneedles were fabricated by polydimethylsiloxane (PDMS) casting with stable polymers. The as-prepared microneedles (MNs) were then coated by gold sputtering. The gold MNs were finally covered by alginate/catechol to provide a liquid electrolyte layer that contained electroactive species, such as catechol, whose redox state can be linked to the concentration of TYR in the skin. The sensor showed high sensitivity of 7.52 µA·mg–1·mL TYR in dummy skin. A relative standard deviation (RSD) of 8.54 % (n=5) demonstrated that the Catechol@alginate: gold MN electrode had excellent reproducibility for continuous glucose detection. Also, five parallel Catechol@alginate: gold MN electrodes were fabricated using the same experimental setup and showed an RSD of 3.95 % (n=5). These results suggest that the electrode fabrication process was reproducible, and Catechol@alginate: gold MN biosensors demonstrated high stability for the repetitive detection of TYR. Furthermore, the sensor has high selectivity in the presence of interfering components towards TYR screening.

Fabrication of Flexible In-Plane Gate Nanowire Transistor on a Paper Substrate

Flexible in-plane gate SnO2 nanowire (NW) transistor gated by SiO2 acting as a solid electrolyte was fabricated on a paper substrate by using a transmission electron microscopy (TEM) Ni grid shadow mask. The operating voltage of in-plane gate SnO2 NW transistor was down to 1 V because of the large electric-double-layer (EDL) capacitance of the SiO2 electrolyte layer. Current on/off ratio (Ion/Ioff) and field-effect electron mobility (µEF) as well as subthreshold slope of this device were ~106, 74.7cm2·V−1s−1 and 80 mV·dec−1, respectively. The proposed flexible and low-voltage SnO2 NW transistors on paper substrate exhibit immense potential for applications in portable and flexible electronic devices.

Features of Electrophoretic Deposition of a Ba-Containing Thin-Film Proton-Conducting Electrolyte on a Porous Cathode Substrate

This paper presents the study of electrophoretic deposition (EPD) of a proton-conducting electrolyte of BaCe0.89Gd0.1Cu0.01O3-δ (BCGCuO) on porous cathode substrates of LaNi0.6Fe0.4O3−δ (LNFO) and La1.7Ba0.3NiO4+δ (LBNO). EPD kinetics was studied in the process of deposition of both a LBNO sublayer on the porous LNFO substrate and a BCGCuO electrolyte layer. Addition of iodine was shown to significantly increase the deposited film weight and decrease the number of EPD cycles. During the deposition on the LNFO cathode, Ba preservation in the electrolyte layer after sintering at 1450 °C was achieved only with a film thickness greater than 20 μm. The presence of a thin LBNO sublayer (10 μm) did not have a pronounced effect on the preservation of Ba in the electrolyte layer. When using the bulk LBNO cathode substrate as a Ba source, Ba was retained in a nominal amount in the BCGCuO film with a thickness of 10 μm. The film obtained on the bulk LBNO substrate, being in composition close to the nominal composition of the BCGCuO electrolyte, possessed the highest electrical conductivity among the films deposited on the various cathode substrates. The technology developed is a base step in the adaptation of the EPD method for fabrication of cathode-supported Solid Oxide Fuel Cells (SOFCs) with dense barium-containing electrolyte films while maintaining their nominal composition and functional characteristics.