By using two-probe current-voltage measurements, a variation of the ZnO sample resistance was evidenced when these samples
were exposed to ammonia. Finally, a superhydrophobic behavior with high water adhesion was observed for all samples regardless of the rod dimensions. Such properties are very helpful for designing devices for sensors, open microfluidic devices based on high adhesive superhydrophobic surface implying no loss of microdroplet Ro 61-8048 in vitro reversible transportation , or micro total analysis systems by their synergetic combination. Methods Initially, a typical standard photolithographic resist patterning step was used in order to create the metallic interdigitated electrode structures.
Thus, a photoresist (AZ 5214E, MicroChemicals, Ulm, Germany) was spin coated on the SiO2/Si substrate, and by thermal treatments and UV light exposures in subsequent steps through a mask, the interdigitated electrodes were formed on a 0.4-mm2-size area having a width of 4 μm and gaps of 4 μm. Further, after the developing procedure, in the sputtering/evaporation step, a 10-nm Ti layer is required before the deposition of a 90-nm Au layer for the improvement of the gold adhesion on the SiO2/Si substrate. After removing the photoresist in acetone by a lift-off procedure, the metallic interdigitated electrodes are ready to use for the selleck products ZnO preparation by chemical bath deposition. Thus, the substrates containing the finger grid structures were immersed in a beaker containing aqueous solutions of zinc nitrate (Zn(NO3)2, Sigma-Aldrich, St. Louis, MO, USA) and hexamethylenetetramine ((CH2)6N4, Sigma-Aldrich) of equal molarities (0.05, 0.1, or 0.2 mM). The beaker was sealed and heated at a constant temperature of 90°. Two deposition times (3
and 6 h) were used. Finally, the samples were removed from the solution, rinsed with distilled water, and dried at room temperature. A schematic representation of Protein kinase N1 the photolithographic and deposition steps is depicted in Figure 1. Figure 1 Schematic illustration of the experimental procedures. Schematic illustration of the experimental procedures involved in the preparation of interdigitated metallic electrodes by photolithography technique, further used in the growth of ZnO network structures by chemical bath deposition. According to , the ZnO synthesis by chemical bath deposition involves the following chemical reactions: Zn(NO3)2 → Zn2+ + 2NO3 -(a) (CH2)6N4 + 6H2O → 6HCHO + 4NH3(b) NH3 + H2O → NH4 + + HO-(c) Zn2+ + 3NH4 + → [Zn(NH3)4]2+(d) [Zn(NH3)4]2+ + 2HO- → Zn(OH)2 + 4NH3(e) Zn(OH)2 → ZnO + H2O(f) The exact function of the (CH2)6N4 in the ZnO synthesis is still unclear. As a non-ionic cyclic tertiary amine, it can act as a bidentate Lewis ligand capable of bridging two Zn2+ ions in solution .