pH sensors Extended gate field effect transistor (EGFET) 5 Field effect transistors 5 Sensing membranes 5 Thin films 5 Titanium dioxide 5 Sol-gels 4 Thermoelectric equipment 4 pH 4 pH effects 4 Deposition 3 Oxide films 3 Tin oxides 3 Titanium oxides 3 Zinc oxide 3 Annealing 2 Costs 2 Electrodes 2 Electronic equipment 2 II-VI semiconductors 2 Indium tin oxide substrates 2 Sol-gel spin coating method 2 Temperature distribution 2 Thin film circuits 2 pH sensing 2 Agricultural robots 1 Agriculture 1 Agriculture monitoring 1 Annealing condition 1 Annealing process 1