pH sensor is an essential component used in many chemical, food, and bio-material industries. Conventional
glass electrodes have been used to construct pH sensors, however, have some disadvantages in specific applications.
It is difficult to use glass electrodes for in vivo biomedical or food monitoring applications due to size limitation and
no deformability. In this paper, we present design and fabrication processes of a miniature iridium oxide thin film
pH sensor array on flexible polymer substrates. The amorphous iridium oxide thin film was used as the sensing
material. A sol-gel dip-coating process of iridium oxide film was demonstrated in this paper. A super-Nernstian
response has been measured on individual sensors of the array with a slope of -71.6±3 mV/pH at 25°C within the
pH range between 2.83 and 11.04.
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