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Fabrication of ISFET-Microsensors based on Ag and Au Nanoelectrodes

Alexandre Kisner
Total Authors: 1
Document type: Master's Dissertation
Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
Defense date:
Examining board members:
Jose Alberto Fracassi da Silva; Lucio Angnes
Advisor: Lauro Tatsuo Kubota

Arrays of ion-sensitive field effect transistors (ISFETs) were developed in this work. An additional step in the fabrication process was employed to implement a thin film of porous anodic alumina on the gate. This porous layer works as dielectric and template to the vertical growth of Ag and Au nanocrystals on the gate. The produced ISFETs were divided in two groups, which the gate dimensions were 10 x 50 mm and 50 x 50 mm. Using a simple anodizing process, a 60 nm thickness porous anodic alumina was developed on the gate. This porous film presented a high density porosity (~ 10 pores/cm) with an average pore diameter of 30 + 6 nm and a regular distribution on the gate of those ISFETs. This porous film lead to a significant increase in the gate area and also worked as a template to the growth of Ag and Au nanocrystals, which were used as gate nanoelectrodes. The results of such sensors to detect different pH of the solutions showed that the produced ISFETs present a short response time (t < 30 s). Moreover, the presence of such Ag and Au nanostructures increased the sensors sensitivity in comparison to those observed without nanoelectrodes. The first results to detect species such as glutathione, indicated that the ISFETs are even sensitive to detect small charged species in a submicromolar concentration range. (AU)