Universidade Estadual de Campinas Instituto de Qu´ımica ...

Abstract
Title : Fabrication of ISFET-Microsensors based on Ag and Au Nanoelectrodes
Author : Alexandre Kisner
Supervisor : Prof. Dr. Lauro Tatsuo Kubota
Keywords : Field Effect Transistors, sensors, noble metal nanocrystals.
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 µm and 50 x 50 µm. 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 11 pores/cm 2 )
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.
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