The present paper describes the electrochemical impedance activity of a hybrid film with graphene and poly(azo-Bismarck Brown Y) as the chemiresistor material. This nanocomposite film exhibits interesting properties based on the redox properties of the azo polymer combined with the great electronic conductivity and stability of graphene. Electrochemical impedance spectroscopy at the poly(azo-BBY)-rGO electrode in solutions with different dissolved O 2 concentrations revealed that the resistance values are very sensitive to variations in the O 2 concentration.
In
the present study, a chemiresistor sensor based on a poly(Bismarck
Brown Y)-reduced graphene oxide nanocomposite was developed to analyze
the respiratory capacity of the constituent complexes of the electron
transport chain. The sensorial platform was characterized using electrochemical
impedance spectroscopy, and oxygen detection was accomplished by measuring
the resistive properties of the sensor at fixed AC frequency. The
impedance decreased significantly in response to small variations
of the O2 concentrations tested up to saturation of the
electrolyte solution with molecular oxygen. The resistive response
of the sensor at 0.1 Hz was linear over the oxygen concentration range
from 1.17 × 10–5 mol L–1 to
1.02 × 10–3 mol L–1, with
a detection limit of 3.60 × 10–7 mol L–1. Using the new O2 sensing platform, we
monitored gradients in static cultures of adherent cells exposed to
graded oxygen both at rest and upon metabolic stimulation. Under high
dissolved oxygen conditions, the respiration of resting cells dictated
that local O2 was moderately reduced, while cell metabolic
stimulation triggered a major redistribution of O2. The
usefulness of the developed sensor was demonstrated by continuous
monitoring of mitochondrial oxygen consumption in various biologic
applications.
This work presents a study of the
formation mechanism of electrochemically
deposited alternating layers of azopolymer and graphene oxide, as
well as a systematic study of the physicochemical characteristics
of the resulting nanocomposite films by electrochemical impedance
spectroscopy. The nanocomposite films were constructed by cyclic electropolymerization,
which allowed for the assembly of thin films with alternating azopolymers
and reduced graphene oxide (rGO) layers in one step. Morphological
characterizations were performed by atomic force microscopy and scanning
electron microscopy and verified that the electrodeposition of the
poly(azo-BBY) polymeric film occurred during the anodic sweep, and
the deposition of graphene oxide sheets took place during the cathodic
sweep. By analyzing the electrochemical impedance spectra using equivalent
circuit models, variations in the resistance and capacitance values
of the system were monitored as a function of the amount of electrodeposited
material on the fluorine doped tin oxide electrode. In addition, the
interfacial phenomena that occurred during the electroreduction of
the rGO sheets were monitored with the same method.
The present paper describes the development of a novel photochemiresistor sensor for the determination of chemical oxygen demand (COD). A chemiresistive device was produced by a thin film of the monoclinic phase of bismuth vanadate deposited on an FTO glass surface. The resistive properties of the photosensor were carried out by electrochemical impedance spectroscopy (EIS). The electrical resistance of the platform was dependent on the presence of organic material in aqueous solution and the incidence of light. The decrease in resistance can be explained by considering that by increasing the amount of organic material, the amount of charge transferred to BiVO 4 increases, as does the amount of the photogenerated conduction band on the film. This behavior is not observed when carrying out the same measurements in the absence of light. Under the optimal experimental conditions, the linear response of the chemiresistor sensor is between 0.20 and 19.9 mg L −1 COD at a fixed AC frequency of 0.1 Hz. There is a good correlation between the charge transfer resistance and COD concentration in the electrolyte solution. Quantification of COD in waste and lake waters was successfully performed using the novel photochemiresistor sensor. The results achieved in the analysis with the sensor are in accordance with the conventional method.
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