Ultraflexible polyvinylidene fluoride film based amperometric enzyme-free sensor for selective detection of uric acid in a trace level.

The present invention describes a novel flexible nanosensor for the electrochemical detection of uric acid (UA) present in urine. The synthesized graphite-boron nanocomposite with an average thickness of ∼32 nm was grown up on a flexible polyvinylidene fluoride film with an average thickness of ∼50 µm and it acts as a nonenzymatic sensor for UA. The developed flexible sensor showed a prominent reduction peak in cyclic voltammetry and amperometric response with the presence of different concentrations of aqueous UA solution. In the electrochemical study, the redox peak was generated near ∼-0.42 V with a detection limit of around ∼2.09 µM as the bottom level. The high robustness of the developed sensor originated from the polymeric film base and the rapid response time of ∼0.5 s for detecting UA present in human urine. The interference property of the sensor was confirmed in the presence of bilirubin and creatinine as an eventual reference toward selectivity. The phase and morphology of the sensor surface were extensively observed before and after sensing to comprehend the electrochemical interaction between the sensor and target molecules. The generated quantitative results of the integrated system were verified by testing known and unknown concentrations of UA solutions.

Tunable, reversible resistive switching behavior of PVA-zirconia nanocomposite films and validation of the trap-assisted switching mechanism by the selective application of external bias voltages.

Flexible, free-standing polyvinyl alcohol (PVA)-zirconia (mean particle size ∼24 nm) nanocomposite films have been synthesized and their performance as a potential next-generation resistive switching device material has been assessed in this report. The nanocomposite films switch from a high resistive state (HRS) to a low resistive state (LRS) at the SET potential and from LRS to HRS at the RESET potential within the voltage window of 5 V. The origination of trap-assisted SET/RESET potentials has been experimentally validated by analyzing the experimental data and invoking various theoretical models. The impregnation of zirconium dioxide (ZrO2) nanoparticles considerably enhances the interfacial charges facilitated by the formation of dangling bonds. The current (I)-voltage (V) characteristics elucidate how the alteration of free volumetric space in the nanocomposites can modify the SET-RESET potential. This leads to tunable SET/RESET potential, good resistance ratio (∼80), and extensive cycling ability of these PVA-ZrO2 organic flexible nanocomposite films. Herein, we have also investigated the effect of applying external bias voltage (equal to the RESET potential) for possible energy bandgap modification and polymer chain orientation. The impedance spectra differ considerably when the sample is subjected to SET, RESET, and zero voltage bias. The observations have been correlated with the UV-vis absorption spectra and electrical studies. The adopted analysis method and obtained results can open up new avenues for designing and analyzing resistive switching-based random-access memory devices.