In this paper we report the results of studies relating to the synthesis of Cobalt Ferrite (CoFe2O4) thin films by a sputtering method. The CoFe2O4 thin film has been prepared onto silicon substrate from the sputtering targets, CoFe. Structural propertiesofthinfilms were characterized byx-ray diffraction and the morphology was characterized by scanning electron microscopy. The growth parameter are: base pressure 2,8 x 10-2 Torr, ratio of Argon:Oxygen flow rate are 100:50 sccm, deposition pressure 5.4 x10-1 Torr, growth temperature 100oC.Nanostructures of the thin film that have been analyzed are crystallite size and micro strain.We obtained the crystallite size of CoFe2O4 thin films for layer thickness of 40 and 48 nm, respectively are: 32 nm and 66 nm, while the micro strain is 8.0 x 10-4 and 10.2 x 10-4.
Fabrication of PVDF films has been making using Hot Roll Press. Preparation of samples carried out for nine different temperatures. This condition is carried out to see the effect of temperature fabrication on electrical properties and crystallite size of PVDF films. The electrical properties like as surface resistivity are discussion focus in this paper. Surface resistivity properties of PVDF can be improved by mechanical treatment on the varying film thickness and the temperature. To obtain the diffraction pattern of sample characterization is performed using X-Ray Diffraction. Crystallite size of PVDF films calculate from broadening pattern of X-Ray Diffraction. Furthermore, from the diffraction pattern calculated β fraction and crystallite size, for calculation to determine the crystallite size of the sample by using the Scherrer equation. Has been obtained an increase piezoelectric properties of PVDF films that characterized by increasing β fraction. Have been obtained β fraction increased from 25.4% up to 44% for temperatures of 130˚C up to 170˚C, respectively. Resistivity value has been obtained at temperature 130˚C up to 170˚C, decreased from 1.23 × 10 4 Ωm up to 0.21 × 10 4 Ωm respectively. From the experimental results and the calculation of crystallite sizes obtained for the samples with temperature 130˚C up to 170˚C respectively are increased from 7.2 nm up to 20.54 nm. These results indicate that mechanical treatment caused increase β fraction and decrease surface resistivity. Increasing temperatures will also increase the size of the crystallite of the sample. This happens because with the increasing temperature causes the higher the degree of crystallization of PVDF film sample is formed, so that the crystallite size also increases.
A polyvinylidene fluoride (PVDF) film-based capacitive biosensor was developed for glucose sensing. This device consists of a PVDF film sandwiched between two electrodes. A capacitive biosensor measures the dielectric properties of the dielectric layers at the interface between the electrolyte and the electrode. A glucose oxidase (GOx) enzyme was immobilized onto the electrode to oxidize glucose. In practice, the biochemical reaction of glucose with the GOx enzyme generates free electron carriers. Consequently, the potential difference between the electrodes is increased, resulting in a measurable voltage output of the biosensor. The device was tested for various glucose concentrations in the range of 0.013 to 5.85 M, and various GOx enzyme concentrations between 4882.8 and 2.5 million units/L. We found that the sensor output increased with increasing glucose concentration up to 5.85 M. These results indicate that the PVDF film-based capacitive biosensors can be properly applied to glucose sensing and provide opportunities for the low-cost fabrication of glucose-based biosensors based on PVDF materials.
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