An Extended Gate Field Effect Transistor (EGFET) pH Microsensor

Here, an extended – gate field effect transistor (EGFET) pH microsensor was developed for use in fast and sensitive pH measurement applications. The system consisted of two components; a pH sensitive modified gold electrode and a simple and cheap metal oxide semiconductor field-effect transistor (MOSFET). Polypyrrole, a semiconductor and pH responsive polymer, was formed by electropolymerization of pyrrole monomer at the surface of the gold electrode in galvostanic mode. Then, measurements were made in PBS at different pH values using the pH sensitive electrode. In this context, the pH sensitivity of polypyrrole with respect to electropolymerization and incubation time were studied. According to the results, the EGFET pH microsensor formed by 4-min pyrrole electropolymerization showed at pH 6-12 the highest pH sensitivity with 67 mV/pH

An Extended Gate Field Effect Transistor (EGFET) pH Microsensor

Here, an extended – gate field effect transistor (EGFET) pH microsensor was developed for use in fast and sensitive pH measurement applications. The system consisted of two components; a pH sensitive modified gold electrode and a simple and cheap metal oxide semiconductor field-effect transistor (MOSFET). Polypyrrole, a semiconductor and pH responsive polymer, was formed by electropolymerization of pyrrole monomer at the surface of the gold electrode in galvostanic mode. Then, measurements were made in PBS at different pH values using the pH sensitive electrode. In this context, the pH sensitivity of polypyrrole with respect to electropolymerization and incubation time were studied. According to the results, the EGFET pH microsensor formed by 4-min pyrrole electropolymerization showed at pH 6-12 the highest pH sensitivity with 67 mV/pH

Study on Electrical Performance of a U-Type Microfluidic Acceleration Switch Using Salt Solution as the Sensitive Electrode

The threshold of microfluidic inertial switch is excessively dependent on the size of the passive valve structure and the gas–liquid surface energy of working liquid. How to achieve high threshold and anti-high overload using liquid with low viscosity and low surface tension is a challenging work. Based on the designed U-type microfluidic inertial switch, the electrical characteristic of salt solution at microscale as well as the threshold and dynamic electrical performance of switch were studied. The VOF and CSD modules in CFD software were employed to analyze the dynamic flow process, and then the air–liquid surface moving displacement curve was compared by the theoretical model. A self-designed acceleration test platform was utilized to measure the static threshold, dynamic threshold, and anti-high overload of the inertial switch. The results show that the U-type microfluidics inertial switch using salt solution as sensitive electrode has better performance in power connection and anti-high overload. In particular, it also has the ability to achieve a range of dynamic threshold by changing the placement of the contact electrode, which can achieve rapid power on and off.

Development of new modified electrode based on β-cyclodextrin for methylene blue detection

Purpose This paper aims to focus on the development and characterization of a new electrochemical sensor, designed for the detection of methylene blue present in aqueous medium. Design/methodology/approach This sensor is obtained through the coupling of a polymeric membrane and an ion-sensitive electrode (platinum electrode). The preparation of the polymeric membrane involves the incorporation of a receptor: β-cyclodextrin (β-CD), a polymer (polyvinylchloride) and a plasticizer (dioctylphtalate). Cyclic voltammetry method (CV) was used to investigate the electrical properties of this electrochemical sensor. The effect of the experimental parameters such as dye initial concentration, scan rate, interfering elements presence and additional Nafion membrane presence was investigated in this paper. Findings The results are interesting because the developed sensor gives a linear response in concentrations range of 10−13 M–10−3 M with a good correlation coefficient of 0.979 and a detection limit of 10−13 M, which reflects the sensitivity of this sensor to the target element. The sensibility value is equal to 2. 40 µA mol−1 L. Originality/value The present study has shown that the modified electrode is a very good candidate in terms of price, sensibility and reproducibility for the construction of the sensitive sensor for the control of wastewater containing methylene blue.

Enhanced Stability and Amplified Signal Output of Single-Wall Carbon Nanotube-Based NH3-Sensitive Electrode after Dual Plasma Treatment

Pristine nanomaterials are normally prepared using finely controlled fabrication processes. Because no imperfect nanostructure remains, they cannot be used directly as electrode substrates of functional devices. This is because perfectly organized nanostructures or nanomaterials commonly require posttreatment to generate intentionally, the kinds of desirable defects inside or on their surfaces that enable effective functionalization. Plasma treatment is an easier, simpler and more widely used way (relative to other methods) to modify a variety of nanomaterials, although plasma-functionalized nano surfaces commonly have a short lifetime. We present herein a dual plasma treatment (DPT) that significantly enhances the degree and lifetime of plasma-induced surface functional groups on single-walled carbon nanotubes (SWCNTs). The DPT process consists of two individually optimized oxygen–plasma treatments. The DPT-modified SWCNT functioned as a sensing material for ammonia gas for more than a month. It also provided more than three times the degree of functionality for amplified signal output than with a single-plasma-treated SWCNT electrode.

Nitro-Oleic Acid in Seeds and Differently Developed Seedlings of Brassica napus L.

Similar to animals, it has recently been proven that nitro-fatty acids such as nitro-linolenic acid and nitro-oleic acid (NO2-OA) have relevant physiological roles as signalling molecules also in plants. Although NO2-OA is of great therapeutic importance, its presence in plants as a free fatty acid has not been observed so far. Since Brassica napus (oilseed rape) is a crop with high oleic acid content, the abundance of NO2-OA in its tissues can be assumed. Therefore, we quantified NO2-OA in B. napus seeds and differently developed seedlings. In all samples, NO2-OA was detectable at nanomolar concentrations. The seeds showed the highest NO2-OA content, which decreased during germination. In contrast, nitric oxide (•NO) levels increased in the early stages of germination and seedling growth. Exogenous NO2-OA treatment (100 µM, 24 h) of Brassica seeds resulted in significantly increased •NO level and induced germination capacity compared to untreated seeds. The results of in vitro approaches (4-Amino-5-methylamino-2′,7′-difluorofluorescein (DAF-FM) fluorescence, •NO-sensitive electrode) supported the •NO liberating capacity of NO2-OA. We observed for the first time that Brassica seeds and seedlings contain free NO2-OA which may be involved in germination as an •NO donor as suggested both by the results of exogenous NO2-OA treatment of seeds and in vitro approaches. Due to their high NO2-OA content, Brassica sprouts can be considered as a good source of dietary NO2-OA intake.

Comparison of H2O2 screen-printed sensors with different Prussian blue nanoparticles as electrode material

In order to determine hydrogen peroxide condensing from gaseous and liquid phases screen-printed electrodes with controlled and adjustable thickness, shape and size of the working electrode as well as electrode paste composition were investigated. For this purpose Prussian blue (PB) nanoparticles with a different particle size distribution of 20-30 nm (synthesized) and 60-100 nm (commercially available) were mixed with carbon paste and screen-printed on Al2O3 templates to establish H2O2-sensitive electrode. These two types of screen-printed sensors were compared to the commercial one during measurements in H2O2/water solutions at concentrations between 10-5 and 10-2 M H2O2. The linear signal in the investigated concentration range was found only for the sensor with the commercially available PB particles. Thus, this sensor prepared with PB particles of the size 60-100 nm showed the most reproducible and time-stable response versus the analyte in comparison to the others. This result offers the possibility to create sensors with adjustable design adapted to the concrete functionality. Thin films of collecting electrolytes based on agarose gels were printed on the sensor structures. They showed a distinct response on the application of H2O2-containing aerosols and gaseous phase.

Highly sensitive electrode materials for the voltammetric determination of nitrofurantoin based on zinc cobaltate nanosheets

Schematic illustration of the electrocatalytic activity of nitrofurantoin (NFT) on ZnCo2O4 nanosheets.