Rotational speed sensor based on the magnetoelectric effect of composite FeSiB/Pb(Zr,Ti)O3.

This paper proposes a rotational speed sensor based on the magnetoelectric coupling effect. The sensor is composed of a permanent magnet array and a magnetoelectric composite FeSiB/Pb(Zr,Ti)O3. The permanent magnet array rotates with the gear to provide a stable sinusoidal alternating magnetic field in its surrounding space, which is simulated and analyzed by using the finite element simulation software. Based on the magnetoelectric coupling effect, the composite FeSiB/Pb(Zr,Ti)O3 senses the magnetic field information and transforms it into electrical information so as to realize the rotating speed measurement. The experiments of sensing distance and linearity are carried out. The proposed sensor is compared and verified by a coil sensor. The results show that the proposed speed sensor has good linearity in the speed measured range, and the sensing distance can reach 15 mm. At the same time, it can be used for low-speed measurement. This kind of speed sensor has broad application prospects in the field of rotational speed measurement.

Sensitive current sensor based on Fe73.5Cu1Nb3Si13.5B9/Pb(Zr,Ti)O3 composite with a tunable magnetic flux concentrator.

This paper presents a sensitive current sensor based on magnetoelectric composite Fe73.5Cu1Nb3Si13.5B9/Pb(Zr,Ti)O3 with a tunable magnetic concentrator. The concentrator with a movable magnetic plate can enable the DC bias magnetic field (Hdc) to become tunable to meet the needed optimal Hdc of Fe73.5Cu1Nb3Si13.5B9/Pb(Zr,Ti)O3 and to reduce the magnetoresistance of the magnetic loop. Furthermore, the sensor's resonant frequency is adjustable to improve the sensitivity for measuring current at different frequencies. From experiments, the proposed sensor has a sensitivity of ∼246.71 mV/A and a linearity of ∼0.98% at 50 Hz current. The results indicate that the proposed current sensor is ideally suited for current-monitoring.

One-pot synthesis of porphyrin functionalized γ-Fe2O3 nanocomposites as peroxidase mimics for H2O2 and glucose detection.

Meso-tetrakis(4-carboxyphenyl)-porphyrin-functionalized γ-Fe2O3 nanoparticles (H2TCPP-γ-Fe2O3) were successfully prepared by one-pot method under hydrothermal conditions and were found to possess intrinsic peroxidase-like activity. The H2TCPP-γ-Fe2O3 nanocomposites can catalytically oxidize peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue color reaction, which can be easily observed by the naked eye. Furthermore, kinetic studies indicate that the H2TCPP-γ-Fe2O3 nanocomposites have an even higher affinity to TMB than that of the natural enzyme, horseradish peroxidase (HRP). On the basis of the high activity, the reaction provides a simple, sensitive and selective method for colorimetric detection of H2O2 over a range of 10-100 µM with a minimum detection limit of 1.73 µM. Moreover, H2TCPP-γ-Fe2O3/glucose oxidase (GOx)/TMB system provides a novel colorimetric sensor for glucose and shows good response toward glucose detection over a range of 5-25 µM with a minimum detection limit of 2.54 µM. The results indicated that it is a simple, cheap, convenient, highly selective, sensitive and easy handling colorimetric assay. Results of a fluorescent probe suggest that the catalase-mimic activity of the H2TCPP-γ-Fe2O3 nanocomposites effectively catalyze the decomposition of H2O2 into H2O and O2.

NiO nanoparticles modified with 5,10,15,20-tetrakis(4-carboxyl pheyl)-porphyrin: promising peroxidase mimetics for H2O2 and glucose detection.

NiO nanoparticles (NPs) and 5,10,15,20-tetrakis(4-carboxyl pheyl)-porphyrin (H2TCPP) functionalized NiO nanoparticles (H2TCPP-NiO nanocomposites) have been prepared by a facile method and characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared spectra (FTIR), respectively. NiO NPs and H2TCPP-NiO nanocomposites have been proven to function as peroxidase mimetics that can catalyze the reaction of peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue color reaction. Kinetic analysis indicated that the catalytic behavior was in accord with typical Michaelis-Menten kinetics. And these nanoparticles also exhibited strong affinity for the substrates of 3,3,5,5-tetramethylbiphenyl dihydrochloride (TMB). Experimental results showed that H2TCPP-NiO NPs exhibited a high sensitivity and a low detection limit towards H2O2 (8.0 × 10(-6) M). The H2TCPP-NiO NPs/glucose oxidase (GOx)/TMB system provides a novel colorimetric sensor for glucose and shows good response toward glucose detection over arrange of 0.05-0.50 mM with a limit of detection 2.0 × 10(-5)M. Fluorescence probe experiments demonstrated that the peroxidase-like activity of H2TCPP-NiO NPs originated from the generation of OH radical. Thus it may provide great potential applications in biomedicine, biotechnology and environmental chemistry.

Higher catalytic activity of porphyrin functionalized Co3O 4 nanostructures for visual and colorimetric detection of H2 O2 and glucose.

5,10,15,20-Tetrakis(4-carboxyl pheyl)-porphyrin (H2TCPP) functionalized chain-like Co3O4 nanoparticles (NPs) were prepared by a facile two-step method. The H2TCPP-Co3O4 nanocomposites were demonstrated to display enhanced peroxidase-like activity than that of pure Co3O4 nanoparticles without modification with H2TCPP molecules, catalyzing oxidation of peroxidase substrate 3,3',5,5'-tetramethyl-benzidine (TMB) in the presence of H2O2 to produce a blue color reaction. Furthermore, H2TCPP-Co3O4 nanocomposites showed typical Michaelis-Menten kinetics and higher affinity to H2O2 and TMB than that of pure Co3O4 NPs alone. Based on H2TCPP-Co3O4 nanocomposites, a simple, sensitive and selective colorimetric method with TMB as the substrate for the detection of H2O2 and glucose was successfully established. This colorimetric method can be used for the colorimetric detection of H2O2 with a low detection limit of 4×10(-7)mol·L(-1) and a dynamic range of 1×10(-6)mol·L(-1) to 75×10(-6)mol·L(-1). This method was designed to detect glucose when combined with glucose oxidase at a low detection limit of 8.6×10(-7)mol·L(-1) and a dynamic range of 1×10(-6)mol·L(-1) to 10×10(-6)mol·L(-1). Results of a fluorescent probe suggested that the peroxidase-mimic activity of the H2TCPP-Co3O4 nanocomposites effectively catalyzed the decomposition of H2O2 into [OH] radicals.

5,10,15,20-tetrakis(4-carboxyl phenyl)porphyrin-CdS nanocomposites with intrinsic peroxidase-like activity for glucose colorimetric detection.

Here, we describe the design of a novel mimic peroxidase, nanocomposites composed by 5,10,15,20-tetrakis(4-carboxyl phenyl)-porphyrin (H2TCPP) and cadmium sulfide (CdS). The H2TCPP-CdS nanocomposites can catalyze oxidation of substrate 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H2O2 and form a blue product which can be seen by the naked eye in 5 min. The mechanism of the catalytic reaction originated from the generation of hydroxyl radical (·OH), which is a powerful oxidizing agent to oxidize TMB to produce a blue product. Then, we developed a colorimetric method that is highly sensitive and selective to detect glucose, combined with glucose oxidase (GOx). The proposed method allowed the detection of H2O2 concentration in the range of 4×10(-6)-1.4×10(-5)M and glucose in the range of 1.875×10(-5)-1×10(-4)M with detectable H2O2 concentration as low as 4.6×10(-7)M and glucose as low as 7.02×10(-6)M, respectively. The results provided the theoretical basis of practical application in glucose detecting and peroxidase mimetic enzymes.

Glucose-sensitive colorimetric sensor based on peroxidase mimics activity of porphyrin-Fe3O4 nanocomposites.

5,10,15,20-Tetrakis(4-carboxyphenyl)-porphyrin-functionalized Fe3O4 nanocomposites (H2TCPP-Fe3O4) were successfully prepared by a simple two-step method. These nanocomposites exhibited ultra-high peroxidase-like activity compared with pure Fe3O4 nanoparticles. Colorless peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) was changed by H2O2 to its blue oxidized state. Kinetic studies indicated that the H2TCPP-Fe3O4 nanocomposites exhibited enhanced affinity toward H2O2 with a higher catalytic activity than Fe3O4 nanoparticles alone. Results of a fluorescent probe suggested that the catalase-mimic activity of the H2TCPP-Fe3O4 nanocomposites effectively catalyzed the decomposition of H2O2 into hydroxyl radicals. A simple, sensitive, and selective visual and colorimetric method with TMB as the substrate was designed to detect glucose when combined with glucose oxidase. This colorimetric method can be used for colorimetric detection of H2O2 with a minimum detection limit of 1.07×10(-6) M and a dynamic range of 5×10(-6) mol·L(-1) to 8×10(-5) mol·L(-1). This method can also be used to detect glucose at a minimum detection limit of 2.21×10(-6) M and a dynamic range of 25×10(-6) mol·L(-1) to 5×10(-6) mol·L(-1). Furthermore, the robustness of the nanocomposites makes them suitable for a wide range of applications in biomedicine and environmental chemistry fields.