sensor

Diabetes is a chronic disease that is known as one of the most common and deadly diseases and a great challenge of the World Health Organization. One of the most important issues for people with diabetes is regular monitoring of the blood glucose level and keeping it under control within the normal range. In this research, hollow and nanoporous spheres made of copper cobaltite were synthesized and used as a new sensor to measure glucose.

Methods & materials: 

Hollow and nanoporous copper cobaltite spheres were synthesized by hydrothermal and calcination method. Its structure and morphology were investigated by spectroscopic and imaging methods, and its electrochemical efficiency was investigated by cyclic voltammetry and chronoamperometry techniques.

The results of structural characterization confirmed the spherical morphology and the hollow and nanoporous structure of copper cobaltite. The results of the electrochemical investigations of the sensor electrode also showed that the responses of this electrode in two ranges of 10 μM to 1.5 mM and 1.5 mM to 13 mM were linear with respect to glucose and had a sensitivity of 6.4 and 11.2 mA mM-1 cm-2, respectively. Its response time was about 3.5 seconds and its detection limit was 5 μM (S/N = 3).

This research confirmed the significant potential of hollow and nanoporous copper cobaltite spheres as a new sensor for electrocatalytic measurement of glucose.

wFiber optic sensor based on surface plasmon resonance has certain drawbacks, including limitations in linearity and vulnerability to external temperature fluctuations. In order to achieve this goal, we evaluate a temperature-compensated surface plasmon resonance biosensor that uses a Mach-Zehnder interferometer. The biosensor is made with a structure consisting of a tapered multimode fiber, a single mode fiber and another multimode fiber. The surface plasmon resonance phenomenon is caused by a silver layer modified using reduced graphene oxide and pyrene-boric acid, which brings glucoses together through π-π interactions and glucose bonding. creates Compensation of the effect of ambient temperature on surface plasmon resonance is obtained by stimulating the effect of Mach-Zehnder interferometer using the structure of a single-mode fiber and a multi-mode fiber. In order to investigate the signals of Mach-Zehnder interferometer and surface plasmon resonance separately, we used fast Fourier transform to distinguish the effects of Mach-Zehnder interferometer and surface plasmon resonance. The linearity of the sensor was improved by using a center fitting method that uses the shift of the center coordinates calculated from a single resonant surface plasmon gradient instead of the resonance wavelength. Our test results showed that our sensor has a glucose sensitivity of 2.819 nM/mM. It has a linear range of 0 to 10 mmol/L and is capable of simultaneous temperature compensation. The surface plasmon resonance sensor proposed in this research is compactly designed and suitable for accurate detection of glucose concentration in human blood.

Gallic acid (GA) is one of the polyphenolic compounds with antioxidant, antimicrobial and radical scavenging activities, which plays a main role in human health against cancer and cardiovascular diseases. GA concentration can be quantitatively measured in food, medicinal plants and body fluids.

In this study, MnO2 nanosheets were prepared by reducing potassium permanganate in the presence of Gum Arabic. MnO2 nanosheets rapidly oxidized dopamine substrate and produced fluorescent polydopamine nanoparticles. GA could reduce MnO2 nanosheets to Mn2+, thus, the amount of MnO2 nanoparticles for the formation of polydopamine nanoparticles decreased and the
fluorescent intensity of the mixture decreased.

GA concentration depended on the reduction of fluorescence intensity of the prepared polydopamine nanoparticles. The effects of different experimental parameters such as pH, time and excitation wavelength on the designed sensor were also examined. Under optimized conditions, a good linear relationship was observed between the fluorescence intensity of the system and the concentration of GA in the range of 1.0–100 μmol L−1 with a detection limit of 0.5 μmol L−1. In addition, the developed sensor has a good selectivity on the GA detection.

Furthermore, as a sensitive and selective fluorescent probe, the polydopamine nanoparticles sensor was successfully employed for the detection of GA in real samples.

The purpose of this study was to design of dual-purpose treadmill and gait simulator device for veterans and disabled people. This device can be used by both healthy and stroke patients, spinal cord injury, Parkinson's disease, MS and people who have lost their ability to walk for a temporary period.

The device design is such that the protective waistcoat has sensors to determine the amount of stress applied to the parts where the supporting rope is attached to the waistcoat. The amount of pressure displayed along with other information is displayed on the screen embedded in the device so that the therapist is aware of the information while practicing.

The treadmill is also designed in two ways, which can be adjusted automatically to allow the individual to move at their desired speed, as well as to be able to manually move the treadmill by applying pressure through the legs.

This treadmill causes of strengthens the muscles of people with disabilities who have lost their ability to walk for a while and, in addition, their muscles have weakened. Also, the protective waistcoat has a pressure sensor that can be adjusted based on body weight.

Meat is one of the main sources of animal protein that is required and used for human consumption. Chicken meat due to the availability and economic reasons has high consumption in human societies and freshness is the most important qualitative feature of chicken meat. A device is required and necessary for detection of fresh-chilled chicken meat from frozen-thawed ones.

In this research, a portable olfactory machine based on eight semiconductor metal oxide sensors was used for detecting the freshness of chicken meat. Ten grams of meat was uesd for each test followed by preprocessing and the data were analyzed by PCA and KNN methods.

Based on the results of PCA and KNN analysis, the freshness of chicken meat was detected with high accuracy by e-nose system. The loading and radar charts showed that the odor of chicken meat had the highest and lowest impact on the MQ136 and the TGS822 sensors, respectively.

The olfactory machine system is a very effective way to identify the freshness of chicken meat, which is based on the speed, low cost and reliability of the sensors.

Dicloran pesticide is used to inhibit the fungal spore germination for different crops. Due to the increasing application of pesticides, evaluating the occupational and environmental exposures by reliable and accurate analytical methods is necessary. This work was aimed to design the high selective sensor to determine the dicloran in biological and environmental samples.
Multi-walls carbon nanotubes and a molecularly imprinted polymer (MIP) were used as modifiers in the senor composition. A dicloran MIP was synthesized and applied in the carbon paste electrode (CP). After optimizing the electrode composition, it was used to determine the concentration of analyte. Parameters affecting the sensor response, such as sample pH, electrolyte concentration and its pH, and the instrumental parameters of square wave voltammetry were selected following some experiments.
The MIP-CP electrode showed very high recognition ability for determining of dicloran in different matrices (tap water, river water, and urine). The obtained linear range was 1×10-6 to 1×10-9 mol L-1. The detection limit was 4.8×10-10 molL-1. No interfering effects was seen due to the other compounds in matrix.
Selective sensors can successfully used to determine the analyte of interest in different environmental and biological samples without special sample pretreatment before analysis.

Para-nitro phenol is one of the most important nitro benzenes witch widely used in synthesis of different industrial compounds. It remains in soil, groundwater and air for a long time and has toxic effects and poses a threat to humans, animals and plants. In order to evaluate the safety of water and food resources, it is important to develop efficient, simple and reliable methods for the determination of trace amounts of p-nitro phenol.
In the preset work in order to determine the trace amount of para-nitro phenol, a very simple and sensitive sensor based on the in situ electro-synthesis of nickel oxide nanostructure on the surface of the glassy carbon (GC) electrode was fabricated. Electro-deposition in acidic media produces hydrogen bubble witch causing deposition of porous film of nickel oxide on the electrode surface. Cyclic voltammetry and electrochemical impedance spectroscopy were used for investigation of electro-deposited film.
Findings: Results showed that electro-deposited film has very good electrocatalytic properties for para-nitro phenol destruction. By modification of glassy carbon electrode surface with this nanostructure film, sensitive electrochemical sensor for determination of p-nitro phenol using cyclic voltammetry method was fabricated. Detection limit (signal/noise = 3), sensitivity and linear range of sensor were 40 nM, 0.3245 µA µm-1 and 40-750 µM, respectively.
Result showed that the sensor can be used for sensitive determination of para-nitro phenol.

Diazinon is commonly used for pest control in the agricultural fields because of its relatively low cost and high efficiency. Due to the increasing application of pesticides, reliable and accurate analytical methods are necessary for their monitoring. This work was aimed to design the high selective electrochemical sensor for determining of diazinon in biological and environmental samples. The composition of sensor was modified with multi-walls carbon nanotubes and a molecularly imprinted polymer (MIP). A diazinon MIP was synthesized and applied in the carbon paste electrode (CP). The prepared sensor was used to determine the concentration of analyte. Parameters affecting the sensor response, such as sample pH, electrolyte concentration and its pH, and the instrumental parameters of square wave voltammetry, were optimized in different levels to select the optimum conditions for analysis of diazinon. The MIP-CP electrode showed very high specificity for determining the analyte. The obtained linear range was 1×10-6 to 5×10-10 mol L-1. The detection limit was 2.7×10-10 molL-1. This sensor was successfully used to determine the diazinon in environmental and biological real samples without special sample pretreatment before analysis.