Comparative study on the validity of monitoring test indexes of healthy fitness cardiopulmonary track and field sensor

With the continuous increase in social pressure and people’s higher urgency for physical health, the concept of healthy physical fitness has become more and more important and prominent. However, the research and standards for the validity of the health fitness monitoring test indicators have not been determined. In order to compare the validity of the health fitness test indicators, we adopt the cardiopulmonary track and field sensor technology to monitor the health fitness cardiopulmonary track and field sensor. A comparative study on the validity of test indicators, mainly to test the rationality of the cardiopulmonary endurance evaluation indicators of healthy physical fitness, and to carry out a new design of the concept of healthy physical fitness in track and field teaching, so that it is more inclined to improve the healthy physical fitness of athletes fitness. Research data shows that the average absolute value of the athlete’s maximum oxygen consumption is 2.51 L/min, the highest value is 3.96 L/min, and the lowest is 2.03 L/min. The average value of the absolute maximum oxygen consumption of girls is 1.79 L/min, the highest value is 2.89 L/min, and the minimum is 1.51 L/min. From these data, we can know that compared with traditional cardiopulmonary monitoring methods, the sensor monitoring studied in this paper has higher accuracy and wider application range. The peak cardiopulmonary power of athletes’ cardiopulmonary function detection using this method is closer to the actual value, while for the peak cardiopulmonary power detected by traditional methods, there is a big difference between the power and the actual value. For different athletes, the advantages of the algorithm in this paper are more obvious, indicating that the method in this paper has a higher detection accuracy for the cardiopulmonary function test of athletes during aerobic training.

Improvement of the detectivity in an Fe-Sn magnetic-field sensor with a large current injection

A ferromagnetic nanocrystalline Fe-Sn is an excellent platform for magnetic-field sensor based on anomalous Hall effect (AHE) owing to simple fabrication and superior thermal stability. For improvement of the magnetic-field sensitivity, doping impurity and increasing injection current are effective approaches. However, in the light of magnetic-field detectivity, the large current may increase the voltage noise. In this study, a maximum allowable current of was improved by employing the overlayer electrode configuration on a Ta-doped Fe-Sn AHE sensor. In noise measurements, the 1/f noise becomes significant with increasing the current at low frequency, resulting in saturation of the detectivity to 240 nTHz-1/2 at 120 Hz. At high frequency, the detectivity reaches 48 nTHz-1/2 at 3.1 mA showing ten times improvement of the detectivity compared with the non-doped Fe-Sn AHE sensor. Material design and device structure optimization will accelerate further improvement of the sensing properties of the Fe-Sn-based AHE sensor.

Surface-Integrated Electric Field Sensor for the Detection of High-Voltage Power Lines

When a drone is used for inspection of facilities, there are often cases in which high-voltage power lines interfere, resulting in the drone being caught or falling. To prevent this type of incident, drones must be capable of detecting high-voltage power lines. Typically, a strong electric field is formed around the high-voltage lines. To detect the electric fields around high-voltage lines, this study proposes an electric field sensor that may be integrated within the body of a drone. In a laboratory environment, a voltage of 25 kV was applied to an overhead line, and the induced voltage in the proposed sensor was measured at various electric field intensities. Over an electric field range of 0.5 to 10.1 kV/m, a voltage of 0 to 0.77 V was measured with each proposed sensor. In addition, the electric field and the voltage induced in the sensor were measured in a real-world railway environment with overhead lines. Under these conditions, the proposed sensor has the compensated value of 4.5 when the measured electric field was 4.05 kV/m. Therefore, the proposed sensor may be applied in drones to measure large electric fields and to detect the presence of high-voltage lines in its vicinity.

Thin-Film-Based SAW Magnetic Field Sensors

In this work, the first surface acoustic-wave-based magnetic field sensor using thin-film AlScN as piezoelectric material deposited on a silicon substrate is presented. The fabrication is based on standard semiconductor technology. The acoustically active area consists of an AlScN layer that can be excited with interdigital transducers, a smoothing SiO2 layer, and a magnetostrictive FeCoSiB film. The detection limit of this sensor is 2.4 nT/Hz at 10 Hz and 72 pT/Hz at 10 kHz at an input power of 20 dBm. The dynamic range was found to span from about ±1.7 mT to the corresponding limit of detection, leading to an interval of about 8 orders of magnitude. Fabrication, achieved sensitivity, and noise floor of the sensors are presented.

A Highly Sensitive and Miniature Optical Fiber Sensor for Electromagnetic Pulse Fields

The detection of an electromagnetic pulse (EMP) field is of great significance in determining the field environment of tested equipment in small spaces. Finger-shaped miniature optical fiber sensors for electromagnetic pulse field measurement were designed. The antenna of a weak field sensor was integrated with a shielding shell, and the wire welded at the direct electro-optic converting circuit connected to an optical fiber through special structure and circuit design was taken as the antenna of a strong field sensor. Measurements in the time domain and frequency domain had been carried out for the two sensors. Experiment results demonstrate that the weak field sensor and the strong field sensor have flat responses from 100 kHz to 1 GHz with a variation of 2.3 dB and 2.9 dB, respectively, and the EMP waveform detected by the sensors agrees well with the applied standard square wave. Moreover, the strong field sensor exhibits linear responses from 645 V/m to 83 kV/m. The resolution of the weak field sensor is as low as 13 V/m. The result indicated that the designed sensors had good performance.

All Fiber Mach–Zehnder Interferometer Based on Intracavity Micro-Waveguide for a Magnetic Field Sensor

A magnetic fluid (MF)-based magnetic field sensor with a filling-splicing fiber structure is proposed. The sensor realizes Mach–Zehnder interference by an optical fiber cascade structure consisting of single mode fiber (SMF), multimode fiber (MMF), and single-hole-dual-core fiber (SHDCF). The core in the cladding and the core in the air hole of SHDCF are used as the reference and sensing light path, respectively, and the air hole of SHDCF is filled with magnetic fluid to realize magnetic field measurement based on magnetic controlled refractive index (RI) characteristics. The theoretical feasibility of the proposed sensing structure is verified by Rsoft simulation, the optimized length of SHDCF is determined by optical fiber light transmission experiment, and the SHDCFs are well fused without collapse through the special parameter setting. The results show that the sensitivity of the sensor is −116.1 pm/Gs under a magnetic field of 0~200 Gs with a good long-term operation stability. The proposed sensor has the advantages of high stability, fast response, simple structure, and low cost, which has development potential in the field of miniaturized magnetic field sensing.

A high-resolution electric field sensor based on piezoelectric bimorph composite

The rapid development of the internet of things (IOT) technology has led to great demand for intelligent electric field sensor (EFS). Several working principles have been proposed, however major challenges remain existed for the requirements of EFS with low-cost, large-range, and high-resolution. In this paper, an EFS based on piezoelectric bending effect using d31 mode is developed, where a bending strain is induced on the sandwiched bimorph structure of PZT/PDMS/PZT under an applied electric field, and the capacitance value of the PDMS layer reveals detectable variation. We demonstrate an electric field sensor operating at the stress-mediated coupling between piezoelectric ceramic and elastic dielectric polymer, which reveals advantages such as simple fabrication process, low-cost and low power consumption. Due to the sandwiched bimorph structure, the strain caused by the electric field can be effectively transferred to improve the resolution of the device. The constitutive equations for the sandwiched bimorph structure are built, and the working principle of the proposed EFS is demonstrated. The EFS exhibits high sensitivity under both AC and DC electric fields, with a resolution of 0.1V/cm in the range of -3 to 3kV/cm. The proposed sensor provides an alternative solution for power equipment fault diagnosis, power frequency electric field detection, etc.