Anisotropy engineering was exploited to prevent the skyrmion Hall effect that is bad for application in memory.

Heat flux sensors(HFSs) are extensively used in combustion-related applications to collect important engineering data. However, most non-water cooling HFSs lack the durability to survive in the harsh, high-temperature environments where they are employed.A new type of thin-film HFS based on a W-5Re/W-26Re thermocouple has been developed for high-temperature heat flux measurement. The sensor consists of 136 pairs of micron-sized W-5Re/W-26Re thin-film thermocouples, an SiO2 thermal-resistance layer, and an AlN substrate. The SiO2 layer is sandwiched between the substrate and thermocouples, and allows the measurement of temperature differences arising from the difference in thermal conductivity between the substrate and the SiO2 layer. A protective layer with a sandwich structure prevents the tungsten-rhenium thin film from oxidizing at high temperatures in air. This small HFS with a protective layer can survive for 1 h in 1000°C air. Calibration data shows that the HFS exhibits repeatable and fast thermal response when a pulsed heat flux of 1000 kW/m2 is applied, and its sensitivity is 3.8×10-6 V/(kW/m2). The experimental data agree with the simulated results. It can be concluded from the experimental results that the tungstenrhenium thin film has a good thermoelectric response to high temperatures after the size is reduced to a micron. Thus, the developed HFS can be a suitable alternative for applications in thermal systems, such as engines, turbines, and rockets.

Magnetic anomaly detection is an effective method for detecting ferromagnetic targets. The practical application of target detection by measuring the magnetic gradient has been confirmed in many studies, and its suppression of background noise has been widely recognized. However, the variation of the unidirectional magnetic field gradient is very small in a short distance, and the amplitude of the signal is also affected by the direction of the target’s magnetic moment and the shaking of the sensor platform itself. These make it difficult to extract the signal from complex background interference. In order to solve these problems, this paper is devoted to use the variation of three axial magnetic gradients in the geomagnetic coordinate system caused by the presence of magnetic target (we call it full magnetic gradient) to construct the magnetic anomaly characteristic of the target. A set of orthonormal basis functions is further derived to linearly describe this characteristic, which improves the signal-to-noise ratio (SNR) of the signal from the perspective of signal energy. The present work main contribution is to propose a full magnetic gradient orthonormal basis function (FMG-OBF) method to effectively characterize magnetic anomaly of magnetic targets. Compared with the traditional one-direction magnetic gradient orthonormal basis function method, the SNR of this method is greatly improved, and it is not affected by a change in the target magnetic moment’s direction nor by the shaking of the sensor carrier platform. Therefore, it has great value in the practical application of aeromagnetic detection.

Objective: Transcranial focused ultrasound (tFUS) is regarded as a promising non-invasive stimulation tool for modulating brain circuits. The aim of this study is to explore the feasibility of tFUS stimulation for analgesia applications. Methods: 50 µl of 3% formalin solution was injected into the rat's left hindpaw to build a pain model, and then the local field potential (LFP) activities of the dorsal horn were tracked after a recording electrode was placed in the spinal cord. Rats were randomly divided into two groups: control group and tFUS group. At the 30 ^th minute after formalin injection, tFUS (US-650 kHz, PD = 1 ms, PRF = 100 Hz, 691 mW/cm ² ) was conducted to stimulate the periaqueductal gray (PAG) for 5 minutes (on 5 s and off 5 s) in the tFUS group, but there was no treatment in the control group. In addition, the analgesia mechanism (LFP recording from the PAG) and safety assessment (histology analysis) were carried out. Results: The tFUS stimulation of the PAG can suppress effectively the nociceptive activity generated by formalin. The findings of the underlying mechanism exploration indicated that the tFUS stimulation was able to activate the PAG directly without causing notable temperature change and tissue injury. Conclusion: The results illustrated that the tFUS stimulation of the PAG can achieve the effect of analgesia. Significance: This work provides new insights into the development of non-invasive analgesic technology in the future.

Recently, super-harmonic ultrasound imaging technology has caused much attention due to its capability of distinguishing microvessles from the tissues surrounding them. However, the fabrication of a dual-frequency confocal transducer is still a challenge. In this work, 270μm PMN-PT single crystal 1-3 composite and 28μm PVDF thick film, acting as transmission layer and receiving layer, respectively, are integrated in a novel co-focusing structure. To realize delicate wave propagation control, microwave transmission line theory is introduced to design such structure. Two acoustic filter layers, 13μm copper layer and 39μm Epoxy 301 layer, are indispensable and should be added between two piezoelectric layers. Therefore, an acoustic issue can be overcome via an electrical method and the successful achievement of a dual-frequency (5MHz/30MHz) ultrasound transducer with confocal distance of 8mm can be realized. The super harmonic ultrasound imaging experiment is conducted using this kind of device. 3D image of 110μm diameter phantom tube injected with microbubbles can be obtained. These promising results demonstrate that this novel dual-frequency (5MHz/30MHz) confocal ultrasound transducer is potentially usable for microvascular medical imaging application in the future.

Magnetoelectric (ME) composite materials have a stronger ME coupling effect in resonant states than in non-resonant states. Typically, these resonant states appear at frequencies of several tens of kHz or even MHz. However, for DC and low-frequency applications of ME composites, obtaining a high ME response is critical. In recent years, many studies have attempted to improve the DC and low-frequency ME performance of ME composite materials at frequencies below 1 kHz. This article reviews the research and major progress in this field and investigates the application of other methods.