scholarly journals Single-Sided Near-Field Wireless Power Transfer by A Three-Dimensional Coil Array

Micromachines ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 200 ◽  
Author(s):  
Amirhossein Hajiaghajani ◽  
Seungyoung Ahn
Keyword(s):  
Magnetic Field ◽  
Printed Circuit Boards ◽  
Signal To Noise Ratio ◽  
Near Field ◽  
3D Structure ◽  
Three Dimensional ◽  
Power Transfer ◽  
Circuit Boards ◽  
Wireless Power ◽  
Halbach Arrays

Wirelessly powered medical microrobots are often driven or localized by magnetic resonance imaging coils, whose signal-to-noise ratio is easily affected by the power transmitter coils that supply the microrobot. A controlled single-sided wireless power transmitter can enhance the imaging quality and suppress the radiation leakage. This paper presents a new form of electromagnet which automatically cancels the magnetic field to the back lobes by replacing the traditional circular coils with a three-dimensional (3D) coil scheme inspired by a generalized form of Halbach arrays. It is shown that, along with the miniaturization of the transmitter system, it allows for improved magnetic field intensity in the target side. Measurement of the produced magnetic patterns verifies that the power transfer to the back lobe is 15-fold smaller compared to the corresponding distance on the main lobe side, whilst maintaining a powering efficiency similar to that of conventional planar coils. To show the application of the proposed array, a wireless charging pad with an effective powering area of 144 cm2 is fabricated on 3D-assembled printed circuit boards. This 3D structure obviates the need for traditional magnetic shield materials that place limitations on the working frequency and suffer from non-linearity and hysteresis effects.

Low-cost and compact 3D circularly polarized Microstrip antenna with high efficiency and wide beamwidth

2017 ◽  
Vol 9 (7) ◽  
pp. 1533-1540 ◽  
Author(s):  
Xi Chen ◽  
Zhen Wei ◽  
Dan Wu ◽  
Long Yang ◽  
Guang Fu
Keyword(s):  
Microstrip Antenna ◽  
Printed Circuit Boards ◽  
High Efficiency ◽  
Low Cost ◽  
3D Structure ◽  
Three Dimensional ◽  
Axial Ratio ◽  
Impedance Bandwidth ◽  
Circuit Boards ◽  
Circularly Polarized

A compact three-dimensional (3D) circularly polarized (CP) microstrip antenna is presented in this paper. The antenna adopts three low-cost printed circuit boards to form an integrated and closed 3D structure, and the radiation patch and the feed patches are etched on the surface of that. A crossed slot is cut on the radiation patch to miniaturize the antenna, and triangular feed patches are introduced to increase the bandwidths. In addition, because of the utilization of a low-loss series feed line, the antenna has a high efficiency of more than 95%. A prototype of the antenna is measured to validate the method. The dimensions of the antenna is 0.064λ × 0.36λ (λ is the wavelength in free space at 1.2 GHz). The results indicate that the impedance bandwidth for voltage standing wave ratio ≤ 2 reaches 23%, and the bandwidth for axial ratio (AR) ≤ 3 dB reaches 10.1%. In the overlap band, the gains are > 4.5dBic. Additionally, the 3 dB beamwidth is more than 114°, and the beamwidth for AR ≤ 3 dB is more than 131° at 1.2 GHz.

Cryomicroscopy of crotoxin complex crystals at 400 KV

1989 ◽  
Vol 47 ◽  
pp. 826-827
Author(s):  
Jaap Brink ◽  
Wah Chiu
Keyword(s):  
Signal To Noise Ratio ◽  
3D Structure ◽  
Three Dimensional ◽  
Carbon Films ◽  
Depth Of Field ◽  
Basic Subunit ◽  
Ewald Sphere ◽  
Diffraction Patterns ◽  
Complex Crystals ◽  
Acidic Subunit

The crotoxin complex is a potent neurotoxin composed of a basic subunit (Mr = 12,000) and an acidic subunit (M = 10,000). The basic subunit possesses phospholipase activity whereas the acidic subunit shows no enzymatic activity at all. The complex's toxocity is expressed both pre- and post-synaptically. The crotoxin complex forms thin crystals suitable for electron crystallography. The crystals diffract up to 0.16 nm in the microscope, whereas images show reflections out to 0.39 nm2. Ultimate goal in this study is to obtain a three-dimensional (3D-) structure map of the protein around 0.3 nm resolution. Use of 100 keV electrons in this is limited; the unit cell's height c of 25.6 nm causes problems associated with multiple scattering, radiation damage, limited depth of field and a more pronounced Ewald sphere curvature. In general, they lead to projections of the unit cell, which at the desired resolution, cannot be interpreted following the weak-phase approximation. Circumventing this problem is possible through the use of 400 keV electrons. Although the overall contrast is lowered due to a smaller scattering cross-section, the signal-to-noise ratio of especially higher order reflections will improve due to a smaller contribution of inelastic scattering. We report here our preliminary results demonstrating the feasability of the data collection procedure at 400 kV.Crystals of crotoxin complex were prepared on carbon-covered holey-carbon films, quench frozen in liquid ethane, inserted into a Gatan 626 holder, transferred into a JEOL 4000EX electron microscope equipped with a pair of anticontaminators operating at −184°C and examined under low-dose conditions. Selected area electron diffraction patterns (EDP's) and images of the crystals were recorded at 400 kV and −167°C with dose levels of 5 and 9.5 electrons/Å, respectively.

scholarly journals Electrochemical migration behavior of moldy printed circuit boards in a 10 mT magnetic field

RSC Advances ◽  
2021 ◽  
Vol 11 (45) ◽  
pp. 28178-28188
Author(s):  
Xuan Liu ◽  
Ziheng Bai ◽  
Qianqian Liu ◽  
Yali Feng ◽  
Chaofang Dong ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Failure Mechanism ◽  
Printed Circuit Boards ◽  
Electrochemical Migration ◽  
Migration Behavior ◽  
Circuit Boards ◽  
Printed Circuit

Proposed failure mechanism of electrochemical migration under an external magnetic field caused by mold.

scholarly journals A Reconfigurable Coil grid for Receiver Localization in Wireless Power Transfer and Magnetic Field Steering

2020 ◽  
pp. 1-1
Author(s):  
Jaafar Al Sinayyid ◽  
Hakim Takhedmit ◽  
Patrick Poulichet ◽  
Marjorie Grzeskowiak ◽  
Antoine Diet ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Wireless Power Transfer ◽  
Power Transfer ◽  
Wireless Power
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