Inch-Sized Thin Metal Halide Perovskite Single-Crystal Wafers for Sensitive X-Ray Detection

Metal halide perovskite single crystals are a promising candidate for X-ray detection due to their large atomic number and high carrier mobility and lifetime. However, it is still challenging to grow large-area and thin single crystals directly onto substrates to meet real-world applications. In this work, millimeter-thick and inch-sized methylammonium lead tribromide (MAPbBr3) single-crystal wafers are grown directly on indium tin oxide (ITO) substrates through controlling the distance between solution surface and substrates. The single-crystal wafers are polished and treated with O3 to achieve smooth surface, lower trap density, and better electrical properties. X-ray detectors with a high sensitivity of 632 µC Gyair−1 cm−2 under –5 V and 525 µC Gyair−1 cm−2 under –1 V bias can be achieved. This work provides an effective way to fabricate substrate-integrated, large-area, and thickness-controlled perovskite single-crystal X-ray detectors, which is instructive for developing imaging application based on perovskite single crystals.

Gain Enhancement of Double-Slot Vivaldi Antenna using Corrugated Edges and Semicircle Director for Microwave Imaging Application

Microwave imaging, such as images for radiological inspection in the medical profession, is one of the applications utilized in ultra-wideband (UWB) frequency ranges. The Vivaldi antenna is one of the most popular antennas for this purpose. The antenna is utilized because of its simple, lightweight, and compact design, as well as its excellent efficiency and gain capabilities. In this work, we present a high-gain Vivaldi antenna for microwave imaging applications. The proposed Vivaldi antenna is designed using a double-slot structure method with the addition of corrugated edges and a semicircle director aimed at improving the gain. The antenna is designed to operate at frequencies ranging from 3.1 to 10.6 GHz. Based on the modeling findings, the suggested antenna attain a bandwidth of 7.5 GHz with operating frequencies from 3.1 GHz to 10.6 GHz for a VSWR of less than two. In comparison to a typical single slot antenna, the suggested antenna provides a substantial boost in gain performance. The increase in gain is proportional to the frequency of operation. The constructed antenna has a lower bandwidth than the simulated one, with operating frequencies of 3.5 GHz – 3.75 GHz and 4.25 – 10.89 GHz, respectively, and useable bandwidths of 250 MHz and 6.64 GHz. All these results suggest that the antenna is suitable for microwave imaging applications.

Synthesis and Characterization of NiFe2O4 Magnetic Nanoparticles for Magnetic Resonance Imaging Application

NiFe2O4 magnetic nanoparticles (MNPs) were synthesized by co-precipitation of iron (III) chloride hexahydrate and nickel (II) chloride hexahydrate in the solution containing 45% hydrazine at 80∘C. Phase, morphology, oxidation state and magnetic properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). In this research, pure NiFe2O4 MNPs synthesized in the solution with the pH of 10 with saturation magnetization of 49.839[Formula: see text]emu/g were detected and were able to be used for magnetic resonance imaging (MRI) application with very high contrast. Highlights:[Formula: see text] NiFe2O4 is used as magnetic nanoparticles. [Formula: see text] They have an excellent saturation magnetization. [Formula: see text] The promising material is used for magnetic resonance imaging application.

Fully Vacuum-Sealed Diode-Structure Addressable ZnO Nanowire Cold Cathode Flat-Panel X-ray Source: Fabrication and Imaging Application

A fully vacuum-sealed addressable flat-panel X-ray source based on ZnO nanowire field emitter arrays (FEAs) was fabricated. The device has a diode structure composed of cathode panel and anode panel. ZnO nanowire cold cathodes were prepared on strip electrodes on a cathode panel and Mo thin film strips were prepared on an anode panel acting as the target. Localized X-ray emission was realized by cross-addressing of cathode and anode electrodes. A radiation dose rate of 10.8 μGy/s was recorded at the anode voltage of 32 kV. The X-ray imaging of objects using different addressing scheme was obtained and the imaging results were analyzed. The results demonstrated the feasibility of achieving addressable flat-panel X-ray source using diode-structure for advanced X-ray imaging.

Pulsed Blue Laser Diode Thermal Desorption Microplasma Imaging Mass Spectrometry

An ambient air laser desorption, plasma ionization imaging method is developed and presented using a microsecond pulsed laser diode for desorption and the flexible microtube plasma for ionization of the neutral desorbate. Inherent parameters such as the laser repetition rate and pulse width are optimized to the imaging application. For the desorption substrate, copper spots on a copper-glass sandwich structure are used. This novel design enables imaging without ablating the metal into the mass spectrometer. On this substrate, fixed calibration markers are used to decrease the positioning error in the imaging process, featuring a 3D offset correction within the experiment. The image is both screened spot-by-spot and per line scanning at a constant speed, which allows direct comparison. In spot-by-spot scanning, a novel algorithm is presented to unfold and to reconstruct the imaging data. This approach significantly decreases the time required for the imaging process, which allows imaging even at decreased sampling rates and thus higher mass resolution. After the experiment, the raw data is automatically converted and interpreted by a second algorithm, which allows direct visualization of the image from the data, even on low-intensity signals. Mouse liver microtome cuts have been screened for dehydrated cholesterol, proving good agreement of the unfolded data with the morphology of the tissue. The method optically resolves 30 μm, with 30 μm diameter copper spots and a 10 μm gap. No conventional chemical matrices or vacuum conditions are required.

Investigation of microwave sensor and integrate with polydimethylsiloxane for medical imaging application

The small-sized wideband antenna is one of the antennas used in the medical field to detect body tissue. The antenna's direct contact with the human body causes reflected signal due to the high body coupling, and the narrower bandwidth tends to reduce the data transfer rate in transmission. Therefore, this paper aims to design a wideband antenna with wearable properties operated in the frequency range of 3 GHz to 6 GHz. The antenna is designed with a rectangular-shaped patch with notches and the t-slot shaped partial slot ground. The connected speech test (CST) studio suite software is used to design and optimize the miniature antenna, which measures 24 mm (W) x 38 mm (L) x 0.168 mm (H). The antenna is then embedded with polydimethylsilixane (PDMS) at the top half of the antenna with the dimension 24 mm (W) x 19 mm (L) x 1 mm (H) and also fully occupied. The antenna is configured with the bending capabilities to adapt the human body surface at an angle of 30º. The antenna is having the benefits of small size, cost-effective, and easy to fabricate. The antenna design can effectively detect unusual body tissue, and it safe to be used.