Flexible Ultrasonic Transducers for Wearable Biomedical Applications: A Review on Advanced Materials, Structural Designs, and Future Prospects.

Due to the rapid developments in materials science and fabrication techniques, wearable devices have recently received increased attention for biomedical applications, particularly in medical ultrasound imaging, sensing, and therapy. Ultrasound is ubiquitous in biomedical applications because of its non-invasive nature, nonionic radiating, high precision, and real-time capabilities. While conventional ultrasound transducers are rigid and bulky, flexible transducers can be conformed to curved body areas for continuous sensing without restricting tissue movement or transducer shifting. This article comprehensively reviews the application of flexible ultrasound transducers in the field of biomedical imaging, sensing, and therapy. First, we review the background of flexible ultrasound transducers. Following that, we discuss advanced materials and fabrication techniques for flexible ultrasound transducers and their enabling technology status. Lastly, we highlight and summarize some promising preliminary data with recent applications of flexible ultrasound transducers in biomedical imaging, sensing, and therapy. We also provide technical barriers, challenges, and future perspectives for further research and development.

TAP: targeting and analysis pipeline for optimization and verification of coil placement in transcranial magnetic stimulation.

Objective.Transcranial magnetic stimulation (TMS) can modulate brain function via an electric field (E-field) induced in a brain region of interest (ROI). The ROI E-field can be computationally maximized and set to match a specific reference using individualized head models to find the optimal coil placement and stimulus intensity. However, the available software lacks many practical features for prospective planning of TMS interventions and retrospective evaluation of the experimental targeting accuracy.Approach.The TMS targeting and analysis pipeline (TAP) software uses an MRI/fMRI-derived brain target to optimize coil placement considering experimental parameters such as the subject's hair thickness and coil placement restrictions. The coil placement optimization is implemented in SimNIBS 3.2, for which an additional graphical user interface (TargetingNavigator) is provided to visualize/adjust procedural parameters. The coil optimization process also computes the E-field at the target, allowing the selection of the TMS device intensity setting to achieve specific E-field strengths. The optimized coil placement information is prepared for neuronavigation software, which supports targeting during the TMS procedure. The neuronavigation system can record the coil placement during the experiment, and these data can be processed in TAP to quantify the accuracy of the experimental TMS coil placement and induced E-field.Main results.TAP was demonstrated in a study consisting of three repetitive TMS sessions in five subjects. TMS was delivered by an experienced operator under neuronavigation with the computationally optimized coil placement. Analysis of the experimental accuracy from the recorded neuronavigation data indicated coil location and orientation deviations up to about 2 mm and 2°, respectively, resulting in an 8% median decrease in the target E-field magnitude compared to the optimal placement.Significance.TAP supports navigated TMS with a variety of features for rigorous and reproducible stimulation delivery, including planning and evaluation of coil placement and intensity selection for E-field-based dosing.

An induction voltage adder with MHz repetition rates and nanosecond duration based on printed circuit board stacked Blumlein lines.

By utilizing the radio-frequency metal-oxide-semiconductor field-effect transistor switch, the multi-stage stacked printed circuit board Blumlein lines, and the induction voltage adder, a voltage generator with MHz repetition rates and nanosecond duration was designed and fabricated. The shunting current of the multi-stage stacked Blumlein lines, which consists of the coupling current at the load ends and the leakage current at the switch ends, is clarified. The circuit simulation and experiment of the three-stage stacked Blumlein lines are carried out; the result shows that the experiment and simulation agree well. The five-stage IVA prototype is designed for generating voltage pulses of ∼10 kV in amplitude and 8-11 ns in duration with MHz burst repetition rates. The voltage generator with MHz repetition rates and nanosecond duration demonstrated an important application prospect to reduce the electron beam initial emittance of the high energy accelerator.

A Fluorescent Sensor Synthesized Using Silica Nanoparticles for Detecting Hg²âº in Aqueous Solution.

With the aim of detecting Hg²âº in aqueous solution, a new fluorescent nanosensor (RhB-APTES-SiNPs) for the determination of Hg²âº has been successfully developed. This senor was synthesized by immobilizing RhB-APTES on the surface of silica nanoparticles (SiNPs), which were prepared using the reverse microemulsion method. RhB-APTES-SiNPs can detect Hg²âº on-line, in real time and with the naked eye, thus providing "turn-on" fluorescence enhancement. The developed nanosensor exhibits highly sensitivity and selectivity over several cations in aqueous solution. Additionally, RhB-APTES-SiNPs exhibits an excellent ability to detect Hg²âº within a linear range from 1 to 6 µM, and its detection limit was calculated to be 0.5 ppb.

catena-Poly[[tetra-µ-formato-κ(8) O:O'-dicopper(II)]-µ-hexa-methyl-ene-tetra-mine-κ(2) N (1):N (5)].

In the title polymeric compound, [Cu2(HCO2)4(C6H12N4)] n , the Cu(II) atom is five-coordinated in a square-pyramidal geometry that is defined by four O atoms from four formate ligands and one N atom from a hexa-methyl-ene-tetra-mine ligand. The two Cu(II) atoms are separated by 2.6850 (7) Å, and together with the four formate ligands they form a paddle-wheel unit. The hexa-mine ligand uses only two of its four N atoms to link Cu2 cluster units, affording a zigzag chain running along the b-axis direction. The hexa-mine ligand lies on a mirror plane.

4,4'-Bipyridine-dimethyl-glyoxime (1/1).

In the title compound, C(10)H(8)N(2)·C(4)H(8)N(2)O(2), both the dimethyl-glyoxime and the 4,4'-bipyridine mol-ecules have crystallographic C(i) symmetry. The mol-ecules stack along the a-axis direction with a dihedral angle of 20.4 (8)° between their planes. In the crystal, the components are linked by O-H⋯N hydrogen bonds into alternating chains along [120] and [1[Formula: see text]0].