Planar Excitation Research Articles

Terminal differentiation precedes functional circuit integration in the peduncle neurons in regenerating Hydra vulgaris

Understanding how neural circuits are regenerated following injury is a fundamental question in neuroscience. Hydra is a powerful model for studying this process because it has a simple neural circuit structure, significant and reproducible regenerative abilities, and established methods for creating transgenics with cell-type-specific expression. While Hydra is a long-standing model for regeneration and development, little is known about how neural activity and behavior is restored following significant injury. In this study, we ask if regenerating neurons terminally differentiate prior to reforming functional neural circuits, or if neural circuits regenerate first and then guide the constituent naive cells toward their terminal fate. To address this question, we developed a dual-expression transgenic Hydra line that expresses a cell-type-specific red fluorescent protein (tdTomato) in ec5 peduncle neurons, and a calcium indicator (GCaMP7s) in all neurons. With this transgenic line, we can simultaneously record neural activity and track the reappearance of the terminally-differentiated ec5 neurons. Using SCAPE (Swept Confocally Aligned Planar Excitation) microscopy, we monitored both calcium activity and expression of tdTomato-positive neurons in 3D with single-cell resolution during regeneration of Hydra’s aboral end. The synchronized neural activity associated with a regenerated neural circuit was observed approximately 4 to 8 hours after expression of tdTomato in ec5 neurons. These data suggest that regenerating ec5 neurons undergo terminal differentiation prior to re-establishing their functional role in the nervous system. The combination of dynamic imaging of neural activity and gene expression during regeneration make Hydra a powerful model system for understanding the key molecular and functional processes involved in neural regeneration following injury.

A simple way to achieve planar excitation of arc-shaped array feeds in two-dimensional beam-steerable spherical lens antenna

In this article, a simple technique for achieving planar excitation positions of arc-shaped array feeds in a two-dimensional (2D) beam-steerable spherical lens antenna (SLA) is proposed. Specifically, a cuboid solder model is introduced to connect the feedlines of the feeds with the coaxial probe. An equivalent circuit model of the bowtie feed unit with solder is proposed to illustrate the impact of the introduced solder on the port matching. Additionally, the excitation position is altered by extending the microstrip feedline, which does not change the radiation structure of the feed nor affect its phase center. Subsequently, a homogeneous dielectric SLA with a 139-element bowtie-shaped dipole feed array is constructed to verify the planar excitation position scheme for the arc-shaped array feeds, which facilitates system integration. The theoretical calculation formulas for the beam pointing angles of numerous beams are also proposed. In the fabricated prototype, all feeds exhibit an overlapping bandwidth of 31–36.7 GHz for reflection coefficients, with the coupling less than -20 dB. The 139 switched beams cover a 2D continuous beam space of [−33°, 33°], with adjacent beam crossover levels around -4 dB. The measured peak gain is 28.7 dBi at 34.5 GHz, with an aperture efficiency of 57%.

Dynamics of a 3D Piezo-Magneto-Elastic Energy Harvester with Axisymmetric Multi-Stability.

In this investigation, a three-dimensional (3D) axisymmetric potential well-based nonlinear piezoelectric energy harvester is proposed to increase the broadband frequency response under low-strength planar external excitation. Here, a two-dimensional (2D) planar bi-stable Duffing potential is generalized into three dimensions by utilizing axial symmetry. The resulting axisymmetric potential well has infinitely many stable equilibria and one unstable equilibria at the highest point of the potential barrier for this cantilevered oscillator. Dynamics of such a 3D piezoelectric harvester with axisymmetric multi-stability are studied under planar circular excitation motion. Bifurcations of average power harvested from the two pairs of piezoelectric patches are presented against the frequency variation. The results show the presence of several branches of large-amplitude cross-well type period-1 and subharmonic solutions. Subharmonics involved in such responses are verified from the Fourier spectra of the solutions. The identified subharmonic solutions perform interesting patterns of curvilinear oscillations, which do not cross the potential barrier through its highest point. These solutions can completely or partially avoid the climbing of the potential barrier, thereby requiring low input excitation energy for barrier crossing. The influence of excitation amplitude on the bifurcations of normalized power is also investigated. Through multiple solution branches of subharmonic solutions, producing comparable power to the period-1 branch, broadband frequency response characteristics of such a 3D axisymmetically multi-stable harvester are highlighted.

Combined ion beam irradiation platform and 3D fluorescence microscope for cellular cancer research.

To improve particle radiotherapy, we need a better understanding of the biology of radiation effects, particularly in heavy ion radiation therapy, where global responses are observed despite energy deposition in only a subset of cells. Here, we integrated a high-speed swept confocally-aligned planar excitation (SCAPE) microscope into a focused ion beam irradiation platform to allow real-time 3D structural and functional imaging of living biological samples during and after irradiation. We demonstrate dynamic imaging of the acute effects of irradiation on 3D cultures of U87 human glioblastoma cells, revealing characteristic changes in cellular movement and intracellular calcium signaling following ionizing irradiation.

Neuromuscular basis of Drosophila larval rolling escape behavior.

When threatened by dangerous or harmful stimuli, animals engage in diverse forms of rapid escape behaviors. In Drosophila larvae, one type of escape response involves C-shaped bending and lateral rolling followed by rapid forward crawling. The sensory circuitry that promotes larval escape has been extensively characterized; however, the motor programs underlying rolling are unknown. Here, we characterize the neuromuscular basis of rolling escape behavior. We used high-speed, volumetric, Swept Confocally Aligned Planar Excitation (SCAPE) microscopy to image muscle activity during larval rolling. Unlike sequential peristaltic muscle contractions that progress from segment to segment during forward and backward crawling, muscle activity progresses circumferentially during bending and rolling escape behavior. We propose that progression of muscular contraction around the larva's circumference results in a transient misalignment between weight and the ground support forces, which generates a torque that induces stabilizing body rotation. Therefore, successive cycles of slight misalignment followed by reactive aligning rotation lead to continuous rolling motion. Supporting our biomechanical model, we found that disrupting the activity of muscle groups undergoing circumferential contraction progression leads to rolling defects. We use EM connectome data to identify premotor to motor connectivity patterns that could drive rolling behavior and perform neural silencing approaches to demonstrate the crucial role of a group of glutamatergic premotor neurons in rolling. Our data reveal body-wide muscle activity patterns and putative premotor circuit organization for execution of the rolling escape response.

The spatial and temporal structure of neural activity across the fly brain

What are the spatial and temporal scales of brainwide neuronal activity? We used swept, confocally-aligned planar excitation (SCAPE) microscopy to image all cells in a large volume of the brain of adult Drosophila with high spatiotemporal resolution while flies engaged in a variety of spontaneous behaviors. This revealed neural representations of behavior on multiple spatial and temporal scales. The activity of most neurons correlated (or anticorrelated) with running and flailing over timescales that ranged from seconds to a minute. Grooming elicited a weaker global response. Significant residual activity not directly correlated with behavior was high dimensional and reflected the activity of small clusters of spatially organized neurons that may correspond to genetically defined cell types. These clusters participate in the global dynamics, indicating that neural activity reflects a combination of local and broadly distributed components. This suggests that microcircuits with highly specified functions are provided with knowledge of the larger context in which they operate.

Temperature profile and thermal piston component of photoacoustic response calculated by the fractional dual-phase-lag heat conduction theory

We present the temperature distribution predictions for photothermal systems by considering an extension of dual-phase lag. It is an extension of the GCE-II and GCE-III models with a fractional dual-phase lag from kinetic relaxation time. Solving the one-dimensional problem considering a planar and periodic excitation, we obtained the temperature distribution and the Photoacoustic (PA) signal for the transmission setup. We also analyze the effects of fractional order derivatives and kinetic relaxation time. It is shown that the derived models have promising results that could be used to explain the experimentally observed behavior of PA signals measured on thin films with an inhomogeneous internal structure.

Analysis and Optimization of Planar Excitation Coil for EPS Torque Senor Based on GWO

Planar coil is usually used as a basic element in various research fields. This paper models a sensor equivalent circuit by taking the planar spiral excitation coil as an optimization object according to the electromagnetic coupling principle. The influence of coil electrical parameters on the coupling efficiency is analysed. The present result shows that the excitation coil should be small size, large inductance and high-quality factor. A two-dimensional planar spiral coil is modelled using ANSYS Maxwell software. The coil structure parameters with significant influence on the coil quality factor are chosen by the single factor experiment. The two-factor, five-level central composite deign principle is selected to establish a multivariate quadratic model by Response Surface Methodology (RSM). Then the paper implemented Grey Wolf Optimizer (GWO) to optimize response surface model, and obtained the optimal coil structure parameters. The conclusion was drawn that the inductance and quality factor of the optimized coil increase from 27.031 μH and 161.293 to 43.171 μH and 175.537, respectively. Compared to the control coil, the inductance is 1.597 times as the original coil and the quality factor is increased by 8.8%.

Design, simulation and fabrication of non-spiral based fluxgate sensor on printed circuit board (PCB)

This paper presents performance characteristics of non-spiral planar excitation and pick-up micro-coils implemented for a fluxgate sensor with a NiFe magnetic rod core.Using Ansys Maxwell's software, the sensor performance is simulated. Magnetic flux[ϕ], magnetic flux density [B], magnetic field intensity [H], coupling coefficient, inductance [L] and magnetic energy [E] of the coils are simulated for a set of excitation currents. A simple, cost-effective and less complex fabrication method is implemented to fabricate the sensor using Printed Circuit Board (PCB) technology. Non-spiral 5-turn fluxgate sensor of dimensions 50mmx 20mmx 0.5 mm [length × breadth × width] is fabricated and analysed at an excitation current with a fundamental frequency of 500 kHz. Two excitation coils and one pick-up coil are deposited on a horizontal PCB plane and NiFe rod type material is placed on it, which acts as the core. Synthetic glue is spread on the coils; it acts a insulator between the coils and the core. Copper is used for deposition of the both the excitation and pick-up coils. On applying different excitation current, the frequency response of the non-spiral fluxgate sensor is plotted. The sensor demonstrated earth magnetic field strength detection (∼25 μT).

Numerical study of coupled slosh modes in a 3D vessel subjected to multi-directional excitations

Present study explores liquid sloshing in a three-dimensional (3D) rectangular tank subjected to surge and coupled surge, sway and heave excitations. A number of applications of practical interest in nuclear systems such as, spent fuel storage tanks, fast reactor vessels, pool type coolant etc will be benefited from such analysis. Effect of harmonic excitation is investigated emphasizing finite liquid depth when the internal resonance condition 1:1 is satisfied between the natural frequencies of dominant modes (1,0), (0,1) and (0,2). The numerical model was validated against available in–house experimental shake table studies. Temporal snapshots of velocity magnitudes and free surface time history at different locations are presented when the tank is excited under two different loading conditions. The amplification of diagonal slosh modes were observed under planar excitation. This analysis assumes significance, as the attendant hydrodynamic forces could eventually cause fatigue failure of the tank structure. Non-linear square-like, swirling and wave breaking features were observed, when the tank was subjected to earthquake excitation.

High-speed light-sheet microscopy for the in-situ acquisition of volumetric histological images of living tissue.

Histological examinations typically require the excision of tissue, followed by its fixation, slicing, staining, mounting and imaging, with timeframes ranging from minutes to days. This process may remove functional tissue, may miss abnormalities through under-sampling, prevents rapid decision-making, and increases costs. Here, we report the feasibility of microscopes based on swept confocally aligned planar excitation technology for the volumetric histological imaging of intact living tissue in real time. The systems' single-objective, light-sheet geometry and 3D imaging speeds enable roving image acquisition, which combined with 3D stitching permits the contiguous analysis of large tissue areas, as well as the dynamic assessment of tissue perfusion and function. Implemented in benchtop and miniaturized form factors, the microscopes also have high sensitivity, even for weak intrinsic fluorescence, allowing for the label-free imaging of diagnostically relevant histoarchitectural structures, as we show for pancreatic disease in living mice, for chronic kidney disease in fresh human kidney tissues, and for oral mucosa in a healthy volunteer. Miniaturized high-speed light-sheet microscopes for in-situ volumetric histological imaging may facilitate the point-of-care detection of diverse cellular-level biomarkers.

A novel planar differential excitation eddy current probe based on the fractal Koch curve

Planar eddy current (EC) probe is one of the most important EC probe for detecting the defects in conductive parts. A novel planar differential excitation EC probe are proposed and its excitation coil is obtained by the topological transformation combining the fractal Koch curve. To explore the right combination of the excitation coil and pickup coil and compare the performance of the probes, ten different configurations of the EC probe are studied by the simulations and experiment. The results show that the best pickup coil of each excitation is with the same shape and size of the excitation; The Koch excitation and Koch pickup probe have higher sensitivity for 3mm and 5mm length defects in the special direction than other configurations.

Open-Ended Transmission Coaxial Probes for Sarcopenia Assessment.

We developed a handheld, side-by-side transmission-based probe for interrogating tissue to diagnose sarcopenia—a condition largely characterized by muscle loss and replacement by fat. While commercial microwave reflection-based probes exist, they can only be used in a lab for a variety of applications. The penetration depth of these probes is only in the order of 0.3 mm, which does not even traverse the skin layer, and minor motion of the coaxial feedlines can completely dismantle the calibration. Our device builds primarily on the transmission-based concept that allows for substantially greater signal penetration depth operating over a very broad bandwidth. Additional features were integrated to further improve the penetration, optimize the geometry for a more focused planar excitation, and juxtapose the coaxial apertures for more controlled interrogation. The larger coaxial apertures further increased the penetration depth while retaining the broadband performance. Three-dimensional printing technology made it possible for the apertures to be compressed into ellipses for interrogation in a near-planar geometry. Finally, fixed side-by-side positioning provided repeatable and reliable performance. The probes were also not susceptible to multipath signal corruption due to the close proximity of the transmitting and receiving apertures. The new concept worked from 100 MHz to over 8 GHz and could sense property changes as deep as 2–3 cm. While the signal changes due to deeper feature aberrations were more subtle than for signals emanating from the skin and subcutaneous fat layers, the large property contrast between muscle and fat is a sarcopenic indication that helps to distinguish even the deepest objects. This device has the potential to provide needed specificity information about the relevant underlying tissue.

High‐Speed 3D Imaging of Multiphase Systems: Applying SCAPE Microscopy to Analog Experiments in Volcanology and Earth Sciences

AbstractMultiphase suspensions are complex systems where microscopic interactions between suspended bubbles, particles, and liquids can significantly alter bulk behavior. Observing the internal mechanics of such suspensions can help constrain the dynamics of natural multiphase flows. To capture these internal processes at high speed and in three dimensions, we propose the use of Swept Confocally Aligned Planar Excitation (SCAPE) microscopy in analog experiments. This imaging technique, developed for neuroscience and biology, uses a sweeping light sheet to illuminate and image fluorophores within a sample. We performed experiments using water and various oils as the liquid phases, glass or PMMA particles for solids, and air or CO2 for gas, which we imaged at rates >50 volumes per second, over a volume size of ∼1 × 1 × 0.4 mm. We focused on three case studies: (1) bubble nucleation, growth, and rise in sparkling water, where we found that bubble detachment from angular PMMA particles left residual bubbles that also grew and detached, generating more bubbles compared to smooth particles; (2) flow of immiscible liquids (water droplets suspended in canola oil) in a porous matrix of PMMA beads, which highlighted the importance of pore and throat sizes on droplet velocities; and (3) injection of air bubbles into concentrated suspensions of glass beads or crushed PMMA particles in a refractive‐index‐matched liquid, which revealed particle motion and strong alterations of the bubble shape. We conclude that SCAPE microscopy is a powerful tool to study the dynamics of multiphase systems.

Compact Dual-Band Dual-Mode SIW Balanced BPF With Intrinsic Common-Mode Suppression

In this letter, a compact dual-band dual-mode substrate integrated waveguide (SIW) balanced band-pass filter (BPF) with intrinsic common-mode (CM) suppression is designed by using a single perturbed SIW circular cavity. The vias and slot perturbations are introduced to tune the resonant modes TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">010</sub> , TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">110</sub> (a pair of degenerate modes), and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">210</sub> of a circular cavity. Thus, they can be used to form two differential-mode (DM) passbands with independently adjustable center frequencies and bandwidths. The SIW can be seen as a natural balun with intrinsic CM suppression. Furthermore, the planar differential excitation structure is designed to excite the perturbed SIW cavity. The CM noise cannot excite SIW cavity due to the characteristics of hybrid electromagnetic boundary. Finally, a compact dual-band dual-mode SIW balanced BPF at 8 and 10 GHz is designed and fabricated, and the measured results show good agreement with the simulated ones.

High gain, wide-angle QCTO-enabled modified Luneburg lens antenna with broadband anti-reflective layer

The gradient-index (GRIN) Luneburg lens antenna offers significant benefits, e.g. high aperture efficiency, low-power, minimal cost, wide beam scanning angle and broad bandwidth, over phased array antennas and reflector antennas. However, the spherical shape of the Luneburg lens geometry complicates the integration of standard planar feed sources and poses significant implementation challenge. To eliminate the feed mismatch problem, the quasi-conformal transformation optics (QCTO) method can be adopted to modify the lens’ spherical feed surface into a planar one. However, Luneburg lenses designed with QCTO method are limited to poor performance due to the presence of the reflections and beam broadening arising from the quasi-conformal mapping. In this paper, we present a new method of implementing QCTO-enabled modified Luneburg lens antenna by designing a broadband anti-reflective layer along with the modified lens’s planar excitation surface. The proposed anti-reflector layer is inherently broadband in nature, has a continuously tapered inhomogeneous dielectric permittivity profile along its thickness, and ensures broadband impedance matching. To show the new QCTO modified Luneburg lens antenna, an example lens antenna was designed at Ka-band (26–40 GHz) and fabricated using fused deposition modeling (FDM) based additive manufacturing technique. Electromagnetic performance of the lens antenna was experimentally demonstrated.

Controllable Orthogonal Mode Rejection for Smart Polarization Diversity at Millimeter-Wave Frequency

A ferromagnetic loaded device for controllable orthogonal mode rejection at millimeter-Wave is presented in this brief. The device is based on dual image dielectric guide (DIDG) capable of supporting both vertical (V-mode) and horizontal (H-mode) polarization. Two ferrite pillboxes are placed vertically (axis parallel to V-mode) and horizontally (axis parallel to H-mode) beside and above the DIDG, receptively. These pillboxes act as whispering gallery mode resonators interacting with the mode parallel to their axis depending on the applied magnetic DC bias, resulting in controllable mode rejection beneficial in smart antenna systems. Despite traditional magnetically tunable ferrite based components, the proposed design is mostly based on the direction of the magnetic bias requiring a small magnetic bias of 1 mT. An aperture coupling transition from Microstrip line to DIDG is used to perform orthogonal mode decomposition as well as proposing planar circuits excitation and integration. Measured polarization filtering bandwidth provided by each pillbox is 0.4 GHz having insertion loss higher than 10 dB (no transmission) and port isolation of higher than 15 dB. Insertion loss of the case, when the rejection mechanism is off, is around 3 dB.

Design, Optimization, and Compensation of a High-Precision Single-Excitation Absolute Capacitance Angular Encoder up to ±4$^{\prime\prime}$

This paper presents a single-excitation absolute capacitive rotary encoder that is small in size, lightweight, robust, and highly precise. The encoder consists of two plates: a rotor and a stator. The rotor consists of a planar coupling ring, a petal-form sensitive electrode, and a rough sensitive electrode, whereas the stator consists of a planar excitation ring and eight groups of collection electrodes. First, the two sensitive electrodes together with the eight sets of collection electrodes encode the angular position into amplitude-modulated signals, which are read out by a single-excitation electronic system. High-precision absolute position information is obtained by using the combination of 36 petal-form sensitive electrodes and a rough sensitive electrode. Then, a linear programming method is used to optimize the critical dimensions of the encoder within a limited area to achieve a miniaturized design. Finally, a harmonic frequency compensation method is used to reduce repeatable and periodical measurement errors, which are caused by manufacturing, circuit, and installation errors. A prototype is fabricated and tested on a high-precision testing turntable. The measurement results show that the resolution is 0.00015° and the accuracy over the full absolute range is 0.0022°, indicating that the encoder has considerable potential for use in high-precision applications.

Real-time volumetric microscopy of in vivo dynamics and large-scale samples with SCAPE 2.0.

The limited per-pixel bandwidth of most microscopy methods requires compromises between field of view, sampling density and imaging speed. This limitation constrains studies involving complex motion or fast cellular signaling, and presents a major bottleneck for high-throughput structural imaging. Here, we combine high-speed intensified camera technology with a versatile, reconfigurable and dramatically improved Swept, Confocally Aligned Planar Excitation (SCAPE) microscope design that can achieve high-resolution volumetric imaging at over 300 volumes-per-second and over 1.2 GHz pixel rates. We demonstrate near-isotropic sampling in freely moving C. elegans, and analyze real-time blood flow and calcium dynamics in the beating zebrafish heart. The same system also permits high-throughput structural imaging of mounted, intact, cleared and expanded samples. SCAPE 2.0’s significantly lower photodamage compared to point-scanning techniques is also confirmed. Our results demonstrate that SCAPE 2.0 is a powerful, yet accessible imaging platform for myriad emerging high-speed dynamic and high-throughput volumetric microscopy applications.

Three-Axis Micofluxgate With a Fluxguide

A CMOS-compatible three-axis fluxgate chip was implemented and characterized in this paper. The thin-film fluxgate core was fabricated onto a silicon chip with integrated planar excitation and sensing coils. A nickel-zinc ferrite fluxguide was aligned and attached to the center of the chip to enable the out-of-plane sensitivity to the external field. The feature size of the microfluxgate chip with a fluxguide is 4.1 mm, and the minimum noise level is 5–7 nT/ $\surd $ Hz at 1 Hz for the in-plane sensing axis. When the sensor is operated in the second-harmonic mode, the optimal excitation frequency is around 50 kHz. The performance of the vector magnetometer for geomagnetic measurement is demonstrated by rotating the device in the earth’s field and recording the azimuth response. The results showed that the proposed designs are valuable for simplifying the construction of miniature three-axis fluxgate, which is promising for applications in orientation determination and position detection, e.g., electronic compass and motion tracking.