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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Multiband Fractal Metasurface with Linear to Linear and Linear to Circular Polarization Conversion
摘要： Mapping the brain centers that mediate the sensory-perceptual processing of visceral afferent signals arising from the body (i.e., interoception) is useful both for characterizing normal brain activity and for understanding clinical disorders related to abnormal processing of visceral sensation. Here, we report a novel closed-system, electrohydrostatically driven master–slave device that was designed and constructed for delivering controlled ?uidic stimulations of visceral organs and inner cavities of the human body within the con?nes of a 3T magnetic resonance imaging (MRI) scanner. The design concept and performance of the device in the MRI environment are described. In addition, the device was applied during a functional MRI (fMRI) investigation of visceral stimulation related to detrusor distention in two representative subjects to verify its feasibility in humans. System evaluation tests demonstrate that the device is MR-compatible with negligible impact on imaging quality [static signal-to-noise ratio (SNR) loss <2.5% and temporal SNR loss <3.5%], and has an accuracy of 99.68% for ?ow rate and 99.27% for volume delivery. A precise synchronization of the stimulus delivery with fMRI slice acquisition was achieved by programming the proposed device to detect the 5 V transistor–transistor logic (TTL) trigger signals generated by the MRI scanner. The fMRI data analysis using the general linear model analysis with the standard hemodynamic response function showed increased activations in the network of brain regions that included the insula, anterior and mid-cingulate and lateral prefrontal cortices, and thalamus in response to increased distension pressure on viscera. The translation from manually operated devices to an MR-compatible and MR-synchronized device under automatic control represents a useful innovation for clinical neuroimaging studies of human interoception.
关键词： automation,fMRI,electrohydrostatic actuation,visceral afferent processing,MR-compatible sensors and actuators
更新于2025-09-23 15:19:57
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Thermo-responsive plasmonic systems: old materials with new applications
摘要： Thermo-responsive plasmonic systems of gold and poly(N-isopropylacrylamide) have been actively studied for several decades but this system keeps reinventing itself, with new concepts and applications which seed new fields. In this minireview, we show the latest few years development and applications of this intriguing system. We start from the basic working principles of this puzzling system which shows different plasmon shifts for even slightly different chemistries. We then present its applications to colloidal actuation, plasmon/meta-film tuning, and bioimaging and sensing. Finally we briefly summarize and propose several promising applications of the ongoing effort in this field.
关键词： plasmon/meta-film tuning,colloidal actuation,poly(N-isopropylacrylamide),bioimaging,gold,sensing,Thermo-responsive plasmonic systems
更新于2025-09-23 15:19:57
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Changing the critical snap-through loads of post-buckled beams using piezoelectric actuation
摘要： Post-buckled and curved structures experience snap-through instabilities when external loads from mechanical, ?uid, or thermal environments result in a loss of local stability and a dramatic jump to a remote stable equilibrium. Fatigue caused by snap-through is a concern in many engineered systems because of the large stress reversals involved. This paper studies the extent to which the strategic placement and actuation of piezoelectric materials bonded to clamped-clamped post-buckled beams can in?uence the loads at which snap-through occurs. The electromechanical system is modeled using elastica theory with extensions to account for the in?uence of piezoelectric actuation on the structure. Static equilibrium positions and their stability are computed across a large con?guration space using numerical integration and a shooting method. The results indicate that the effect of piezoelectric actuation on critical snap-through load depends on the degree to which the beam is buckled, the location of the external load, the placement of the piezoelectric material, and the applied actuation voltage. Experiments are performed to validate the numerical results and provide a physical demonstration of changing snap-through loads with piezoelectric actuation. Experimental results demonstrate that critical snap-through loads can be altered by factors ranging from 0.4 to 2.0, and numerical results indicate that even larger changes to snap-through loads are physically realizable.
关键词： piezoelectric actuation,elastica theory,snap-through,post-buckled beams
更新于2025-09-23 15:19:57
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Motile Piezoelectric Nanoeels for Targeted Drug Delivery
摘要： The field of small-scale robotics is undergoing a paradigm shift toward the use of soft smart materials. The integration of soft smart components in micro- and nanorobotic platforms not only allows for more sophisticated locomotion mechanisms, but also more closely mimicks the functioning of biological systems. A soft hybrid nanorobot that mimics an electric eel, a knifefish with an elongated cylindrical body that is able to generate electricity during its motion, is presented here. These nanoeels consist of a flexible piezoelectric tail composed of a polyvinylidene fluoride–based copolymer, linked to a polypyrrole nanowire, which is decorated with nickel rings for magnetic actuation. Upon the application of rotating magnetic fields, the piezoelectric soft tail is deformed causing changes in its electric polarization. Capitalizing on this magnetically coupled piezoelectric effect, electrostatically enhanced on-demand release of therapeutic cargo loaded on the surface of the piezoelectric tail is demonstrated. It is also shown that this approach allows for a pulsatile release of payloads. Interestingly, the driving magnetic parameters can be selected to provide the nanoeel with translational motion or to control the discharge kinetics of the drug.
关键词： magnetic actuation,nanowires,drug delivery,piezoelectricity,soft robotics
更新于2025-09-19 17:15:36
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Modeling and stabilization of current-controlled piezo-electric beams with dynamic electromagnetic field
摘要： Piezoelectric materials can be controlled with current (or charge) as the electrical input, instead of voltage. The main purpose of this paper is to derive the governing equations for a current-controlled piezo-electric beam and to investigate stabilizability. The magnetic permeability in piezo-electric materials is generally neglected in models. However, it has a significant qualitative effect on properties of the control system such as stabilizability. Besides the consideration of current control, there are several new aspects to the model. Most importantly, a fully dynamic magnetic model is included. Also, electrical potential and magnetic vector potential are chosen to be quadratic-through thickness to include the induced effects of the electromagnetic field. Hamilton’s principle is used to derive a boundary value problem that models a single piezo-electric beam actuated by a current (or charge) source at the electrodes. Two sets of decoupled system of partial differential equations are obtained; one for stretching of the beam and another one for bending motion. Since current (or charge) controller only affects the stretching motion, attention is focused on control of the stretching equations in this paper. It is shown that the Lagrangian of the beam is invariant under certain transformations. A Coulomb type gauge condition is used. This gauge condition decouples the electrical potential equation from the equations of the magnetic potential. A semigroup approach is used to prove that the Cauchy problem is well-posed. Unlike voltage actuation, a bounded control operator in the natural energy space is obtained. The paper concludes with analysis of stabilizability and comparison with other actuation approaches and models.
关键词： Piezoelectric,distributed parameter system,charge actuation,current actuation,induced voltage,partial differential equations,control,stabilization,electromotive force
更新于2025-09-19 17:13:59
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Actuation Framework for 5G-Enabled Network Slices with QoE/QoS Guarantees
摘要： Network slicing is identified as the enabling technology for efficient service delivery in future 5G networks. Moreover, a key aspect in 5G network slicing relates to the delivery and maintenance of QoS/QoE guarantees for the provisioned slices. This paper discusses an overall framework for coordinating and orchestrating the proper actuations to restore the provisioned end-to-end network slices requirements. In particular, a policy-based actuation system is adopted, where a policy framework applies policies tied to specific behaviours. Such policies, that may trigger configurations in the different segments of the infrastructure, are aimed to maintain or restore the QoS/QoE requirements of the slice.
关键词： network slicing,QoE actuation,optical networks,QoE monitoring,5G service maintenance
更新于2025-09-19 17:13:59
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[IEEE 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Daejeon, Korea (South) (2019.7.28-2019.8.1)] 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - A Large Aperture 2-Axis Electrothermal MEMS Mirror for Compact 3D LiDAR
摘要： Low-cost LiDAR with long distance, high resolution, and stable laser scanning are needed for robotics and automobiles. This paper reports a large-aperture, 2-axis electrothermal MEMS mirror for LiDAR applications. The MEMS mirror has a mirror plate of 2 × 2.5 mm2 and an optical field view (FoV) of 15° by 12°. The beam divergence of 0.5 mrad is achieved with a 1.3-mm laser beam. The rotational scanning resonant mode is at 0.7 kHz, which is achieved by the meshed bimorph actuators with improved stiffness.
关键词： large aperture,LiDAR,electrothermal actuation,MEMS micromirror
更新于2025-09-16 10:30:52
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Remotely Light‐Powered Soft Fluidic Actuators Based on Plasmonic‐Driven Phase Transitions in Elastic Constraint
摘要： Materials capable of actuation through remote stimuli are crucial for untethering soft robotic systems from hardware for powering and control. Fluidic actuation is one of the most applied and versatile actuation strategies in soft robotics. Here, the first macroscale soft fluidic actuator is derived that operates remotely powered and controlled by light through a plasmonically induced phase transition in an elastomeric constraint. A multiphase assembly of a liquid layer of concentrated gold nanoparticles in a silicone or styrene–ethylene–butylene–styrene elastic pocket forms the actuator. Upon laser excitation, the nanoparticles convert light of specific wavelength into heat and initiate a liquid-to-gas phase transition. The related pressure increase inflates the elastomers in response to laser wavelength, intensity, direction, and on–off pulses. During laser-off periods, heating halts and condensation of the gas phase renders the actuation reversible. The versatile multiphase materials actuate—like soft “steam engines”—a variety of soft robotic structures (soft valve, pnue-net structure, crawling robot, pump) and are capable of operating in different environments (air, water, biological tissue) in a single configuration. Tailored toward the near-infrared window of biological tissue, the structures actuate also through animal tissue for potential medical soft robotic applications.
关键词： fluidic actuation,soft robotics,soft steam engines,plasmonic actuation
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Seoul, Korea (South) (2019.1.27-2019.1.31)] 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - A Closed-Loop Controlled Cmos Mems Biaxial Scanning Mirror for Projection Display
摘要： This work presents a bi-axial electromagnetically-driven piezoresistively sensed scanning mirror with a θopt?D?fr,fast product over 2400 deg?mm?kHz, showing the capability to achieve HD720 (720 × 1280) display resolution. Both driving and sensing capabilities are conveniently realized by CMOS MEMS technologies. The transduction mechanism provides a more linear response than capacitively transduced scanning mirrors. Based on the open-loop characterization of the driving and sensing performance, closed-loop control of slow-axis motion is designed and demonstrated.
关键词： piezoresistive sensing,closed-loop control,scanning mirror,CMOS MEMS,electromagnetic actuation,projection display
更新于2025-09-12 10:27:22
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Stable transitions between remote equilibria of post-buckled beams using piezoelectric actuation
摘要： This paper considers the extent to which a clamped-clamped post-buckled beam bonded to two elongating piezoelectric actuators can be made to stably transition between remote equilibria. The electromechanical system is modeled using elastica theory with extensions to account for the influence of the actuators on the structure. It expresses this piezoelectric coupling effect in terms of a non-dimensional parameter, σ, that can be easily calculated for candidate substrate/actuator configurations. Parameter studies determining the threshold values of σ required to execute stable transitions under different actuation and loading situations are presented. The results indicate that the lowest threshold values of σ occur when the beam is actuated from approximately 15%–85% of its span. Experiments validate the numerical results and offer the first physical demonstrations of the use of piezoelectric actuators to achieve stable transitions between remote equilibria.
关键词： elastica theory,snap-through,piezoelectric actuation,post-buckled beams,elastic stability
更新于2025-09-12 10:27:22