Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userA Fiber Optoacoustic Emitter with Maximized Conversion Efficiency and Controlled Ultrasound Frequency for Biomedical Applications
376
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Focused ultrasound has attracted great attention in minimally invasive therapy, gene delivery, brain stimulation, etc. Frequency below 1 MHz has been identified preferable for high-efficacy drug delivery, gene transfection and neurostimulation due to minimized tissue heating and cell fragmentation. However, the poor spatial resolution of several millimeters and the large device diameter of ~25 mm of current sub-MHz ultrasound technology severely hinders its further applications for effective, precise, safe and wearable biomedical studies and clinical use. To address this issue, we report the development of a novel fiber-based optoacoustic emitter (FOE). The FOE, a new miniaturized ultrasound source, is composed of an optical diffusion coating layer and an expansion coating layer at an optical fiber distal end with a diameter of approximately 500 microns. Taking advantage of the fiber size and diffusive nanoparticles introduced, the ultrasound generated by the FOEs showed a spatial confinement of sub-millimeter. The optoacoustic conversion efficiency was maximized through choosing absorbing nanomaterials and thermal expansion matrix. Controllable frequencies in the range of 0.083 MHz to 5.500 MHz were achieved through using the diffusion layer as a damping material or modifying the nano-composition in the expansion layer. This sub-MHz frequency controllability allows FOEs to be used as a localized ultrasound source for precise cell modulation. We demonstrated optoacoustic cell membrane sonoporation with a localization of sub-millimeter and negligible heat deposition, implicating its broad biomedical applications, including region-specific drug delivery, gene transfection as well as localized neuron stimulation.
rate research
Read More
As an emerging technology, transcranial focused ultrasound has been demonstrated to successfully evoke motor responses in mice, rabbits, and sensory/motor responses in humans. Yet, the spatial resolution of ultrasound does not allow for high-precision stimulation. Here, we developed a tapered fiber optoacoustic emitter (TFOE) for optoacoustic stimulation of neurons with an unprecedented spatial resolution of 20 microns, enabling selective activation of single neurons or subcellular structures, such as axons and dendrites. A single acoustic pulse of 1 microsecond converted by the TFOE from a single laser pulse of 3 nanoseconds is shown as the shortest acoustic stimuli so far for successful neuron activation. The highly localized ultrasound generated by the TFOE made it possible to integrate the optoacoustic stimulation and highly stable patch clamp recording on single neurons. Direct measurements of electrical response of single neurons to acoustic stimulation, which is difficult for conventional ultrasound stimulation, have been demonstrated for the first time. By coupling TFOE with ex vivo brain slice electrophysiology, we unveil cell-type-specific response of excitatory and inhibitory neurons to acoustic stimulation. These results demonstrate that TFOE is a non-genetic single-cell and sub-cellular modulation technology, which could shed new insights into the mechanism of neurostimulation.
In this paper, a single layer Coplanar Waveguide-fed microstrip patch antenna array is presented for biomedical applications. The proposed antenna array is realized on a transparent and flexible Polyethylene Terephthalate substrate, has 1x4 radiating elements and measures only 280 x 192 mm2. The antenna array resonates at 2.68 GHz and has a peak-simulated gain of 10 dBi. A prototype is also fabricated, and the conductive patterns are drawn using cost-efficient adhesive copper foils instead of conventional copper or silver nanoparticle ink. The corresponding measured results agree well with the simulated results. The proposed low profile and cost-efficient transmit antenna array has the potential for wearable born-worn applications, including wireless powering of implantable medical devices.
In this paper, we propose Plane Wave Elastography (PWE), a novel ultrasound shear wave elastography (SWE) approach. Currently, commercial methods for SWE rely on directional filtering based on the prior knowledge of the wave propagation direction, to remove complicated wave patterns formed due to reflection and refraction. The result is a set of decomposed directional waves that are separately analyzed to construct shear modulus fields that are then combined through compounding. Instead, PWE relies on a rigorous representation of the wave propagation using the frequency-domain scalar wave equation to automatically select appropriate propagation directions and simultaneously reconstruct shear modulus fields. Specifically, assuming a homogeneous, isotropic, incompressible, linear-elastic medium, we represent the solution of the wave equation using a linear combination of plane waves propagating in arbitrary directions. Given this closed-form solution, we formulate the SWE problem as a nonlinear least-squares optimization problem which can be solved very efficiently. Through numerous phantom studies, we show that PWE can handle complicated waveforms without prior filtering and is competitive with state-of-the-art that requires prior filtering based on the knowledge of propagation directions.
We present a sensor capable of detecting solution-based nanoparticles using an optical fiber tip functionalized with a photonic crystal cavity. When sensor tips are retracted from a nanoparticle solution after being submerged, we find that a combination of convective fluid forces and optically-induced trapping cause an aggregation of nanoparticles to form directly on cavity surfaces. A simple readout of quantum dot photoluminescence coupled to the optical fiber shows that nanoparticle presence and concentration can be detected through modified cavity properties. Our sensor can detect both gold and iron oxide nanoparticles and can be utilized for molecular sensing applications in biomedicine.
Microresonator-based Kerr frequency comb (microcomb) generation can potentially revolutionize a variety of applications ranging from telecommunications to optical frequency synthesis. However, phase-locked microcombs have generally had low conversion efficiency limited to a few percent. Here we report experimental results that achieve ~30% conversion efficiency (~200 mW on-chip comb power excluding the pump) in the fiber telecommunication band with broadband mode-locked dark-pulse combs. We present a general analysis on the efficiency which is applicable to any phase-locked microcomb state. The effective coupling condition for the pump as well as the duty cycle of localized time-domain structures play a key role in determining the conversion efficiency. Our observation of high efficiency comb states is relevant for applications such as optical communications which require high power per comb line.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
