10 research outputs found
Scalable trapping of single nanosized extracellular vesicles using plasmonics
Heterogeneous nanoscale particles released by cells known as extracellular
vesicles (EVs) are actively investigated for early disease detection1,
monitoring2, and advanced therapeutics3. Due to their extremely small size, the
stable trapping of nano-sized EVs using diffraction-limited optical tweezers4
has been met with challenges. Plasmon-enhanced optical trapping can confine
light to the nanoscale to generate tight trapping potentials. Unfortunately, a
long-standing challenge is that plasmonic tweezers have limited throughput and
cannot provide rapid delivery and trapping of particles at plasmonic hotspots
while precluding the intrinsic plasmon-induced photothermal heating effect at
the same time. We report our original geometry-induced electrohydrodynamic
tweezers (GET) that generate multiple electrohydrodynamic potentials for the
parallelized transport and trapping of single EVs in parallel within seconds
while enhancing the imaging of single trapped EVs. We show that the integration
of nanoscale plasmonic cavities at the center of each GET trap results in the
parallel placement of single EVs near plasmonic cavities enabling instantaneous
plasmon-enhanced optical trapping upon laser illumination without any
detrimental heating effect for the first time. These non-invasive scalable
hybrid nanotweezers open new horizons for high-throughput tether-free
plasmon-enhanced single EV trapping and spectroscopy. Other potential areas of
impact include nanoplastics characterization, and scalable hybrid integration
for quantum photonics.Comment: 21 pages, 5 figure
Nanomanipulation with Designer Thermoplasmonic Metasurface
Plasmonic nanoantennas provide an efficient platform to confine electromagnetic energy to the deeply subwavelength scales. The resonant absorption of light by the plasmonic nanoantennas provides the means to engineer heat distribution at the micro and nanoscales. We present thermoplasmonic metasurfaces for on-chip trapping, dynamic manipulation and sensing of micro and nanoscale objects. This ability to rapidly concentrate objects on the surface of the metasurface holds promise to overcome the diffusion limit in surface-based optical biosensors. This platform could be applied for the trapping and label-free sensing of viruses, biological cells and extracellular vesicles such as exosomes
Towards rapid extracellular vesicles colorimetric detection using optofluidics-enhanced color-changing optical metasurface
Efficient transportation and delivery of analytes to the surface of optical
sensors are crucial for overcoming limitations in diffusion-limited transport
and analyte sensing. In this study, we propose a novel approach that combines
metasurface optics with optofluidics-enabled active transport of extracellular
vesicles (EVs). By leveraging this combination, we show that we can rapidly
capture EVs and detect their adsorption through a color change generated by a
specially designed optical metasurface that produces structural colors. Our
results demonstrate that the integration of optofluidics and metasurface optics
enables robust colorimetric read-out for EV concentrations as low as 107
EVs/ml, achieved within a short incubation time of two minutes, while using a
CCD camera or naked eye for the read-out. This approach offers the potential
for rapid sensing without the need for spectrometers and provides a short
response time. Our findings suggest that the synergy between optofluidics and
metasurface platforms can enhance the detection efficiency of low concentration
bioparticle samples by overcoming the diffusion limits
Multiplexed long-range electrohydrodynamic transport and nano-optical trapping with cascaded bowtie photonic crystal cavities
Photonic crystal cavities have been widely studied for optical trapping due
to their ability to generate high quality factor resonances. However, prior
photonic crystal nanotweezers possess mode volumes significantly larger than
those of plasmonic nanotweezers, which limit the gradient force. Additionally,
they also suffer from low particle capture rates. In this paper, we propose a
nanotweezer system based on a 1D bowtie photonic crystal nanobeam that achieves
extreme mode confinement and an electromagnetic field enhancement factor of 68
times, while supporting a high-quality factor of 15,000 in water. Furthermore,
by harnessing the localized heating of a water layer near the bowtie cavity
region, combined with an applied alternating current electric field, our system
provides long-range transport of particles with average velocities of 5
m/s towards the bowtie cavities on demand. Once transported to the
bowtie cavity region, our results show that a 20 nm quantum dot will be
confined in a potential well with a depth of 35 T. Thus, our approach
effectively addresses the challenge of limited capture rate in photonic crystal
nanotweezers for the first time. Finally, we present the concept of multiplexed
long-range transport for hand-off of a single emitter from one cavity to the
next by simply switching the wavelength of the input light. This novel
multiplexed integrated particle trapping platform is expected to open new
opportunities in directed assembly of nanoscale quantum emitters and
ultrasensitive sensors for single particle spectroscopy.Comment: 11 pages, 4 figure
Single-peak and narrow-band mid-infrared thermal emitters driven by mirror-coupled plasmonic quasi-BIC metasurfaces
Wavelength-selective thermal emitters (WS-EMs) hold considerable appeal due
to the scarcity of cost-effective, narrow-band sources in the mid-to-long-wave
infrared spectrum. WS-EMs achieved via dielectric materials typically exhibit
thermal emission peaks with high quality factors (Q factors), but their optical
responses are prone to temperature fluctuations. Metallic EMs, on the other
hand, show negligible drifts with temperature changes, but their Q factors
usually hover around 10. In this study, we introduce and experimentally verify
a novel EM grounded in plasmonic quasi-bound states in the continuum (BICs)
within a mirror-coupled system. Our design numerically delivers an
ultra-narrowband single peak with a Q factor of approximately 64, and
near-unity absorptance that can be freely tuned within an expansive band of
more than 10 {\mu}m. By introducing air slots symmetrically, the Q factor can
be further augmented to around 100. Multipolar analysis and phase diagrams are
presented to elucidate the operational principle. Importantly, our infrared
spectral measurements affirm the remarkable resilience of our designs'
resonance frequency in the face of temperature fluctuations over 300 degrees
Celsius. Additionally, we develop an effective impedance model based on the
optical nanoantenna theory to understand how further tuning of the emission
properties is achieved through precise engineering of the slot. This research
thus heralds the potential of applying plasmonic quasi-BICs in designing
ultra-narrowband, temperature-stable thermal emitters in mid-infrared.
Moreover, such a concept may be adaptable to other frequency ranges, such as
near-infrared, Terahertz, and Gigahertz.Comment: 39 pages, 12 figure
Meta-form near eye visor
Thesis (Master's)--University of Washington, 2017-06This thesis is about meta-form near-eye visor (NEV). Near eye visor is the core component in a head mounted display (HMD), because it directly decides the quality and volume of HMD. Regarding freeform NEV, a limitation on Field of View (FOV) is proposed. A flat shape phase mask visor, termed here as meta-form visor, is used to replace the freeform NEV to lift the limitation. Metasurface is chosen to work as the visor, because of its flat surface and capability to implement spatial modulation to incident light wave. Metasurface is a two-dimensional array of subwavelength scatterers. Meta-form visor’s vision performance is simulated in Zemax. Image simulation using the designed metasurface is performed in Lumerical FDTD. In this design dielectric material is chosen to compose the metasurface, for its lower loss in visible frequency than metallic metasurface
Comparative Transcriptome Analysis of Developing Seeds and Silique Wall Reveals Dynamic Transcription Networks for Effective Oil Production in <i>Brassica napus</i> L.
Vegetable oil is an essential constituent of the human diet and renewable raw material for industrial applications. Enhancing oil production by increasing seed oil content in oil crops is the most viable, environmentally friendly, and sustainable approach to meet the continuous demand for the supply of vegetable oil globally. An in-depth understanding of the gene networks involved in oil biosynthesis during seed development is a prerequisite for breeding high-oil-content varieties. Rapeseed (Brassica napus) is one of the most important oil crops cultivated on multiple continents, contributing more than 15% of the world’s edible oil supply. To understand the phasic nature of oil biosynthesis and the dynamic regulation of key pathways for effective oil accumulation in B. napus, comparative transcriptomic profiling was performed with developing seeds and silique wall (SW) tissues of two contrasting inbred lines with ~13% difference in seed oil content. Differentially expressed genes (DEGs) between high- and low-oil content lines were identified across six key developmental stages, and gene enrichment analysis revealed that genes related to photosynthesis, metabolism, carbohydrates, lipids, phytohormones, transporters, and triacylglycerol and fatty acid synthesis tended to be upregulated in the high-oil-content line. Differentially regulated DEG patterns were revealed for the control of metabolite and photosynthate production in SW and oil biosynthesis and accumulation in seeds. Quantitative assays of carbohydrates and hormones during seed development together with gene expression profiling of relevant pathways revealed their fundamental effects on effective oil accumulation. Our results thus provide insights into the molecular basis of high seed oil content (SOC) and a new direction for developing high-SOC rapeseed and other oil crops
Supplementary document for Single-peak and narrow-band mid-infrared thermal emitters driven by mirror-coupled plasmonic quasi-BIC metasurfaces - 6827598.pdf
The Supplemental Material contains details of the multipolar decomposition, discussions on the angular dispersion, numerical analysis of the gas detection application, details of simulation and experiment methods and additional discussions