Publications by authors named "Chia-Yi Huang"

13 Publications

  • Page 1 of 1

Electrically controllable terahertz metamaterials with large tunabilities and low operating electric fields using electrowetting-on-dielectric cells.

Opt Lett 2021 Dec;46(23):5962-5965

A simple method that is compatible with all geometrical structures of terahertz (THz) metamaterials for increasing their frequency tunabilities and decreasing their operating electric fields is proposed. This method uses the displacement of glycerol droplets with various volumes to tune the resonance frequency of a THz metamaterial in an electrowetting-on-dielectric (EWOD) cell. The experimental results reveal that the THz metamaterial has a large frequency tunability of 28% at an operating electric field that is smaller than 0.2 V/µm as the glycerol droplets move in and out of the path of a THz beam. The frequency tunability is large because the near field of the metamaterial "experiences" a large difference between the refractive indices of glycerol and air. The EWOD cell with the THz metamaterial is a great achievement for developing electrically controllable band-stop filters with large frequency tunabilities and small operating electric fields.
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http://dx.doi.org/10.1364/OL.444842DOI Listing
December 2021

Organic Solvent Sensors Using Polymer-Dispersed Liquid Crystal Films with a Pillar Pattern.

Polymers (Basel) 2021 Aug 29;13(17). Epub 2021 Aug 29.

Department of Optometry, Chung Shan Medical University, Taichung 40201, Taiwan.

An organic solvent sensor of polymer-dispersed liquid crystals (PDLCs) film is fabricated by a combination of tri-functional monomers and LCs. When the patterned PDLC film comes into contact with the organic solvent, the organic solvent will penetrate into the film to induce the orientation of the liquid crystals, which will change from an ordered to a disordered state, which causes the PDLC film to scatter incident light. The experiment used acetone and ethanol as the organic solvents of interest. The results show that the patterned PDLC film has a stronger response to acetone than to ethanol. Based on the difference in the intensity of light scattering and the response time of the patterned PDLC film to different organic solvents, the results can be used to identify and recognize different types of organic solvents.
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http://dx.doi.org/10.3390/polym13172906DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8434618PMC
August 2021

Large shift of resonance wavelengths of silver nanoslit arrays using electrowetting-on-dielectric cells.

Opt Lett 2021 Feb;46(4):705-708

A simple design for shifting the resonance wavelength of silver nanoslits using an electrowetting-on-dielectric (EWOD) cell is proposed. The EWOD cell comprises a polycarbonate (PC) substrate with Teflon-coated silver nanoslits and a glass substrate with Teflon-coated electrodes. A glycerol droplet is placed between the two substrates, and out of the path of a probe beam at zero electric field. Application of an electric field smaller than 0.3 V/µm on the electrodes moves the glycerol droplet into the path of the probe beam, shifting the resonance wavelength of the silver nanoslits by 135 nm. A change (0.33) in the refractive index of the effective medium that is adjacent to the silver nanoslits causes a large shift in the resonance wavelength. The spectral shift of the silver nanoslits is repeatable by the electric field. This simple design is a great achievement for high-performance electro-optical devices with large wavelength shift ranges such as optical switches, variable optical attenuators, and sensor applications.
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http://dx.doi.org/10.1364/OL.415500DOI Listing
February 2021

Continuously tunable intensity modulators with large switching contrasts using liquid crystal elastomer films that are deposited with terahertz metamaterials.

Opt Express 2020 Sep;28(19):27676-27687

A liquid crystal elastomer (LCE) film is successfully deposited with a terahertz metamaterial using thermal evaporation via a programmed electronic shutter and high-efficiency cooling system. The transmittance of the metamaterial at its resonance frequency is monotonically increased from 0.0036 to 1.0 as a pump beam bends the LCE film, so the metamaterial has a large switching contrast of 277 at the frequency. The monotonic increase in the resonance transmittance arises from the constant resonance frequency of the metamaterial at the transmittance modulation and depicts that the metamaterial-deposited LCE film can continuously tune the transmitted intensity of a terahertz beam. The metamaterial-deposited LCE film has potential in developing continuously tunable intensity modulators with large switching contrasts for the application of terahertz imaging and terahertz communication. Therefore, the thermal evaporation expands the application of metamaterials and improves their optical properties.
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http://dx.doi.org/10.1364/OE.399581DOI Listing
September 2020

Polymer LEDs with improved efficacy via periodic nanostructure-based aluminum.

Opt Lett 2019 Sep;44(17):4327-4330

Periodic aluminum-capped nanoslit arrays were produced on a polycarbonate plastic substrate by rapid hot embossing nanoimprint lithography and thermal evaporation, and they were used as a transparent window for blue-emitting polymer light-emitting diodes (PLEDs). The external quantum efficiency of blue-emitting PLEDs was enhanced by the surface plasmon polaritons of the periodic aluminum-capped nanoslit arrays. A maximum current efficiency of 4.84 cd/A was achieved for the proposed PLED, which was over 2.2 times that of the reference PLED (2.18 cd/A). These results demonstrate that periodic nanostructure can assist in the simple and low-cost fabrication of high-performance polymer optoelectronic devices.
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http://dx.doi.org/10.1364/OL.44.004327DOI Listing
September 2019

K Channel Kv3.4 Is Essential for Axon Growth by Limiting the Influx of Ca into Growth Cones.

J Neurosci 2017 04 20;37(17):4433-4449. Epub 2017 Mar 20.

Institute of Neuroscience, Brain Research Center, National Yang-Ming University, Taipei 112, Taiwan

Membrane excitability in the axonal growth cones of embryonic neurons influences axon growth. Voltage-gated K (Kv) channels are key factors in controlling membrane excitability, but whether they regulate axon growth remains unclear. Here, we report that Kv3.4 is expressed in the axonal growth cones of embryonic spinal commissural neurons, motoneurons, dorsal root ganglion neurons, retinal ganglion cells, and callosal projection neurons during axon growth. Our (cultured dorsal spinal neurons of chick embryos) and (developing chick spinal commissural axons and rat callosal axons) findings demonstrate that knockdown of Kv3.4 by a specific shRNA impedes axon initiation, elongation, pathfinding, and fasciculation. In cultured dorsal spinal neurons, blockade of Kv3.4 by blood depressing substance II suppresses axon growth via an increase in the amplitude and frequency of Ca influx through T-type and L-type Ca channels. Electrophysiological results show that Kv3.4, the major Kv channel in the axonal growth cones of embryonic dorsal spinal neurons, is activated at more hyperpolarized potentials and inactivated more slowly than it is in postnatal and adult neurons. The opening of Kv3.4 channels effectively reduces growth cone membrane excitability, thereby limiting excessive Ca influx at subthreshold potentials or during Ca-dependent action potentials. Furthermore, excessive Ca influx induced by an optogenetic approach also inhibits axon growth. Our findings suggest that Kv3.4 reduces growth cone membrane excitability and maintains [Ca] at an optimal concentration for normal axon growth. Accumulating evidence supports the idea that impairments in axon growth contribute to many clinical disorders, such as autism spectrum disorders, corpus callosum agenesis, Joubert syndrome, Kallmann syndrome, and horizontal gaze palsy with progressive scoliosis. Membrane excitability in the growth cone, which is mainly controlled by voltage-gated Ca (Cav) and K (Kv) channels, modulates axon growth. The role of Cav channels during axon growth is well understood, but it is unclear whether Kv channels control axon outgrowth by regulating Ca influx. This report shows that Kv3.4, which is transiently expressed in the axonal growth cones of many types of embryonic neurons, acts to reduce excessive Ca influx through Cav channels and thus permits normal axon outgrowth.
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http://dx.doi.org/10.1523/JNEUROSCI.1076-16.2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6596659PMC
April 2017

Effect of swelling of a photoresist on electromagnetic resonance of terahertz metamaterials.

Opt Lett 2016 Jun;41(12):2879-82

This work uses isopropyl alcohol (IPA) to develop a photoresist. IPA dissolves the photoresist that is not exposed to UV light, and swells the photoresist that is exposed to UV light. The swelling of the photoresist distorts the split-ring resonators (SRRs). The distorted SRRs have a larger loop length, smaller line width, and smaller split gap than undistorted SRRs. The change in the dimensions of the SRRs is caused by the extension of the SRR arms in their longitudinal directions. The resonance frequency of the distorted SRRs is smaller than that of the undistorted SRRs, and the resonance frequency decreases with the development time. The resonance frequency of the distorted SRRs depends on not only their dimensions, but also the bending of their arms. The distorted SRRs in this work have a frequency tuning range with a maximum width of 0.13 THz. The method that is proposed herein uses IPA to fabricate passively tunable terahertz metamaterials, which exhibit the advantages of high reliability, low cost, and ease of fabrication.
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http://dx.doi.org/10.1364/OL.41.002879DOI Listing
June 2016

A High Circulating Tumor Cell Count in Portal Vein Predicts Liver Metastasis From Periampullary or Pancreatic Cancer: A High Portal Venous CTC Count Predicts Liver Metastases.

Medicine (Baltimore) 2016 Apr;95(16):e3407

From the Department of Surgery (YWT, H-CK, B-IH); Department of Internal Medicine (M-CC, Y-TC); Department of Nuclear Medicine, National Taiwan University Hospital (M-FC); Genomics Research Center, Academia Sinica, Taipei (H-LC, T-YL, C-FW, C-YH, J-YS, YCC, EYL, W-HL); and Institute of Clinical Medicine, China Medical University, Taiwan (EYL, W-HL).

Circulating tumor cells (CTCs) released from a periampullary or pancreatic cancer can be more frequently detected in the portal than the systemic circulation and potentially can be used to identify patients with liver micrometastases. Aims of this study is to determine if CTCs count in portal venous blood of patients with nonmetastatic periampullary or pancreatic adenocarcinoma can be used as a predictor for subsequent liver metastases. CTCs were quantified in portal and peripheral venous blood samples collected simultaneously during pancreaticoduodenectomy in patients with presumed periampullary or pancreatic adenocarcinoma without image-discernible metastasis. Postoperatively patients were monitored for liver metastasis by abdominal magnetic resonance imaging or computed tomography every 3 months for 1 year. Sixty patients with a pathological diagnosis of periampullary or pancreatic adenocarcinoma were included in the study. Multivariate analysis indicated that portal CTC count was a significant predictor for liver metastases within 6 months after surgery. Eleven of 13 patients with a high portal CTCs count (defined as >112 CMx Platform estimated CTCs in 2 mL blood) developed liver metastases within 6 months after surgery. In contrast, only 6 of 47 patients with a low portal CTC count developed liver metastases (P < 0.0001). A value of 112 CMx Platform estimated CTCs had 64.7% sensitivity and 95.4% specificity to predict liver metastases within 6 months after surgery. We concluded that a high CTC count in portal venous blood collected during pancreaticoduodenectomy in patients with periampullary or pancreatic adenocarcinoma without metastases detected by currently available imaging tools is a significant predictor for liver metastases within 6 months after surgery.
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http://dx.doi.org/10.1097/MD.0000000000003407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4845834PMC
April 2016

Coexpression of auxiliary subunits KChIP and DPPL in potassium channel Kv4-positive nociceptors and pain-modulating spinal interneurons.

J Comp Neurol 2016 Mar 18;524(4):846-73. Epub 2015 Aug 18.

Institute of Neuroscience, Brain Research Center, National Yang-Ming University, Taipei, Taiwan.

Subthreshold A-type K(+) currents (ISA s) have been recorded from the somata of nociceptors and spinal lamina II excitatory interneurons, which sense and modulate pain, respectively. Kv4 channels are responsible for the somatodendritic ISA s. Accumulative evidence suggests that neuronal Kv4 channels are ternary complexes including pore-forming Kv4 subunits and two types of auxiliary subunits: K(+) channel-interacting proteins (KChIPs) and dipeptidyl peptidase-like proteins (DPPLs). Previous reports have shown Kv4.3 in a subset of nonpeptidergic nociceptors and Kv4.2/Kv4.3 in certain spinal lamina II excitatory interneurons. However, whether and which KChIP and DPPL are coexpressed with Kv4 in these ISA -expressing pain-related neurons is unknown. In this study we mapped the protein distribution of KChIP1, KChIP2, KChIP3, DPP6, and DPP10 in adult rat dorsal root ganglion (DRG) and spinal cord by immunohistochemistry. In the DRG, we found colocalization of KChIP1, KChIP2, and DPP10 in the somatic surface and cytoplasm of Kv4.3(+) nociceptors. KChIP3 appears in most Aβ and Aδ sensory neurons as well as a small population of peptidergic nociceptors, whereas DPP6 is absent in sensory neurons. In the spinal cord, KChIP1 is coexpressed with Kv4.3 in the cell bodies of a subset of lamina II excitatory interneurons, while KChIP1, KChIP2, and DPP6 are colocalized with Kv4.2 and Kv4.3 in their dendrites. Within the dorsal horn, besides KChIP3 in the inner lamina II and lamina III, we detected DPP10 in most projection neurons, which transmit pain signal to brain. The results suggest the existence of Kv4/KChIP/DPPL ternary complexes in ISA -expressing nociceptors and pain-modulating spinal interneurons.
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http://dx.doi.org/10.1002/cne.23876DOI Listing
March 2016

Continuously tunable and fast-response terahertz metamaterials using in-plane-switching dual-frequency liquid crystal cells.

Opt Lett 2015 May;40(9):2021-4

A metamaterial that is embedded in an in-plane-switching dual-frequency liquid crystal cell is used to develop an electrically controllable terahertz (THz) metamaterial. The resonance peak of the metamaterial can be redshifted and blueshifted as the frequency of an external voltage is switched, and the response times for the redshift and blueshift are 1.044 and 1.376 ms, respectively. A simulation confirms the spectral redshift and blueshift. The variation in peak frequency as a function of applied frequency at the external voltage is presented. Experimental results show that the resonance peak of the metamaterial can be continuously tuned within a frequency range of 15 GHz as the applied frequency is switched between 19 and 22 kHz. Therefore, this metamaterial is a continuously tunable and fast-response THz filter and could be used for THz imaging and THz telecommunications.
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http://dx.doi.org/10.1364/OL.40.002021DOI Listing
May 2015

Resonance enhancement of terahertz metamaterials by liquid crystals/indium tin oxide interfaces.

Opt Express 2013 Mar;21(5):6519-25

Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore.

This work fabricates a terahertz (THz) metamaterial device, whose structure consists of split ring resonator array/ plastic substrate/ Indium Tin Oxide (ITO) film/ liquid crystals/ ITO film/ plastic substrate. Experiment results show that the resonance of the THz metamaterial device can be enhanced as voltage is applied to the liquid crystals. The enhancement will be more significant as higher voltage applied. The resonance enhancement is attributed to the fact that the liquid crystals/ITO interfaces exhibit the large difference in terms of refractive index between the two materials in THz regime. The interfaces reflect the incident electromagnetic wave and cause the reflected wave to enhance the resonance of the metamaterials. As those frequency-tunable metamaterial devices show different resonant transmittance at different frequencies, which is undesired, the liquid crystals/ITO interfaces can improve those frequency-tunable metamaterial devices with a constant transmittance at different frequencies.
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http://dx.doi.org/10.1364/OE.21.006519DOI Listing
March 2013

Coexpression of high-voltage-activated ion channels Kv3.4 and Cav1.2 in pioneer axons during pathfinding in the developing rat forebrain.

J Comp Neurol 2012 Nov;520(16):3650-72

Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan 112.

Precise axon pathfinding is crucial for establishment of the initial neuronal network during development. Pioneer axons navigate without the help of preexisting axons and pave the way for follower axons that project later. Voltage-gated ion channels make up the intrinsic electrical activity of pioneer axons and regulate axon pathfinding. To elucidate which channel molecules are present in pioneer axons, immunohistochemical analysis was performed to examine 14 voltage-gated ion channels (Kv1.1-Kv1.3, Kv3.1-Kv3.4, Kv4.3, Cav1.2, Cav1.3, Cav2.2, Nav1.2, Nav1.6, and Nav1.9) in nine axonal tracts in the developing rat forebrain, including the optic nerve, corpus callosum, corticofugal fibers, thalamocortical axons, lateral olfactory tract, hippocamposeptal projection, anterior commissure, hippocampal commissure, and medial longitudinal fasciculus. We found A-type K⁺ channel Kv3.4 in both pioneer axons and early follower axons and L-type Ca²⁺ channel Cav1.2 in pioneer axons and early and late follower axons. Spatially, Kv3.4 and Cav1.2 were colocalized with markers of pioneer neurons and pioneer axons, such as deleted in colorectal cancer (DCC), in most fiber tracts examined. Temporally, Kv3.4 and Cav1.2 were expressed abundantly in most fiber tracts during axon pathfinding but were downregulated beginning in synaptogenesis. By contrast, delayed rectifier Kv channels (e.g., Kv1.1) and Nav channels (e.g., Nav1.2) were absent from these fiber tracts (except for the corpus callosum) during pathfinding of pioneer axons. These data suggest that Kv3.4 and Cav1.2, two high-voltage-activated ion channels, may act together to control Ca²⁺ -dependent electrical activity of pioneer axons and play important roles during axon pathfinding.
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http://dx.doi.org/10.1002/cne.23119DOI Listing
November 2012

All-optical and polarization-independent spatial filter based on a vertically-aligned polymer-stabilized liquid crystal film with a photoconductive layer.

Opt Express 2009 Dec;17(25):22386-92

Institute of Electro-Optical Science and Engineering and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan 701, Republic of China.

An all-optical and polarization-independent spatial filter was developed in a vertically-aligned (VA) polymer-stabilized liquid crystal (PSLC) film with a photoconductive (PC) layer. This spatial filter is based on the effect of light on the conductivity of PC layer: high (low)-intensity light makes the conductivity of the PC layer high (low), resulting in a low (high) threshold voltage of the PC-coated VA PSLC cell. Experimental results indicate that this spatial filter is a high-pass filter with low optical-power consumption (about 1.11 mW/cm(2)) in an optical Fourier transform system. The high-pass characteristic was confirmed by simulation. Accordingly, the all-optical and polarization-independent spatial filter can be used to enhance the edges of images.
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http://dx.doi.org/10.1364/OE.17.022386DOI Listing
December 2009
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