Publications by authors named "Lingling Shui"

91 Publications

Lithography-free synthesis of periodic, vertically-aligned, multi-walled carbon nanotube arrays.

Nanotechnology 2021 Nov 18;33(6). Epub 2021 Nov 18.

International Academy of Optoelectronics at Zhaoqing, South China Normal University, Zhaoqing, 526238 Guangdong, People's Republic of China.

Until now, the growth of periodic vertically aligned multi-walled carbon nanotube (VA-MWCNT) arrays was dependent on at least one lithography step during fabrication. Here, we demonstrate a lithography-free fabrication method to grow hexagonal arrays of self-standing VA-MWCNTs with tunable pitch and MWCNT size. The MWCNTs are synthesized by plasma enhanced chemical vapor deposition (PECVD) from Ni catalyst particles. Template guided dewetting of a thin Ni film on a hexagonally close-packed silica particle monolayer provides periodically distributed Ni catalyst particles as seeds for the growth of the periodic MWCNT arrays. The diameter of the silica particles directly controls the pitch of the periodic VA-MWCNT arrays from 600 nm to as small as 160 nm. The diameter and length of the individual MWCNTs can also be readily adjusted and are a function of the Ni particle size and PECVD time. This unique method of lithography-free growth of periodic VA-MWCNT arrays can be utilized for the fabrication of large-scale biomimetic materials.
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http://dx.doi.org/10.1088/1361-6528/ac345aDOI Listing
November 2021

Design of Quasi-MOF Nanospheres as a Dynamic Electrocatalyst toward Accelerated Sulfur Reduction Reaction for High-Performance Lithium-Sulfur Batteries.

Adv Mater 2022 Jan 7;34(2):e2105541. Epub 2021 Nov 7.

Department of Chemical Engineering, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.

Lithium-sulfur (Li-S) batteries are considered as one of the most promising next-generation rechargeable batteries owing to their high energy density and cost-effectiveness. However, the sluggish kinetics of the sulfur reduction reaction process, which is so far insufficiently explored, still impedes its practical application. Metal-organic frameworks (MOFs) are widely investigated as a sulfur immobilizer, but the interactions and catalytic activity of lithium polysulfides (LiPs) on metal nodes are weak due to the presence of organic ligands. Herein, a strategy to design quasi-MOF nanospheres, which contain a transition-state structure between the MOF and the metal oxide via controlled ligand exchange strategy, to serve as sulfur electrocatalyst, is presented. The quasi-MOF not only inherits the porous structure of the MOF, but also exposes abundant metal nodes to act as active sites, rendering strong LiPs absorbability. The reversible deligandation/ligandation of the quasi-MOF and its impact on the durability of the catalyst over the course of the electrochemical process is acknowledged, which confers a remarkable catalytic activity. Attributed to these structural advantages, the quasi-MOF delivers a decent discharge capacity and low capacity-fading rate over long-term cycling. This work not only offers insight into the rational design of quasi-MOF-based composites but also provides guidance for application in Li-S batteries.
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http://dx.doi.org/10.1002/adma.202105541DOI Listing
January 2022

Autonomous capillary microfluidic devices with constant flow rate and temperature-controlled valving.

Soft Matter 2021 Sep 5;17(33):7781-7791. Epub 2021 Aug 5.

National Center for International Research on Green Optoelectronics & South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.

In this paper, we report on a capillary microfluidic device with constant flow rate and temperature-triggered stop valve function. It contains a PDMS channel that was grafted by a thermo-responsive polymer poly(N-isopropylacrylamide) (PNIPAm). The channel exhibits a constant capillary filling speed. By locally increasing the temperature in the channel from 20 °C to 37 °C using a microfabricated heater, a change of the surface wettability from hydrophilic to hydrophobic is obtained creating a hydrophobic stop valve. The valve can be reopened by lowering the temperature. The device is simple to fabricate and can be used as an actuatable capillary pump operating around room temperature. To understand the constant capillary filling speed, we performed contact angle measurements, in which we found slow wetting kinetics of PNIPAm-g-PDMS surfaces at temperatures below the lower critical solution temperature (LCST) of PNIPAm and fast wetting kinetics above the LCST. We interpret this as the result of the diffusive hydration process of PNIPAm below the LCST and the absence of hydration on the hydrophobic PNIPAm thin layer above the LCST.
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http://dx.doi.org/10.1039/d1sm00625hDOI Listing
September 2021

Enhanced Bandwidth Broadening of Infrared Reflector Based on Polymer Stabilized Cholesteric Liquid Crystals with Poly(N-vinylcarbazole) Used as Alignment Layer.

Polymers (Basel) 2021 Jul 8;13(14). Epub 2021 Jul 8.

SCNU-TUE Joint Lab of Device Integrated Responsive Materials (DIRM), National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, China.

Alignment layer plays a critical role on liquid crystal (LC) conformation for most LC devices. Normally, polyimide (PI) or polyvinyl alcohol (PVA), characterized by their outstanding thermal and electrical properties, have been widely applied as the alignment layer to align LC molecules. Here, we used a semi-conductive material poly(N-vinylcarbazole) (PVK) as the alignment layer to fabricate the cholesteric liquid crystal (CLC) device and the polymer-stabilized cholesteric liquid crystals (PSCLC)-based infrared (IR) reflectors. In the presence of ultraviolet (UV) irradiation, there are hole-electron pairs generated in the PVK layer, which neutralizes the impurity electrons in the LC-PVK junction, resulting in the reduction in the built-in electric field in the LC device. Therefore, the operational voltage of the CLC device switching from cholesteric texture to focal conic texture decreases from 45 V to 30 V. For the PSCLC-based IR reflectors with the PVK alignment layer, at the same applied electric field, the reflection bandwidth is enhanced from 647 to 821 nm, ranging from 685 to 1506 nm in the IR region, which makes it attractive for saving energy as a smart window.
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http://dx.doi.org/10.3390/polym13142238DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8309408PMC
July 2021

Electrolyte Design for Lithium Metal Anode-Based Batteries Toward Extreme Temperature Application.

Adv Sci (Weinh) 2021 Sep 17;8(18):e2101051. Epub 2021 Jul 17.

Department of Chemical Engineering, Waterloo Institute of Nanotechnology, University of Waterloo, Waterloo, N2L 3G1, Canada.

Lithium anode-based batteries (LBs) are highly demanded in society owing to the high theoretical capacity and low reduction potential of metallic lithium. They are expected to see increasing deployment in performance critical areas including electric vehicles, grid storage, space, and sea vehicle operations. Unfortunately, competitive performance cannot be achieved when LBs operating under extreme temperature conditions where the lithium-ion chemistry fail to perform optimally. In this review, a brief overview of the challenges in developing LBs for low temperature (<0 °C) and high temperature (>60 °C) operation are provided followed by electrolyte design strategies involving Li salt modification, solvation structure optimization, additive introduction, and solid-state electrolyte utilization for LBs are introduced. Specifically, the prospects of using lithium metal batteries (LMBs), lithium sulfur (Li-S) batteries, and lithium oxygen (Li-O ) batteries for performance under low and high temperature applications are evaluated. These three chemistries are presented as prototypical examples of how the conventional low temperature charge transfer resistances and high temperature side reactions can be overcome. This review also points out the research direction of extreme temperature electrolyte design toward practical applications.
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http://dx.doi.org/10.1002/advs.202101051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8456284PMC
September 2021

Microfluidic Magnetic Analyte Delivery Technique for Separation, Enrichment, and Fluorescence Detection of Ultratrace Biomarkers.

Anal Chem 2021 06 1;93(23):8273-8280. Epub 2021 Jun 1.

School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, China.

A microfluidic magnetic analyte delivery (μMAD) technique was developed to realize sample preparation and ultrasensitive biomarker detection. A simply designed microfluidic device was employed to carry out this technique, including a poly(dimethylsiloxane)-glass hybrid microchip having four straight rectangular channels and a permanent magnet. In the μMAD process, functionalized magnetic beads (MBs) were used to recognize and isolate analytes from a complex sample matrix, deliver analytes into tiny microchannels, and preconcentrate analytes in the magnetic trapping/detection region for in situ fluorescence detection. In the feasibility study and sensitivity optimization, horseradish peroxidase-labeled MBs were used, and critical parameters for the signal amplification performance of μMAD were carefully evaluated. At optimized conditions, a sensitivity improvement of at least 2 orders of magnitude was achieved. As a proof of concept, μMAD was combined with the enzyme-linked immunosorbent assay (ELISA), while carcinoembryonic antigen (CEA), prostate-specific antigen (PSA), and interleukin 6 (IL-6) were selected as model biomarkers. The limits of detection (LODs) of μMAD-ELISA were as low as 0.29 pg/mL for CEA, 0.047 pg/mL for PSA, and 0.021 pg/mL for IL-6, which corresponded to an over 200-fold reduction compared to their commercial ELISA results. Meanwhile, μMAD-ELISA revealed high selectivity and reproducibility. In clinical sample analysis, good accuracy was acquired for human serum analysis relative to commercial ELISA kits, and satisfied recoveries of 85.1-102% with RSDs of 1.7-9.8% for IL-6 and 84.7-113% with RSDs of 3.2-8.3% for interferon-γ were obtained. This ultrasensitive and easy operation technique provides a valuable approach for trace-level biomarker detection for practical applications.
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http://dx.doi.org/10.1021/acs.analchem.1c01130DOI Listing
June 2021

Flow-Field-Assisted Dielectrophoretic Microchips for High-Efficiency Sheathless Particle/Cell Separation with Dual Mode.

Anal Chem 2021 06 18;93(21):7606-7615. Epub 2021 May 18.

International Joint Laboratory of Optofluidic Technology and System, National Center for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics and School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, China.

Prefocusing of cell mixtures through sheath flow is a common technique used for continuous and high-efficiency dielectrophoretic (DEP) cell separation. However, it usually limits the separation flow velocity and requires a complex multichannel fluid control system that hinders the integration of a DEP separator with other microfluidic functionalities for comprehensive biomedical applications. Here, we propose and develop a high-efficiency, sheathless particle/cell separation method without prefocusing based on flow-field-assisted DEP by combining the effects of AC electric field (E-field) and flow field (F-field). A hollow lemon-shaped electrode array is designed to generate a long-range E-field gradient in the microchannel, which can effectively induce lateral displacements of particles/cells in a continuous flow. A series of arc-shaped protrusion structures is designed along the microchannel to form a F-field, which can effectively guide the particles/cells toward the targeted E-field region without prefocusing. By tuning the E-field, two distinct modes can be realized and switched in one single device, including the sheathless separation (ShLS) and the adjustable particle mixing ratio (AMR) modes. In the ShLS mode, we have achieved the continuous separation of breast cancer cells from erythrocytes with a recovery rate of 95.5% and the separation of polystyrene particles from yeast cells with a purity of 97.1% at flow velocities over 2.59 mm/s in a 2 cm channel under optimized conditions. The AMR mode provides a strategy for controlling the mixing ratio of different particles/cells as a well-defined pretreatment method for biomedical research studies. The proposed microchip is easy to use and displays high versatility for biological and medical applications.
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http://dx.doi.org/10.1021/acs.analchem.1c00018DOI Listing
June 2021

Symmetric Pearcey Gaussian beams.

Opt Lett 2021 May;46(10):2461-2464

In this Letter, a new, to the best of our knowledge, type of autofocusing and symmetric beam arisen from two quartic spectral phases is introduced in theory and experiment. The symmetric Pearcey Gaussian beam (SPGB), formed with a Gaussian term and two multiplying Pearcey integrals, processes a focusing intensity approximately 1.32 times stronger than the intensity of the symmetric Airy beam. Its four off-axis main lobes split into four bending trajectories symmetrically after focusing. The rectangular intensity distribution and the focal length of the SPGB can be adjusted by two kinds of distribution factors. Additionally, the vortex-guiding property of the beam is demonstrated by embedding an off-axis vortex into the SPGB, which can be applied in particle guiding.
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http://dx.doi.org/10.1364/OL.425889DOI Listing
May 2021

Hierarchical Micro-Nanoclusters of Bimetallic Layered Hydroxide Polyhedrons as Advanced Sulfur Reservoir for High-Performance Lithium-Sulfur Batteries.

Adv Sci (Weinh) 2021 Apr 29;8(7):2003400. Epub 2021 Jan 29.

Department of Chemical Engineering University of Waterloo Waterloo ON N2L 3G1 Canada.

Rational construction of sulfur electrodes is essential in pursuit of practically viable lithium-sulfur (Li-S) batteries. Herein, bimetallic NiCo-layered double hydroxide (NiCo-LDH) with a unique hierarchical micro-nano architecture is developed as an advanced sulfur reservoir for Li-S batteries. Compared with the monometallic Co-layered double hydroxide (Co-LDH) counterpart, the bimetallic configuration realizes much enriched, miniaturized, and vertically aligned LDH nanosheets assembled in hollow polyhedral nanoarchitecture, which geometrically benefits the interface exposure for host-guest interactions. Beyond that, the introduction of secondary metal intensifies the chemical interactions between layered double hydroxide (LDH) and sulfur species, which implements strong sulfur immobilization and catalyzation for rapid and durable sulfur electrochemistry. Furthermore, the favorable NiCo-LDH is architecturally upgraded into closely packed micro-nano clusters with facilitated long-range electron/ion conduction and robust structural integrity. Due to these attributes, the corresponding Li-S cells realize excellent cyclability over 800 cycles with a minimum capacity fading of 0.04% per cycle and good rate capability up to 2 C. Moreover, highly reversible areal capacity of 4.3 mAh cm can be achieved under a raised sulfur loading of 5.5 mg cm. This work provides not only an effective architectural design but also a deepened understanding on bimetallic LDH sulfur reservoir for high-performance Li-S batteries.
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http://dx.doi.org/10.1002/advs.202003400DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8025003PMC
April 2021

Design of Driving Waveform Based on a Damping Oscillation for Optimizing Red Saturation in Three-Color Electrophoretic Displays.

Micromachines (Basel) 2021 Feb 7;12(2). Epub 2021 Feb 7.

College of Electron and Information, University of Electronic Science and Technology of China Zhongshan Institute, Zhongshan 528402, China.

At present, three-color electrophoretic displays (EPDs) have problems of dim brightness and insufficient color saturation. In this paper, a driving waveform based on a damping oscillation was proposed to optimize the red saturation in three-color EPDs. The optimized driving waveform was composed of an erasing stage, a particles activation stage, a red electrophoretic particles purification stage, and a red display stage. The driving duration was set to 360 ms, 880 ms, 400 ms, and 2400 ms, respectively. The erasing stage was used to erase the current pixel state and refresh to a black state. The particles' activation stage was set as two cycles, and then refreshed to the black state. The red electrophoretic particles' purification stage was a damping oscillation driving waveform. The red and black electrophoretic particles were separated by changing the magnitude and polarity of applied electric filed, so that the red electrophoretic particles were purified. The red display stage was a low positive voltage, and red electrophoretic particles were driven to the common electrode to display a red state. The experimental results showed that the maximum red saturation could reach 0.583, which was increased by 27.57% compared with the traditional driving waveform.
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http://dx.doi.org/10.3390/mi12020162DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7915761PMC
February 2021

Bimetallic Hollow Tubular NiCoO as a Bifunctional Electrocatalyst for Enhanced Oxygen Reduction and Evolution Reaction.

ACS Appl Mater Interfaces 2021 Feb 4;13(6):7334-7342. Epub 2021 Feb 4.

National Center for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronic, South China Normal University, Guangzhou 510006, China.

The development of high-efficiency oxygen electrocatalysts with earth-abundant transition metals rather than scarce noble metals has aroused growing interests due to their potential for energy storage and conversion applications. Herein, we developed a facile strategy to synthesize hollow tubular bimetallic Ni-Co oxide rooted with dense nanosheets for enhanced bifunctionality and facilitated redox reaction kinetics. Owing to the rational design of morphology and well-dispersed Ni and Co ions, the bimetallic samples exhibit admirable bifunctional electrocatalytic activities. This bimetallic Ni-Co oxide shows superior oxygen electrocatalytic performance in comparison with the monometallic Ni and Co oxides, according to the electrocatalytic synergistic effect from the bimetallic system. The optimized sample with the specific mass ratio of Ni and Co displays the oxygen reduction reaction (ORR) property comparable to commercial Pt/C and oxygen evolution reaction (OER) performance superior to commercial RuO. The electrochemical tests and structural characterizations offer in-depth dissection on the electrocatalytic behaviors, especially the superb stability in both ORR and OER tests, as well as the outstanding resistance to methanol poisoning, representing a promising candidate in the renewable energy field.
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http://dx.doi.org/10.1021/acsami.0c21974DOI Listing
February 2021

Direct Growth of Oxygen Vacancy-Enriched CoO Nanosheets on Carbon Nanotubes for High-Performance Supercapacitors.

ACS Appl Mater Interfaces 2021 Jan 12;13(3):4419-4428. Epub 2021 Jan 12.

South China Academy of Advanced Optoelectronics & International Academy of Optoelectronics at Zhaoqing, South China Normal University, Guangdong 510631, P. R. China.

Ultrathin CoO nanosheets (NSs) with abundant oxygen vacancies on conductive carbon nanotube (CNT) nanocomposites (termed as CoO-NSs/CNTs) are easily achieved by an effective NaBH-assisted cyanogel hydrolysis strategy under ambient conditions. The specific capacitance of CoO-NSs/CNTs with 5% CNT mass can reach 1280.4 F g at 1 A g and retain 112.5% even after 10 000 cycles, demonstrating very high electrochemical capability and stability. When assembled in the two-electrode CoO-NSs/CNTs-5%//reduced graphene oxide (rGO) system, a maximum specific energy density of 37.2 Wh kg (160.2 W kg) is obtained at room temperature. Ultrathin structure of nanosheets, abundant oxygen vacancies, and the synergistic effect between CoO-NSs and CNTs are crucial factors for excellent electrochemical performance. Specifically, these characteristics favor rapid electron transfer, complete exposure of the active interface, and sufficient adsorption/desorption of electrolyte ions within the active material. This work gives insights into the efficient construction of two-dimensional hybrid electrodes with high performance for the new-generation energy storage system.
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http://dx.doi.org/10.1021/acsami.0c21330DOI Listing
January 2021

Strain Engineering of a MXene/CNT Hierarchical Porous Hollow Microsphere Electrocatalyst for a High-Efficiency Lithium Polysulfide Conversion Process.

Angew Chem Int Ed Engl 2021 Feb 4;60(5):2371-2378. Epub 2021 Jan 4.

Department of Chemical Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.

Tensile-strained Mxene/carbon nanotube (CNT) porous microspheres were developed as an electrocatalyst for the lithium polysulfide (LiPS) redox reaction. The internal stress on the surface results in lattice distortion with expanding Ti-Ti bonds, endowing the Mxene nanosheet with abundant active sites and regulating the d-band center of Ti atoms upshifted closer to the Fermi level, leading to strengthened LiPS adsorbability and accelerated catalytic conversion. The macroporous framework offers uniformed sulfur distribution, potent sulfur immobilization, and large surface area. The composite interwoven by CNT tentacle enhances conductivity and prevents the restacking of Mxene sheets. This combination of tensile strain effect and hierarchical architecture design results in smooth and favorable trapping-diffusion-conversion of LiPS on the interface. The Li-S battery exhibits an initial capacity of 1451 mAh g at 0.2 C, rate capability up to 8 C, and prolonged cycle life.
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http://dx.doi.org/10.1002/anie.202011493DOI Listing
February 2021

Designing Splicing Digital Microfluidics Chips Based on Polytetrafluoroethylene Membrane.

Micromachines (Basel) 2020 Nov 30;11(12). Epub 2020 Nov 30.

College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan 528402, China.

As a laboratory-on-a-chip application tool, digital microfluidics (DMF) technology is widely used in DNA-based applications, clinical diagnosis, chemical synthesis, and other fields. Additional components (such as heaters, centrifuges, mixers, etc.) are required in practical applications on DMF devices. In this paper, a DMF chip interconnection method based on electrowetting-on-dielectric (EWOD) was proposed. An open modified slippery liquid-infused porous surface (SLIPS) membrane was used as the dielectric-hydrophobic layer material, which consisted of polytetrafluoroethylene (PTFE) membrane and silicone oil. Indium tin oxide (ITO) glass was used to manufacture the DMF chip. In order to test the relationship between the splicing gap and droplet moving, the effect of the different electrodes on/off time on the minimum driving voltage when the droplet crossed a splicing gap was investigated. Then, the effects of splicing gaps of different widths, splicing heights, and electrode misalignments were investigated, respectively. The experimental results showed that a driving voltage of 119 V was required for a droplet to cross a splicing gap width of 300 μm when the droplet volume was 10 μL and the electrode on/off time was 600 ms. At the same time, the droplet could climb a height difference of 150 μm with 145 V, and 141 V was required when the electrode misalignment was 1000 μm. Finally, the minimum voltage was not obviously changed, when the same volume droplet with different aqueous solutions crossed the splicing gap, and the droplet could cross different chip types. These splicing solutions show high potential for simultaneous detection of multiple components in human body fluids.
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http://dx.doi.org/10.3390/mi11121067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7760364PMC
November 2020

Faradaic Electrodes Open a New Era for Capacitive Deionization.

Adv Sci (Weinh) 2020 Nov 11;7(22):2002213. Epub 2020 Oct 11.

Department of Chemical Engineering Waterloo Institute of Nanotechnology University of Waterloo 200 University Ave West Waterloo Ontario N2L 3G1 Canada.

Capacitive deionization (CDI) is an emerging desalination technology for effective removal of ionic species from aqueous solutions. Compared to conventional CDI, which is based on carbon electrodes and struggles with high salinity streams due to a limited salt removal capacity by ion electrosorption and excessive co-ion expulsion, the emerging Faradaic electrodes provide unique opportunities to upgrade the CDI performance, i.e., achieving much higher salt removal capacities and energy-efficient desalination for high salinity streams, due to the Faradaic reaction for ion capture. This article presents a comprehensive overview on the current developments of Faradaic electrode materials for CDI. Here, the fundamentals of Faradaic electrode-based CDI are first introduced in detail, including novel CDI cell architectures, key CDI performance metrics, ion capture mechanisms, and the design principles of Faradaic electrode materials. Three main categories of Faradaic electrode materials are summarized and discussed regarding their crystal structure, physicochemical characteristics, and desalination performance. In particular, the ion capture mechanisms in Faradaic electrode materials are highlighted to obtain a better understanding of the CDI process. Moreover, novel tailored applications, including selective ion removal and contaminant removal, are specifically introduced. Finally, the remaining challenges and research directions are also outlined to provide guidelines for future research.
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http://dx.doi.org/10.1002/advs.202002213DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7675053PMC
November 2020

Regulating the Li -Solvation Structure of Ester Electrolyte for High-Energy-Density Lithium Metal Batteries.

Small 2020 Nov 2;16(47):e2004688. Epub 2020 Nov 2.

Department of Chemical Engineering, Waterloo Institute of Nanotechnology, University of Waterloo, 200 University Ave West, Waterloo, Ontario, N2L 3G1, Canada.

The development of high-energy-density Li metal batteries are hindered by electrolyte consumption and uneven lithium deposition due to the unstable lithium-electrolyte interface (SEI). In this work, tetraglyme is introduced into ester electrolyte to regulate the Li -solvation structures for stable SEI while remaining appropriate voltage window for high-voltage cathodes. In the modified solvation structures, an enhanced lowest unoccupied molecular orbital energy level occurs, resulting in relieved electrolyte degradation. In addition, the modified solvation structures can facilitate adequate LiNO dissolution in the ester electrolyte (denoted as E-LiNO ), contributing to constant supplement of constructing highly conductive LiN O -containing SEI for dendrite-free Li deposition under high capacity condition. As a result, the Li||Cu cell-based on this electrolyte exhibits high Li plating/stripping Coulombic efficiency of 98.2% over 350 cycles. Furthermore, when paired with high-voltage LiNi Co Mn O cathodes, the E-LiNO enables a stable cycling with a high-energy-density of 296 Wh kg based on the full cell under realistic testing conditions (lean electrolyte of 3 g Ah , limited Li excess of 2.45-fold, and high areal capacity of 4 mAh cm ).
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http://dx.doi.org/10.1002/smll.202004688DOI Listing
November 2020

Novel 2D/2D BiOBr/UMOFNs direct Z-scheme photocatalyst for efficient phenol degradation.

Nanotechnology 2021 Jan;32(4):045711

South China Academy of Advanced Optoelectronics & International Academy of Optoelectronics at Zhaoqing, South China Normal University, Guangdong, 510631, People's Republic of China.

A novel 2D/2D BiOBr/ultrathin metal-organic framework nanosheets (UMOFNs) direct Z-scheme photocatalyst was successfully synthesized by using a simple deposition-precipitation method. The photocatalytic performance was evaluated under light irradiation, which revealed that the 2D/2D BiOBr/UMOFNs Z-scheme photocatalyst exhibits higher photocatalytic degradation of phenol compared to pristine BiOBr and UMOFNs. A BiOBr/UMOFNs-40% (mass ratio for BiOBr and UMOFNs of 1:0.4) photocatalyst was found to show the best photocatalytic degradation efficiency and stability, reaching 99% phenol degradation under light irradiation of 270 min and maintaining 97% degradation after 5 recycling runs. Results obtained from a trapping experiment and electron paramagnetic resonance suggest that reactive ·OH and O play a major role in phenol degradation. Photoluminescence and photocurrent results reveal that the excellent photocatalytic activity of the 2D/2D BiOBr/UMOFNs photocatalyst can be ascribed to the efficient separation of photogenerated electron-hole pairs through a direct Z-scheme system. This article provides a possible reference for designing Z-scheme photocatalysts by using MOFs and semiconductors for practical organic pollutant treatment.
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http://dx.doi.org/10.1088/1361-6528/abc113DOI Listing
January 2021

Emergent Ferroelectricity in Otherwise Nonferroelectric Oxides by Oxygen Vacancy Design at Heterointerfaces.

ACS Appl Mater Interfaces 2020 Oct 25;12(40):45602-45610. Epub 2020 Sep 25.

Key Laboratory of Magnetic Materials Devices & Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.

Introducing point defects in complex metal oxides is a very effective route to engineer crystal symmetry and therefore control physical properties. However, the inversion symmetry breaking, which is vital for many tantalizing properties, such as ferroelectricity and chiral spin structure, is usually hard to be induced in the bulk crystal by point defects. By designing the oxygen vacancy formation energy profile and migration path across the oxide heterostructure, our first-principles density functional theory (DFT) calculations demonstrate that the point defects can effectively break the inversion symmetry and hence create novel ferroelectricity in superlattices consisting of otherwise nonferroelectric materials SrTiO and SrRuO. This induced ferroelectricity can be significantly enhanced by reducing the SrTiO thickness. Inspired by theory calculation, SrTiO/SrRuO superlattices were experimentally fabricated and are found to exhibit surprising strong ferroelectric properties. Our finding paves a simple and effective pathway to engineer the inversion symmetry and thus properties by point defect control in oxide heterostructures.
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http://dx.doi.org/10.1021/acsami.0c13314DOI Listing
October 2020

Fabrication of Photo-Crosslinkable Poly(Trimethylene Carbonate)/Polycaprolactone Nanofibrous Scaffolds for Tendon Regeneration.

Int J Nanomedicine 2020 25;15:6373-6383. Epub 2020 Aug 25.

National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, People's Republic of China.

Background: The treatment of tendon injuries remains a challenging problem in clinical due to their slow and insufficient natural healing process. Scaffold-based tissue engineering provides a promising strategy to facilitate tendon healing and regeneration. However, many tissue engineering scaffolds have failed due to their poor and unstable mechanical properties. To address this, we fabricated nanofibrous polycaprolactone/methacrylated poly(trimethylene carbonate) (PCL/PTMC-MA) composite scaffolds via electrospinning.

Materials And Methods: PTMC-MA was characterized by nuclear magnetic resonance. Fiber morphology of composite scaffolds was evaluated using scanning electron microscopy. The monotonic tensile test was performed for determining the mechanical properties of composite scaffolds. Cell viability and collagen deposition were assessed via PrestoBlue assay and enzyme-linked immunosorbent assay, respectively.

Results: These PCL/PTMC-MA composite scaffolds had an increase in mechanical properties as PTMC-MA content increase. After photo-crosslinking, they showed further enhanced mechanical properties including creep resistance, which was superior to pure PCL scaffolds. It is worth noting that photo-crosslinked PCL/PTMC-MA (1:3) composite scaffolds had a Young's modulus of 31.13 ± 1.30 MPa and Max stress at break of 23.80 ± 3.44 MPa that were comparable with the mechanical properties of native tendon (Young's modulus 20-1200 MPa, max stress at break 5-100 MPa). In addition, biological experiments demonstrated that PCL/PTMC-MA composite scaffolds were biocompatible for cell adhesion, proliferation, and differentiation.
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http://dx.doi.org/10.2147/IJN.S246966DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7457647PMC
November 2020

Synthesis of Perovskite Nanocrystals and Their Photon-Emission Application in Conjunction With Liquid Crystals.

Front Chem 2020 28;8:574. Epub 2020 Jul 28.

Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, China.

Perovskite nanocrystals have attracted worldwide attention due to their outstanding optical versatility, high photoluminescence quantum yields, and facile synthesis. In this review, we firstly revisit the synthetic methods for perovskite nanocrystals (PNCs), including hot injection, anion exchange, solvothermal reaction, etc. In the meantime, we discuss effects of the different synthetic methods on the properties of PNCs, including the crystal size, emission spectral feature, quantum yield, etc., followed by several optimizing strategies. Finally, lasing and display applications of these PNCs in combination with liquid crystal materials are discussed thoroughly. Outlooks on the challenges and opportunities of these nanocrystalline materials in terms of adjunct applications with liquid crystals have been presented at the end, which are highly promising for next-generation light emission applications.
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http://dx.doi.org/10.3389/fchem.2020.00574DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7399476PMC
July 2020

22% Efficiency Inverted Perovskite Photovoltaic Cell Using Cation-Doped Brookite TiO Top Buffer.

Adv Sci (Weinh) 2020 Aug 2;7(16):2001285. Epub 2020 Jul 2.

Material Research Institute Pennsylvania State University University Park PA 16802 USA.

Simultaneously achieving high efficiency and high durability in perovskite solar cells is a critical step toward the commercialization of this technology. Inverted perovskite photovoltaic (IP-PV) cells incorporating robust and low levelized-cost-of-energy (LCOE) buffer layers are supposed to be a promising solution to this target. However, insufficient inventory of materials for back-electrode buffers substantially limits the development of IP-PV. Herein, a composite consisting of 1D cation-doped TiO brookite nanorod (NR) embedded by 0D fullerene is investigated as a top modification buffer for IP-PV. The cathode buffer is constructed by introducing fullerene to fill the interstitial space of the TiO NR matrix. Meanwhile, cations of transition metal Co or Fe are doped into the TiO NR to further tune the electronic property. Such a top buffer exhibits multifold advantages, including improved film uniformity, enhanced electron extraction and transfer ability, better energy level matching with perovskite, and stronger moisture resistance. Correspondingly, the resultant IP-PV displays an efficiency exceeding 22% with a 22-fold prolonged working lifetime. The strategy not only provides an essential addition to the material inventory for top electron buffers by introducing the 0D:1D composite concept, but also opens a new avenue to optimize perovskite PVs with desirable properties.
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http://dx.doi.org/10.1002/advs.202001285DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7435259PMC
August 2020

Plasmonic Nanocrystal Arrays on Photonic Crystals with Tailored Optical Resonances.

ACS Appl Mater Interfaces 2020 Aug 5;12(33):37657-37669. Epub 2020 Aug 5.

BIOS Lab-on-a-Chip Group, MESA+ Institute for Nanotechnology, Technical Medical Centre & Max Planck Center for Complex Fluid Dynamics, University of Twente, 7522 NB Enschede, the Netherlands.

Hierarchical plasmonic-photonic microspheres (PPMs) with high controllability in their structures and optical properties have been explored toward surface-enhanced Raman spectroscopy. The PPMs consist of gold nanocrystal (AuNC) arrays (3rd-tier) anchored on a hexagonal nanopattern (2nd-tier) assembled from silica nanoparticles (SiONPs) where the uniform microsphere backbone is termed the 1st-tier. The PPMs sustain both photonic stop band (PSB) properties, resulting from periodic SiONP arrangements of the 2nd-tier, and a surface plasmon resonance (SPR), resulting from AuNC arrays of the 3rd-tier. Thanks to the synergistic effects of the photonic crystal (PC) structure and the AuNC array, the electromagnetic (EM) field in such a multiscale composite structure can tremendously be enhanced at certain wavelengths. These effects are demonstrated by experimentally evaluating the Raman enhancement of benzenethiol (BT) as a probe molecule and are confirmed via numerical simulations. We achieve a maximum SERS enhancement factor of up to ∼10 when the resonances are tailored to coincide with the excitation wavelength by suitable structural modifications.
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http://dx.doi.org/10.1021/acsami.0c05596DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7441488PMC
August 2020

A Cost-Effective, Aqueous-Solution-Processed Cathode Interlayer Based on Organosilica Nanodots for Highly Efficient and Stable Organic Solar Cells.

Adv Mater 2020 Sep 13;32(38):e2002973. Epub 2020 Aug 13.

Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China.

The performance and industrial viability of organic photovoltaics are strongly influenced by the functionality and stability of interface layers. Many of the interface materials most commonly used in the lab are limited in their operational stability or their materials cost and are frequently not transferred toward large-scale production and industrial applications. In this work, an advanced aqueous-solution-processed cathode interface layer is demonstrated based on cost-effective organosilica nanodots (OSiNDs) synthesized via a simple one-step hydrothermal reaction. Compared to the interface layers optimized for inverted organic solar cells (i-OSCs), the OSiNDs cathode interlayer shows improved charge carrier extraction and excellent operational stability for various model photoactive systems, achieving a remarkably high power conversion efficiency up to 17.15%. More importantly, the OSiNDs' interlayer is extremely stable under thermal stress or photoillumination (UV and AM 1.5G) and undergoes no photochemical reaction with the photoactive materials used. As a result, the operational stability of inverted OSCs under continuous 1 sun illumination (AM 1.5G, 100 mW cm ) is significantly improved by replacing the commonly used ZnO interlayer with OSiND-based interfaces.
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http://dx.doi.org/10.1002/adma.202002973DOI Listing
September 2020

Charge Trapping-Based Electricity Generator (CTEG): An Ultrarobust and High Efficiency Nanogenerator for Energy Harvesting from Water Droplets.

Adv Mater 2020 Aug 6;32(33):e2001699. Epub 2020 Jul 6.

Physics of Complex Fluids, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente, Enschede, 7500AE, The Netherlands.

Strategies toward harvesting energy from water movements are proposed in recent years. Reverse electrowetting allows high efficiency energy generation, but requires external electric field. Triboelectric nanogenerators, as passive energy harvesting devices, are limited by the unstable and low density of tribo-charges. Here, a charge trapping-based electricity generator (CTEG) is proposed for passive energy harvesting from water droplets with high efficiency. The hydrophobic fluoropolymer films utilized in CTEG are pre-charged by a homogeneous electrowetting-assisted charge injection (h-EWCI) method, allowing an ultrahigh negative charge density of 1.8 mC m . By utilizing a dedicated designed circuit to connect the bottom electrode and top electrode of a Pt wire, instantaneous currents beyond 2 mA, power density above 160 W m , and energy harvesting efficiency over 11% are achieved from continuously falling water droplets. CTEG devices show excellent robustness for energy harvesting from water drops, without appreciable degradation for intermittent testing during 100 days. These results exceed previously reported values by far. The approach is not only applicable for energy harvesting from water droplets or wave-like oscillatory fluid motion, but also opens up avenues toward other applications requiring passive electric responses, such as diverse sensors and wearable devices.
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http://dx.doi.org/10.1002/adma.202001699DOI Listing
August 2020

Nitrogen defects-rich porous graphitic carbon nitride for efficient photocatalytic hydrogen evolution.

J Colloid Interface Sci 2020 Oct 8;578:788-795. Epub 2020 Jun 8.

Guangdong Provincial Key Laboratory of Optical Information Materials and Technology& Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, China. Electronic address:

Graphitic carbon nitride (CN) is considered as a promising photocatalyst for solar energy conversion. However, low specific surface area and fast electrons and holes recombination restrict the photocatalytic applications of CN material. Herein, a nitrogen defect-rich and highly porous CN nanostructure (CN-LT) was prepared by combining two strategies, i.e., LiOH treatment and heat etching. The as-prepared nitrogen defect-rich porous CN-LT not only has a larger specific surface area, as compared with pristine CN, but also the photogenerated electron-hole separation was boosted remarkably. Using Pt as a co-catalyst and lactic acid aqueous solutions as sacrificial reagent under visible light irradiation (λ > 400 nm), the hydrogen evolution reaction (HER) rate for CN-LT (1.54 mmol h g) was 19.25 times higher than that for pristine CN (0.08 mmol h g). While subjecting pristine CN to heat etching under the same experimental conditions, excepting the use of LiOH (CN-T), an increase in HER rate of 7.5 times was obtained. Our current study may shed more light on the enhancement of the photocatalytic activity of bulk CN materials by altering their microstructure.
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http://dx.doi.org/10.1016/j.jcis.2020.06.023DOI Listing
October 2020

Hollow-Core Photonic Crystal Fiber Gas Sensing.

Sensors (Basel) 2020 May 25;20(10). Epub 2020 May 25.

Advanced Fiber Devices and Systems Group, Key Laboratory of Micro and Nano Photonic Structures (MoE), Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.

Fiber gas sensing techniques have been applied for a wide range of industrial applications. In this paper, the basic fiber gas sensing principles and the development of different fibers have been introduced. In various specialty fibers, hollow-core photonic crystal fibers (HC-PCFs) can overcome the fundamental limits of solid fibers and have attracted intense interest recently. Here, we focus on the review of HC-PCF gas sensing, including the light-guiding mechanisms of HC-PCFs, various sensing configurations, microfabrication approaches, and recent research advances including the mid-infrared gas sensors via hollow core anti-resonant fibers. This review gives a detailed and deep understanding of HC-PCF gas sensors and will promote more practical applications of HC-PCFs in the near future.
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http://dx.doi.org/10.3390/s20102996DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7288133PMC
May 2020

Cell elasticity measurement using a microfluidic device with real-time pressure feedback.

Lab Chip 2020 06;20(13):2343-2353

School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen, Shenzhen 518055, China.

The study of cell elasticity provides new insights into not only cell biology but also disease diagnosis based on cell mechanical state variation. Microfluidic technologies have made noticeable progress in studying cell deformation with capabilities of high throughput and automation. This paper reports the development of a novel microfluidic system to precisely measure the elasticity of cells having large deformation in a constriction channel. It integrated i) a separation unit to isolate rod- or flake-shaped particles that might block the constriction channel to increase the measurement throughput and ii) a pressure feedback system precisely detecting the pressure drop inducing the deformation of each cell. The fluid dynamics of the separation unit was modeled to understand the separation mechanism before the experimental determination of separation efficiency. Afterward, the pressure system was characterized to demonstrate its sensitivity and reproducibility in measuring the subtle pressure drop along a constriction channel. Finally, the microfluidic system was employed to study the stiffness of both K562 and endothelial cells. The cell protrusion and pressure drop were employed to calculate the mechanical properties based on a power-law rheology model describing the viscoelastic behaviors of cells. Both the stiffness and the fluidity of K562 and endothelial cells were consistent with those in previous studies. The system has remarkable application potential in the precise evaluation of cell mechanical properties.
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http://dx.doi.org/10.1039/d0lc00092bDOI Listing
June 2020

A highly efficient preconcentration route for rapid and sensitive detection of endotoxin based on an electrochemical biosensor.

Analyst 2020 Jun;145(12):4204-4211

Key Disciplines Lab of Novel Micro-Nano Devices and System Technology & Key Laboratory of Optoelectronic Technology and Systems (Ministry of Education), College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China. and International R & D center of Micro-nano Systems and New Materials Technology, Chongqing University, Shapingba, Chongqing 400044, China.

An impedimetric aptasensor for the detection of endotoxin in a microfluidic chip was proposed, in which the Apt/AuNPs/SPCE sensing surface was fabricated in a screen-printed electrode with good biological activity and stability. The quantitative detection of endotoxin was accomplished by electrochemical impedance spectroscopy (EIS) measurement before and after exposing to samples. The impedance biosensor offers an ultrasensitive and selective detection of endotoxin down to 500 pg mL-1 with a wide linear range from 500 pg mL-1 to 200 ng mL-1. According to the Langmuir isotherm model, the interactions between the target molecules and the sensing surface had been analyzed and strong binding was concluded. Compared to the traditional static incubation methods, the microfluidic biosensor realizes the enrichment of endotoxin owing to the confined space and continuous flow nature, so that the lowest detection concentration is reduced from 5 ng mL-1 to 500 pg mL-1, which is much lower than the existing technology, and the total assay time is shortened from 1.0 h to 0.5 h. The proposed microfluidic impedance biosensor provides a new strategy for the design of an aptasensor to realize the rapid detection of target biomolecules with high sensitivity and it can be integrated into wearable medical devices due to its flexible properties.
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http://dx.doi.org/10.1039/d0an00315hDOI Listing
June 2020

Janus Nanoparticles with Tunable Amphiphilicity for Stabilizing Pickering-Emulsion Droplets via Assembly Behavior at Oil-Water Interfaces.

ACS Appl Mater Interfaces 2020 Jun 1;12(23):26374-26383. Epub 2020 Jun 1.

National Center for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.

Janus particles (JNPs) with controlled anisotropies are regarded as promising materials for sophisticated building blocks and assembly. Herein a straightforward method was proposed for the synthesis of uniformly distributed JNPs with controllable anisotropies, showing two compartmental bulbs with different surface wettability. The synthetic strategy is based on the phase separation-induced styrene liquid protrusion on seed poly(styrene--acrylic acid) (CPSAA) nanoparticles via controlled swelling, with the formed polystyrene (PS) and CPSAA compartments corresponding to the amount of monomers. The size (lateral length) ratio of formed PS and CPSAA bulbs, /, defined as "Janusity", has been precisely tuned in the range of 0-0.91 by controlling the mass ratio of two monomers. Obtained JNPs with tunable amphiphilicity are utilized as colloid surfactants to prepare Pickering-emulsions of both water-in-oil (W/O) and oil-in-water (O/W) with proper Janusity. The stability of achieved W/O and O/W Pickering-emulsions is dependent on the adhesion energy of a JNP at the water-oil interfaces. Prepared JNPs have also being utilized to prepare and stabilize monodisperse droplets in microfluidic devices, demonstrating their high potential for fundamental research and practical applications.
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http://dx.doi.org/10.1021/acsami.0c05625DOI Listing
June 2020

Driving Waveform Design of Electrophoretic Display Based on Optimized Particle Activation for a Rapid Response Speed.

Micromachines (Basel) 2020 May 14;11(5). Epub 2020 May 14.

Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.

Electrophoretic displays (EPDs) have excellent paper-like display features, but their response speed is as long as hundreds of milliseconds. This is particularly important when optimizing the driving waveform for improving the response speed. Hence, a driving waveform design based on the optimization of particle activation was proposed by analyzing the electrophoresis performance of particles in EPD pixels. The particle activation in the driving waveform was divided into two phases: the improving particle activity phase and the uniform reference grayscale phase. First, according to the motion characteristics of particles in improving the particle activity phase, the real-time EPD brightness value can be obtained by an optical testing device. Secondly, the derivative of the EPD brightness curve was used to obtain the inflection point, and the inflection point was used as the duration of improving particle activity phase. Thirdly, the brightness curve of the uniform reference grayscale phase was studied to set the driving duration for obtaining a white reference grayscale. Finally, a set of four-level grayscale driving waveform was designed and validated in a commercial E-ink EPD. The experimental results showed that the proposed driving waveform can cause a reduction by 180 ms in improving particle activity phase and 120 ms in uniform reference grayscale phase effectively, and a unified reference grayscale can be achieved in uniform reference grayscale phase at the same time.
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http://dx.doi.org/10.3390/mi11050498DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281290PMC
May 2020
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