Co-reporter:Peng Ge, Shuli Wang, Yongshun Liu, Wendong Liu, Nianzuo Yu, Jianglei Zhang, Huaizhong Shen, Junhu Zhang, and Bai Yang
Langmuir July 25, 2017 Volume 33(Issue 29) pp:7248-7248
Publication Date(Web):July 6, 2017
DOI:10.1021/acs.langmuir.7b01934
In this paper, we report the preparation of anisotropic wetting surfaces that could control various wetting behaviors of liquids in a wide surface tension range (from water to oil), which could be employed as a platform for controlling the flow of liquids in microfluidics (MFs). The anisotropic wetting surfaces are chemistry-asymmetric “Janus” silicon cylinder arrays, which are fabricated via selecting and regulating the functional groups on the surface of each cylinder unit. Liquids (in a wide surface tension range) wet in a unidirectional manner along the direction that was modified by the group with large surface energy. Through introducing the Janus structure into a T-shaped pattern and integrating it with an identical T-shaped poly(dimethylsiloxane) microchannel, the as-prepared chips can be utilized to perform as a surface tension admeasuring apparatus or a one-way valve for liquids in a wide surface tension range, even oil. Furthermore, because of the excellent ability in controlling the flowing behavior of liquids in a wide surface tension range in an open system or a microchannel, the anisotropic wetting surfaces are potential candidates to be applied both in open MFs and conventional MFs, which would broaden the application fields of MFs.
Co-reporter:Shuli Wang;Tieqiang Wang;Peng Ge;Peihong Xue;Zibo Li;Shunsheng Ye;Hongxu Chen;Bai Yang
Langmuir April 7, 2015 Volume 31(Issue 13) pp:4032-4039
Publication Date(Web):2017-2-22
DOI:10.1021/acs.langmuir.5b00328
We report the flow behavior of water in microfluidic systems based on a chemically patterned anisotropic wetting surface. When water flows inside a microchannel on top of a micropatterned surface with alternating hydrophilic/hydrophobic stripes, it exhibits an anisotropic flowing characteristic owing to the anisotropic wettability; thus, the patterned surface acts as a microvalve for the microfluidic system. The anisotropic flow of water is influenced by the microscale features of the patterns and the dimensions of the microchannels. Furthermore, by reasonably combining the patterned surface and microchannel together, we realize the transportation of water in a microchannel along a “virtual” wall, which is the boundary of the hydrophilic and hydrophobic area. We believe that the chemically patterned surfaces could be an alternative strategy to control the flow behavior of water in microfluidic channels.
Co-reporter:Peng Ge;Shuli Wang;Wendong Liu;Tieqiang Wang;Nianzuo Yu;Peihong Xue;Hongxu Chen;Huaizhong Shen;Bai Yang
Advanced Materials Interfaces 2017 Volume 4(Issue 12) pp:
Publication Date(Web):2017/06/01
DOI:10.1002/admi.201700034
This paper reports the directional wetting behavior of water on a patterned heterogeneous surface, which is integrated by two asymmetric nanostructures with different directions. The asymmetric nanostructures are Janus silicon cylinder arrays (Si-CAs) modified by molecules with distinct surface energies on two sides. Through a photolithography process, the two asymmetric nanostructures are integrated in a single surface to form chessboard patterns with different directions. When water is injected onto the patterned surface, water droplets wet in a unidirectional manner, and the wetting direction is along resultant direction of the two wetting directions of water on the two asymmetric patterns. This paper investigates the factors which may influence the wetting behavior of water on the surface, experimental results show that patterned asymmetric surfaces prepared from different chessboard pattern size, Si-CAs with different diameters, and different morphology-symmetric structures do not affect the wetting property, but the molecules modified on two sides do. Larger surface energy difference between the modified molecules improves the ability of the surfaces induce water moving. It is believed that the patterned asymmetric nanostructure arrays provide a new strategy to modulate the wetting behavior of water, which will show potential applications in microfluidics and others involving unidirectional liquid manipulation.
Co-reporter:Peihong Xue;Shunsheng Ye;Hongyang Su;Shuli Wang;Jingjie Nan;Xingchi Chen;Weidong Ruan;Zhanchen Cui;Bai Yang
Nanoscale (2009-Present) 2017 vol. 9(Issue 20) pp:6724-6733
Publication Date(Web):2017/05/25
DOI:10.1039/C7NR01505D
We present an effective approach for fabricating graded plasmonic arrays based on ordered micro-/nanostructures with a geometric gradient. Ag nanowell arrays with graded geometric parameters were fabricated and systematically investigated. The order of the graded plasmonic arrays is generated by colloidal lithography, while the geometric gradient is the result of inclined reactive ion etching. The surface plasmon resonance (SPR) peaks were measured at different positions, which move gradually along the Ag nanowell arrays with a geometric gradient. Such micro-/nanostructure arrays with graded and integrated SPR peaks can work as a fine plasmonic “library” (FPL), and the spectral range can be controlled using a “coarse adjustment knob” (lattice constant) and a “fine adjustment knob” (pore diameter). Additionally, the spectral resolution of the FPL is high, which benefits from the high value of the full height/full width at half-maximum and the small step size of the wavelength shift (0.5 nm). Meanwhile, the FPL could be effectively applied as a well-defined model to verify the plasmonic enhancement in surface enhanced Raman scattering. As the FPL is an integrated optical material with graded individual SPR peaks, it can not only be a theoretical model for fundamental research, but also has great potential in high-throughput screening of optical materials, multiplex sensors, etc.
Co-reporter:Shunsheng Ye;Hongyu Wang;Hongyang Su;Lingxia Chang;Shuli Wang;Xuemin Zhang;Bai Yang
Journal of Materials Chemistry C 2017 vol. 5(Issue 16) pp:3962-3972
Publication Date(Web):2017/04/20
DOI:10.1039/C7TC00064B
A facile strategy is reported for the electrostatic self-assembly of homogeneous and gradient plasmonic nanoparticle arrays with tunable interparticle distances and optical properties. The interparticle distance is dominated by the surface charge density of the substrate, which is tuned via thermal annealing according to the temperature-dependent molecular mobility of the polymer. Oxygen plasma is employed to endow neutral polystyrene (PS) films with sufficient charges, enabling subsequent electrostatic adsorption. The density of surface charges can be readily tuned via a thermal annealing step after plasma treatment, which is confirmed by quantitative analyses of oxygen and nitrogen using X-ray photoelectron spectroscopy. Afterwards, PS films with regulated charge densities reshape the double layers around nanoparticles to various degrees during the assembly, leading to tunable interparticle separations. UV-Vis spectroscopy reveals tunable plasmonic properties owing to the critical role of interparticle separation in plasmon coupling. Here such structures are demonstrated to act as wavelength-selective substrates for multiplexed acquisition of surface enhanced Raman scattering. Alternatively, by applying a temperature gradient in the annealing step, we create a macroscopic surface with a continuous gradient in plasmonic properties. Such a “plasmonic library” can be a promising material for fast screening of interparticle distance or extinction spectrum in specific applications on one single substrate.
Co-reporter:Shunsheng Ye;Hongyu Wang;Hailong Wang;Lingxia Chang;Bai Yang
Journal of Materials Chemistry C 2017 vol. 5(Issue 44) pp:11631-11639
Publication Date(Web):2017/11/16
DOI:10.1039/C7TC03527F
A large-scale, uniform array of particle-in-aperture (PIA) hybrid architectures for highly reproducible surface-enhanced Raman spectroscopy (SERS) is rationally designed and prepared via electrostatic self-assembly of Au nanospheres and vertical deposition of Ag. By controlling the thickness of the Ag coating, polarization-independent ring-shaped hot spots with tunable width can be created around individual nanospheres, offering far higher Raman enhancements than a bare Au nanosphere array and a flat Ag film do. Three PIA substrates with different Ag thicknesses and an identical nanosphere diameter of 58 nm were investigated. Consequently, it is found that a 28 nm Ag coating enables the wavelength matching between the plasmonic coupling band and the laser line, leading to an enhancement factor of up to 4.5 × 106. Meanwhile, remarkable reproducibility of SERS signals is realized by ruling out the impact of anomalous hot spots. To this end, three guidelines are meticulously followed, i.e. using monodisperse Au nanospheres, distributing nanoring cavities evenly onto the substrate, and decoupling adjacent nanoparticles by isolating them far away from each other. This work offers a reliable strategy to fabricate high-performance SERS substrates in a simple, cost-effective and scalable manner, paving the way for practical sensing applications, such as quantitative SERS measurements.
Co-reporter:Peng Ge, Shuli Wang, Wendong Liu, Tieqiang Wang, Nianzuo Yu, Shunsheng Ye, Huaizhong Shen, Yuxin Wu, Junhu ZhangBai Yang
Langmuir 2017 Volume 33(Issue 9) pp:
Publication Date(Web):February 14, 2017
DOI:10.1021/acs.langmuir.7b00034
We report the unidirectional wetting behavior of liquids (water and oil) on Janus silicon cylinder arrays (Si-CAs) under various media (air, water, and oil). The Janus cylinders were prepared by chemical modification of nanocylinders with different molecules on two sides. Through adjusting surface energies of the modified molecules, the as-prepared surfaces could control the wetting behavior of different types of liquids under various media. We discuss the regularity systematically and propose a strategy for preparing anisotropic wetting surfaces under arbitrary media. That is, to find two surface modification molecules with different surface energies, one of the molecules is easy to be wetted by the liquid under the corresponding media, while the other one is difficult. Additionally, by introducing thermal-responsive polymer brushes onto one part of Janus Si-CAs, the surfaces show thermal-responsive anisotropic wetting property under various media. We believe that due to the excellent unidirectional wettability under various media, the Janus surfaces could be applied in water/oil transportation, oil-repellent and self-cleaning coatings, water/oil separation, microfluidics, and so on.
Co-reporter:Nianzuo Yu, Shuli Wang, Yongshun Liu, Peihong Xue, Peng Ge, Jingjie Nan, Shunsheng Ye, Wendong Liu, Junhu ZhangBai Yang
Langmuir 2017 Volume 33(Issue 2) pp:
Publication Date(Web):December 21, 2016
DOI:10.1021/acs.langmuir.6b03896
We show morphology-patterned stripes modified by thermal-responsive polymer for smartly guiding flow motion of fluid in chips. With a two-step modification process, we fabricated PNIPAAm-modified Si stripes on silicon slides, which were employed as substrates for fluid manipulation in microchannels. When the system temperature switches between above and below the lower critical solution temperature (LCST) of PNIPAAm, the wettability of the substrates also switches between strong anisotropy and weak anisotropy, which resulted in anisotropic (even unidirectional) flow and isotropic flow behavior of liquid in microchannels. The thermal-responsive flow motion of fluid in the chip is influenced by the applied pressure, the thickness of PNIPAAm, and dimension of the microchannels. Moreover, we measured the feasible applied pressure scopes under different structure factors. Because of the excellent reversibility and quick switching speed, the chip could be used as a thermal-responsive microvalve. Through tuning the system temperature and adding the assistant gas, we realized successive “valve” function. We believe that the practical and simple chip could be widely utilized in medical detection, immunodetection, protein analysis, and cell cultures.
Co-reporter:Shuli Wang, Nianzuo Yu, Tieqiang Wang, Peng Ge, Shunsheng Ye, Peihong Xue, Wendong Liu, Huaizhong Shen, Junhu Zhang, and Bai Yang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 20) pp:13094
Publication Date(Web):April 29, 2016
DOI:10.1021/acsami.6b01785
This article shows morphology-patterned stripes as a new platform for directing flow guidance of the fluid in microfluidic devices. Anisotropic (even unidirectional) spreading behavior due to anisotropic wetting of the underlying surface is observed after integrating morphology-patterned stripes with a Y-shaped microchannel. The anisotropic wetting flow of the fluid is influenced by the applied pressure, dimensions of the patterns, including the period and depth of the structure, and size of the channels. Fluids with different surface tensions show different flowing anisotropy in our microdevice. Moreover, the morphology-patterned surfaces could be used as a microvalve, and gas–water separation in the microchannel was realized using the unidirectional flow of water. Therefore, benefiting from their good performance and simple fabrication process, morphology-patterned surfaces are good candidates to be applied in controlling the fluid behavior in microfluidics.Keywords: anisotropic wetting; fluid control; gas−liquid separation; microfluidics; surface patterning
Co-reporter:Tieqiang Wang, Hongxu Chen, Kun Liu, Shuli Wang, Peihong Xue, Ye Yu, Peng Ge, Junhu Zhang, and Bai Yang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 1) pp:376
Publication Date(Web):December 5, 2014
DOI:10.1021/am5063647
In this paper, Janus micropillar array (MPA) with fore–aft controllable wettability difference was demonstrated. With two-step modification process, we successfully decorate the Janus pillar skeletons with wettability-switchable polymer brush on one side and hydrophilic self-assembled monolayer on the other. Owing to the switchable wettability of the polymer brush, the patterned surface could switch between anisotropic wetting and isotropic wetting at different temperatures, which gives the possibility of coupling the well-designed surface with microfluidic channel to manipulate the microfluid motion. Additionally, a further photothermal control of microfluid was also established based on the thermal-responsive Janus MPA through introducing infrared light to adjust the temperature of the microfluidic system. We believe that the thermal-responsive Janus micropillar arrays would provide a new strategy to control the flow and motion of fluids in microfluidic channels and show potential applications in the future microfluidic chips.Keywords: anisotropic wetting; Janus pillar array; smart microfluidic manipulation; thermoresponsive
Co-reporter:Zibo Li
The Journal of Physical Chemistry C 2015 Volume 119(Issue 21) pp:11839-11845
Publication Date(Web):April 27, 2015
DOI:10.1021/acs.jpcc.5b02263
In this article, we report the morphology modulation of gold nanoparticle (NP) arrays by polymer-assisted thermal treatment. Simultaneously, localized surface plasmon resonance (LSPR) UV–vis extinction (absorption plus scattering) of gold NP arrays was monitored and analyzed. First, through horizontal lifting, gold NP monolayers were transferred from a water/hexane interface to glass slides. After thin polymer films were spin-coated on the gold NP monolayers, thermal treatment was carried out, which results in apparent color changes in the obtained samples. The color changes could be attributed to the shift of the surface plasmon band (SPB), along with increasing gold NP size and interparticle distance. We found that different polymers show different effects on the modulation of gold NPs’ morphology, accompanied by different shifts of the SPB. Polymers with relatively lower glass transition temperatures (Tg), such as poly(methyl methacrylate), promoted gold NPs to merge into spheres, while polymers with relatively higher Tg, such as polyphenylene sulfone resins, inhibited the fusion of gold NPs, which collapsed as a whole slice. We believe that the difference should be attributed to the polymer chain’s ability to move during heating. Therefore, the temperature of thermal treatment and the Tg of the polymer play critical roles in the merging process of gold NPs. Moreover, through combining colloidal lithography technology, patterned gold NP monolayers have been fabricated. The current strategy is simple and facile to control the morphology of gold NP arrays, as well as to control their optical properties.
Co-reporter:Hongxu Chen;Tieqiang Wang;Huaizhong Shen;Wendong Liu;Shuli Wang
Nano Research 2015 Volume 8( Issue 9) pp:2871-2880
Publication Date(Web):2015 September
DOI:10.1007/s12274-015-0792-0
We demonstrate a facile method combining colloidal lithography, selective ion-exchange, and the in situ reduction of Ag ions (Ag+) for the fabrication of multi-segmented barcode nanorods. First, polymer multilayer films were prepared by spin-coating alternating thin films of polystyrene and polyacrylic acid (PAA), and then multi-segmented polymer nanorods were fabricated via reactive ion etching with colloidal masks. Second, Ag nanoparticles (Ag NPs) were incorporated into the PAA segments by an ion exchange and the in situ reduction of the Ag+. The selective incorporation of the Ag NPs permitted the modification of the specific bars of the nanorods. Lastly, the Ag NP/polymer composite nanorods were released from the substrate to form suspensions for further coding applications. By increasing the number of segments and changing the length of each segment in the nanorods, the coding capacity of nanorods was improved. More importantly, this method can easily realize the density tuning of Ag NPs in different segments of a single nanorod by varying the composition of the PAA segments. We believe that numerous other coded materials can also be obtained, which introduces new approaches for fabricating barcoded nanomaterials.
Co-reporter:Tieqiang Wang, Hongxu Chen, Kun Liu, Yang Li, Peihong Xue, Ye Yu, Shuli Wang, Junhu Zhang, Eugenia Kumacheva and Bai Yang
Nanoscale 2014 vol. 6(Issue 7) pp:3846-3853
Publication Date(Web):27 Jan 2014
DOI:10.1039/C3NR05865D
In this paper, we demonstrate a facile strategy for the fabrication of a one-way valve for microfluidic (MF) systems. The micro-valve was fabricated by embedding arrays of Janus Si elliptical pillars (Si-EPAs) with anisotropic wettability into a MF channel fabricated in poly(dimethylsiloxane) (PDMS). Two sides of the Janus pillar are functionalized with molecules with distinct surface energies. The ability of the Janus pillar array to act as a valve was proved by investigating the flow behaviour of water in a T-shaped microchannel at different flow rates and pressures. In addition, the one-way valve was used to achieve gas–liquid separation. We believe that the Janus Si-EPAs modified by specific surface functionalization provide a new strategy to control the flow and motion of fluids in MF channels.
Co-reporter:Tieqiang Wang, Junhu Zhang, Peihong Xue, Hongxu Chen, Shunsheng Ye, Shuli Wang, Ye Yu and Bai Yang
Journal of Materials Chemistry A 2014 vol. 2(Issue 13) pp:2333-2340
Publication Date(Web):06 Jan 2014
DOI:10.1039/C3TC31338G
We demonstrate a facile method to fabricate gold plasmonic microstructures based on the combination of colloidal lithography and a nanotransfer printing method. Poly(dimethylsiloxane) PDMS hemisphere arrays were fabricated through colloidal lithography and used as a “stamp” for the nanotransfer printing. Three kinds of plasmonic microstructures, gold disk, ring and crescent arrays, were fabricated by transferring gold “ink” onto the PDMS stamp, then to the substrate based on covalent “glue”. By adjusting the pressure applied during the printing process, the diameter of the as-prepared gold disks and gold rings can be precisely controlled, and these plasmonic arrays all exhibited significant diameter dependent LSPR properties in the NIR or Mid-IR range. In addition, by obliquely depositing gold ink onto the PDMS stamp, a gold crescent array with asymmetrical geometry was also prepared on the substrate. Owing to the asymmetric structure of the gold crescents, the gold crescent array showed significant polarization dependent LSPR properties in the Mid-IR range. We believe that these as-prepared gold plasmonic microstructures could show promising potential for application as real-time, label-free plasmonic sensing platforms in the IR range.
Co-reporter:Hainan Gao, Junhu Zhang, Fangyuan Liu, Zhuo Ao, Sidi Liu, Shoujun Zhu, Dong Han and Bai Yang
Journal of Materials Chemistry A 2014 vol. 2(Issue 41) pp:7192-7200
Publication Date(Web):27 Aug 2014
DOI:10.1039/C4TB01081G
As a typical conducting material, polyaniline (PANI) has been processed into various nanostructured materials that have been applied in fields including fuel cells, smart materials and anticorrosive coatings. However, few studies have investigated the properties of PANI nanostructures as biointerfaces. Herein, we developed a controlled and stable PANI nanostructured interface on high-performance poly(etheretherketone) (PEEK) surfaces utilizing the self-initiation of PEEK to graft poly(acrylic acid) (PAAc) interlayers and the in situ diluted polymerization of PANI. The prepared PANI nanofiber array surfaces produced chemical factor and nanocue coeffects enabling PEEK to possess enhanced biocompatibility and controlled cell behaviours with nanosensitivity. Atomic force microscopy (AFM) was adopted to characterize the bioadhesion of a simulated protein particle/single cell to various substrates. The cell behaviours of rat mesenchymal stem cells (rMSCs) on PANI and PEEK surfaces were investigated using scanning electron microscopy (SEM) and immunofluorescence. The PANI-grafted PEEK surfaces have enhanced biocompatibilities and controlled nanocues to mediate the behaviours of MSCs.
Co-reporter:Shunsheng Ye;Xuemin Zhang;Lingxia Chang;Tieqiang Wang;Zibo Li;Bai Yang
Advanced Optical Materials 2014 Volume 2( Issue 8) pp:779-787
Publication Date(Web):
DOI:10.1002/adom.201400208
A high-performance plasmonic biosensor based on two-dimensional (2D) Ag nanowell crystals is rationally designed and fabricated by colloidal lithography. The crystals act as 2D metallic gratings that directly couple incident photons to surface plasmon polaritons (SPPs). The nanowell sizes are properly tuned to enable coupling between the SPPs and Raleigh anomalies, which proves to greatly contribute to sharp reflectance dips. Other geometric parameters including the nanowell depth and the lattice constant are respectively adjusted to optimize the lineshape and sensitivity. These inferences and experimental results are verified by finite-difference time-domain (FDTD) calculations. In this study, the fabricated crystal with 670 nm lattice constant, 483 nm nanowell size, and 40 nm nanowell depth possesses the highest refractive index sensitivity (RIS) (623.7 nm RIU−1), the maximum figure of merit (FOM) (55.2 RIU−1), and a very high value of full height/full width at half-maximum (FH/FWHM) (28.3 ×10−3 nm−1). As a proof-of-concept, we adopt the well-studied antigen-antibody couple as a model system to illustrate the potential of the nanowell crystal in a quantitative analytical bioassay. The excellent sensing performance, together with the compact structure and the simple read-out apparatus, suggest that the 2D Ag nanowell crystal is an excellent candidate for a label-free biosensing platform.
Co-reporter:Xukun Qian, Ning Wang, Yunfeng Li, Junhu Zhang, Zhichuan Xu, and Yi Long
Langmuir 2014 Volume 30(Issue 35) pp:10766-10771
Publication Date(Web):2017-2-22
DOI:10.1021/la502787q
Vanadium dioxide (VO2) films with moth-eye nanostructures have been fabricated to enhance the thermochromic properties with different periodicity (d) to achieve antireflection (AR). It is revealed that the films with smaller d (210 and 440 nm) could increase both the luminous transmission (Tlum) and infrared transmission (TIR) at 25 and 90 oC, as the d is smaller than the given wavelength and the gradient refractive index produces antireflection. The average Tlum and TIR of VO2 increase with decreasing d. Compared with the planar film, the AR sample with periodicity of 210 nm and thickness of 140 nm can offer approximately 10% enhancement of Tlum and 24.5% increase in solar modulation (ΔTsol). With the addition of hydrophobic overcoat on the patterned VO2, ∼120° contact angle could be achieved. The present approach can tailor the optical transmittance in different wavelengths at high and low temperature together with self-cleaning, opening new avenues for producing hydrophobic VO2 with enhanced thermochromic properties for smart window applications.
Co-reporter:Tieqiang Wang, Junhu Zhang, Xun Zhang, Peihong Xue, Hongxu Chen, Xiao Li, Ye Yu and Bai Yang
Journal of Materials Chemistry A 2013 vol. 1(Issue 6) pp:1122-1129
Publication Date(Web):27 Nov 2012
DOI:10.1039/C2TC00302C
In this paper, we demonstrate a facile modified colloidal lithography (CL) method for the fabrication of morphology-controlled elliptical nanoring arrays (ERAs), which combines template-guided dewetting of polymer film and oxygen reactive ion etching. The elliptical templates were fabricated via a modified micromolding method using colloidal nanosphere arrays as the original templates, which were used to guide the dewetting of the polymer film to form ERAs. The height, aspect ratio and size of the resulting arrays could be controlled exactly. Moreover, through etching the underlying functional materials or mixing functional materials into the polymer film, elliptical ring arrays of different functional materials could also be fabricated, such as gold ERAs, silicon ERAs, ferromagnetic Fe–Ni composite ERAs, Fe3O4 ERAs and fluorescent ERAs. A potential application of the as-prepared functional ERAs is to provide a model for the fundamental research of anisotropic properties of the asymmetric patterned surface arrays and the fabrication of anisotropic surface pattern based devices for potential applications of shape-dependent optical and magnetic devices.
Co-reporter:Xuemin Zhang, Shunsheng Ye, Xun Zhang, Zibo Li, Shan Wu, Junhu Zhang, Tieqiang Wang and Bai Yang
Journal of Materials Chemistry A 2013 vol. 1(Issue 5) pp:933-940
Publication Date(Web):23 Nov 2012
DOI:10.1039/C2TC00013J
Plasmonic structural color is one of the most fascinating applications of recently fast developing plasmonics, which is a promising candidate technology for information processing, color displays and optical measurement devices. However, the implementation of plasmonic structural color in modern optical and spectral imaging systems demands strongly a simple fabrication process, low power consumption, and complex color pattern integration. Thus far, tuning of the plasmonic color has been generally achieved by morphology alteration or adjusting the lattice constants of plasmonic nanostructures. Nevertheless, this strategy suffers greatly from high cost and low throughput when designing complex color patterns. Herein, by precisely controlling the refractive indices on two sides of Ag nanohole arrays (NAs) that are embedded between a silica coating and a glass substrate, we are capable of filtering white light into individual colors across the entire visible band. Moreover, the straightforward strategy we propose is compatible with the traditional photolithography process, with which complex color patterns can be easily achieved. We further experimentally demonstrate that these engineered colored samples can be used as chromatically switchable anti-counterfeit tags. We anticipate that the method we demonstrate can provide a new approach for the fabrication of compact color filtering devices.
Co-reporter:Xuemin Zhang, Zibo Li, Shunsheng Ye, Shan Wu, Junhu Zhang, Liying Cui, Anran Li, Tieqiang Wang, Shuzhou Li and Bai Yang
Journal of Materials Chemistry A 2012 vol. 22(Issue 18) pp:8903-8910
Publication Date(Web):02 Mar 2012
DOI:10.1039/C2JM30525A
Label-free molecular sensing is one of the most fascinating applications of recently fast developing plasmonics. However, the implementation of plasmonic sensors in modern analytical systems strongly demands high sensitivity. Herein, by combining colloidal lithography with subsequent isotropic chemical etching of an underlying glass substrate, we report the fabrication of elevated Ag nanohole arrays (EANAs) which exhibit the property of extraordinary optical transmission. Finite-difference time-domain calculations show that the optical properties of the EANAs behave as though floating above the substrate with no support whatsoever. Compared with the original Ag nanohole arrays directly attached to a glass substrate, the refractive index sensitivity of the EANAs increases to ∼648 nm/RIU from the original ∼252 nm/RIU. This greatly enhanced sensing performance makes the EANAs very attractive as a platform for plasmonic sensing systems. As a proof-of-concept, we corroborated these findings with the label-free detection of anti-human IgG using the as-prepared EANAs.
Co-reporter:Fei Jia, Wei Sun, Junhu Zhang, Yunfeng Li and Bai Yang
Journal of Materials Chemistry A 2012 vol. 22(Issue 6) pp:2435-2441
Publication Date(Web):22 Dec 2011
DOI:10.1039/C1JM14319K
Although ordered macroporous rutile titania is seldom successfully fabricated because it is hard to maintain its integrated structure at the high calcination temperature, we herein describe a facile approach to obtain inverse rutile titania opals under a relatively mild condition. By employing SnO2 as the additive for enhancing the phase transformation from anatase to rutile, we investigated various kinds of differences (pore size, backbone filling fraction, reflection peaks, etc.) between the macroporous structures with the two different kinds of crystalline phases (anatase and rutile), which were hardly stressed in other reports because the two phases could not be obtained separately under the same calcination condition if using other approaches.
Co-reporter:Jing Xie ; Xuemin Zhang ; Zenghui Peng ; Zhanhua Wang ; Tieqiang Wang ; Shoujun Zhu ; Zhaoyi Wang ; Liang Zhang ; Junhu Zhang ;Bai Yang
The Journal of Physical Chemistry C 2012 Volume 116(Issue 4) pp:2720-2727
Publication Date(Web):January 6, 2012
DOI:10.1021/jp2098312
By applying an electric field to nematic liquid crystals (LCs) to change the molecular alignment of LCs, we achieve feasible tuning of the localized surface plasmon resonance (LSPR) of novel gold island film immersed in the LCs, realizing the switching behavior of LSPR at low electric field intensity. In addition, we find that the liquid crystal can amplify the angle dependence of gold island film LSPR, which may provide a new method for research on the tiny and indistinct change of the gold nanoparticles’ LSPR. At the same time, the LSPR can be used for detection of nematic LCs’ thermal–optic effect, especially when the temperature is around the clearing point. For the entire experimental procedure, self-assembly and experimental tests are simple and require only common laboratory supplies and equipment, and both of them are novel relative to previous studies, which help us further investigate coupling the metal nanoparticles with the LCs.
Co-reporter:Zhihui Zhao, Junhu Zhang, Fengxia Dong, Bai Yang
Journal of Colloid and Interface Science 2011 Volume 359(Issue 2) pp:351-358
Publication Date(Web):15 July 2011
DOI:10.1016/j.jcis.2011.04.042
The construction of supercrystals with non-spherical building blocks has attracted increasing attention due to their potential applications in the fabrication of novel devices. In this study, we report the large-scale preparation of dimension-controllable supercrystals of polyhedral PbS nanocrystals through a solvent evaporation approach. Because of the capillary flow of the drying droplet on the substrate, nanocrystals self-assemble into three distinct types of supercrystals on specific regions of the substrate during the solvent evaporation: two-dimensional supercrystals appear in the central region; three-dimensional faceted supercrystals and three-dimensional bulk supercrystals are found near the edge of the substrate. Moreover, the formation of superlattice structure of each type of supercrystals can be tuned by changing the shape of building blocks. The influences of experimental factors on self-assembly are investigated as well. We anticipate that our research can provide some new insights into the construction of supercrystals with novel structures and large sizes.Graphical abstractThree different types of supercrystals are generated on specific regions of the substrate through a solvent-evaporation approach, using polyhedral PbS nanocrystals as building blocks.Highlights► Large-scale preparation of supercrystals of polyhedral PbS nanocrystals has been achieved by solvent-evaporation. ► Three different types of supercrystals form on specific regions of the substrate. ► Superlattice structures are greatly affected by the shape of building blocks.
Co-reporter:Weili Yu;Tongjie Yao;Xiao Li;Tieqiang Wang;Hainan Gao;Bai Yang
Journal of Applied Polymer Science 2011 Volume 119( Issue 2) pp:1052-1059
Publication Date(Web):
DOI:10.1002/app.32516
Abstract
Electrochemical cyclic voltammetry (C-V) method was reported to prepare highly hydrophobic polythiophene (PTh) films with high adhesion force. Using this technique, the morphology and surface roughness of PTh film can be controlled by adjusting cycle number, monomer concentration, and applied voltage. After fluorination, the PTh film with hierarchical morphology showed high hydrophobicity as well as a strong adhesion force. This method provides a simple solution for the preparation of highly hydrophobic polymer film with high adhesion force. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Xiaolu Chen, Yanfang Wang, Junhu Zhang, Tieqiang Wang, Xuemin Zhang, Kai Zhang, Bai Yang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2011 380(1–3) pp: 162-168
Publication Date(Web):
DOI:10.1016/j.colsurfa.2011.02.039
Co-reporter:Wei Sun, Fei Jia, Zhiqiang Sun, Junhu Zhang, Yang Li, Xun Zhang, and Bai Yang
Langmuir 2011 Volume 27(Issue 13) pp:8018-8026
Publication Date(Web):June 1, 2011
DOI:10.1021/la2002207
A new concept for dealing with cracks in colloidal crystals has been proposed. We induce the cracks rather than eliminate them via templates that possess hydrophilic/hydrophobic patterns on the surface (surface energy patterns), leading the cracks to propagate along the predetermined lines. Colloidal crystal arrays with various kinds of element figures separated by cracks could be reproducibly fabricated. Diverse crack patterns other than common stripes have been observed, and the mechanism of these behaviors has been explored. The factors that influence the crack density have been investigated to ensure that the templates could function effectively. Moreover, we obtained microcrystal blocks with specific shapes, detached from the substrate.
Co-reporter:Xuemin Zhang, Junhu Zhang, Zhiyu Ren, Xun Zhang, Tian Tian, Yunan Wang, Fengxia Dong and Bai Yang
Nanoscale 2010 vol. 2(Issue 2) pp:277-281
Publication Date(Web):30 Sep 2009
DOI:10.1039/B9NR00055K
Herein we present a novel but simple method to fabricate photoinduced cleaning substrates with patterned superhydrophobic hierarchical silicon cone arrays (SCAs) and superhydrophilic TiO2nanorod clusters (TNCs). In our experiment, the photoinduced cleaning properties of the obtained substrate are investigated by repeatedly adsorbing and decomposing rhodamine B (RhB) molecules for at least six cycles. In addition, we demonstrate that the low-surface-energy coating on the superhydrophobic areas is stable, resulting in the high wettability contrast being well preserved during the renewal process. This straightforward method may open up new possibilities for the practical use of microchips with patterned superhydrophobic and superhydrophilic areas.
Co-reporter:Tieqiang Wang, Xiao Li, Junhu Zhang, Zhiyu Ren, Xuemin Zhang, Xun Zhang, Difu Zhu, Zhanhua Wang, Fang Han, Xianzhe Wang and Bai Yang
Journal of Materials Chemistry A 2010 vol. 20(Issue 1) pp:152-158
Publication Date(Web):14 Oct 2009
DOI:10.1039/B915205A
In this paper, we demonstrate a facile modified micromolding method to fabricate morphology-controlled elliptical hemisphere arrays (EHAs) by using stretched poly(dimethylsiloxane) (PDMS) nanowell arrays as molds. The PDMS nanowell arrays were fabricated via casting PDMS prepolymer onto two-dimensional (2D) non-close-packed (ncp) colloidal sphere arrays. By varying the stretching direction, stretching force, size of the colloidal spheres used and other experimental conditions in the fabrication process, we can control the shape, aspect ratio and size of the resulting microstructures. Moreover, our method does not involve any costly micromanufacture technique and can be applied to a great many materials, such as oil soluble polymers (e.g. polystyrene (PS)), water soluble polymers (e.g. poly(vinyl pyrrolidone) (PVP)), cross-linked polymers (e.g. photopolymerizable resin) and a variety of composites (e.g. polymer/nanoparticle composite). The anisotropic wetting properties of these EHAs were demonstrated. Potential application of the EHAs is to provide a model for the fundamental research of anisotropic surfaces and a template or mask for the fabrication of anisotropic surface patterns for potential applications of shape-dependent optical and magnetic devices.
Co-reporter:Shoujun Zhu, Yunfeng Li, Junhu Zhang, Changli Lü, Xin Dai, Fei Jia, Hainan Gao, Bai Yang
Journal of Colloid and Interface Science 2010 Volume 344(Issue 2) pp:541-546
Publication Date(Web):15 April 2010
DOI:10.1016/j.jcis.2009.12.047
In this paper, we report the fabrication of superhydrophobic polyimide (PI) nanotube arrays with different topographies, which possess slippery or “sticky” superhydrophobicity. The PI nanotube arrays were fabricated by the porous alumina membrane molding method. We regulated three kinds of solvent evaporation and drying processes, which controlled different congregated and noncongregated topographies of PI nanotube arrays. Large scale comb-like congregated topography possesses a small sliding angle (SA < 5°) , small scale comb-like congregated topography possesses a medium sliding angle (SA is about 30°), noncongregated topography possesses a large sliding angle (strong adhesive force to water droplet). Moreover, the as-prepared superhydrophobic PI nanotube arrays have remarkable resistivity to acid, weak base, high temperature (up to 350 °C) and various organic solvents. Our work provides a facile and promising strategy to fabricate superhydrophobic surfaces with controlled sliding angles by utilizing self-organization effect, and such high performance superhydrophobic PI nanotube arrays can be used as coating materials in various harsh conditions.Three kinds of superhydrophobic polyimide (PI) nanotube arrays with controllable sliding angles were prepared by controlling the solvent evaporation and drying process.
Co-reporter:Zhihui Zhao, Kai Zhang, Junhu Zhang, Kai Yang, Chengzhi He, Fengxia Dong, Bai Yang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 355(1–3) pp:114-120
Publication Date(Web):20 February 2010
DOI:10.1016/j.colsurfa.2009.12.009
Monodisperse PbS nanocrystals (NCs) with various sizes and shapes have been prepared by controlling the thermal decomposition of thioacetamide (TAA) in aqueous solution of lead acetate (Pb(Ac)2), with the assistance of cetyltrimethylammonium bromide (CTAB) as surfactant. The sizes and shapes of PbS NCs are modulated by simply adjusting the concentration of sulfide resource in TAA. Size decreases and shape changes from octahedral to cubic are observed with the increase of TAA concentration. Furthermore, a detailed growth mechanism is proposed, based on the experimental results of changing the concentrations of CTAB and Pb(Ac)2. It is very interesting to notice that the synthesized PbS NCs self-assemble into diverse superlattices, and the assembly structure strongly depends on the shape of PbS NCs.
Co-reporter:Xun Zhang, Junhu Zhang, Difu Zhu, Xiao Li, Xuemin Zhang, Tieqiang Wang, and Bai Yang
Langmuir 2010 Volume 26(Issue 23) pp:17936-17942
Publication Date(Web):October 25, 2010
DOI:10.1021/la103778m
We present a novel and simple method to fabricate two-dimensional (2D) poly(styrene sulfate) (PSS, negatively charged) colloidal crystals on a positively charged substrate. Our strategy contains two separate steps: one is the three-dimensional (3D) assembly of PSS particles in ethanol, and the other is electrostatic adsorption in water. First, 3D assembly in ethanol phase eliminates electrostatic attractions between colloids and the substrate. As a result, high-quality colloidal crystals are easily generated, for electrostatic attractions are unfavorable for the movement of colloidal particles during convective self-assembly. Subsequently, top layers of colloidal spheres are washed away in the water phase, whereas well-packed PSS colloids that are in contact with the substrate are tightly linked due to electrostatic interactions, resulting in the formation of ordered arrays of 2D colloidal spheres. Cycling these processes leads to the layer-by-layer assembly of 3D colloidal crystals with controllable layers. In addition, this strategy can be extended to the fabrication of patterned 2D colloidal crystals on patterned polyelectrolyte surfaces, not only on planar substrates but also on nonplanar substrates. This straightforward method may open up new possibilities for practical use of colloidal crystals of excellent quality, various patterns, and controllable fashions.
Co-reporter:Tieqiang Wang, Xiao Li, Junhu Zhang, Xianzhe Wang, Xuemin Zhang, Xun Zhang, Difu Zhu, Yudong Hao, Zhiyu Ren and Bai Yang
Langmuir 2010 Volume 26(Issue 16) pp:13715-13721
Publication Date(Web):July 23, 2010
DOI:10.1021/la1017505
We demonstrate a facile etching method to fabricate silicon elliptical pillar arrays (Si-EPAs) with unique anisotropic optical and wetting characters using polystyrene elliptical hemisphere arrays (EHAs) as mask. The EHAs were fabricated via a modified micromolding method. By varying the experimental conditions in the fabrication process, the morphology of the resulting microstructures can be controlled exactly. Because of the anisotropic morphology of the elliptical pillar, the Si-EPA shows unique anisotropic properties, such as anisotropic surface reflection and anisotropic wetting property. Additionally, through oblique evaporation deposition of Au and selective chemical modification to turn the elliptical pillars into “Janus” elliptical pillars, the “Janus” Si-EPA shows more peculiar anisotropic properties owing to the further increased asymmetry. We believe that the Si-EPAs will have potential applications in anisotropic optical and electronic devices.
Co-reporter:Xiao Li, Tieqiang Wang, Junhu Zhang, Difu Zhu, Xun Zhang, Yang Ning, Hao Zhang and Bai Yang
ACS Nano 2010 Volume 4(Issue 8) pp:4350
Publication Date(Web):July 27, 2010
DOI:10.1021/nn9017137
We report a novel technique for generating polymer fluorescent barcode nanorods by reactive ion etching of polymer multilayer films using nonclose-packed (ncp) colloidal microsphere arrays as masks. The fluorescent polymer multilayer films were spin-coated on a substrate, and ncp microsphere arrays were transferred onto these films. The exposed polymers were then etched away selectively, leaving color-encoded nanorods with well-preserved fluorescent properties. By modifying the spin-coating procedure, the amount of polymer in each layer could be tuned freely, which determined the relative fluorescence intensity of the barcode nanorods. These nanorod arrays can be detached from the substrate to form dispersions of coding materials. Moreover, the shape of the nanorods is controllable according to the different etching speeds of various materials, which also endows the nanorods with shape-encoded characters. This method offers opportunities for the fabrication of novel fluorescent barcodes which can be used for detecting and tracking applications.Keywords: colloidal lithography; fluorescent barcode; microarray; multisegments; nanorod
Co-reporter:Hainan Gao, Junhu Zhang, Weili Yu, Yunfeng Li, Shoujun Zhu, Yang Li, Tieqiang Wang, Bai Yang
Sensors and Actuators B: Chemical 2010 Volume 145(Issue 2) pp:839-846
Publication Date(Web):19 March 2010
DOI:10.1016/j.snb.2010.01.066
High-performance monolithic actuators responding to acid/base were fabricated based on polyaniline (PANI) nanofibers and polyvinyl alcohol (PVA) nanocomposite. Flash-welding technique was adopted to endow PANI/PVA films with asymmetric structure, which drove rapid reversible actuation in acid/base. Compared with conventional PANI actuators, the PANI/PVA actuators were capable of providing tunable actuation degree and responsive rate, as well as enhanced mechanical properties and reversible repeatability. Moreover, the PANI/PVA actuators had much better recoverability in base than pure PANI nanofiber actuators. On the basis of PANI/PVA monolithic beam, we also fabricated PANI/PVA monolithic cubic boxes which showed tunable folding/unfolding response in acid/base via proper modulation. It is anticipated that the monolithic PANI/PVA nanocomposite actuators with tunable stimuli-responsive properties will have large potential for applications in micromechanical system, on-demand devices, chemical sensors and biomedical materials.
Co-reporter:Xiao Li, Tieqiang Wang, Junhu Zhang, Xin Yan, Xuemin Zhang, Difu Zhu, Wei Li, Xun Zhang and Bai Yang
Langmuir 2010 Volume 26(Issue 4) pp:2930-2936
Publication Date(Web):August 28, 2009
DOI:10.1021/la9027018
We report a simple method to fabricate two-dimensional (2D) periodic non-close-packed (ncp) arrays of colloidal microspheres with controllable lattice spacing, lattice structure, and pattern arrangement. This method combines soft lithography technique with controlled deformation of polydimethylsiloxane (PDMS) elastomer to convert 2D hexagonal close-packed (hcp) silica microsphere arrays into ncp ones. Self-assembled 2D hcp microsphere arrays were transferred onto the surface of PDMS stamps using the lift-up technique, and then their lattice spacing and lattice structure could be adjusted by solvent swelling or mechanical stretching of the PDMS stamps. Followed by a modified microcontact printing (μcp) technique, the as-prepared 2D ncp microsphere arrays were transferred onto a flat substrate coated with a thin film of poly(vinyl alcohol) (PVA). After removing the PVA film by calcination, the ncp arrays that fell on the substrate without being disturbed could be lifted up, deformed, and transferred again by another PDMS stamp; therefore, the lattice feature could be changed step by step. Combining isotropic solvent swelling and anisotropic mechanical stretching, it is possible to change hcp colloidal arrays into full dimensional ncp ones in all five 2D Bravais lattices. This deformable soft lithography-based lift-up process can also generate patterned ncp arrays of colloidal crystals, including one-dimensional (1D) microsphere arrays with designed structures. This method affords opportunities and spaces for fabrication of novel and complex structures of 1D and 2D ncp colloidal crystal arrays, and these as-prepared structures can be used as molds for colloidal lithography or prototype models for optical materials.
Co-reporter:Weili Yu;Bin Xu;Qingfeng Dong;Yinhua Zhou
Journal of Solid State Electrochemistry 2010 Volume 14( Issue 6) pp:1051-1056
Publication Date(Web):2010 June
DOI:10.1007/s10008-009-0919-x
Electrochemistry provides a simple and promising method for preparing organic solar cells (OSCs). In this paper, we present a two-step solution-based method to prepare bilayer heterojunction OSCs by electrodepositing polythiophene (PTh) and then spin-coating chloroform solution of [6,6]-phenyl C61-butyric acid methyl ester (PCBM) onto the PTh layer. The influence of film thickness on performance of bilayer solar cells was investigated, and the best performance was achieved when the thickness of PTh and PCBM was 15 nm and 30 nm, respectively. The optimized solar cell showed power conversion efficiency of 0.1% under the illumination of AM 1.5 (100 mW cm−2) simulated solar light. This solution-based method offers a new way for processing bilayer OSCs.
Co-reporter:Hainan Gao, Junhu Zhang, Weili Yu, Yunfeng Li, Shoujun Zhu, Yang Li, Tieqiang Wang, Bai Yang
Sensors and Actuators B: Chemical (19 March 2010) Volume 145(Issue 2) pp:839-846
Publication Date(Web):19 March 2010
DOI:10.1016/j.snb.2010.01.066
High-performance monolithic actuators responding to acid/base were fabricated based on polyaniline (PANI) nanofibers and polyvinyl alcohol (PVA) nanocomposite. Flash-welding technique was adopted to endow PANI/PVA films with asymmetric structure, which drove rapid reversible actuation in acid/base. Compared with conventional PANI actuators, the PANI/PVA actuators were capable of providing tunable actuation degree and responsive rate, as well as enhanced mechanical properties and reversible repeatability. Moreover, the PANI/PVA actuators had much better recoverability in base than pure PANI nanofiber actuators. On the basis of PANI/PVA monolithic beam, we also fabricated PANI/PVA monolithic cubic boxes which showed tunable folding/unfolding response in acid/base via proper modulation. It is anticipated that the monolithic PANI/PVA nanocomposite actuators with tunable stimuli-responsive properties will have large potential for applications in micromechanical system, on-demand devices, chemical sensors and biomedical materials.
Co-reporter:Shunsheng Ye, Hongyu Wang, Hongyang Su, Lingxia Chang, Shuli Wang, Xuemin Zhang, Junhu Zhang and Bai Yang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 16) pp:NaN3972-3972
Publication Date(Web):2017/03/20
DOI:10.1039/C7TC00064B
A facile strategy is reported for the electrostatic self-assembly of homogeneous and gradient plasmonic nanoparticle arrays with tunable interparticle distances and optical properties. The interparticle distance is dominated by the surface charge density of the substrate, which is tuned via thermal annealing according to the temperature-dependent molecular mobility of the polymer. Oxygen plasma is employed to endow neutral polystyrene (PS) films with sufficient charges, enabling subsequent electrostatic adsorption. The density of surface charges can be readily tuned via a thermal annealing step after plasma treatment, which is confirmed by quantitative analyses of oxygen and nitrogen using X-ray photoelectron spectroscopy. Afterwards, PS films with regulated charge densities reshape the double layers around nanoparticles to various degrees during the assembly, leading to tunable interparticle separations. UV-Vis spectroscopy reveals tunable plasmonic properties owing to the critical role of interparticle separation in plasmon coupling. Here such structures are demonstrated to act as wavelength-selective substrates for multiplexed acquisition of surface enhanced Raman scattering. Alternatively, by applying a temperature gradient in the annealing step, we create a macroscopic surface with a continuous gradient in plasmonic properties. Such a “plasmonic library” can be a promising material for fast screening of interparticle distance or extinction spectrum in specific applications on one single substrate.
Co-reporter:Tieqiang Wang, Junhu Zhang, Xun Zhang, Peihong Xue, Hongxu Chen, Xiao Li, Ye Yu and Bai Yang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 6) pp:NaN1129-1129
Publication Date(Web):2012/11/27
DOI:10.1039/C2TC00302C
In this paper, we demonstrate a facile modified colloidal lithography (CL) method for the fabrication of morphology-controlled elliptical nanoring arrays (ERAs), which combines template-guided dewetting of polymer film and oxygen reactive ion etching. The elliptical templates were fabricated via a modified micromolding method using colloidal nanosphere arrays as the original templates, which were used to guide the dewetting of the polymer film to form ERAs. The height, aspect ratio and size of the resulting arrays could be controlled exactly. Moreover, through etching the underlying functional materials or mixing functional materials into the polymer film, elliptical ring arrays of different functional materials could also be fabricated, such as gold ERAs, silicon ERAs, ferromagnetic Fe–Ni composite ERAs, Fe3O4 ERAs and fluorescent ERAs. A potential application of the as-prepared functional ERAs is to provide a model for the fundamental research of anisotropic properties of the asymmetric patterned surface arrays and the fabrication of anisotropic surface pattern based devices for potential applications of shape-dependent optical and magnetic devices.
Co-reporter:Tieqiang Wang, Xiao Li, Junhu Zhang, Zhiyu Ren, Xuemin Zhang, Xun Zhang, Difu Zhu, Zhanhua Wang, Fang Han, Xianzhe Wang and Bai Yang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 1) pp:NaN158-158
Publication Date(Web):2009/10/14
DOI:10.1039/B915205A
In this paper, we demonstrate a facile modified micromolding method to fabricate morphology-controlled elliptical hemisphere arrays (EHAs) by using stretched poly(dimethylsiloxane) (PDMS) nanowell arrays as molds. The PDMS nanowell arrays were fabricated via casting PDMS prepolymer onto two-dimensional (2D) non-close-packed (ncp) colloidal sphere arrays. By varying the stretching direction, stretching force, size of the colloidal spheres used and other experimental conditions in the fabrication process, we can control the shape, aspect ratio and size of the resulting microstructures. Moreover, our method does not involve any costly micromanufacture technique and can be applied to a great many materials, such as oil soluble polymers (e.g. polystyrene (PS)), water soluble polymers (e.g. poly(vinyl pyrrolidone) (PVP)), cross-linked polymers (e.g. photopolymerizable resin) and a variety of composites (e.g. polymer/nanoparticle composite). The anisotropic wetting properties of these EHAs were demonstrated. Potential application of the EHAs is to provide a model for the fundamental research of anisotropic surfaces and a template or mask for the fabrication of anisotropic surface patterns for potential applications of shape-dependent optical and magnetic devices.
Co-reporter:Fei Jia, Wei Sun, Junhu Zhang, Yunfeng Li and Bai Yang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 6) pp:
Publication Date(Web):
DOI:10.1039/C1JM14319K
Co-reporter:Xuemin Zhang, Shunsheng Ye, Xun Zhang, Zibo Li, Shan Wu, Junhu Zhang, Tieqiang Wang and Bai Yang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 5) pp:NaN940-940
Publication Date(Web):2012/11/23
DOI:10.1039/C2TC00013J
Plasmonic structural color is one of the most fascinating applications of recently fast developing plasmonics, which is a promising candidate technology for information processing, color displays and optical measurement devices. However, the implementation of plasmonic structural color in modern optical and spectral imaging systems demands strongly a simple fabrication process, low power consumption, and complex color pattern integration. Thus far, tuning of the plasmonic color has been generally achieved by morphology alteration or adjusting the lattice constants of plasmonic nanostructures. Nevertheless, this strategy suffers greatly from high cost and low throughput when designing complex color patterns. Herein, by precisely controlling the refractive indices on two sides of Ag nanohole arrays (NAs) that are embedded between a silica coating and a glass substrate, we are capable of filtering white light into individual colors across the entire visible band. Moreover, the straightforward strategy we propose is compatible with the traditional photolithography process, with which complex color patterns can be easily achieved. We further experimentally demonstrate that these engineered colored samples can be used as chromatically switchable anti-counterfeit tags. We anticipate that the method we demonstrate can provide a new approach for the fabrication of compact color filtering devices.
Co-reporter:Xuemin Zhang, Zibo Li, Shunsheng Ye, Shan Wu, Junhu Zhang, Liying Cui, Anran Li, Tieqiang Wang, Shuzhou Li and Bai Yang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 18) pp:NaN8910-8910
Publication Date(Web):2012/03/02
DOI:10.1039/C2JM30525A
Label-free molecular sensing is one of the most fascinating applications of recently fast developing plasmonics. However, the implementation of plasmonic sensors in modern analytical systems strongly demands high sensitivity. Herein, by combining colloidal lithography with subsequent isotropic chemical etching of an underlying glass substrate, we report the fabrication of elevated Ag nanohole arrays (EANAs) which exhibit the property of extraordinary optical transmission. Finite-difference time-domain calculations show that the optical properties of the EANAs behave as though floating above the substrate with no support whatsoever. Compared with the original Ag nanohole arrays directly attached to a glass substrate, the refractive index sensitivity of the EANAs increases to ∼648 nm/RIU from the original ∼252 nm/RIU. This greatly enhanced sensing performance makes the EANAs very attractive as a platform for plasmonic sensing systems. As a proof-of-concept, we corroborated these findings with the label-free detection of anti-human IgG using the as-prepared EANAs.
Co-reporter:Tieqiang Wang, Junhu Zhang, Peihong Xue, Hongxu Chen, Shunsheng Ye, Shuli Wang, Ye Yu and Bai Yang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 13) pp:NaN2340-2340
Publication Date(Web):2014/01/06
DOI:10.1039/C3TC31338G
We demonstrate a facile method to fabricate gold plasmonic microstructures based on the combination of colloidal lithography and a nanotransfer printing method. Poly(dimethylsiloxane) PDMS hemisphere arrays were fabricated through colloidal lithography and used as a “stamp” for the nanotransfer printing. Three kinds of plasmonic microstructures, gold disk, ring and crescent arrays, were fabricated by transferring gold “ink” onto the PDMS stamp, then to the substrate based on covalent “glue”. By adjusting the pressure applied during the printing process, the diameter of the as-prepared gold disks and gold rings can be precisely controlled, and these plasmonic arrays all exhibited significant diameter dependent LSPR properties in the NIR or Mid-IR range. In addition, by obliquely depositing gold ink onto the PDMS stamp, a gold crescent array with asymmetrical geometry was also prepared on the substrate. Owing to the asymmetric structure of the gold crescents, the gold crescent array showed significant polarization dependent LSPR properties in the Mid-IR range. We believe that these as-prepared gold plasmonic microstructures could show promising potential for application as real-time, label-free plasmonic sensing platforms in the IR range.
Co-reporter:Hainan Gao, Junhu Zhang, Fangyuan Liu, Zhuo Ao, Sidi Liu, Shoujun Zhu, Dong Han and Bai Yang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 41) pp:NaN7200-7200
Publication Date(Web):2014/08/27
DOI:10.1039/C4TB01081G
As a typical conducting material, polyaniline (PANI) has been processed into various nanostructured materials that have been applied in fields including fuel cells, smart materials and anticorrosive coatings. However, few studies have investigated the properties of PANI nanostructures as biointerfaces. Herein, we developed a controlled and stable PANI nanostructured interface on high-performance poly(etheretherketone) (PEEK) surfaces utilizing the self-initiation of PEEK to graft poly(acrylic acid) (PAAc) interlayers and the in situ diluted polymerization of PANI. The prepared PANI nanofiber array surfaces produced chemical factor and nanocue coeffects enabling PEEK to possess enhanced biocompatibility and controlled cell behaviours with nanosensitivity. Atomic force microscopy (AFM) was adopted to characterize the bioadhesion of a simulated protein particle/single cell to various substrates. The cell behaviours of rat mesenchymal stem cells (rMSCs) on PANI and PEEK surfaces were investigated using scanning electron microscopy (SEM) and immunofluorescence. The PANI-grafted PEEK surfaces have enhanced biocompatibilities and controlled nanocues to mediate the behaviours of MSCs.
