Micro-patterning of Copper Based on Photolithographed Self-assembly Monolayers

A new method has been developed for fabrication of copper micro-pattern by selective chemical copper deposition based on photolithographed (3-mercaptopropyl)-trimethoxysilane (MPTS) self-assembly monolayers (SAMs). As confirmed by scanning electron microscopy (SEM), Cu closely replicated the mask features. The present approach makes this technic to be cheap and may be applicable to assembly of microelectronic circuits.

Low-thermal-budget Au-free ohmic contact to an ultrathin barrier AlGaN/GaN heterostructure utilizing a micro-patterned ohmic recess

A pre-ohmic micro-patterned recess process,is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier(UTB)AlGaN/GaN heterostructure,featuring a significantly reduced ohmic contact resistivity of 0.56Ω·mm at an alloy temperature of 550℃.The sheet resistances increase with the temperature following a power law with the index of +2.58,while the specific contact resistivity decreases with the temperature.The contact mechanism can be well described by thermionic field emission(TFE).The extracted Schottky barrier height and electron concentration are 0.31 eV and 5.52×10^(18) cm^(−3),which suggests an intimate contact between ohmic metal and the UTB-AlGaN as well as GaN buffer.A good correlation between ohmic transfer length and the micro-pattern size is revealed,though in-depth investigation is needed.A preliminary CMOS-process-compatible metal-insulator-semiconductor high-mobility transistor(MIS-HEMT)was fabricated with the proposed Au-free ohmic contact technique.

Laser Micro-Printing of Dye-Molecules on Polymeric Surfaces

We describe a technique for micro-patterning and immobilization of dyes on polymer substrates using a low-power visible laser for dye-excitation. Deposits from an aqueous medium containing the dye can be attached at any desired spot on the substrate simply by exposing the area to laser light. The area of the laser beam can control the spot-size of immobilized dye, in the range of 10 - 100 microns. The immobilization technique is characterized by micro-printing numerals, alphabets and patterns on polybutadiene substrates with Rhodamine (Rh6G) dye. Adsorption of laser-excited dye molecules within the polymer appears to be the mechanism for laser-printing technique.

Angular color uniformity enhancement of white light-emitting diodes by remote micro-patterned phosphor film

Angular color uniformity(ACU)is a key factor used to evaluate the light quality of white-light emitting diodes(LEDs).In this study,a novel double remote micro-patterned phosphor film(double RMPP film)was used to enhance the ACU of a remote phosphor(RP)down-light lamp.A conventional RP film and remote phosphor film with single micro-patterned film(single RMPP film)also were examined for comparison.The angular correlated color temperature(CCT)distributions and the optical performance of the films were experimentally measured.The measurement results showed that double RMPP film configuration exhibited better color uniformity with a CCT deviation of only 441 K,compared with 556 K for the single RMPP film configuration and 1390 K for the RP film configuration.A simulation based on FDTD and ray tracing combined method also confirmed the ACU improvement.In addition,compared with the conventional RP film,the luminous efficiency of single and double RMPP film configurations was increased by 6.68% and 4.69%,respectively,at a driving current of 350 mA.The enhancement of the ACU and luminous efficiency are due to the scattering and mixing effect of the micropatterned film.Moreover,the double RMPP film configuration had better CCT stability at different currents than the other two configurations.The results demonstrated the effectiveness and superiority of double RMPP film in white LED applications.

Micro-patterned hydroxyapatite/silk fibroin coatings on Mg-Zn-Y-Nd-Zr alloys for better corrosion resistance and cell behavior guidance

In this study,a micro-patterned hydroxyapatite/silk fibroin(HA-SF)coating was firstly fabricated on the surface of Mg-Zn-Y-Nd-Zr alloy by template-assisted electrospraying technique coupling with spin coating technique.Two types of micro-patterns were achieved with high contour accuracy,namely HA SF(line-pattern)and HA-SF(dot-pattern).The microstructure,composition,surface wettability and corrosion behaviors of the coatings were investigated by SEM,EDS,FTIR,XRD,water contact angle and potentiodynamic polarization test.The results revealed the hydrophilic nature of coatings and two orders of magnitude reduction of corrosion density(icorr)as compared with that of the substrate.All the micro-patterned surfaces promoted the attachment of MC3T3-E1 cells with visible filopodia after 1 d incubation.In addition,coatings with line pattern exhibited the superior guidance to cell migration as compared to dot pattern,and the preference of cell attachment in the convex zone was observed.In summary,the obtained micro-patterned HA-SF coatings possessed the remarkably improvement of anticorrosion ability and good efficacy in guidance of cell attachment and alignment,which can serve as a promising strategy for cellular response modulation at the interface of magnesium-based implants and bone.

A novel method of encoded multiplexing readout for micro-pattern gas detectors

The requirement of a large number of electronic channels poses a big challenge to the further applications of Micro-pattern Gas Detectors （MPGDs）. By using the redundancy that at least two neighboring strips record the signal of a particle, a novel method of encoded multiplexing readout for MPGDs is presented in this paper. The method offers a feasible and easily-extensible way of encoding and decoding, and can significantly reduce the number of readout channels. A verification test was carried out on a 5 cm×5 cm Thick Gas Electron Multiplier （THGEM） detector using a 8 keV Cu X-ray source with 100um slit, where 166 strips were read out by 21 encoded readout channels. The test results show good linearity in its position response, and the spatial resolution root-mean-square （RMS） of the test system is about 260um. This method has potential to build large area detectors and can be easily adapted to other detectors similar to MPGDs.

A prototype scalable readout system for micro-pattern gas detectors

A scalable readout system （SRS） is designed to provide a general solution for different micro-pattern gas detectors in various applications. The system mainly consists of three kinds of modules： the ASIC card, the adapter card and the front-end card （FEC）. The ASIC cards, mounted with particular ASIC chips, are designed for receiving detector signals. The adapter card is in charge of digitizing the output signals from several ASIC cards. The FEC, edged-mounted with the adapter, has field-programmable gate array （FPGA）-based reconfigurable logic and I/O interfaces, allowing users to choose different ASIC cards and adapters for different experiments, which expands the system to various applications. The FEC transfers data through Gigabit Ethernet protocol realized by a TCP processor （SiTCP） IP core in FPGA. By assembling a flexible number of FECs in parallel through Gigabit Ethernet, the readout system can be tailored to specific sizes to adapt to the experiment scales and readout requirements. In this paper, two kinds of multi-channel ASIC chip, VA140 and AGET, are applied to verify the scalability of this SRS architecture. Based on this VA140 or AGET SRS, one FEC covers 8 ASIC （VA140） cards handling 512 detector channels, or 4 ASIC （AGET） cards handling 256 detector channels, respectively. More FECs can be assembled in crates to handle thousands of detector channels.

Study of 2D interpolating readout for a micro-pattern gaseous detector

The two-dimensional interpolating readout, a new readout concept based on resistive anode structure, was studied for the micro-pattern gaseous detector. Within its high spatial resolution, the interpolating resistive readout structure leads to an enormous reduction of electronic channels compared with pure pixel devices, and also makes the detector more reliable and robust, which is attributed to its resistive anode relieving discharge. A GEM （gaseous electron multiplier） detector with 2D interpolating resistive readout structure was set up and the performance of the detector was studied with ^55Fe 5.9 keV X-ray. The detector worked stably at the gain up to 3.5 × 104 without any discharge. An energy resolution of about 19%, and a spatial resolution of about 219 μm （FWHM） were reached, and good imaging performance was also obtained.

Micro-patterned liquid crystal Pancharatnam-Berry axilens

A liquid crystal Pancharatnam–Berry（PB） axilens is proposed and fabricated via a digital micro-mirrordevice-based photo-patterning system. The polarization-dependent device behaves as an axilens for a lefthanded circularly polarized incident beam, for which an optical ring is focused with a long focal depth in the transverse direction at the output, and an anti-axilens for a right-handed circularly polarized incident beam,for which an optical ring gradually expands at the output. The modification of the size and the sharpness of the diffracted ring beam is demonstrated by encoding a positive（negative） PB lens term into the director expression of a PB（anti-）axicon.

Application of Bioinspired Superhydrophobic Surfaces in Two-phase Heat Transfer Experiments

This paper addresses the potential to use Lotus leafbioinspired surfaces in applications involving heat transfer with phase change, namely pool boiling and spray impingement. Besides describing the role of bioinspired topographical features, using an innovative technique combining high-speed visualization and time-resolved infrared thermography, surface durability is also addressed. Water is used for pool boiling and for spray impingement systems （simplified as single droplet impact）, while HFE7000 is used in a pool boiling cooler for electronic components. Results show that surface durability is quickly compro- mised for water pool boiling applications, as the chemical treatment does not withstand high temperatures （T 〉 100 ℃） during long time intervals （3 h - 4 h）. For HFE7000 pool boiling （depicting lower saturation temperature - 34 ℃）, heat transfer en- hancement is governed by the topography. The regular hierarchical pattern of the bioinspired surfaces promotes the heat transfer coefficient to increase up to 22.2%, when compared to smooth surfaces, while allowing good control of the interaction mechanisms until a distance between micro-structures of 300 gm- 400 Ixm. Droplet impingement was studied for surface temperatures ranging between 60 ℃ - 100 ℃. The results do not support the use of superhydrophobic surfaces for cooling applications, but reveal great potential for other applications involving droplet impact on heated surfaces （e.g. metallurgy in- dustry）.

Research on the technology of femtosecond laser micromachining based on image edge tracing

Aiming at fabrication of complex microstructures and micro-patterns, a kind of femtosecond laser micromachining technology based on the BMP image edge tracing was proposed. We introduced the general principle of this technology and discussed the implementation of the machining paths extraction, optimization, tracing and the feedback of the machining procession in detail. On the basis of this technology, control software for femtosecond laser micromachining was developed. Furthermore, we have accomplished the fabrication of complicated two-dimensional (2D) micro-patterns on a copper thin film. The results indicate that this technology can be used for digital control micromachining of complex patterns or microstructures at micron and submicron scales by femtosecond laser.

Topography guiding the accelerated and persistently directional cell migration induced by vaccinia virus

The rapid transmission of vaccinia virus(VACV)in vivo is thought to be closely related to the cell migration induced by it.Cell migration involved in dynamic changes of cell-substrate adhesion and actin cytoskeleton organization,which can influence by the micro/nano-scale topographic structures that cells are naturally exposed to via contact guidance.However,migration behaviors of VACV-infected cells exposed to topographic cues are still unknown.Herein,we designed an open chip with microgrooved poly(dimethyl siloxane)(PDMS)substrate to explore the topography roles in VACV-induced cell migration.Differed from the random cell migration observed in traditional scratch assay on planar substrate,VACV-infected cells had a tendency to persistently migrate along the axis parallel to microgroove with increased velocity.Moreover,infected cells exhibited a dominant elongated protrusion aligned to the micro-grating axis compare to the shorter lamella extended in any direction on smooth substrate.Interestingly,the Golgi complex preferred to relocate behind the nucleus confined within the micro-grating axis in majority of infected migratory cells.The directional polarization of cells embodied in protrusion formation and Golgi reorientation was responsible for the directionally persistent migration behaviors induced by VACV on microgrooved substrate.Infected cells response to substrate topography,causing the actin-filled stretched protrusion containing numerous virions and accelerated movement is likely to facilitate direct and rapid spread of VACV.This work opens a window for us to understand the migration behaviors of infected cells in vivo,and also provides a cue for revealing the relationship between virus-induced cell migration and virus rapid spread.

Reconstruction algorithm study of 2D interpolating resistive readout structure

Systematic investigations including both simulation and prototype tests have been done about the interpolating resistive readout structure with GEM （Gaseous Electron Multiplier） detector. From the simulation, we have a good knowledge of the process of charge diffusion on the surface of the readout plane and develop several reconstruction methods to determine the hit position. The total signal duration time of a typical event with the readout structure was about several hundred nanoseconds, which implied an ideal count rate up to 106 Hz. A stable working prototype was designed and fabricated after the simulation. Using 55Fe 5.9 performance of the prototype was examined with flat field image and some special geometry energy resolution of about 17% was obtained. keV X-ray, the image shapes, meanwhile, an