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The Fluidic Self-Alignment Approach provides an alternative means for fast, economic, and precise handling of thousands of micro-scale parts. The present study aims to examine the important parameters which govern the mechanisms of the fluidic self-assembly process by numerical simulations. A simplified 2D model system consists of a solid plate, a micro-scale liquid slug and a micropart. The computational model is based on first principle conservation equations and is constructed by the coupling of two-phase modeling, solid structure modeling, and fluid–structure coupling. A matching experimental system is set up for the micropart of aspect ratio from 3:1 to 10:1 to validate the 2D computational simulations. Simulations reveal that a high degree of hydrophilicity between the lubricant and the solid surfaces is required for the self-assembly of microparts. A lower lubricant height, a higher surface tension coefficient and a higher viscosity enforce the re-alignment/restoration process also. Characterization of the flow field inside lubricant slug also indicates that the asymmetry of the vortices/stress distribution at both ends of the lubricant meniscus is resulted as the micropart in a back-and-forth restoration process. [ABSTRACT FROM AUTHOR]

Fiber attachment soldering is low cost and high-precision technology in direct-coupling optoelectronic packaging. For accurate alignment, it is crucial to understand the self-alignment behavior of solder joint. In this research, the self-alignment method by using surface tension of molten solder and by adopting specific pad shape was proposed. First, the self-alignment model of solder joint in fiber attachment soldering was developed by using the public domain software called SURFACE EVOLVER and the three-dimensional geometry of solder joint with different solder volume was analyzed. Then, the self-alignment behavior of solder joint with an initial yaw misalignment was discussed and the theoretical equilibrium positions of ellipse and square pad were calculated. Next, based on the minimum potential energy theorem and data from geometry simulation, the influences of design and material parameters on the standoff height (SOH) were analyzed. Furthermore, experiments were done to examine the theoretical equilibrium positions of ellipse and square pad and the SOHs of solder joints were measured by using confocal scanning laser microscope. The numerical results show that the theoretical equilibrium positions of ellipse and square pad are the major axis of ellipse and the diagonal of square, respectively. SOH can be controlled by adopting proper solder volume, which is above the critical value for specific pad. The experimental results show that the solder joint with initial yaw angle can be self-aligned to the theoretical equilibrium position of pad and solder joint with ellipse pad substrate demonstrates smaller alignment error than those with square pad substrate. The measurement results of SOH are in agreement with the simulation results. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this research is to develop a self-alignment mechanism using surface tension and solid edge for tiny microchips package. The solid edge of a rectangular protrusion replaced the surface treatment, which is usually used in the self-alignment technology. The experiments result showed that the commercial Radio Frequency Identification (RFID) microchip could be accurately auto-aligned on the protrusion. The edge effect, which confined the droplet spreading, is stronger than the boundary of hydrophilic and hydrophobic surface generated by the surface treatment. The standard deviation of aligned position was smaller than 16μm when the surface area of water droplet on protrusion was near to the bottom area of RFID microchip. The self-alignment completed in a tenth of a second. There was no visible position shift on aligned RFID microchip after suffering the simulated motion of transportation. The self-alignment mechanism in this paper can begin a new era of an innovative microchip package process without extra requirement on the microchips. [Copyright &y& Elsevier]

In this paper, we present a novel 2-D microelectromechanical systems (MEMS) scanner that enables dual-axes confocal microscopy. Dual-axes confocal microscopy provides high resolution and long working distance, while also being well suited for miniaturization and integration into endoscopes for in vivo imaging. The gimbaled MEMS scanner is fabricated on a double silicon-on-insulator (SOI) wafer (a silicon wafer bonded on a SOI wafer) and is actuated by self-aligned vertical electrostatic combdrives. Maximum optical deflections of ±4.8° and ±5.5° are achieved in static mode for the outer and inner axes, respectively. Torsional resonant frequencies are at 500 Hz and 2.9 kHz for the outer and inner axes, respectively. The imaging capability of the MEMS scanner is successfully demonstrated in a breadboard setup. Reflectance images with a field of view of 344 µm × 417 µm are achieved at 8 frames/s. The transverse resolutions are 3.94 and 6.68 µm for the horizontal and vertical dimensions, respectively. [ABSTRACT FROM AUTHOR]

Aligned silver nanoparticles, grown by combining two simple bottom-up techniques, are reported. Physical vapor-deposited silver adatoms are shown to form nanoparticles preferentially in the valleys of rippled silicon templates prepared by low-energy ion bombardment. A 35-nm ripple periodicity produced highly aligned structures with a 0.21 eV polarization-dependent shift in the plasmon resonance peak. The speed and simplicity of the method is viable for cost-effective, large-scale production of mesoscale aligned nanostructures with adjustable periodicity. [ABSTRACT FROM AUTHOR]

Abstract: The seesaw-oscillation of a small circular pad on a single droplet was studied both numerically and experimentally. The circular pad with a diameter of 2.0–3.8mm onto a water or glycerol droplet with a volume of 1–10μL, and a bottom substrate with a smaller diameter than that of the pad were used in the experiment. The pad was then tilted and then the tilting fixture was quickly removed. The pad alternately oscillated and then finally stabilized in a horizontal position. The numerical model considering the surface tension and the viscous force of the droplet was developed and calculated using the same configurations as those in the experiment. The experimental and numerical data showed good agreement not only in terms of the oscillating frequency and damping ratio but the transient motion of the circular pad and instantaneous droplet surface shape. [Copyright &y& Elsevier]

Alignment structure and optical properties of Langmuir-Blodgett (LB) films of urethane-substituted polydiacetylene (poly-4BCMU) was investigated. During compression, the coil to rod transition in molecular conformation of poly-4BCMU was induced and the polymer main chains were aligned perpendicular to the compressing direction. The dichroic ratio of absorption intensity of poly-4BCMU monolayer film was about 6. LC molecules were sandwiched with two glass plates covered with the poly-4BCMU monolayer films. LC molecules aligned spontaneously along the main chain direction of poly-4BCMU in the parallel cell. On the other hand, they formed a twisted structure of 90° in the crossed cell. The monolayer film of poly-4BCMU had a high potential as rubbing-free alignment layer of LC molecules. [ABSTRACT FROM AUTHOR]

We report on the performance of an intra-multichip-module free-space optical interconnect that integrates microlenses and a deflection prism above a dense optoelectronic chip, under various fabrication and assembly errors. This paper describes the results of a combination of mechanical Monte Carlo analysis and optical simulations. Both the technological requirements to ensure a high process yield, and the specifications of the technology we use at our laboratories to fabricate the microoptical and micromechanical components, deep lithography with protons (DLP), are discussed. Therefore, we first conduct a sensitivity analysis that is subsequently used to set the variances of the random perturbations of the Monte Carlo simulation. By scaling these variances, we are able to investigate the effect of a technology accuracy enhancement on the fabrication and assembly yield. We estimate that 40% of the systems fabricated with DLP will show an optical transmission efficiency above -4.32 dB, which is -3.02 dB below the theoretical obtainable value. In this paper, we also discuss our efforts to implement an optomechanical Monte Carlo simulator. It allows us to deal with specific issues not directly related with the microoptical or DLP components, such as the influence of gluing layers and structures that allow for self-alignment, by combining mechanical tolerancing algorithms with optical simulation software. In particular, we determine that DLP provides ample accuracy to meet the requirements of a high manufacturing yield (around 91% meet an optical transmission that is -0.75 dB below the theoretical maximum). The adhesive bonding of optoelectronic devices in their package, however, is subject to further improvement to enhance the tilt accuracy of the devices with respect to the optical interconnect modules [ABSTRACT FROM PUBLISHER]

In this paper, we present a high fill-factor micromirror array actuated by self-aligned vertical electrostatic combdrives. To meet the requirements of applications in free-space communication and imaging, each micromirror has three degrees of freedom of motion: rotation around two axes in the mirror plane and linear translation perpendicular to the mirror plane. Our approach is to integrate the high fill-factor reflectors into the fabrication process of the actuators on the wafer-scale. Multilevel silicon-on-insulator (SOI) bonding is utilized to form the high optical quality reflectors and high aspect-ratio vertical combdrive actuators. The wiring for electrical access to the multielectrode per pixel array is fabricated on separate wafers by thin film processing, and flip-chip bonded to the reflector/actuator chip. This architecture overcomes the fill-factor limitation of top-side accessed electrical addressing of mirrors made on SOI. Our 360 μm pixel size mirror array achieves a 99% fill-factor with optically flat reflectors. [ABSTRACT FROM AUTHOR]

In this paper, we describe angular vertical-comb-drive torsional microactuators made in a new process that induces residual plastic deformation of single-crystal-silicon torsion bars. Critical dimensions of the vertically interdigitated moving-and fixed-comb actuators are self-aligned in the fabrication process and processed devices operate stably over a range of actuation voltages. We demonstrate MEMS scanning mirrors that resonate at 2.95 kHz and achieve optical scan angles up to 19.2 degrees with driving voltages of 40Vdc plus 13Vpp. After continuous testing of five billion cycles at the maximum scanning angle, we do not observe any signs of degradation in the plastically deformed silicon torsion bars. [ABSTRACT FROM AUTHOR]

Anisotropic self-alignment of the noncircular pads is investigated to reduce the misalignment in electronic packaging, and the effects of the direction and length ratio of the noncircular pads are analyzed. The restoring forces of circular and noncircular pads are calculated numerically using the surface evolver and are compared with the experimental data. The restoring force in the minor-axis direction of the noncircular pad becomes largest followed by the circular pad and the major-axis direction of the noncircular pad. Directionality increases with the length ratio, which implies that more accurate alignment can be achieved in the specific direction. [ABSTRACT FROM AUTHOR]

Abstract: Shortened single-wall carbon nanotubes (sSWCNTs) were self-aligned vertically on poly(diallyl dimethyl ammonium) chloride (PDAC) self-assembled surfaces (silicon wafer and ITO glass). The self-aligned sSWCNT layer density was measured by atomic force microscopy (AFM) in dependence of reaction time, pH and salt concentration. It was found that the density of self-aligned sSWCNTs was high for pH 4 and 7 at low salt concentrations. At pH 2, the density of vertically adsorbed sSWCNTs was lowest since salt formation close to the isoelectric point (IEP) of the sSWCNTs. For measurements at pH values higher than the IEP of sSWCNTs, with the lower the ionic strength, the higher density of self-aligned sSWCNTs on the substrate was observed. This was also independent of the substrate used. It is suggested that the observed density dependence on ionic strength may be caused by a screening effect of the counter ions. Zeta potential measurements and colloidal stability of sSWCNTs dispersions are reported. Data strongly suggest that the density control of sSWCNTs is caused by screening via counter ions. [Copyright &y& Elsevier]

Self-alignment of soldered electronic components such as flip-chips (FC), ball grid arrays (BGA) and optoelectronic devices during solder reflow is important as it ensures good alignment between components and substrates. Two uncoupled analytical models are presented which provide estimates of the dynamic time scales of both the chip and the solder in the self-alignment process. These predicted time scales can be used to decide whether a coupled dynamic analysis is required for the analysis of the chip motion. In this paper, we will show that for flip-chips, the alignment dynamics can be described accurately only when the chip motion is coupled with the solder motion because the two have similar time-scale values. To study this coupled phenomenon, a dynamic modeling method has been developed. The modeling results show that the uncoupled and coupled calculations result in significantly different predictions. The calculations based on the coupled model predict much faster rates of alignment than those predicted using the uncoupled approach. [ABSTRACT FROM AUTHOR]

We present micromirrors actuated by self-aligned, high aspect ratio, vertical electrostatic combdrives with multi-level electrical isolation that allows bi-directional and dual-mode (independent rotation and piston motion) operation. The fabrication process, which requires only front-side processing, is based on self-aligned deep-reactive ion etching (DRIE) of silicon-on-insulator (SOI) wafers with two device layers. The two oxide layers between the device layers provide electrode isolation and etch stops for thickness control. Self-alignment of electrostatic combs in the two device layers is accomplished by creating masking features in the upper layer that are transferred into the lower layer. The masking features are typically removed, but in some cases they remain as an integral part of the completed device. SEM pictures show perfectly aligned vertical combteeth both with and without removal of the masking features. We demonstrate micromirrors of this type with ±9° of optical scanning and 7.5 μm of piston motion under static actuation. Micromirrors designed for resonant scanning have optical scan angles up to ±25° at 13.5 kHz. [Copyright &y& Elsevier]

In this paper, fully monolithic silicon optical scanners are demonstrated with large static optical beam deflection. The main advantage of the scanners is their high speed of operation for both axes: namely, the actuators allow static two-axis rotation in addition to pistoning of a micromirror without the need for gimbals or specialized isolation technologies. The basic device is actuated by four orthogonally arranged vertical comb-drive rotators etched in the device layer of an silicon-on-insulator wafer, which are coupled by mechanical linkages and mechanical rotation transformers to a central micromirror. The transformers allow larger static rotations of the micromirror from the comb-drive stroke limited rotation of the actuators, with a magnification of up to 3× angle demonstrated. A variety of one-axis and two-axis devices have been successfully fabricated and tested, in all cases with 600-μm-diameter micromirrors. One-axis micromirrors achieve static optical beam deflections of >20° and peak-to-peak resonant scanning of >50° in one example at a resonant frequency of 4447 Hz. Many two-axis devices utilizing four rotators were tested, and exhibit >18° of static optical deflection at <150 V, while their lowest resonant frequencies are above 4.5 kHz for both axes. A device which utilizes only three bidirectional rotators for tip-tilt-piston actuation achieves -10° to 10° of optical deflection in all axes, and exhibits minimum resonant frequencies of 4096 and 1890 Hz for rotation and pistoning, respectively. Finally, we discuss the preliminary results in scaling tip-tilt-piston devices down to 0.4 × 0.4 mm on a side for high fill-factor optical phased arrays. These array elements include bonded low-inertia micromirrors which fully cover the actuators to achieve high fill-factor. [ABSTRACT FROM PUBLISHER]

A microfabrication technology has been developed and demonstrated, which enhances the capabilities and applications of high aspect ratio silicon-on-insulator microelectromechanical systems (SOI-MEMS) by enabling additional independent degrees of freedom of operation: both upward and downward vertical pistoning motion as well as bi-directional rotation. This is accomplished by applying multiple-mask high aspect ratio etches from both the front- and back-side of the SOI device layer, forming beams at different levels. The processes utilize four masks, two for front-side and two for back-side etching. As a result, single-crystal silicon beams with four different cross-sections are fabricated, and can be combined to form many additional beam cross-sections. This provides a wide variety of possible mechanical designs that can be optimized for optical and other applications. By this methodology, unique high aspect ratio micromirror devices were demonstrated with fully isolated and accurately self-aligned vertical combdrives in the SOI device layer, with initial combfinger overlap. Examples of fabricated devices are shown with performance summaries. [ABSTRACT FROM AUTHOR]

A new type of self-aligned spotsize converter (SSC) integrated 1.55 μm DFB lasers had been proposed in this article. The upper optical confinement layer and the butt-coupled tapered thickness waveguide were regrown simultaneously, which not only offered the separate optimization of the active region and the integrated SSC, but also reduced the difficulty of the butt-joint selective regrowth. The vertical and horizontal far field angles were 9° and 12° respectively, the 1-dB misalignment tolerance were both 3.6 and 3.4 μm. The directed coupling efficiency to tapered single mode fiber was 48%. [ABSTRACT FROM AUTHOR]

The purpose of this research is to establish a self-alignment technique for microparts assembly using liquid surface tension. The factors that influence alignment performance are examined and ways of performance improvement are discussed experimentally and theoretically. First, the relationship between the alignment accuracy and the behavior of the micropart and the water droplet is examined in the alignments with six different water droplet volumes. The experimental results show that the volume influences the alignment accuracy and the behavior. Next, the relationship between restoring force induced theoretically and the experimental alignment accuracy is discussed. Then, the effect of pattern change of the boundary between different wettability areas on the alignment accuracy is examined experimentally. In the experiments, the micropart with the hexagonal boundary pattern demonstrates smaller alignment error than those with the square, triangular, cross and star patterns. [Copyright &y& Elsevier]

Movable vertical mirror arrays optical microswitch matrixes and their electromagnetic actuation with microcoils are presented as an extension of previous results on a first prototype of microswitch (Helin et al., 2000) a new mechanical design is developed to further increase the density of integration of the optical bypass. Deep reactive ion etching and KOH etching are successively used to realize the whole structure getting the advantages of both (self-alignment between vertical smooth mirrors and fiber guides). Microcoils are fabricated in order to actuate the microswitches electromagnetically. Efforts are done to increase the electromagnetic force generated by the microcoils in order to allow down scaling the sizes and large displacements of the microswitch movable parts in the same dimensions as the optical fibers. A high aspect ratio SU8 pattern and the use of ferromagnetic materials should achieve these requirements [ABSTRACT FROM PUBLISHER]

• A deep convolutional neural network is used to evaluate and correct the alignment of an orbital angular momentum sorter. • The convolutional neural network automatically analyses OAM spectra at a rate of 50 ms/spectrum, allowing for real time implementation. • The method is easily transferable to any programmable beam shaping technique. A convolutional neural network is used to align an orbital angular momentum sorter in a transmission electron microscope. The method is demonstrated using simulations and experiments. As a result of its accuracy and speed, it offers the possibility of real-time tuning of other electron optical devices and electron beam shaping configurations. [ABSTRACT FROM AUTHOR]

The seamless coalescence of parallelly aligned 2D materials is the primary route toward the synthesis of wafer-scale single crystals (WSSCs) of 2D materials. The epitaxial growth of various 2D materials on a single-crystal substrate, which is an essential condition of the seamless coalescence approach, has been extensively explored in previous studies. Here, by using hexagonal boron nitride (hBN) growth on a liquid gold surface as an example, we demonstrate that growth of WSSCs of 2D materials via the seamless coalescence of self-aligned 2D islands on a liquid substrate is possible. Here we show that, in the presence of hydrogen, all the hBN edges tend to be hydrogen terminated and the coalescence of hBN islands occurs only if their crystallographic lattices of neighboring hBN islands are aligned parallelly. The mechanism of hBN self-alignment revealed in this study implies that, under the optimum experimental condition, the seamless coalescence of 2D materials on a liquid substrate is possible and thus provides guidance for synthesizing WSSCs of various 2D materials by using liquid phase substrates.

• Gravity observation vector is reconstructed to smooth measurement noise. • Observation vector inertia and eigenvalue decomposition are presented. • Extended Wahba problem is defined and solved for estimating both latitude and attitude. • Anti-swaying self-alignment method is proposed for strapdown inertial navigation system. • Experiments and comparison show the effectiveness and efficiency of the proposed method. The self-alignment of strapdown inertial navigation system that does not depend on any external aid still has huge application requirements. This study presents an anti-swaying self-alignment method based on the inertia tensor of gravity observation vectors and aims to improve the accuracy and efficiency of the latitude and attitude estimation by making full use of inertial measurements. The time-varying attitude matrix is decomposed first to isolate the swaying interference and gravity observation vectors are reconstructed to smooth the measurement noise. Then the body attitude estimation with unknown latitude is defined as an extended Wahba problem, which is solved by eigenvalue decomposition based on the inertia tensor of gravity observation vectors. Simulation and experiments verify the effectiveness of the proposed method and two common methods are used for comparison, which show that the proposed method has faster convergence speed, stronger anti-interference ability, and higher accuracy of the latitude and attitude estimation. [ABSTRACT FROM AUTHOR]

• A new anticorrosion strategy inspired by natural nacre and mussels was designed. • The biomimetic sandwich epoxy anticorrosive coating was successfully prepared. • Graphene-dopamine binders are used to enhance interface compatibility. • Hydrogen bonding and electrostatic interaction cause the graphene to align in parallel. • The bionic sandwich coating has extraordinary long-term anticorrosion. The special "brick-mud" layered micro-nano structure of nacre has undergone millions of years of biological evolution, which can withstand the corrosion of seawater in different environments, and has both high strength and toughness. Inspired by mussels and natural nacre, we successfully designed a bionic epoxy-(graphene-dopamine) n -epoxy sandwich composite coating. Not only does dopamine act as a binder to improve the interfacial compatibility and adhesion between epoxy resin and graphene, but due to the hydrogen bonding and the electrostatic interaction of –COO− and –NH 3 +, graphene interlayers is parallel to the substrate and arranged between two epoxy coatings. This not only gives full play to the barrier effect of graphene, but also shielding the galvanic corrosion by avoiding direct contacting with the substrate. The results show that the composite coating prepared 10 scanning of dopamine functionalized graphene oxide has a low-frequency impedance of 1.30 × 109 O cm2 after immersion in 3.5 wt% NaCl solution for 90 days, which is three orders of magnitude higher than that of pure coating, revealing remarkable long-term anticorrosion. We consider that our strategy can be readily extended to the self-alignment of a variety of two-dimensional nanofillers to facilitate the development of long-term corrosion resistant coatings. [ABSTRACT FROM AUTHOR]

To improve the reproducibility of the properties of thin-film transistors (TFTs) formed by using solid-phase grown polycrystalline silicon, a self-aligned grain boundary control technique was developed. In this technique, the gate electrode of a coplanar TFT serves as a mark for ion implantation to the source and drain regions. At the same time, it limits amorphization of polycrystalline silicon only to the channel region. The channel region becomes amorphized by a high-energy silicon ion beam through the gate electrode and oxide. However, since the silicon ions penetrate through the source and drain regions, crystalline seeds remain in the regions. Then the solid-phase growth is carried out in the regions from the source and drain regions to the center of the channel before the crystalline nuclei are formed in the channel region. By this process, the presence of the grain boundary is limited to the center of the channel. When this technique is used, the mobility is improved by 60 percent and the scattering of the mobility value is reduced to half. [ABSTRACT FROM AUTHOR]

This paper describes a novel vertical power MOS-FET with low on-resistance and large avalanche current, called US-DMOS (U-grooved self-signed DMOS). It features a U-grooved self-aligned source and base con bets with respect to the gate electrode, which reduces the cell aim to two-thirds the conventional cell size and reduces the parasitic base resistance. Using three-dimensional simulation on this device structure, the reduction on the on-resistance by the formation of the U-groove and the increase of the avalanche current by the reduction of the base resistance were proved. In an n-channel test device with a drain current of 60 V, the on-resistance was 156 mωmm², which is 30 percent lower than in a comparable device with a conventional structure. In addition, the avalanche current was one order of magnitude higher in this device. [ABSTRACT FROM AUTHOR]

We demonstrate a new digital etch technique for controllably thinning III-V semiconductor heterostructures with sub-1-nm resolution. This is a two-step process consisting of low-power O2 plasma oxidation, followed by diluted H2SO4 rinse for selective oxide removal. This approach can etch a combination of InP, InGaAs, and InAlAs in a precise and nonselective manner. We have also developed a method to determine the etch rate per cycle, and to control the etch depth in actual device structures. For InP, the etch rate is \sim0.9~nm/cycle. We illustrate the new process by fabricating Lg=60\-nm self-aligned buried-channel InGaAs MOSFETs. These devices feature a composite gate dielectric consisting of 1-nm InP and 2-nm HfO2 for an overall sub-1-nm effective oxide thickness. A typical device shows a peak transconductance of 1.53 mS/\mum(Vds=0.5~\rm V), subthreshold swing of 89 mV/decade, and 102 mV/decade at Vds=0.05 and 0.5 V, respectively, and on current of 326 \muA/\mum at IOFF=100~nA/\mum and Vdd=0.5~\rm V. [ABSTRACT FROM AUTHOR]

The growing demand for ubiquitous data collection has driven the development of sensing technologies with local data processing. As a result, solution-processed semiconductors are widely employed due to their compatibility with low-cost additive manufacturing on a wide range of substrates. However, to fully realize their potential in sensing applications, high-performance scalable analog amplifiers must be realized. Here, ohmic-contact-gated transistors (OCGTs) based on solution-processed semiconducting single-walled carbon nanotubes are introduced to address this unmet need. This new device concept enables output current saturation in the short-channel limit without compromising output current drive. The resulting OCGTs are used in common-source amplifiers to achieve the highest width-normalized output current (≈30 µA µm -1 ) and length-scaled signal gain (≈230 µm -1 ) to date for solution-processed semiconductors. The utility of these amplifiers for emerging sensing technologies is demonstrated by the amplification of complex millivolt-scale analog biological signals including the outputs of electromyography, photoplethysmogram, and accelerometer sensors. Since the OCGT design is compatible with other solution-processed semiconducting materials, this work establishes a general route to high-performance, solution-processed analog electronics., (© 2021 Wiley-VCH GmbH.)

Light-driven micromotors have stimulated considerate interests due to their potentials in biomedicine, environmental remediation, or serving as the model system for non-equilibrium physics of active matter. Simultaneous control over the motion direction and speed of micro/nanomotors is crucial for their functionality but still difficult since Brownian motion always randomizes the orientations. Here, a highly efficient light-driven ZnO/Pt Janus micromotor capable of aligning itself to illumination direction and exhibiting negative phototaxis at high speeds (up to 32 µm s -1 ) without the addition of any chemical fuels is developed. A light-triggered self-built electric field parallel to the light illumination exists due to asymmetrical surface chemical reactions induced by the limited penetration depth of light along the illumination. The phototactic motion of the motor is achieved through electrophoretic rotation induced by the asymmetrical distribution of zeta potential on the two hemispheres of the Janus micromotor, into alignment with the electric field. Notably, similar phototactic propulsion is also achieved on TiO 2 /Pt and CdS/Pt micromotors, which presents explicit proof of extending the mechanism of dipole-moment induced phototactic propulsion in other light-driven Janus micromotors. Finally, active transportation of yeast cells are achieved by the motor, proving its capability in performing complex tasks., (© 2021 Wiley-VCH GmbH.)

Self-aligned vertical alignment (SA-VA) technique in liquid crystal display (LCD), in which the alignment layer coating process is not necessary, has attracted significant attention owing to its cost-effectiveness and usefulness in the control of LC alignment and the fabrication of LCDs. However, it presents a critical drawback pertaining to the occurrence of LC alignment defects caused by non-uniform additive attachment on the surface; as a result, the technology has not yet been adopted for commercial applications. Here, we propose an advanced SA-VA technology using novel additives containing thiol groups and thermally induced physicochemical adsorption of additives on the surface. Using the new materials as well as method, we successfully demonstrate a perfect vertical alignment of LC without non-uniform alignment defects. In addition, it is confirmed that the electro-optical performance of the cell is comparable to that of a conventional commercial device. Thus, our method can overcome the limitation of existing SA-VA technology, and may be applied to commercial SA-VA mode displays. Further, with its self-alignment feature, the technology may be useful for the future display applications such as cost-effective smart window using LC. Unlabelled Image • Self-alignment LC mixture containing a novel additive with thiol group (-SH) • Thermal energy-initiated adsorption of thiol additive on ITO surface • Uniform additive density on the surface and resulting uniform LC alignment • Excellent electro-optical performance of the self-aligned LC cell comparable to conventional LC cell [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a self-assembly formation of SU-8 microspheres integrated with a self-alignment fabrication of silicon pillars for realizing contact microprobes, which can be used to determine the profile of high-aspect-ratio micro-structures. This new process combines an SU-8 microsphere and a silicon pillar to form one mechanical device. The SU-8 microspheres were assembled by interfacial tension against a NaDBS solution. The pillars were patterned by the microlens-assisted self-writing of SU-8 resist waveguides. This process enables the center of the microsphere to accurately coincide with the longitudinal axis of the pillar, and hence the measurement error resulting from the probe can be significantly reduced. The high-aspect-ratio pillar consists of a SU-8 portion and a silicon portion which was fabricated by deep reactive ion etching. [Copyright &y& Elsevier]

Abstract: Si nanowire (SiNW) channel non-volatile memory (NVM) cells were fabricated by a “self-alignment” process. First, a layer of thermal SiO2 was grown on a silicon wafer by dry oxidation, and the SiNWs were then grown by chemical vapor deposition in pre-defined locations. This was followed by depositing the gate dielectric, which almost surrounds the nanowire and consists of three stacked layers: SiO2 blocking layer, HfO2 charge-storing layer and a thin tunneling oxide layer. Source/drain and gate electrodes were formed by photolithography and lift-off, and the devices were electrically tested. As expected from this fabrication process and the enhanced electrostatic control of the “surrounding” gate, excellent cell characteristics were obtained. [Copyright &y& Elsevier]

We propose a novel self-alignment process of optical devices with optical fiber. A vertical-cavity surface-emitting laser (VCSEL) was automatically coupled with a multimode fiber (MMF) through the surface tension of a liquid adhesive within 1.5 s. Misalignment between the center of the VCSEL and the fiber was measured to be 15 mum, which is acceptable for coupling the VCSEL with the MMF. High-speed pulse modulation of the self-aligned VCSEL up to 5 Gb/s, as well as at 1 Gb/s, was demonstrated. The average optical output power was as high as -5.9 dBm at 1 Gb/s. [ABSTRACT FROM PUBLISHER]