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The purpose of this article is to present a new method of analysis for the structural design of pin-supported rocking wall-moment frames with supplementary devices and post-tensioned stabilizers. The function of the wall is to prevent soft story failure, impose uniform drift and provide support for the supplementary equipment. The proposed methodology lends itself well to several seismic design strategies, ranging from severe damage avoidance, to collapse prevention, to structural self-alignment and repairability. Repairability means avoiding major damage to columns and foundations. The success of the resulting solutions is due to the single degree of freedom behavior of the combined system and the fact that its overall performance is not significantly affected by minor changes in the stiffness of the wall. The sensitivity of the response to wall rigidity is addressed by comparing the maximum elastic slope of the wall with a fraction of the specified uniform drift. The limitations of rocking wall-moment frames, as viable lateral resisting systems, have been addressed. Several worked examples have been presented to provide insight and technical information that may not be readily available from electronic output. The proposed solutions are exact within the bounds of the theoretical assumptions and are ideally suited for manual as well as spreadsheet computations. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The self-assembly of known good dies on hosting substrates using liquid surface tension is a promising technology to create highly integrated 3-D and heterogeneous microelectronic systems. In this paper, we investigate the effects of the edge structures of self-assembled chips on alignment accuracies. Nine types of 100- \mu \textm -thick Si chips (3 mm $\times \,\, 3$ mm) with and without step geometries on their hydrophilic or hydrophobic peripheries are self-assembled onto hydrophilic assembly sites formed on planar- and plateau-type host substrates. When hydrophobic peripheries with step geometries are applied to both the edges of chips and assembly sites formed on substrates, the resulting average alignment accuracy is 300 nm. Total accuracy variation within 2 100~\mu \text{m} . [2014-0298] [ABSTRACT FROM AUTHOR]

Heteronuclear and homonuclear direct (D) and indirect (J) spin-spin interactions are important sources of structural information about nucleic acids (NAs). The Hamiltonians for the D and J interactions have the same functional form; thus, the experimentally measured apparent spin-spin coupling constant corresponds to a sum of J and D. In biomolecular NMR studies, it is commonly presumed that the dipolar contributions to Js are effectively canceled due to random molecular tumbling. However, in strong magnetic fields, such as those employed for NMR analysis, the tumbling of NA fragments is anisotropic because the inherent magnetic susceptibility of NAs causes an interaction with the external magnetic field. This motional anisotropy is responsible for non-zero D contributions to Js. Here, we calculated the field-induced D contributions to 33 structurally relevant scalar coupling constants as a function of magnetic field strength, temperature and NA fragment size. We identified two classes of Js, namely J and J couplings, whose quantitative interpretation is notably biased by NA motional anisotropy. For these couplings, the magnetic field-induced dipolar contributions were found to exceed the typical experimental error in J-coupling determinations by a factor of two or more and to produce considerable over- or under-estimations of the J coupling-related torsion angles, especially at magnetic field strengths >12 T and for NA fragments longer than 12 bp. We show that if the non-zero D contributions to J are not properly accounted for, they might cause structural artifacts/bias in NA studies that use solution NMR spectroscopy. [ABSTRACT FROM AUTHOR]

In this paper, self-alignment problem for strapdown inertial navigation system based on tracing gravity drift in inertial frame and dual-vector attitude determination is studied. Aiming to further ease, the interference from sensor random errors, especially accelerometer random noise, without adding alignment time, a novel alignment method based on integrating gravitational apparent motion to form apparent velocity is designed, using recursive least squares algorithm to recognize the parameters describing the theoretical apparent velocity from the calculated velocity containing random noise. Analysis and simulation indicate that with this method, random noise can be effectively removed compared with the only operation of integration. Meanwhile, a reconstruction algorithm with current recognized parameters for dual-velocity vectors is devised which can fully utilize all measurement information and completely avoid collinear problem. Simulation and turntable results show that compared with the existing integrating methods, the proposed method can acquire sound alignment results with lower standard variances and can improve alignment accuracy with the same alignment time or shorten alignment time with the same accuracy. [ABSTRACT FROM AUTHOR]

Wafer level chip scale package (WLCSP) is one of the most promising methods for the integration of micro-electromechanical systems (MEMS) with integrated circuits (IC). In our previous works, we have successfully developed a 2-step approach by using a carrier wafer for size-free MEMS-IC integration. This approach exhibits both excellent process flexibility and high efficiency. This approach has been proved practically valuable when compared to chip to wafer (C2W) bonding or wafer to wafer (W2W) bonding. For the improvement of above approach, the phenomenon of the chip to carrier wafer self-alignment was investigated in this work. The process parameters and the chip-dicing processes, which may affect yields and accuracy of the self-alignment, were analyzed. A hybrid process was then proposed for chip-dicing to reduce the process cost as well as to decrease the exhaust of greenhouse gases. Moreover, a surface activated room temperature bonding process was introduced and optimized for transferring of above chips from the carrier wafer to a target wafer with less damage to those chips. A full size-free MEMS-IC integration process was finally demonstrated, and then evaluated from both electrical and mechanical points-of-view. [ABSTRACT FROM AUTHOR]

We present a pick-and-place approach driven by capillarity for highly precise and cost-effective assembly of mesoscopic components onto structured substrates. Based on competing liquid bridges, the technology seamlessly combines programmable capillary grasping, handling, and passive releasing with capillary self-alignment of components onto prepatterned assembly sites. The performance of the capillary gripper is illustrated by comparing the measured lifting capillary forces with those predicted by a hydrostatic model of the liquid meniscus. Two component release strategies, based on either axial or shear capillary forces, are discussed and experimentally validated. The release-and-assembly process developed for a continuously moving assembly substrate provides a roll-to-roll-compatible technology for high-resolution and high-throughput component assembly. [ABSTRACT FROM PUBLISHER]

Although conventional laser ablation (CLA) method has widely been used in patterning of organic semiconductor thin films, its quality control still remains unsatisfied due to the ambiguous photochemical and photothermal processes. Based on industrial available near-infrared laser source, herein, a novel 'layer-filter threshold' (LFT) technique is proposed, which involves the decomposition of targeted 'layer-filter' and subsequent explosive evaporation process to purge away the upper layers instead of layer-by-layer ablation. For photovoltaic device with structure of metal/blend/PEDOT:PSS/ITO/glass, the PEDOT:PSS layer as the 'layer-filter' is first demonstrated to be effective, and then the merged P1-P2 line and metal electrode layer are readily patterned through the 'self-aligned' effect and regulation of ablation direction, respectively. The correlation between laser fluence and explosive ablation efficacy is also investigated. Finally, photovoltaic modules based on classical P3HT:PC61BM and low-bandgap PBDT-TFQ:PC71BM systems are separately fabricated following the LFT technique. It is found that over 90% of geometric fill factor is achieved while device performances maintain in a limited change with increased number of series cells. In comparison to conventional laser ablation methods, the LFT technique does not require sophisticated instruments but reaches comparable processing accuracy, which shows promising potential in the fabrication and commercialization of organic semiconductor thin-film devices. [ABSTRACT FROM AUTHOR]

Many applications that rely on organic electronic circuits still suffer from the limited switching speed of their basic elements – the organic thin film transistor (OTFT). For a given set of materials the OTFT speed scales inversely with the square of the channel length, the parasitic gate overlap capacitance, and the contact resistance. For maximising speed we pattern transistor channels with lengths from 10 μm down to the sub-micrometre regime by industrially scalable UV-nanoimprint lithography. The reduction of the overlap capacitance is achieved by minimising the source–drain to gate overlap lengths to values as low as 0.2 μm by self-aligned electrode definition using substrate reverse side exposure. Pentacene based organic thin film transistors with an exceptionally low line edge roughness <20 nm of the channels, a mobility of 0.1 cm 2 /Vs, and an on–off ratio of 10 4 , are fabricated on 4″ × 4″ flexible substrates in a carrier-free process scheme. The stability and spatial distribution of the transistor channel lengths are assessed in detail with standard deviations of L ranging from 185 to 28 nm. Such high-performing self-aligned organic thin film transistors enabled a ring-oscillator circuit with an average stage delay below 4 μs at an operation voltage of 7.5 V. [ABSTRACT FROM AUTHOR]

A capacitive-piezoelectric (also known as, capacitive-piezo) transducer that combines the strengths of capacitive and piezoelectric mechanisms to achieve a combination of electromechanical coupling and Q higher than otherwise attainable by either mechanism separately, has allowed demonstration of a 1.2-GHz contour-mode aluminum nitride (AlN) ring resonator with Q > 3000 on par with the highest measured d31-transduced AlN-only piezoelectric resonators past 1 GHz, and a 50-MHz disk array with an even higher Q > 12 000. Here, the key innovation is to separate the piezoelectric resonator from its metal electrodes by tiny gaps to eliminate metal material and metal-to-piezoelectric interface losses thought to limit thin-film piezoelectric resonator Q, while also maintaining high electric field strength to preserve a strong piezoelectric effect. While Q increases, electromechanical coupling decreases, but the k ^2eff\cdot Q product can still increase overall. More importantly, use of the capacitive-piezo transducer allows a designer to trade electromechanical coupling for Q, providing a very useful method to tailor Q and coupling for narrowband radio frequency (RF) channel-selecting filters for which Q trumps coupling. This capacitive-piezo transducer concept does not require dc-bias voltages and allows for much thicker electrodes that reduce series resistance without mass loading the resonant structure. The latter is especially important as resonators and their supports continue to scale toward even higher frequencies. [2013-0395] [ABSTRACT FROM AUTHOR]

In recent years, the robotic research area has become extremely prolific in terms of wearable active exoskeletons for human body motion assistance, with the presentation of many novel devices, for upper limbs, lower limbs, and the hand. The hand shows a complex morphology, a high intersubject variability, and offers limited space for physical interaction with a robot: as a result, hand exoskeletons usually are heavy, cumbersome, and poorly usable. This paper introduces a novel device designed on the basis of human kinematic compatibility, wearability, and portability criteria. This hand exoskeleton, briefly HX, embeds several features as underactuated joints, passive degrees of freedom ensuring adaptability and compliance toward the hand anthropometric variability, and an ad hoc design of self-alignment mechanisms to absorb human/robot joint axes misplacement, and proposes a novel mechanism for the thumb opposition. The HX kinematic design and actuation are discussed together with theoretical and experimental data validating its adaptability performances. Results suggest that HX matches the self-alignment design goal and is then suited for close human–robot interaction. [ABSTRACT FROM PUBLISHER]

Arrays of liquid crystal defects-linear smectic dislocations-are used to trap semiconductor CdSe/CdS dot-in-rods which behave as single-photon emitters. Measurements of the emission diagram are combined together with measurements of the emitted polarization of the single emitters. It is shown that the dot-in-rods are confined parallel to the linear defects to allow for a minimization of the disorder energy associated with the dislocation cores. It is demonstrated that the electric dipoles associated with the dot-in-rods, tilted with respect to the rods, remain oriented in the plane including the smectic linear defects and perpendicular to the substrate, most likely due to dipole/dipole interactions between the dipoles of the liquid crystal molecules and those of the dot-in-rods. Using smectic dislocations, nanorods can consequently be oriented along a unique direction for a given substrate, independently of the ligands' nature, without any induced aggregation, leading as well to a fixed azimuthal orientation for the dot-in-rods' dipoles. These results open the way for the fine control of nanoparticle anisotropic optical properties, in particular, fine control of single-photon emission polarization. [ABSTRACT FROM AUTHOR]

Based on the alignment idea of tracing gravitational apparent motion in inertial frame, a novel self-alignment and latitude calculation method for Strapdown Inertial Navigation System (SINS) is designed. In this method, the problem of acquiring attitude matrix between body frame and navigation frame is attributed to acquiring the matrix between initial body frame and current navigation frame, and the gravitational apparent motion vectors at three moments are used to construct corresponding vectors and matrix through vector-operation. Meanwhile, the latitude information can be obtained by virtue of the geometric relationships among gravitational apparent vectors. Furthermore, the validity of the proposed method is proved by mathematical proof, and the theoretical expressions for evaluating accuracies of initial alignment and latitude calculation are deduced detailedly. Simulation and turntable results indicate that the proposed method can fulfill self-alignment and latitude calculation under a swinging condition without translational motion. [ABSTRACT FROM AUTHOR]

This paper introduces a new integration technology for cost-effective high-precision mechanical and electrical integration of mesoscopic functional foil components onto foil substrates. The foil-to-foil assembly process is based on topological surface structuring via laser patterning that enables accurate capillarity-driven self-alignment of foil dies. The concurrent establishment of high-yield electrical interconnections is obtained through conductive adhesives. The foil surface energy controls the acceptance window of initial offsets for optimal self-alignment performance. The proposed topological patterning and system design enable alignment accuracies for centimeter-sized foil dies as high as 15 μm, barely influenced by the evaporation of the assembly liquid and curing of the conductive paste. Full foil-to-foil system integration is demonstrated through the electrically functional assembly of an array of Au-sputtered capacitive humidity sensors onto a patterned base foil circuitry. [ABSTRACT FROM AUTHOR]

To reduce the impact of offshore launching platform motion and swaying on the self-alignment accuracy of a launch vehicle, a rapid self-alignment strategy, which involves an optimal combination of anti-swaying coarse alignment (ASCA), backtracking navigation, and reverse Kalman filtering is proposed. During the entire alignment process, the data provided by the strapdown inertial navigation system (SINS) are stored and then applied to forward and backtrack self-alignment. This work elaborates the basic principles of coarse alignment and then analyzes the influence of ASCA time on alignment accuracy. An error model was built for the reverse fine alignment system. The coarse alignment was carried out based on the above work, then the state of the alignment system was retraced using the reverse inertial navigation solution and reverse Kalman filtering with the proposed strategy. A cycle-index control function was designed to approximate strict backtracking navigation. Finally, the attitude error was compensated for after the completion of the first and the last forward navigation. To demonstrate the effectiveness of the proposed strategy, numerical simulations were carried out in a scenario of launch vehicle motion and swaying. The proposed strategy can maximize the utilization of SINS data and hence improve the alignment accuracy and further reduce the alignment time. The results show that the fully autonomous alignment technology of the SINS can replace the complex optical aiming system and realize the determination of the initial attitude of a launch vehicle before launch.

We report on the fabrication and characterization of self-aligned organic thin-film transistors with copper gate electrodes structured by nanoimprint lithography (NIL). The process has been improved to increase the compatibility with solution processed materials for future fabrication of fully printed, NIL structured transistors. We provide detailed analysis of the influence of the channel length on the fabricated devices. The on-current, the swing and the onset voltage are studied for channel lengths between 25 μm and 800 nm. The results indicate that for the given system a channel length of 5 μm results in the best device performance regarding the on-current and the subthreshold swing. This work marks a first step towards our goal of fabricating self-aligned NIL OTFTs consisting solely of printable materials. [ABSTRACT FROM AUTHOR]

We review a general class of models for self-organized dynamics based on alignment. The dynamics of such systems is governed solely by interactions among individuals or "agents," with the tendency to adjust to their "environmental averages." This, in turn, leads to the formation of clusters, e.g., colonies of ants, flocks of birds, parties of people, rendezvous in mobile networks, etc. A natural question which arises in this context is to ask when and how clusters emerge through the self-alignment of agents, and what types of "rules of engagement" influence the formation of such clusters. Of particular interest to us are cases in which the self-organized behavior tends to concentrate into one cluster, reflecting a consensus of opinions, flocking of birds, fish, or cells, rendezvous of mobile agents, and, in general, concentration of other traits intrinsic to the dynamics. Many standard models for self-organized dynamics in social, biological, and physical sciences assume that the intensity of alignment increases as agents get closer, reflecting a common tendency to align with those who think or act alike. Moreover, "similarity breeds connection" reflects our intuition that increasing the intensity of alignment as the difference of positions decreases is more likely to lead to a consensus. We argue here that the converse is true: when the dynamics is driven by local interactions, it is more likely to approach a consensus when the interactions among agents increase as a function of their difference in position. Heterophily, the tendency to bond more with those who are different rather than with those who are similar, plays a decisive role in the process of clustering. We point out that the number of clusters in heterophilious dynamics decreases as the heterophily dependence among agents increases. In particular, sufficiently strong heterophilious interactions enhance consensus. [ABSTRACT FROM AUTHOR]

We have developed a new microstructure film for wide viewing liquid crystal displays (LCDs). By attaching it to the surface of a conventional LCD, the viewing angle characteristics of LCD has drastically improved without causing a blur of the frontal image and a decrease in the contrast ratio under bright ambient light conditions. This film can be applied to various LC modes including twisted nematic and multidomain vertical alignment by changing its internal micrometer-size 3D structure. Further, this film can be mass-produced efficiently by self alignment roll-to-roll process. [ABSTRACT FROM AUTHOR]

A microstructure film with many micro cavities positioned behind small black dots has been developed for improving LCD viewing-angle characteristics. The micro cavities are fabricated by the self-alignment photolithography of the transparent photoresist using the black dots as photo masks. The cavity shapes are optimized by controlling the photolithography conditions. [ABSTRACT FROM AUTHOR]

Accurate positioning of an object is important in many industrial applications. This task is usually performed using closed-loop control. The self-alignment of an object using stick–slip vibrations on a periodically excited table might be an alternative open-loop method for macroscale applications. In this paper, this method is experimentally validated. The table surface consists of two parts: a low-friction region and a high-friction region. A steady-state motion of the object is developed, when it is on the low-friction region of the table. Theory predicts five possible types of steady-state motion. All types have been observed in practice. The positioning principle is to stop the mass due to an increase in friction when it enters the high-friction region of the table. Theoretically predicted steady-state and accurate stopping behavior is in accordance with the experimental observations. [ABSTRACT FROM PUBLISHER]

The precisely controllable growth of self-aligned single-crystal graphene grains on liquid Cu surface by ambient pressure chemical vapor deposition is reported. Large scale monolayer graphene arrays are modulated by varying growth conditions such as flow rate of carbon source, growth temperature, and growth time. Further, bilayer graphene grains are also controllably prepared under optimized growth conditions. The self-alignment mechanism of graphene is also studied and a growth model is proposed to explain that process involving surface tension of liquid phase. In all, the growth mechanism of graphene arrays is firstly probed and the grown graphene arrays show reasonable mobility and high current density, posing great potential for graphene-based electronics. [ABSTRACT FROM AUTHOR]

Abstract: Misalignment is a problematic challenge in RF MEMS resonators. It causes asymmetry in the ultra symmetric radial contour mode disk resonators and degrades their performance by increasing the insertion loss and decreasing their quality factors (Q). Self-alignment method seems to be a good solution for misalignment problem, but it cannot be directly applied on high performance ring shape anchored resonators. This paper discusses misalignment effects for the ring shape anchored resonators and proposes a method for reconfiguring its anchor to be compatible with self-alignment process. Simulation results validate that the crossed ring anchor structure has the same resonance characteristics with the complete ring shape anchored resonator. [Copyright &y& Elsevier]

Powered knee exoskeletons have shown potential for mobility restoration and power augmentation. However, the benefits of exoskeletons are partially offset by some design challenges that still limit their positive effects on people. Among them, joint misalignment is a critical aspect mostly because the human knee joint movement is not a fixed-axis rotation. In addition, remarkable mass and stiffness are also limitations. Aiming to minimize joint misalignment, this paper proposes a bio-inspired knee exoskeleton with a joint design that mimics the human knee joint. Moreover, to accomplish a lightweight and high compliance design, a high stiffness cable-tension amplification mechanism is leveraged. Simulation results indicate our design can reduce 49.3 and 71.9% maximum total misalignment for walking and deep squatting activities, respectively. Experiments indicate that the exoskeleton has high compliance (0.4 and 0.1 Nm backdrive torque under unpowered and zero-torque modes, respectively), high control bandwidth (44 Hz), and high control accuracy (1.1 Nm root mean square tracking error, corresponding to 7.3% of the peak torque). This work demonstrates performance improvement compared with state-of-the-art exoskeletons., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Yu, Huang, Di Lallo, Zhang, Wang, Fu and Su.)

Highlights: [•] Organic thin-film transistors (OTFTs) with sub-micrometer channel length. [•] Self-aligned gate/source–drain contacts. [•] Field-effect mobility over 0.1cm2/Vs. [•] Combining existing models into a simple DC model successfully simulates their behavior. [Copyright &y& Elsevier]

Packaging is one of the major cost drivers for microelectromechanical systems (MEMS). Currently wire bonding is the dominant method for electrically connecting MEMS chips to the substrate. Using self-alignment, a method for packaging multiple MEMS at the same time has been developed. The presented process achieves high throughput and precise alignment at low cost. The controlled collapse chip connection (C4) process has been adapted to the specific requirements of MEMS. The combination of coarse robotics and liquid solder self-alignment guarantees precise positioning and alignment of the individual MEMS chips to the respective substrates. The new method has been implemented in a case study. In the study, force sensors were packaged. Precise angular alignment of the sensors is critical for making accurate measurements. Results of the case study are presented. The alignment motion is analyzed, compared with results in the literature, and simulated. These simulations, in combination with our experiments, indicate that the motion is dominated by solder-specific effects such as oxide removal, wetting, and flux solvent evaporation. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate self-alignment of microchips on a simple-to-fabricate hybrid template with both water and UV-curing adhesive (EPO-TEK UVO-114). The hybrid template contains receptor sites with solid edges for droplet confinement and large wetting contrast between the receptor sites and the substrate for microchip manipulation. Nanostructured black silicon surface functionalized with fluoropolymer is used as a substrate, while protruded silicon dioxide patterns covered with fluoropolymer serve as receptor sites. A simple and fast process consisting only of one pass of photolithography, cryogenic deep reactive-ion etching (RIE), and RIE steps is used to fabricate the hybrid template. The self-assembly tests are carried out in a hybrid microassembly setup. Dummy microchips of sizes 200\ \mu\m \times\break 200\ \mu\m \times 50\ \mu\m are self-aligned on 200\ \mu\m \times 200\ \mu\m receptor sites in ambient air with both water and adhesive. \hfill[2012-0178] [ABSTRACT FROM AUTHOR]

Capillary-driven self-alignment using droplets is currently extensively investigated for self-assembly and microassembly technology. In this technique, surface tension forces associated to capillary pinning create restoring forces and torques that tend to bring the moving part into the alignment. So far, most studies have addressed the problem of square chip alignment on a dedicated patch of a wafer, aiming to achieve 3D microelectronics. In this study, we investigate the shift-restoring forces for more complex moving parts such as regular-convex and non-convex-polygons and regular polygons with regular polygonal cavities. A closed-form approximate expression is derived for each of these polygonal geometries; this expression agrees with the numerical results obtained with the Surface Evolver software. For small shifts, it is found that the restoring force does not depend on the shift direction or on the polygonal shape. In order to tackle the problem of microsystem packaging, an extension of the theory is done for polygonal shapes pierced with connection vias (channels), and a closed form of the shift-restoring force is derived for these geometries and again checked against the numerical model. In this case, the restoring force depends on the shift direction. Finally, a non-dimensional number, the shift number, is proposed that indicates the isotropic or anisotropic behavior of the chip according to the shift direction. [ABSTRACT FROM AUTHOR]

Abstract: Si nanowire field effect transistors (SiNW FETs) with multiple nanowire channels and different gate lengths have been fabricated by using a directed assembly approach combined with a standard photolithographic process. The electrical characteristics of SiNW FETs containing different numbers of nanowire channels were measured and compared. The multi-channel SiNW FETs show excellent performance: small subthreshold slope (≈75mV/dec), large ON/OFF ratio (≈108), good break-down voltage (>30V) and good carrier mobility (μ p ≈100cm2 V−1s−1). These excellent device properties were achieved by using a clean self-alignment process and an improved device structure with Schottky barriers at the source and drain contacts. Such high-performance multi-nanowire FETs are attractive for logic, memory, and sensor applications. [Copyright &y& Elsevier]

Abstract: So far, metal oxide semiconductor field-effect transistors (MOSFETs) have been fabricated using either optical lithography or imprint lithography with an alignment step between the different layers. Here, we report on the new process for the fabrication of top gate MOSFETs where the number of fabrication steps is reduced significantly. The 3D topography of a top gate MOSFET using as primary master is inversely replicated into a flexible mold that is subsequently transferred to the imprint resist layer. By reactive ion etching, this self aligned 3D pattern is transferred into the underlying semiconductor stack creating functional transistor structures. Preliminary electrical characterizations demonstrate fully operational transistor functions. [Copyright &y& Elsevier]

Abstract: We present a new manufacturing method for the bottom-gate type organic field-effect transistor (OFET) having a self-aligned gate electrode based on conducting poly(aniline). This method utilizes the possibility to turn the insulating emeraldine base (PANI-EB) form of poly(aniline) into the conducting emeraldine salt (PANI-ES) form by using UV exposure and photoacid generator (PAG) material. When the source–drain electrodes are used as the mask layer in the UV exposure step an optimal alignment between the gate electrode and source–drain electrodes can be reached, and the parasitic capacitance of the transistor can be minimized. We anticipate that the proposed concept also simplifies the fabrication of the transistors since no additional processing of the photoresist layers is needed to pattern the gate electrode or the gate insulator layer. [Copyright &y& Elsevier]

Solder self-alignment is an important phenomenon enabling cost-effective optoelectronics assembly. In thts study, the wetting of Sn-rich solder to under bump metallization (UBM) pads is identified as a cntzcal factor affecting self-alignment accuracy. Incomplete wetttng of solder to the metallization pads is responsible for chip-to-substrate misalignment larger than 1 &mgr;m, whzle fabncatwn tolerances, such as solder volume variation and pad diameter deviation, only account for misalignments in the submicron range. To quantitatively investigate the effect of incomplete wetting on self-alignment accuracy, a threedzmensional (3D) model based on a force optimization method was developed. With the input parameters of incomplete solder metallurgical wetting area, position and diameter of metallization pad, volume of individual solder bumps, coefficient of solder surface tension, mass of the chip, external forces acting on the chip, and initial pick-and-place position of the chip before assembly, the model predicts the assembled position of the chip in terms of the misalignments in the X-Y plane and the rotation angle along the Z axis. The model further confirmed that incomplete wetting of solder is the most critical modulator among the undesirable factors affecting solder self-alignment accuracy. [ABSTRACT FROM AUTHOR]

Abstract: A new fabrication process and first experimental results of a surface stress based capacitive biosensor array are presented. Flexible membranes and a fixed electrode on the substrate constitute the capacitive sensors. Probe molecules are immobilized on the membrane surface and the surface stress variations during biological interactions force the membrane to deflect and effectively change the capacitance between the flexible membrane and the fixed substrate. The array consists of 60 sensors and thus is suitable for parallel sensing. The process is characterized by the self-alignment of the sensitive flexible membranes and the use of silicon fusion bonding to fabricate the complete device. First experimental results on biosensing indicate that the sensors are able to detect the hybridization of beta-thalassemia oligonucleotides. [Copyright &y& Elsevier]

Abstract: Recent development of solution processable organic semiconductors delineates the emergence of a new generation of air-stable, high performance p- and n-type materials. This makes it indeed possible for printed organic complementary circuits (CMOS) to be used in real applications. The main technical bottleneck for organic CMOS to be adopted as the next generation organic integrated circuit is how to deposit and pattern both p- and n-type semiconductor materials with high resolutions at the same time. It represents a significant technical challenge, especially if it can be done for multiple layers without mask alignment. In this paper, we propose a one-step self-aligned fabrication process which allows the deposition and high resolution patterning of functional layers for both p- and n-channel thin film transistors (TFTs) simultaneously. All the dimensional information of the device components is featured on a single imprinting stamp, and the TFT-channel geometry, electrodes with different work functions, p- and n-type semiconductors and effective gate dimensions can all be accurately defined by one-step imprinting and the subsequent pattern transfer process. As an example, we have demonstrated an organic complementary inverter fabricated by 3D imprinting in combination with inkjet printing and the measured electrical characteristics have validated the feasibility of the novel technique. [Copyright &y& Elsevier]

We describe a 3-D model for predicting the self-alignment accuracy of solder flip-chip assemblies. The model was developed using a force optimization method based on an explicit regression model, and validated experimentally using flip-chip test vehicles. The experimental results correlate with the model prediction to within 3% for the lateral alignment and 2% for the standoff height. The effects of important manufacturing parameters such as solder volume variations and distributions, chip mass, and die tilt, on the post-assembly alignment accuracies were investigated and characterized with the model. This model can be used to aid in the design of flip-chip assemblies requiring high alignment accuracies, such as those found in optoelectronics packaging. [ABSTRACT FROM PUBLISHER]

We demonstrate an inkjet-based microfluidic technique as droplet vaporization deposition (DVD) that can be applied in the incorporation of hydrophobic substrates with microcavities to generate individual polymeric structures. Using soft-lithography method, the SU-8 and polydimethysiloxane were patterned to form various polygon-shaped cavities (side length \sim\!\! 200– 700\ \mu\m and depth \sim\!\! 25–110\ \mu\m) which acted as micromolds (templates) for forming the shapes of the droplets deposited. With aqueous polyurethane droplets generated (single volume \sim381 pL), the novel various microstructures in polygonal (tri- to hexagonal) forms were created through the deposition and evaporation processes and characterized with exotic performances in optics such as those of microlenses and micromirrors. Experimental and analytical results illustrated that the curved-surface (sinusoidal) topographies of the structures self-formed and detached from the underlying substrates were dominated by capillary action of fluid during evaporation. The merits over the existing techniques such as photolithography includes the one-step, low-temperature (ambient condition, \sim1 atm at 25 ^\circ \C), and cost-effective (no waste materials) processes of solid formations. The successful formation of these structures suggests a new mechanism for self-releasing/detaching from the molds. As a reliable technique for the fabrication of such microstructures, the present DVD method presents an alternative method for various applications particularly including optical microelectromechanical system devices and parts used for assembly.\hfill[2010-0238] [ABSTRACT FROM PUBLISHER]

In this paper, one-dimensional self-alignment of a rigid object via stick-slip vibrations is studied. The object is situated on a table, which has a prescribed periodic motion. Friction is exploited as the mechanism to move the object in a desired direction and to stop and self-align the mass at a desired end position with the smallest possible positioning error. In the modeling and analysis of the system, theory of discontinuous dynamical systems is used. Analytic solutions can be derived for a model based on Coulomb friction and an intuitively chosen table acceleration profile, which allows for a classification of different possible types of motion. Local stability and convergence is proven for the solutions of the system, if a constant Coulomb friction coefficient is used. Next, near the desired end position, the Coulomb friction coefficient is increased (e.g. by changing the roughness of the table surface) in order to stop the object. In the transition region from low friction to high friction coefficient, it is shown that, under certain conditions, accumulation of the object to a unique end position occurs. This behavior can be studied analytically and a mapping is given for subsequent stick positions. [ABSTRACT FROM AUTHOR]

Abstract: An improved self-alignment scheme for strapdown Inertial Navigation System (SINS) based on the extended Kalman filter (EKF) and augmented measurements is proposed. Monte Carlo simulations show that the method provides good azimuth alignment, improved rate of convergence of azimuth attitude error and reduction in sensitivity to gyro biases. [Copyright &y& Elsevier]

Abstract: Layer-to-layer registration is a significant problem in printed electronics since parasitic overlap capacitances resulting from the poor registration of conventional printers substantially degrade device operating speeds. To overcome this, a novel inkjet printing process was utilized to demonstrate an all inkjet-printed and fully self-aligned transistor, as well as fully self-aligned inverters for the first time. Self-alignment of transistor source/drain electrodes to gates was achieved by a printed wetting-based roll-off process, resulting in an improved overlap capacitance as small as 0.14–0.23pFmm−1. Circuit building blocks including transistor arrays and inverters were demonstrated using a novel self-split source/drain and a self-aligned interconnect printing technique. Due to the substantial reduction in overlap capacitance, demonstrated inverters showed a propagation delay as low as 0.488ms at a fan-out of 1, despite using materials with mobility of 0.01cm2 V−1 s−1, thus showing a performance that is suitable for use in a range of low-cost electronics applications, realized using a simple, scalable process. [ABSTRACT FROM AUTHOR]

Conventional flip chip, on board processing involves four major steps: flux application, solder reflow, underfill flow, and underfill cure. The latter two steps are particularly time consuming. To address this issue, a new flip chip process has been developed in which underfill is dispensed prior to chip placement or directly on the wafer and solder reflow and underfill cure occur simultaneously. This reduces the cycle time required for manufacturing. However the presence of the underfill can affect the flip chips' capacity for self-alignment. Self-alignment occurs in controlled collapse bonding when the solder interconnects become liquidus and, driven by surface tension, pull the chip into registration with the substrate. To study flip chip self-alignment in the presence of underfill, the viscous forces acting on the chip during realignment are modeled after Couette flow and the overall system is modeled as a spring-mass-damper. This paper details the modeling process and includes parametric studies to predict those conditions that are more conducive to alignment, as well as those which are not. [ABSTRACT FROM AUTHOR]

We fabricated back-channel-cut and back-channelpassivated hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) on clear-plastic (CP) foil substrates using a silicon nitride (\SiNx) deposition temperature of 300 ^\circ \C. The TFTs were fabricated on CP and are as stable under high gate bias as TFTs made on glass substrates. A self-alignment technique was developed to align the channel passivation, the a-Si:H island, and the source/drain (S/D) terminals to the gate. Self-alignment allowed us to fabricate discrete TFTs across \7 \times \7\ \cm^2 of a free-standing sheet of CP foil to reduce the TFT channel length L to 3 \mu\m and reduce the S/D overlap with the gate LSD to \sim\!\! \1\ \mu\m. To test the self-alignment techniques, we fabricated ring oscillators on the CP substrates. These results show that it is possible to fabricate state-of-the-art self-aligned a-Si:H TFTs and TFT circuits on plastic substrates. [ABSTRACT FROM PUBLISHER]

The galvanic behavior of a hollow cathode discharge versus an external weak magnetic field is investigated. The application of this field leads to disordering of the self-aligned states, which is detected as a resonance in the discharge current, named the magneto-galvanic signal. A correlation magneto-galvanic signal-operating voltage-current point is established and attributed to Penning ionization. The contribution of the metastable Ne I 1 s5 to the magneto-galvanic resonance is also verified. [ABSTRACT FROM AUTHOR]