UV Nano-Imprint Lithography for Manufacturing Applications

Researchers have demonstrated that imprint lithography techniques have remarkable replication resolution and can pattern sub-5nm structures. However, a fully capable lithography approach needs to address several challenges in order to be useful in nano-manufacturing applications. This paper presents the key technical challenges as well as the progress achieved to-date in these areas. A promising nanoimprint technique that has been previously discussed in the literature is a UV curing technique known as Step and Flash Imprint Lithography (S-FIL). In this article, a variant of the S-FIL process — known as drop-on-demand UV nano-imprint process — that addresses many of the key manufacturing challenges is discussed. This process has the ability to address challenges such as process repeatability in residual layer control, low defectivity, ability to fully automate the lithography process, nano-resolution alignment, and the ability to handle pattern density variations. All nano-imprint lithography techniques essentially replicate the patterns present in a master mold (or template). One of the demanding challenges is the creation of this template. Patterning, metrology, inspection, and defect repair issues relevant to template fabrication are discussed. Finally, with a brief discussion of near-term practical applications in the areas of photonics, magnetic storage, and CMOS devices is presented.

Studying the Dynamics of the Architecture of Software Products

This paper reports on an exploratory study of how the architecture of a software product evolves over time. Because software is embedded in many of today’s complex products, and it is prone to relatively rapid change, it is instructive to study software architecture evolution for general insights into product design. We use metrics to capture the intrinsic complexity of software architectures as they evolve through successive generations (version releases). We introduce a set of product representations and metrics that take into account two important features used to manage the complexity in software products: layers and modules. We also capture organizational data associated with the product under development. We propose a three-step approach for the analysis and illustrate it using successive versions of an open source product, Ant. One of our findings is that software architectures seem to evolve in a non-linear manner similar to the S-shaped curve that characterizes technology evolution at the industry level. We also find several parallel patterns among architectural and organizational dynamics. Implications for research and practice are discussed.

A Novel Chloroplastmimic Photovoltaics With Full Visible Spectrum Operation

A novel and very simple chloroplastmimic photovoltaic scheme, in which water is photolyzed by a new photocatalyst fabricated by depositing a thin film of TiO2 on an array of carbon nanotubes (CNT), has been made. Multiple reflections within the photocatalyst extend the optical response from the ultraviolet range to the full visible range. Hydrogen ions with various concentrations are separated by an artificial thylakoid membrane, resulting in a transmembrane chemiosmotic potential, generating ion-diffusion-induced electricity. Experimental results demonstrate that the proposed simple chloroplastmimic photovoltaics can produce a photocurrent directly from visible light.

Contact Angle Manipulation for Liquid Bridge Based Microgripper

Manipulation of micron sized components is essential for microassembly. Understanding the dominant adhesive forces in the micro-scale as well as devising techniques to control them is needed in order to design a proper micro manipulation apparatus. A liquid bridge based micromanipulation scheme is presented in this paper. The adhesive forces like capillary and surface tension force are prominent in micro scale due to scaling law and provides sufficient force for pickup of an object. The main problem resides in the systematic release of the object from the gripper surface. The focus of this paper is on the feasibility study of contact angle manipulation by electrowetting method for prompt release of an object. Preliminary results from numerical solution of Laplace-Young equation and CFD analysis shows that by increasing the contact angle a critical contact angle is reached after which Laplace-Young equation does not produce a feasible solution and the CFD analysis results in an unstable solution. This result demonstrates that the contact angle manipulation is capable of breaking a liquid bridge and provides a feasible solution for the release mechanism in microgripping.

Evaluating the Use of Cyberinfrastructure in the Classroom to Enhance Product Dissection

Recent cyberinfrastructure initiatives seek to create ubiquitous, comprehensive, interactive, and functionally complete digital environments that consist of people, data, information, tools, and instruments for research communities. With product dissection as our unifying theme, we are forging a cyberinfrastructure to support undergraduate design engineering education through CIBER-U: Cyber-Infrastructure-Based Engineering Repositories for Undergraduates. CIBER-U pairs two of the nation’s leading design repository developers with several active users and their students to realize a high-impact application of cyberinfrastructure in engineering undergraduate curricula involving freshmen through seniors. Specifically, CIBER-U combines product dissection activities at three universities with two digital design repositories, CAD modeling and animation, video, MediaWiki technology, multimedia, and undergraduate summer research experiences to enable cyberinfrastructure-based product dissection activities. Nearly 700 students have participated in the Phase I efforts of CIBER-U, which have focused primarily on generating, capturing, and storing data in two digital design repositories. Lessons learned from these efforts are presented from the students’ perspectives as well as that of the faculty in both engineering and computer science. The implications for implementing CIBER-U on a national scale are discussed along with ongoing research.

Dynamic Maskless Holographic Lithography

Maskless patterning techniques are increasingly implemented in semiconductor research and manufacturing eliminating the need for costly masks or masters. Recent application of these techniques to DNA and cell patterning demonstrates the adaptability of maskless processes. In this paper we present a new lithographic process for dynamically reconfiguring and arbitrarily positioning computer-generated patterns through the use of phase holograms. Similar to current maskless patterning methods this process can achieve pattern transfer through serially tracing an image onto a substrate. The novelty of our process, however, lies in the ability to rapidly fabricate complex micro/nanoscale structures through single-shot exposure of a substrate.

Applying Function-Based Failure Propagation in Conceptual Design

When designing a product, the earlier the potential risks can be identified, the more costs can be saved, as it is easier to modify a design in its early stages. Several methods exist to analyze the risk in a system, but all require a mature design. However, by applying the concept of “common interfaces” to a functional model and utilizing a historical knowledge base, it is possible to analyze chains of failures during the conceptual phase of product design. This paper presents a method based on these “common interfaces” to be used in conjunction with other methods such as Risk in Early Design in order to allow a more complete risk analysis during the conceptual design phase. Finally, application of this method is demonstrated in a design setting by applying it to a thermal control subsystem.

An Interactive Morphological Matrix Computational Design Tool: A Hybrid of Two Methods

This paper builds on previous concept generation techniques explored at the University of Missouri - Rolla and presents an interactive concept generation tool aimed specifically at the early concept generation phase of the design process. Research into automated concept generation design theories led to the creation of two distinct design tools: an automated morphological search that presents a designer with a static matrix of solutions that solve the desired input functionality and a computational concept generation algorithm that presents a designer with a static list of compatible component chains that solve the desired input functionality. The merger of both the automated morphological matrix and concept generation algorithm yields an interactive concept generator that allows the user to select specific solution components while receiving instantaneous feedback on component compatibility. The research presented evaluates the conceptual results from the hybrid morphological matrix approach and compares interactively constructed solutions to those returned by the non-interactive automated morphological matrix generator using a dog food sample packet counter as a case study.

Scale-Model Test Rig for Passive and Active Suspension Control Comparison

This paper presents the design and validation of an experimental test rig for direct visual and analytic comparison of fully active and semi-active suspension control algorithms using electromagnetic actuation. A linear mathematical model simulation of the test rig is presented, as well as experimental validation test results comparing passive against fully active and semi-active skyhook control algorithms. A variety of fully active and semi-active vibration control methods have been developed for primary suspensions. Our goal is to provide a development platform in which new algorithms can easily be implemented, in a cost effective manner on a physical system, and compared against existing algorithms to determine the performance characteristics of each. This platform will provide a standard of evaluation in which multiple control algorithms can be tested, and will help to simplify the design process.

Experimental Validation of a Squeeze-Film Damping Model Based on the Direct Simulation Monte Carlo Method

A model for computing the force from a gas film squeezed between parallel plates was recently developed using Direct Simulation Monte Carlo simulations in conjunction with the classical Reynolds equation. This paper compares predictions from that model with experimental data. The experimental validation used an almost rectangular MEMS oscillating plate with piezoelectric base excitation. The velocities of the suspended plate and of the substrate were measured with a laser Doppler vibrometer and a microscope. Experimental modal analysis yielded the damping ratio of twelve test structures for several different gas pressures. Small perforation holes in the plates did not alter the squeeze-film damping substantially. These experimental data suggest that the model predicts squeeze-film damping forces accurately. From this comparison, it is seen that these structures have a tangential-velocity accommodation coefficient close to unity.