Graphene is an ideal candidate for building microelectromechanical system (MEMS) devices because of its extraordinary electronic and mechanical properties. Some research has been done to study the MEMS pull-in phenomenon in suspended graphene, but no one has yet considered the effects of polymer residue. Polymer residue is an inevitable consequence when transferring polycrystalline graphene (PCG) grown using chemical vapor deposition, the most common graphene growth method. Polymer residue is also introduced when using photolithography to build MEMS devices. In this paper, the authors study the effects of polymer residue on the pull-in of suspended PCG ribbon devices and find that thick polymer residues cause a variation in pull-in voltage. However, after removing most of the polymer residue using a more abrasive chloroform treatment, the authors find that the graphene structure is no longer able to suspend itself as the graphene-substrate interaction energy becomes greater than the strain energy needed to conform graphene to the substrate. Therefore, polymer residue is found to cause variation in the pull-in voltage but is also found to help in graphene’s suspension at high length to displacement ratios.
Today, automotive design has to face numerous exciting challenges. The growing globalization causes an intensified competition amongst car manufacturers and forces them to reduce the required development time in order to shorten time to market, to appear first with attractive new products. Efficient and flexible processes and tools are necessary to handle the arising complexity efficiently. Parametric-associative 3D-CAD systems offer ideal conditions to face this challenge in virtual development. The present paper focusses on a special issue in automotive concept phasethe vehicle architecture layout process and required parameterization strategies. In most cases, parametric-associative relations defined within 3D-CAD models are of rigid kind. This implies that a formula, which is defined within a 3D-CAD model in order to evaluate a specific parameter, cannot change the input/output situation of involved parameters. In most application cases, this disadvantage can be neglected, but not in case of vehicle layouting in the early concept phase. Since geometric boundary conditions which define the geometric base of a vehicle concept can vary significantly, a rigid model parameterization is not the proper solution and prevents efficient reuse of 3D-CAD models. Additionally, rigid parameterization concepts lack of the required flexibility when having to manage multiple design variants in a single model. Therefore, the present paper outlines a possible strategy, which enables the use of advantages of parametric-associative design, while allowing changes of relations-evaluation behavior in context of respective technical issues and simultaneously preserving necessary geometrical model consistency.
This paper investigates the design of a nano-injection system that can deliver genetic material to cells within live tissue. The approach to creating such a system was to create candidate designs that meet all the requirements for successful in vivo injection and can be fabricated using silicon etching. The designs were tested through large-scale prototyping and through models that describe the systems’ behavior on the micrometer scale. One design consists of an array of lances on a rigid backing. The other design consists of an array of lances grouped in sets of three on a backing that can conform to the shape of the tissue being injected. Each design was prototyped in 3D printed ABS plastic. Preliminary results were qualitative and showed that the rigid and flexible designs performed similarly on mostly flat and irregular surfaces. On convex surfaces with a strong curvature (radius of curvature of about 2 cm), the flexible array gave slightly better results. Final testing gave a quantitative comparison of the two designs’ efficiencies on strongly curved convex surfaces. These results supported the preliminary results that the flexible array is more efficient in reaching points on the tissue than the rigid array is. As the applied force increased, each array performed more efficiently.
This paper investigates the design of an electrostatic discharge protection device made of single-layer graphene nanoribbons. The device is meant to trigger electrostatic discharge at a target voltage of 1.5V. Other design requirements include the minimization of parasitic capacitance, electrical response time and mechanical response time. The device is designed to discharge static electricity by being pulled to ground through electrostatic forces, then making contact with ground before returning to its original position. Previous designs experienced repeatability issues due to a lack of securing the ribbon and mechanical failure due to high stresses at the boundary conditions. New designs are presented and optimized to maintain a high effective spring constant for the device while reducing stress during electrostatic pull-in. A single-degree of freedom model is used in conjunction with the Bernoulli-Euler beam equations and Castigliano’s method to guide the design process. Behavior of each design is validated, and repeatability is assessed using finite-element simulations. The new designs are to be fabricated using a low pressure chemical vapor deposition process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.