Silicon rubbers are widely used in a variety of products ranging from cooking utensils and electronics to medical devices and implants. Recently, they have sparked an interest among soft robotics researchers as they can be easily formed into various shapes and actuated in a relatively fast and easy way. In this article, we examine the nonlinear elastic response of a silicon rubber, Ecoflex, under both compressible and incompressible constraints. An experimental test on a uniaxial tension indicates a slight compressibility, and the compressibility increases with stretching. Five different constitutive material models are considered to describe the nonlinear elastic responses of Ecoflex under both compressible and incompressible conditions. In addition, finite element (FE) analysis is presented to analyze multiaxial response of structures or devices made of Ecoflex under complex boundary conditions. This study highlights the variations in the multiaxial response of structures at large deformations from different constitutive models under different compressible and incompressible constraints. For a high precision control in soft robotics applications, there is a need to understand the multiaxial response of silicon rubbers, especially under large deformations.
Abstract:Wave energy converters have been developed and commercialized in past decades; they have now faced numerous challenges of large volume sizes, environmental hazards, and high costs of deployment, components and maintenance. To address these challenges and make a wave energy converter practically available for various applications at a reasonable cost, we have developed a soft wave energy harvester that integrated low-cost soft material structures and piezoelectric-based Macro Fiber Composite (MFC). This integrated soft wave energy converter has a straightforward fabrication process and structure that can harvest energy from a broad working frequency of waves. The innovative design combined low-cost and commercially available materials and formed a harvester that addressed the aforementioned problems of commercially available harvesters. Additionally, the low cost and simple design are scalable for large energy conversion in the future. The energy conversion performance of the proposed platform has been investigated in a wave flume with low-frequency incoming waves (<2Hz). The soft energy conversion platform is hung like a curtain and produces a maximum 487nW. Also, the low cost and durable encapsulation can protect the electrical properties of MFCs and circuits, and a single harvester can last through all experiment steps without any degradation, which was more than 170 hours.
A microfiuidically-tunable substrate integrated cav ity filter is presented for the first time. Quarter mode cylindrical substrate integrated waveguide (SIW) cavities are used to design an ultra-compact two-pole filter with a center frequency of �1.12 GHz. A corner via is connected to a surface ring gap in order to capacitively load each SIW cavity resonator. Frequency tuning of the filter is achieved using the capacitive loading effect of a liquid metal channel placed on top of the surface gap capacitors. The Polydimethylsiloxane (PDMS) structure including the micro-channel is bonded to the SIW circuit board using a unique fabrication technique. Measured results verify a tuning ratio of 1.72:1 and an insertion loss of 2.5 and 3.45 dB at 1.12 and 0.65 GHz, respectively.
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.