Fabrication and performance analysis of a DEA cuff designed for dry-suit applications

Abstract

A method for manufacturing a cylindrical dielectric elastomer actuator (DEA) is presented. The cylindrical DEA can be used in fabricating the cuff area of dry-suits where the garment is very tight and wearing the suit is difficult. When electrically actuated, the DEA expands radially and the suit can be worn more comfortably. In order to study the performance of the DEA, a customized testing setup was designed, and silicone-made cuff samples with different material stiffnesses were tested. Analytical and FEM modeling were considered to evaluate the experimental output. The results revealed that although the stiffness of the DEA material has a direct relationship with the radial constrictive pressure caused by mechanically stretching the DEA, it has a minor effect on the actuation pressure. It was also found that stacking multiple layers of the DEA to fabricate a laminated structure enabled the attainment of a desired variation of pressure required for the implementation of an electrically tunable cuff.

Low Spring Index NiTi Coil Actuators for Use in Active Compression Garments

“…An ideal active material candidate for integration into a wearable compression garment would meet the following criteria: 1) Can repeatably generate high forces and have the ability to produce large displacements when stimulated 2) Can be packaged or integrated into a textile structure easily and without adding significant bulk or mass 3) Can be stimulated in a way that is both feasible and safe for the wearer Given these requirements, many of the available active material candidates are currently ill-suited for the task (e.g., carbon nanotubes exhibit active strains of <1%, an impractically small activation stroke for the purpose of producing compression, and ferroelectric polymers often require bulky magnets) [12]. DEAs, SMPs, and SMAs all theoretically meet the minimum active stress requirements to achieve MCP design specifications (29.6 kPa) with at least single-digit active strains and form factors suitable for wearable systems [9], [10], [12], [15], [16]. Initial investigations into these materials suggest that DEAs and SMPs, in their current technical state, suffer from significant performance limitations: DEAs were shown to have very limited durability while requiring high (i.e., >1 kV) activation voltages [17], [18]; SMPs were shown to be deficient as they experience significant viscoelastic and irrecoverable strain effects [19].…”

A Deformable Motor Driven by Dielectric Elastomer Actuators and Flexible Mechanisms

“…The DC/DC converter is required to generate the high voltage that drives the DEA. Previous studies demonstrated that EMCO Q 101-5 works acceptably on robots made with DEAs (Wingert et al, 2006;Ahmadi et al, 2012;Shintake et al, 2015a). We set the maximum output to 3 kV because electrical breakdown within the DEAs occurred above this voltage.…”

On the design of a DEA-based device to pot entially assist lower leg disorders: an analytical and FEM investigation accounting for nonlinearities of the leg and device deformations

“…In this section, an analytical model of the cylindrical DEA [ 10 , 16 ] is combined to the model of the human calf described by ( 2 ). The total pressure applied by the ACB has two components, the mechanical pressure which is the pressure resulting from the mechanical stress in the ACB before actuating the ACB, and the actuation pressure, which is the pressure variation after actuating the ACB.…”

“…As the stretch ratio of the ACB changes the amount of compression that is exerted on the calf is also changed. The amount of this compression is obtained using the following equation [ 16 ].…”

“…DEAs are a category of electro-active polymers (EAPs) which have drawn much attention due to their simplicity, stability, fast response, high stretch ratio, high applicable force, and low cost [ 14 ]. Numerous studies are presented in literature that discuss the DEA applications and characterize them in various shapes and configuration such as roll [ 14 ], planar [ 15 ], cylindrical [ 16 ] and spherical [ 17 , 18 ] actuators. A simple DEA unit consists of a dielectric elastomer that is sandwiched between a pair of compliant electrodes.…”