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Dielectric Elastomer Actuators (dielectric + elastomer_actuator)
Selected AbstractsHigh Breakdown Field Dielectric Elastomer Actuators Using Encapsulated Polyaniline as High Dielectric Constant FillerADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Martin Molberg Abstract A novel method allowing rapid production of reliable composites with increased dielectric constant and high dielectric strength for dielectric elastomer actuators (DEA) is reported. The promising approach using composites of conductive particles and insulating polymers generally suffers from low breakdown fields when applied to DEA devices. The present publication shows how to overcome this deficiency by using conductive polyaniline (PANI) particles encapsulated into an insulating polymer shell prior to dispersion. PANI particles are encapsulated using miniemulsion polymerization (MP) of divinylbenzene (DVB). The encapsulation process is scaled up to approximately 20 g particles per batch. The resulting particles are used as high dielectric constant (,,) fillers. Composites in a polydimethylsiloxane (PDMS) matrix are prepared and the resulting films characterized by dielectric spectroscopy and tensile tests, and evaluated in electromechanical actuators. The composite films show a more than threefold increase in ,,, breakdown field strengths above 50 V ,m,1, and increased strain at break. These novel materials allow tuning the actuation strain or stress output and have potential as materials for energy harvesting. [source] Fault-Tolerant Dielectric Elastomer Actuators using Single-Walled Carbon Nanotube Electrodes,ADVANCED MATERIALS, Issue 3 2008W. Yuan Fault-tolerant actuators. Single-walled carbon nanotubes were studied as new compliant electrodes for dielectric elastomers. The spray-coated SWNT electrodes drive electromechanical strains greater than 200,%. When a fault is present due to pin puncture or internal defect in the elastomer films, dielectric breakdown causes localized self-clearing of the SWNT electrodes and isolation of the fault. The increased fault tolerance may enhance the actuation reliability of dielectric elastomers actuators. [source] High Breakdown Field Dielectric Elastomer Actuators Using Encapsulated Polyaniline as High Dielectric Constant FillerADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Martin Molberg Abstract A novel method allowing rapid production of reliable composites with increased dielectric constant and high dielectric strength for dielectric elastomer actuators (DEA) is reported. The promising approach using composites of conductive particles and insulating polymers generally suffers from low breakdown fields when applied to DEA devices. The present publication shows how to overcome this deficiency by using conductive polyaniline (PANI) particles encapsulated into an insulating polymer shell prior to dispersion. PANI particles are encapsulated using miniemulsion polymerization (MP) of divinylbenzene (DVB). The encapsulation process is scaled up to approximately 20 g particles per batch. The resulting particles are used as high dielectric constant (,,) fillers. Composites in a polydimethylsiloxane (PDMS) matrix are prepared and the resulting films characterized by dielectric spectroscopy and tensile tests, and evaluated in electromechanical actuators. The composite films show a more than threefold increase in ,,, breakdown field strengths above 50 V ,m,1, and increased strain at break. These novel materials allow tuning the actuation strain or stress output and have potential as materials for energy harvesting. [source] Metal Ion Implantation for the Fabrication of Stretchable Electrodes on ElastomersADVANCED FUNCTIONAL MATERIALS, Issue 3 2009Samuel Rosset Abstract Here, the use of low-energy metal ion implantation by filtered cathodic vacuum arc to create highly deformable electrodes on polydimethylsiloxane (PDMS) membranes is reported. Implantation leads to the creation of nanometer-size clusters in the first 50,nm below the surface. When the elastomer is stretched, these small clusters can move relative to one another, maintaining electrical conduction at strains of up to 175%. Sheet resistance versus ion dose, resistance versus strain, time stability of the resistance, and the impact of implantation on the elastomer's Young's modulus are investigated for gold, palladium, and titanium implantations. Of the three tested metals, gold has the best performance, combining low and stable surface resistance, very high strain capabilities before loss of electrical conduction, and low impact on the Young's modulus of the PDMS membrane. These electrodes are cyclically strained to 30% for more than 105 cycles and remain conductive. In contrast, sputtered or evaporate metals films cease to conduct at strains of order 3%. Additionally, metal ion implantation allows for creating semi-transparent electrodes. The optical transmission through 25-µm-thick PDMS membranes decreases from 90% to 60% for Pd implantations at doses used to make stretchable electrodes. The implantation technique presented here allows the rapid production of reliable stretchable electrodes for a number of applications, including dielectric elastomer actuators and foldable or rollable electronics. [source] Millimetre-scale bubble-like dielectric elastomer actuatorsPOLYMER INTERNATIONAL, Issue 3 2010Federico Carpi Abstract Hydrostatic coupling has recently been reported as a means to improve the versatility and safety of electromechanical actuators based on dielectric elastomers (DEs). Hydrostatically coupled DE actuators rely on an incompressible fluid that mechanically couples a DE-based active part to a passive part interfaced to the load. The work reported here was aimed at developing millimetre-scale bubble-like versions of such transducers. Silicone-made oil-filled actuators were manufactured as both single units and arrays of parallel elements. Bubbles had a base diameter of 6 mm and were driven up to a voltage of 2.25 kV, applied across a silicone film with a thickness of 42 µm. Active relative displacements and stresses up to 18% and 2.2 kPa, respectively, were recorded with static driving. Dynamic investigations reported a ,3 dB bandwidth of the order of 100 Hz and a resonance frequency of about 250 Hz. Millimetre-scale hydrostatically coupled DE actuators might play a useful role in several fields of application. Among them, we are currently exploring novel tactile displays and cutaneous stimulators, made of wearable, distributed and flexible devices. Although further miniaturization is required for high-resolution uses, this technology holds promise to properly combine performance with safe and compliant interfaces with users, low specific weight, no acoustic noise and low cost. Copyright © 2009 Society of Chemical Industry [source] Fault-Tolerant Dielectric Elastomer Actuators using Single-Walled Carbon Nanotube Electrodes,ADVANCED MATERIALS, Issue 3 2008W. Yuan Fault-tolerant actuators. Single-walled carbon nanotubes were studied as new compliant electrodes for dielectric elastomers. The spray-coated SWNT electrodes drive electromechanical strains greater than 200,%. When a fault is present due to pin puncture or internal defect in the elastomer films, dielectric breakdown causes localized self-clearing of the SWNT electrodes and isolation of the fault. The increased fault tolerance may enhance the actuation reliability of dielectric elastomers actuators. [source] | ||||||||||