5 research outputs found
Effects of Electrode Materials and Compositions on the Resistance Behavior of Dielectric Elastomer Transducers
Dielectric elastomer (DE) transducers possess various advantages in comparison to alternative actuator technologies, such as, e.g., electromagnetic drive systems. DE can achieve large
deformations, high driving frequencies, and are energy efficient. DEs consist of a dielectric membrane
sandwiched between conductive electrodes. Electrodes are especially important for performance,
as they must maintain high electrical conductivity while being subjected to large stretches. Low
electrical resistances allow faster actuation frequencies. Additionally, a rate-independent, monotonic,
and hysteresis-free resistance behavior over large elongations enables DEs to be used as resistive
deformation sensors, in contrast to the conventional capacitive ones. This paper presents a systematic
study on various electrode compositions consisting of different polydimethylsiloxane (PDMS) and
nano-scaled carbon blacks (CB). The experiments show that the electrode resistance depends on the
weight ratio of CB to PDMS, and the type of CB used. At low ratios, a high electrical resistance
accompanied by a bimodal behavior in the resistance time evolution was observed, when stretching
the electrodes cyclic in a triangular manner. This phenomenon decreases with increasing CB ratio.
The type of PDMS also influences the resistance characteristics during elongation. Finally, a physical
model of the observed phenomenon is presented
Electrode Impact on the Electrical Breakdown of Dielectric Elastomer Thin Films
Dielectric Elastomer Actuators (DEAs) enable the realization of energy-efficient and compact actuator systems. DEAs operate at the kilovolt range with typically microampere-level currents
and hence minimize thermal losses in comparison to low voltage/high current actuators such as
shape memory alloys or solenoids. The main limiting factor for reaching high energy density in high
voltage applications is dielectric breakdown. In previous investigations on silicone-based thin films,
we reported that not only do environmental conditions and film parameters such as pre-stretch play
an important role but that electrode composition also has a significant impact on the breakdown
behavior. In this paper, we present a comprehensive study of electrical breakdown on thin silicone
films coated with electrodes manufactured by five different methods: screen printing, inkjet printing,
pad printing, gold sputtering, and nickel sputtering. For each method, breakdown was studied
under environmental conditions ranging from 1 â—¦C to 80 â—¦C and 10% to 90% relative humidity. The
effect of different manufacturing methods was analyzed as was the influence of parameters such as
solvents, silicone content, and the particle processing method. The breakdown field increases with
increasing temperature and decreases with increasing humidity for all electrode types. The stiffer
metal electrodes have a higher breakdown field than the carbon-based electrodes, for which particle
size also plays a large role
Design, Manufacturing, and Characterization of Thin, Core-Free, Rolled Dielectric Elastomer Actuators
In this work, we develop a coreless rolled dielectric elastomer actuator (CORDEA) to be
used as artificial muscles in soft robotic structures. The new CORDEA concept is based on a 50 µm
silicone film with screen-printed electrodes made of carbon black suspended in polydimethylsiloxane.
Two printed silicone films are stacked together and then tightly rolled in a spiral-like structure.
Readily available off-the-shelf components are used to implement both electrical and mechanical
contacts. A novel manufacturing process is developed to enable the production of rolled actuators
without a hollow core, with a focus on simplicity and reliability. In this way, actuator systems
with high energy density can be effectively achieved. After presenting the design, an experimental
evaluation of the CORDEA electromechanical behavior is performed. Finally, actuator experiments
in which the CORDEA is pre-loaded with a mass load and subsequently subject to cycling voltage
are illustrated, and the resulting performance is discussed
Effects of Electrode Materials and Compositions on the Resistance Behavior of Dielectric Elastomer Transducers
Dielectric elastomer (DE) transducers possess various advantages in comparison to alternative actuator technologies, such as, e.g., electromagnetic drive systems. DE can achieve large deformations, high driving frequencies, and are energy efficient. DEs consist of a dielectric membrane sandwiched between conductive electrodes. Electrodes are especially important for performance, as they must maintain high electrical conductivity while being subjected to large stretches. Low electrical resistances allow faster actuation frequencies. Additionally, a rate-independent, monotonic, and hysteresis-free resistance behavior over large elongations enables DEs to be used as resistive deformation sensors, in contrast to the conventional capacitive ones. This paper presents a systematic study on various electrode compositions consisting of different polydimethylsiloxane (PDMS) and nano-scaled carbon blacks (CB). The experiments show that the electrode resistance depends on the weight ratio of CB to PDMS, and the type of CB used. At low ratios, a high electrical resistance accompanied by a bimodal behavior in the resistance time evolution was observed, when stretching the electrodes cyclic in a triangular manner. This phenomenon decreases with increasing CB ratio. The type of PDMS also influences the resistance characteristics during elongation. Finally, a physical model of the observed phenomenon is presented