Research On Stacked Dielectric Elastomer Actuators Based On The Electrodes Of Carbon Nanotubes

Dielectric elastomer (DE) actuators have promising potential in fields like aviation, robots and medical equipment as muscle-like actuators due to their high energy densities, large active deformations and high efficiency. According to the deformation principle of dielectric elastomer film, deformations in both planar and thickness directions can work against external loads. Up to now, most research work has been focused on the planar expanding actuation mode since the acrylic film can be easily processed to planar actuators when pre-strained. Compared to planar actuators, the contractive actuators using the deformation in thickness direction perform better on output power and life span. Therefore, in this paper the contractive actuators, so called stacked actuators composed of an array of the same size film covered with compliant electrodes in a pile-up configuration, are selected as the research objects.In this paper, selection criteria of actuator parameters were given based on the analysis of how different parameters impact a stacked actuator’s performance. Among parameters, the width of discharge zone and the thickness of electrode were optimized by analyzing fabrication errors and response time. Also, a fabrication process with the aid of self-designed auxiliary devices was illustrated and the fabricated stacked actuator of5.5mm height has an output of1mm in displacement and2.02N in force. Besides, ties in fabrication of folded actuator were made and the problems during fabrication were discussed.Due to the stack configuration of the actuator, commonly used pre-strained acrylic film was replaced by the400%prestrained interpenetrating polymer network (IPN) modified stress-free acrylic film VHB4910(3M) in order to eliminate the need for external pre-strain supporting structures. So in this paper the IPN process and optimization measures were illustrated and properties of the IPN modified film were tested. The shrinking percentage, elastic modulus and active deformation in area are20%,2.3MPa and120%, respectively.This paper take the lead in applying single-walled carbon nanotube (SWNT) as electrode in stacked actuator considering not only its good conductivity and fault tolerance but also that the obtained extremely thin electrode of SWNT make acrylic film maintain some stickiness that meets the configuration of stacked actuator better. Moreover, after confirming the structure of SWNT was not been damaged by ultrasound probe through SEM and Raman spectroscopy, ultrasonic probe was introduced as the new dispersion approach. The dispersion performances of ultrasonic probe and conventional ultrasonic cleaner were tested separately and the homogeneities of manual spraying and automatic spraying were also tested. The thickness of SWNT electrode sprayed by the machine was tested to be about70nm by AFM.In this paper the stress-free IPN modified film and SWNT compliant electrode with good properties are used at the same time for stacked actuator. The paper can provide a reference and guidance for the IPN experiments, SWNT spraying and stacked actuator fabrication.