Dielectric elastomers (DEs) have been extensively studied as DE actuators, DE generators, and DE sensors. Compared with DE actuators and generators, DE sensing application has the advantage that it is no need for high voltage. However, to realize the high sensitivity of the DE sensor, a well-designed structure is essential. A typical DE sensor consists of DE membrane covered by compliant electrodes on both sides. Expanding in the area and shrinking in the thickness of DE membrane subjected to external force will lead to the increasement of the capacitance. We propose a novel DE sensor to detect compressive force. The DE sensor consists of three layers. The two layers of outside can penetrate each other to deform the middle layer and achieve high sensitivity for compressive force measurement. This sensor consists of a series of sensor elements made of DE membrane with out-of-plane deformation. Each sensor element experiences highly inhomogeneous large deformation to obtain high sensitivity. We conduct the experiment to optimize the performance of the sensor element, and also the corresponding theoretical analysis is developed. The effects of the prestretches and the aspect ratios of the sensor element on the sensitivity are achieved. The soft sensor composed of a series of such sensor elements may comply with complicated surfaces and can be used to detect both the total value and the distribution of the compressive force exerted on the surface. Furthermore, the reliability of the sensor element is studied by additional experimental investigation. The experiment shows that the sensor element operates steadily after 2000 cyclic loadings. This study provides guidance for the design and performance analysis of soft sensors.
This work has been published in the Journal of Applied Mechanics, 82(10), No. 101004 (2015).
Dielectric elastomer (DE) actuators can convert electrical energy to mechanical energy. However, actuating DE
membranes requires applying high voltage. Continuously applying high voltage on DE actuator causes failures such as
current leakage and electric breakdown. To overcome the high voltage actuation drawbacks of DE actuators, this paper
raises a new actuation method using DE interacting with external elastic structures. The analysis is demonstrated based
on continuum mechanics, and agrees very well with experiment measurements.
Mechanical energy and electrical energy can be converted to each other by using a dielectric elastomer transducer. Large
voltage-induced deformation has been a major challenge in the practical applications. The voltage-induced deformation
of dielectric elastomer is restricted by electromechanical instability (EMI) and electric breakdown. We study the loading
path effect of dielectric elastomer and introduce various methods to achieve giant deformation in dielectric elastomer and
demonstrate the principles of operation in experiments. We use a computational model to analyze the operation of DE
generators and actuators to guide the experiment. In actuator mode, we get three designing parameters to vary the
actuation response of the device, and realize giant deformation with appropriate parameter group. In the generator mode,
energy flows in a device with inhomogeneous deformation is demonstrated.