Electrical breakdown detection system for dielectric elastomer actuators

Abstract

Electrical breakdown of dielectric elastomer actuators (DEAs) is an issue that has to be carefully addressed when designing systems based on this novel technology. Indeed, in some systems electrical breakdown might have serious consequences, not only in terms of interruption of the desired function but also in terms of safety of the overall system (e.g. overheating and even burning). The risk for electrical breakdown often cannot be completely avoided by simply reducing the driving voltages, either because completely safe voltages might not generate sufficient actuation or because internal or external factors might change some properties of the actuator whilst in operation (for example the aging or fatigue of the material, or an externally imposed deformation decreasing the distance between the compliant electrodes). So, there is the clear need for reliable, simple and cost-effective detection systems that are able to acknowledge the occurrence of a breakdown event, making DEA-based devices able to monitor their status and become safer and "selfaware". Here a simple solution for a portable detection system is reported that is based on a voltage-divider configuration that detects the voltage drop at the DEA terminals and assesses the occurrence of breakdown via a microcontroller (Beaglebone Black single-board computer) combined with a real-time, ultra-low-latency processing unit (Bela cape an open-source embedded platform developed at Queen Mary University of London). The system was used to both generate the control signal that drives the actuator and constantly monitor the functionality of the actuator, detecting any breakdown event and discontinuing the supplied voltage accordingly, so as to obtain a safer controlled actuation. This paper presents preliminary tests of the detection system in different scenarios in order to assess its reliability.

Electrical and Mechanical Self‐Healing in High‐Performance Dielectric Elastomer Actuator Materials

“…To facilitate observation of the breakdown site and healing no electrode was used and similar pin-hole breakdown defects were formed when metallic electrodes were used ( Figure S1). The pristine elastomer experienced electrical breakdown at a 9.5 kV voltage (and electric field of 32.8 kV mm -1 ), as shown in Figure 1(A)-(1) which leads to the formation of a carbonized [18] pin-hole of ~ 90 µm in diameter, as shown in Figure 1(B). Both the upper and lower surfaces of the elastomer had carbon deposits produced near the defect, due to the reaction of the vaporized material with air during breakdown.…”

Low‐Voltage Reversible Electroadhesion of Ionoelastomer Junctions

“…Current electro-adhesives based on electronic conductors and insulating dielectric layers, however, are typically limited by the need for applied potentials in the range of several kV, which, in addition to presenting safety concerns and requiring specialized circuit elements compatible with high voltages, [21] can easily lead to dielectric breakdown and corresponding irreversible device failures. [22,23] One strategy to reduce operating voltage is to decrease the dielectric layer thickness of the electro-adhesives, as a standard parallel plate capacitor model would suggest that electrostatic force is inversely proportional to the square of the dielectric thickness. [5,24] Indeed, Chen et al [4] demonstrated that the use of a thin (< 0.8 µm) parylene dielectric layer prepared by chemical vapor deposition provided an electro-adhesive surface that could support a shear stress of 120 kPa with an operating voltage of only 50 V. Similarly, Rivaz et al [13] used a thin (~ 12.5 µm) polyimide dielectric layer that supported a 6 kPa shear stress at 250 V. However, reliable fabrication of mechanicallyrobust and defect-free dielectric layers becomes challenging as the thickness of the dielectric layer is further decreased, [4] and operation in the range of only a few volts has not previously been possible with dielectric electro-adhesives.…”

Multilayer Dielectric Elastomer with Reconfigurable Electrodes for Artificial Muscle

“…There were many reasons that caused the failure of dielectric elastomers as shown in the literature, [55,56] which limited the extensive application of DEAs. Some ways have been used to detect the different breakdowns of DEAs, [57][58][59] which may be further applied to detect the failure of the DE layers in multilayer. Once the damaged layers may be replaced, the elec-trode layer in the multilayer structure fabricated by the vacuum lamination process may be recycled to form the new device.…”