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Abstract-Debris in space present an ever-increasing problem for spacecraft in Earth orbit. As a step in the mitigation of this issue, the CleanSpace One (CSO) microsatellite has been proposed. Its mission is to perform active debris removal of a decommissioned nanosatellite (the CubeSat SwissCube). An important aspect of this project is the development of the gripper system that will entrap the capture target. We present the development of roll-able dielectric elastomer minimum energy structures (DEMES) as the main component of CSO's deployable gripper. DEMES consist of a prestretched dielectric elastomer actuator membrane bonded to a flexible frame. The actuator finds equilibrium in bending when the prestretch is released and the bending angle can be changed by the application of a voltage bias. The inherent flexibility and lightweight nature of the DEMES enables the gripper to be stored in a rolled-up state prior to deployment. We fabricated proof of concept actuators of three different geometries using a robust and repeatable fabrication methodology. The resulting actuators were mechanically resilient to external deformation, and display conformability to objects of varying shapes and sizes. Actuator mass is less than 0.65 g and all the actuators presented survived the rolling-up and subsequent deployment process. Our devices demonstrate a maximum change of bending angle of more than 60 degrees and a maximum gripping (reaction) force of 2.2 mN for a single actuator.Index Terms-Active debris removal (ADR), artificial muscles, deployable mechanism, dielectric elastomer actuator (DEA), space debris.

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an elastomeric dielectric membrane sandwiched between two compliant electrodes. The large actuation strains of these transducers when used as actuators (over 300% area strain) and their soft and compliant nature has been exploited for a wide range of applications, including electrically tunable optics, haptic feedback devices, wave-energy harvesting, deformable cell-culture devices, compliant grippers, and propulsion of a bioinspired fish-like airship. In most cases, DETs are made with a commercial proprietary acrylic elastomer and with hand-applied electrodes of carbon powder or carbon grease. This combination leads to non-reproducible and slow actuators exhibiting viscoelastic creep and a short lifetime. We present here a complete process flow for the reproducible fabrication of DETs based on thin elastomeric silicone films, including casting of thin silicone membranes, membrane release and prestretching, patterning of robust compliant electrodes, assembly and testing. The membranes are cast on flexible polyethylene terephthalate (PET) substrates coated with a water-soluble sacrificial layer for ease of release. The electrodes consist of carbon black particles dispersed into a silicone matrix and patterned using a stamping technique, which leads to preciselydefined compliant electrodes that present a high adhesion to the dielectric membrane on which they are applied.

A key element in stretchable actuators, sensors and systems based on elastomer materials are compliant electrodes. While there exist many methodologies for fabricating electrodes on dielectric elastomers, very few succeed in achieve high-resolution patterning over large areas. We present a novel approach for the production of mechanically robust, highresolution compliant electrodes for stretchable silicone elastomer actuators and sensors. 2 to 50 µm thick cast poly(dimethylsiloxane)(PDMS)-carbon composite layers are patterned by laser ablation and subsequently bonded to a PDMS membrane by oxygen plasma activation. The technique affords great design flexibility and high-resolution, and readily scales to large area arrays of devices. We validate our methodology by producing arrays of actuators and sensors on 2 up to A4-size substrates, reporting on micro-scale dielectric elastomer actuators (DEA) generating area strains of over 25%, and interdigitated capacitive touch sensors with high sensitivity yet insensitivity to substrate stretching. We demonstrate the ability to co-fabricate highly integrated multifunctional transducers using the same process flow, showing the methodology's promise in realizing sophisticated and reliable complex stretchable devices with fine features over large areas.

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