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Dielectric elastomer switches have shown large potential for integrating signal processing directly into multifunctional dielectric elastomers. Previously presented continuum dielectric elastomer switches (cDES) utilize percolation effects within piezoresistive membranes to directly switch high voltages, controlling dielectric elastomer actuators. The here presented geometric dielectric elastomer switches (gDES) use geometric air gaps in encapsulated soft sensor structures to switch both high and low voltages.
gDES consist only of soft materials such as silicones and carbon-doped conductive silicones. The structured conductive electrode areas are arranged in such a way that they create small gaps within a shielded cavity. The gap can be opened or closed by an external deformation or pressure. Depending on the electrode design and mechanical characteristics, the necessary amount of deformation and pressure can be tailored exactly to the requirements of the application. Arrays of these switches can be integrated in soft robotic grippers and extend the features of those grippers by touch and shear force detection. Furthermore, gDES can act as limit switches and can be introduced in automation technology. One of the key advantages is that the switches themselves are entirely shielded and not affected by environmental influences.
gDESs have an advantage of operation at lower voltages than related cDES. This reduces the necessary amount of driving voltage and opens up the application in classic automation technologies and robotics. gDESs possess conductive silicone composites containing conductive fillers. The switching points and the general behaviour (normally-open [NO] or normally-closed [NC]) are tuned by the geometry of conductive parts associated with the shielding silicone structures. Related to percolation-based cDESs, the gDESs are produced by classic microelectronic production technologies, such as soft lithography.
We present the principle design of different gDESs and arrays of the same, the production techniques and first results of distributed touch sensing for soft robotic grippers. Methods and design parameters for adjusting the switching characteristics are presented and experimentally evaluated.
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