<p style="text-align: justify">The technological advances in the manufacturing process of electroactive polymers allow the realization of soft-devices for several transduction solutions, i.e., actuators or sensors. Dielectric Elastomer Transducers (DETs) are examples of this technology-class, consisting of an electro-mechanical system composed of compliant electrodes printed on a highly deformable dielectric elastomeric membrane. Thanks to their high adaptability, flexibility, and low-cost fabrication, DETs are favorite candidates for several mechatronic systems. In this context, this paper presents an electric-capacitive Dielectric Elastomer Sensor (DES) for angular measurement applications, as the relative angle of two bodies linked by a rotating joint or as for the bending angle of a flexible structure when changing its curvature. However, due to the nature of the measurement and the capacitive sensitivity depends on the dielectric elastomer geometry, several electrode dispositions and shapes can be employed for a capacitance measurement related to the sensor deformation angle. Therefore, in this work, two DES solutions are proposed and experimentally compared, both assembled by the same components made of silicone PDMS material but with different electrode designs. The first solution comprises a flexible structure sandwiched by two individual DESs, each one composed of a silicone membrane between two compliant electrodes. In this case, the differential capacitance between both individual sensors is demonstrated to be linearly dependent on the holding structure bending angle. In contrast, the second sensing strategy implements two interdigitated electrodes disposed on the same surface of a silicon substrate membrane, coupling the differential capacitance measurement with the fringing electrode field variation when the holding structure is subjected to a certain curvature. For both sensor solutions, the operation and physical insight explanation principles are reported and discussed. Furthermore, an experimental campaign is implemented and executed thanks to a dedicated test-bench for bending angle measurements and characterization procedure. Finally, the test results from multiple sensor samples for each of the two DES concepts are compared, identifying the pros, cons, and sensitivity of both sensing strategies.</p>

Performance Comparison of Capacitive Silicone-Based Curvature Sensors With Planar and Interdigitated Electrodes

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2021/volume/85499

ASME 2021 Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS2021)

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