Vibration exciter using soft electromagnetic actuator

This study proposes a novel soft vibration exciter, employing a soft electromagnetic actuator (SEMA). The SEMA comprises soft polymeric substrates with stretchable electrical circuits, and is actuated based on the electromagnetic force in externally generated magnetic fields. Characteristics of SEMAs are their high stretchability, large deformation, fast response and low-voltage actuation. Here, vibration applications of the soft actuators can be utilised in vibration experiments involving flexible structures with curved surfaces and in wearable devices such as haptic displays. The low actuation voltage of the SEMA can make these applications safer for humans. To develop novel SEMA vibration devices, their fundamental performance should be evaluated by performing vibration experiments for simple mechanical structures. First, the proposed SEMA is fabricated by combining a soft substrate made of silicone material and a stretchable coil made of liquid metal. A permanent magnet is used to generate an electromagnetic force. For the SEMA to obtain a larger electromagnetic force, two different permanent magnet configurations are tested by varying their location and orientation. Second, to estimate the distribution of the SEMA electromagnetic force, a finite-element method (FEM)-based simulation is performed. In the vibration experiment system, the SEMA is attached directly to the simple rigid cantilever beam using adhesive tape. Then, the frequency responses are analysed to verify the performance of the vibration excitation of the SEMA. Finally, to consider realistic scenarios, the vibration experiment includes the SEMA suspended by the fixture, which is attached to the surface of the cantilever beam owing to its actuation, is applied to the vibration experiment. Experimental results verify the effectiveness of the proposed soft vibration exciter using the SEMA.