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A soft pneumatic actuator with integrated deformation sensing elements produced exclusively with extrusion based additive manufacturing
Antonia Georgopoulou * 1, 2 , Lukas Egloff 1 , Bram Vanderborght 2 , Frank Jörg Clemens * 1
1  Department of Functional Materials, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
2  Department of Mechanical Engineering (MECH), Vrije Universiteit Brussel (VUB), and Flanders Make Pleinlaan 2, B-1050 Brussels, Belgium.

10.3390/I3S2021Dresden-10097 (registering DOI)

In recent years, soft pneumatic actuators have come in the spotlight because of their simple con-trol and the wide range of complex motions. To monitor the deformation of soft robotic systems, elastomer-based sensors are being used. However, embedding of sensors into soft actuator mod-ules by polymer casting is time consuming and difficult to upscale. In this study, it is shown how a pneumatic bending actuator with an integrated sensing element can be produced using extru-sion-based additive manufacturing method, e.g. fused deposition modeling (FDM). The advantage of FDM against direct printing or robocasting is the significantly higher resolution and the ability to print large objectives in short time. New, commercial launched pellet-based FDM printers are able to 3D print thermoplastic elastomers of low shore hardness that are required for soft robotic applications, to avoid high pressure for activation. A soft pneumatic actuator with the in-situ in-tegrated piezoresistive sensor element was successfully printed using a commercial styrene-based thermoplastic elastomer (TPS) and a developed TPS/carbon black (CB) sensor composite. It has been demonstrated that the integrated sensing elements could monitor the deformation of the pneumatic soft robotic actuator. The findings of this study contribute to extending the applicabil-ity of additive manufacturing for integrated soft sensors in large soft robotic systems.

Keywords: piezoresistive sensor; soft robotics; additive manufacturing; fused deposition modeling; pneumatic actuator