Multi-material 3D Printing of Thermoplastic Elastomers for Development of Soft Robotic Structures with Integrated Sensor Elements

Embedded sensing can benefit soft robots with the ability to interact
with their environment but producing embedded soft sensors can be challenging.
Multi-material Fused Deposition Modeling (FDM) additive manufacturing
allows producing complex structures, by combining more than one kind of
polymeric material. For multi-material FDM, conductive thermoplastic elastomer
filaments have been developed. This allows the printing of flexible
functional structures, based on thermoplastic elastomer structures with conductive
paths that are of great interest for stretchable electronics and soft robotic
applications. In this study, stretchable piezoresistive elastomer strain sensor
composites were successfully produced by using multi-material FDM.
A piezoresistive thermoplastic elastomer was printed on the top of a nonconductive,
flexible thermoplastic elastomer strip using FDM multi-material 3D
printer. FDM elastomer filaments with different shore hardness as substrate
materials for the gripper structure were used. The hardness of the elastomer
affected the printability and the adhesion to the conductive elastomer material,
which was used as a strain sensor material. The hardness affected the strain
sensor properties too. The piezoresistive response, dynamic behavior, drift,
relaxation and sensitivity of the printed multi-material strips were investigated
by tensile tests. Soft robotic grippers with integrated sensing elements to detect
deformation while touching the objective were selected as a case study. The soft
grippers with the integrated sensors exhibited intelligent response by recognizing
when they were griping a small or big object and when an obstacle was
inhibiting their function.

ISBN:978-3-030-54333-4

Jaar van publicatie:2020