A Piezoresistive Printable Strain Sensor for Monitoring and Control of Soft Robotic Links

摘要

Integrating sensors into soft links with complex geometries without compromising their flexibility, precision, or structural integrity remains one of the main challenges in soft robotics. This article presents the design, fabrication, and electromechanical evaluation of a 3D-printed flexible strain sensor tailored for monitoring and controlling these links. By combining Fused Filament Fabrication (FFF) and Direct Ink Writing (DIW) technologies, we manufactured a sensor composed of a thermoplastic polyurethane (TPU) substrate and a pattern of silver (Ag) nanoparticles ink, ensuring high flexibility and conductivity. We performed electromechanical tests to assess the sensor's performance, including three-point bending tests, cyclic loading to evaluate its durability, and angular deflection measurements to confirm its precision in detecting bending angles. The sensor demonstrated efficient piezoresistive behavior within a defined working range between 3% and 8% of flexure strain with a Gauge Factor (GF) of 0.24 and stable repeatability. We also tested its integration into a soft link, showing that the sensor maintains flexibility and accuracy during deformation.