Design, Development and Characterization of a Novel Fully Additively Manufactured Deformable Conductive Force Sensor

Additive manufacturing methods are becoming increasingly popular across various fields for realizing objects. Fused Deposition Modeling (FDM), a widely used technique in this regard, allows the production of objects with complex geometries at affordable prices and short lead times. FDM stands out due to its ability to incorporate conductive particles into thermoplastic filaments, enabling the fabrication of conductive elements with unique electrical and mechanical properties. However, the use of fully printed conductive sensors, especially those with piezoresistive properties, for the measurement of physical and chemical quantities remains relatively unexplored in existing literature. In this paper, we introduce a novel deformable bi-layer sensor created using conductive filaments and discuss its design, development, and metrological characterization. The sensor working principle is based on the resistance variation in response to external force application. Electromechanical tests were conducted to characterize the sensor, wherein forces up to 20 N were applied. These tests aimed to determine the mechanical compressive strain, assess the static sensitivity, and evaluate the sensor's performance during cyclic tests. The sensor showed a more pronounced compressive strain at lower applied forces (<5 N). The maximum value of 7.74 ± 0.42% was found when a force of 20 N was applied. The relationship between resistance change and force was non-linear and is well described by a second-order exponential decay function. The sensor exhibited higher sensitivity values up to 5 N of applied force, consistently higher than −1%.N
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