3D-printed Pressure Sensor with Heterogeneous Polymer Material and Annealing Effect

In this paper, the performances of the capacitance characteristics of the Fused Deposition Modeling (FDM) 3D-printed pressure sensor was evaluated. The FDM 3D printing sensor is composed of flexible-material thermoplastic polyurethane and a conductive PLA (carbon black conductive polylactic acid) polymer. While 3D printing, polymer filaments heat up quickly before being extruded and cooled down quickly. Polymers have poor thermal conductivity, so the heating and cooling cause unevenness, which then results in internal stress on the printed parts due to the rapidity of the heating and cooling. The results validate that the capacitance measurement of 3D-printed pressure sensor is unstable due to internal stress before annealing. Therefore, annealing was performed to eliminate the instability of repeat measurement mismatch. In comparison to non-annealed sensor, the annealed sensor demonstrates that thermal annealing removes residual stress on the sensor, so the repeated measurement capacitance precision of the sensor somewhat stable. The results of this study will be very useful for the fabrication of various devices that employ 3D-printed sensor that have multiple degrees of freedom and is not limited by size and shape.