Embedding Sensing Capabilities in FDM-Printed Objects

The objective of this work is to demonstrate how the flexure properties of ABS plastic in a 3D printed object can be exploited to enable embedded pressure sensing capabilities. Designing non-static 3D printed parts broadens the scope of fused deposition modeling (FDM) to include printable ‘smart’ objects that utilize their intrinsic material properties to act as microphones, load sensors, accelerometers, etc. This research undertakes the task of developing a 3D printed pressure sensor to show proof-of-concept for non-static prints. Sensors with diaphragms of 1mm thickness deform more sensitively than 2mm diaphragms at \u3e1psi. Securing a strain gage directly on top of the diaphragm traced a reference pressure more closely than diaphragms with the strain gage embedded halfway into the diaphragm. An additional strain gage was suspended above the secured gage, inside a 3D printed cavity. The additional gage allowed for a half-bridge circuit in lieu of the quarter-bridge circuit; furthermore, the half-bridge circuit minimized drift due to temperature change. The ABS diaphragm showed no signs of elastic hysteresis or nonlinear buckling. When sealed with 100% acetone, diaphragms leaked ~50x slower than control sensors. Each of the ‘optimal’ sensors showed precision to themselves when exposed to sustained pressure. However, consistency from sensor to sensor was lacking—an expected symptom of FDM. The self-precision of each of the final generation sensors indicates that ‘smart’ objects printed using an FDM process could be individually calibrated to make repeatable recordings. This work demonstrates a concept overlooked previous to now—FDM printed objects are not limited to static models. Altering FDM’s bottom-up process can allow for easily embedding sensing elements that result in printed objects which are functional on the mesoscale