3D Printing-Assisted Soft Capacitive Inclinometers for Simultaneous Monitoring of Tilt Angles and Directions

This study presents capacitive-type inclinometers composed of flexible polymer pillars and dome-shaped roof frames that were manufactured using the three-dimensional (3D) printing method. Polylactic acid (PLA) filaments and acrylonitrile butadiene styrene (ABS) filaments were printed by the fused deposition modeling type 3D printer to fabricate the dome-shaped roof frames and the polymer curing molds, respectively. The operating principle of the inclinometer was to detect the change in capacitance between the helix-shaped electrode coiled around the polymer pillar and the built-in electrode in the roof frame. When the inclinometer was tilted, the polymer pillar was bent, and the physical distance between each electrode was changed with respect to the tilt angle and direction. Therefore, the tilt angles and directions were simultaneously estimated by distinguishing the capacitance and peak capacitance, respectively. The results of the experiments revealed that the inclinometer using the polymer pillar that was electrically connected to a standard weight and the roof frame with a roof angle of 45° exhibited a higher sensitivity (1.391 pF at a tilt angle of 40°) compared to those using roof angles of 90° and 135°. This study supports the use of 3D printing technology for the facile manufacturing of inclinometers that can detect tilt angles and directions simultaneously, which is not achievable with conventional inclinometers.