3D-Printed shear force sensors

Easily manufacturing of sensors with little waste and manufacturing costs is often desired in many fields, an example is the field of rehabilitation engineering. There is a way of manufacturing that can fulfil these needs called Additive Manufacturing (AM) and more specific 3D-printing. This research will delve into seeing if it is possible to design and create a 3D-printed shear force sensor using carbon doped thermoplastics. There are many designs that can be approached but this research will be focused on a three layer design and cylindrical design. The three layer design consists of two layers of conductive filament called ETPU separated by beams of flexible filament called x60. The cylindrical design consists of two half cylinders with different radii consisting of ETPU with beams of x60 between them. A model will be determined which takes the normal force, shear force and fringing effect into account. The measurement setup includes separately designed tools that are 3D-printed out of an ABS plastic filament. The range of shear force will be between zero and twelve Newton for both the model and the measurement. There were multiple discrepancies between the model and the measurements for the three layer design which were most likely caused by the small size of the sensor making the dimensions of the sensor harder to accurately determine. The cylindrical design deformed when a shear force was applied due to its flexibility. This caused it to behave differently than expected in the model. This made the model unusable with this type of cylindrical sensor consisting of the flexible materials. It was possible to measure shear force using capacitive readout with the three layered design for forces ranging from two to twelve Newtons. However, a stable normal force acting on the sensor is needed for it to work properly.