Precision evaluation of tactile sensor fabrication using a robotic additive manufacturing platform

This paper presents the NeXus, a precision robotic platform with additive manufacturing capabilities that can be used to prototype strain gauge-based tactile sensors - SkinCells - on flexible substrates. An Aerosol Inkjet printer was employed to print the strain gauge structures of the SkinCell sensor. The design of this sensor combines curvilinear geometries representing both a radial shape structure and an arc shape structure, which have opposite gauge responses when the force is applied to the center of the sensor. The fabrication process of the SkinCell sensor is predicated on a parametric kinematic calibration of the NeXus to identify features on the sensor substrate and align them to the printing and metrology tools. Several strain gauge SkinCell sensor samples were printed on pre-fabricated flexible substrates using the NeXus. Results indicate a calibration precision of approximately 36 microns with 100 microns line-width features. This precision is sufficient to ensure that all printed gauges are electrically connected to the prefabricated contacts. Furthermore, the printing errors accumulating during a continuous four-sensor array print also fall within the contact tolerance.