Effect of printing parameters on the sensing performance of a 3D printed elastomeric pressure sensor

Abstract

Additive manufacturing processes have created new opportunities for the printing of functional electronics. Commercial 3D printers fall short in providing the capabilities to directly print with functional inks, especially, with thermosetting non-Newtonian materials. Also, open-source slicing software are generally designed to generate g-code for thermoplastics. In this work, we modified an inexpensive commercial 3D printer to print functional inks for electronics. A plunger-based extrusion mechanism was developed using a stepper motor and lead screw. The heated extruder in the commercial printer was replaced by the new mechanism. Next, the system was employed to print ionic liquid-based soft pressure sensors, followed by an ultraviolet light curing process to polymerize the printed structure. Sensor ink was prepared by mixing ionic liquid into an acrylate-based monomer. To obtain proper rheology for printing, fumed silica was added to the ink. The effect of different printing parameters on the sensing performance of the printed sensors was studied and presented. The parameters studied were sensor thickness, nozzle diameter, extrusion rate, and raster angle. Multiple sets of sensors were printed by changing these parameters, and they are evaluated for their sensitivity. The sensitivity was measured in terms of relative change in the voltage output from the sensor system. The results show that varying the printing parameters significantly affects the sensing performance. The sensitivity increases with the decrease in sensor thickness, increase in nozzle diameter, and increase in print flow rate. The findings from this study can be employed to modulate the sensitivity of a sensor for different applications by changing various print parameters.