AN INEXPENSIVE 3D PRINTING SYSTEM FOR FUNCTIONAL INKS USED IN ELECTRONICS AND BIO APPLICATIONS

Numerous extrusion-based 3D printing processes for electronics and bio-applications have been reported in the past decade. However, these direct ink writing (DIW) systems are mostly expensive and complex to build. Here, we report an inexpensive and open-source extrusion-based 3d printer that could be employed for printing functional inks, especially for various electronics and bio fabrication. A low-cost fused filament fabrication (FFF) 3D printer was modified to build the DIW system. An extrusion mechanism was developed with a stepper motor, a lead screw, a syringe-plunger system, and spur gears. The existing FFF heated extruder was replaced by a new extrusion mechanism. The printer was utilized to print thermosetting viscous pre-polymers. A photocurable resin was thickened using fumed silica to induce non-Newtonian shear thinning properties, and it was used for printing experiments. G-code for printing was generated using an open-source slicer software. Different extrusion rates were examined by controlling the extrusion motor rotation and speed. Also, various print parameters were investigated such as travel speed, ink viscosity, and nozzle size. The dimension of the printed geometry was studied with the change of print parameters. The printed structures were photocured using ultraviolet light. The printed geometries before and after curing were compared. To check printability for electronics, a soft pressure-sensitive membrane was 3D printed using the developed system. An acrylate-based monomer was mixed with a photoinitiator, crosslinker, fumed silica, and ionic liquid to prepare the functional ink for sensor fabrication. The printed sensor was tested under different load conditions.