An Integrative 3D printing method for rapid additive manufacturing of a capacitive force sensor

With the rapid development of the three-dimensional printing (3D printing) technique, several electronic devices have been fabricated by 3D printing. Compared with the traditional micro electromechanical system (MEMS) manufacturing processes, the 3D printing technique provides a convenient method to meet the customers' personalized demands. However, the applications of 3D printing are restricted by the electrically insulating properties of the commonly used polymers. Besides, additional alignment and assembling processes are still indispensable to fabricate the MEMS devices with geometrically complex structures using the conventional 3D printers. In order to solve these problems, an integrative 3D printing approach for rapid manufacturing is presented in this paper. With a triple-extruder 3D printer, the electrically insulating polylactic acid (PLA) filament, the electrically conductive PLA filament, and the soluble high impact polystyrene filament can be printed alternately in the 3D printing process. As an application of the method, a capacitive force sensor with a relatively complex suspended beam-plate structure was fabricated in a one-step 3D printing process without using any additional metallization process, unloading-reloading filament process, alignment process, and assembling process. With a good dynamic performance, the 3D printed force sensor was used to monitor human's blood pulse. The results show that the integrative 3D printing method has potential to meet the emerging requirement for manufacturing of MEMS devices for personalized applications.