Additive manufacturing systems, often called 3D printers, are poised to displace conventional manufacturing operations in many meso-scale applications (parts from 1 to 100 millimeters in size). Similarly, 3D printing at the micro-scale (from 0.001 to 0.1 millimeters in size) has the potential to revolutionize the way that biological and chemical sensors and integrated circuits are prototyped and manufactured. 3D printers build up complex parts by depositing one thin layer of material at a time. Electrohydrodynamic jet, or e-jet, printing is a promising micro-scale version of this process. This project will add sensors to a standard e-jet printer, and apply an innovative control law to greatly improve the precision of the resulting parts. The control law is based on the observation that 3D printed features typically change very little from one layer to the next. By observing how a layer deviates from its desired shape, the baseline e-jet control can be modified to improve the accuracy of the next layer. In this project, an atomic force microscope will be integrated with an e-jet printer to measure the shape of each layer. To better correct the printing process, the electric field around each layer will also be measured. The technical research plan is integrated with educational outreach to initiate undergraduate "micro-maker" clubs and catalyze an open-source, bottom-up movement based on inexpensive ink-jet printing of custom microcircuits and sensors.
Micro-scale Additive Manufacturing, and in particular, electrohydrodynamic jet printing, has the potential to revolutionize 3D, functional, micro-scale device fabrication. Limiting this step change in manufacturing capabilities is the reliance of micro-scale Additive Manufacturing systems on a process monitoring, regulation, and quality control paradigm that is performed post-process and in an ad hoc manner. This research will break this open-loop paradigm by generating fundamental scientific knowledge in two areas: 1) the synthesis of a controls theoretic framework to compensate for spatial disturbances with a robust and computationally efficient learning-based algorithm and 2) the study of interactions between charged jets of materials and substrates in electrohydrodynamic jet printing using first principles physics models and validated by empirical studies leveraging a novel integration of electrohydrodynamic jet printing and atomic force microscopy. This research will contribute the fundamental knowledge required to transform 3D micro-scale Additive Manufacturing from a nascent, open-loop and ad hoc technology set to a fully automated, accurate, and robust closed-loop system.
