Integrated Sensing-/Model-Based Online Estimation of Jet Dispensing

Jet dispensing has been widely considered as the next generation of dispensing technology. Since there is no online measurement of the droplet volume in the jetting process, the dispensing usually operates in open loop without any online control. The droplet consistency has been a long-standing challenge. As the jetting process is driven by the needle motion, the dispensed volume will be greatly affected by the needle motion. To monitor the jetting process, a novel measurement mechanism is designed for sensing the needle motion of the jet dispenser. Using the space/time separation method, the complex distributed fluid flow model is approximated by a simple analytical model. With the added motion measurement, this hybrid sensing/model approach can serve for online estimation of the dispensing performance. The model parameters can be identified using the experimental data. The experimental study verifies that the proposed method can satisfactorily estimate the dispensed volume in real-time operation.