Browsing by Subject "electrohydrodynamic jet printing"

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High-Resolution Electrohydrodynamic Jet Printing of Molten Polycaprolactone
(University of Texas at Austin, 2017) Sammons, Patrick M.; Barton, Kira
Polycaprolactone (PCL) is a biocompatible and biodegradable polymer that is commonly used in drug delivery systems, medical structures, and tissue engineering applications. Typical additive manufacturing methods of PCL structures for tissue engineering applications either require harsh organic solvents or are only capable of producing relatively large feature sizes, which are not compatible with some of the desired applications. Electrohydrodynamic jet (e-jet) printing, an additive manufacturing process which uses an electric field to induce jetting from a microcapillary nozzle, is an attractive method for producing PCL tissue engineering structures due to the achievable resolution and the ability to print highly viscous inks. In this work, experimental investigation into the ability to print pure, molten PCL using the e-jet process is carried out. A characterization of the process inputs that yield suitable printing regimes is presented. Demonstration of the achievable resolution with e-jet printing is presented in the form of printed, high-resolution structures.
Numerical Modeling of High Resolution Electrohydrodynamic Jet Printing Using OpenFOAM
(University of Texas at Austin, 2017) Wu, Maxwell; Sammons, Patrick M.; Barton, Kira
Electrohydrodynamic jet (e-jet) printing is a micro-/nano-scale additive manufacturing (AM) method that has emerged in recent years as a process to rival similar technologies such as inkjet printing. By utilizing electrostatic forces to induce fluid flow, e-jet has shown the ability to fabricate high resolution features with a wide variety of materials. Because it is a relatively new AM process, the printing behavior of many different types of inks are not completely understood, as existing knowledge of the process relies almost entirely on empirical methods that can be time intensive and difficult to implement for materials that are hazardous or not readily available. This paper discusses procedures for modeling both the electric and fluid dynamics of the e-jet printing process within OpenFOAM, an open-source computational fluid dynamics (CFD) solver. Further discussion has been provided to show simulations of the process at typical high resolution e-jet printing scales and to present existing limitations of the model.
Temperature and Humidity Variation Effect on Process Behavior in Electrohydrodynamic Jet Printing of a Class of Optical Adhesives
(University of Texas at Austin, 2017) Sammons, Patrick; Bollineri, Sahit; Sibal, Ritika; Barton, Kira
Electrohydrodynamic jet (e-jet) printing is an emerging additive manufacturing process that utilizes an electric field to eject material from a micro-/nano-scale microcapillary nozzle. Due to its contemporary nature and the complex physics which govern the process, little is known about printing behavior sensitivity with respect to environmental condition variability. The aim of this work is to construct a systematic experimental design to test and evaluate the relationship between two environmental variables, temperature and relative humidity, and key process metrics initiating ejection voltage, printing frequency, and diameter of material ejected. A factorial statistical design of experiments is used to investigate the parameter space. Results are used to identify temperature and humidity ranges that give robust printing regimes for a specific class of optical adhesives. Best-fit curves are determined for several of the input-output relationships, which provide a predictive model for the ink behavior.