Interfacial Instabilities in Soft Matter 3D Printing

Abstract

All forms of printing boil down to the act of transferring one medium to another. Three-dimensional (3D) printing injects ink onto a platform into the desired shape, building it one layer at a time. The ink for traditional 3D printing must be a self-hardening material. The ink must be soft enough to be shaped into the desired design while remaining sturdy enough that the design remains intact. Complications due to gravity arise with this method of printing. Gravitational forces limit the user to print only hard materials and can cause some designs to collapse. In order to print soft materials, a new method of 3D printing is needed. This leads us to soft matter 3D printing. Soft matter 3D printing is printing soft, malleable materials such as oils and cells into another soft material. In order to 3D print soft matter, the medium in which you print cannot be air because the force of gravity would overpower the soft material. In order to negate the effects of gravity, the Soft Matter Engineering Lab at the University of Florida has created a microgel material which suspends the printed object while it is being printed, holding it in place until it is ready to be removed. In order to understand the full capabilities of the microgel, it is important to understand all of its interfacial instabilities. This paper explores a new method of printing a sheet of silicone oil into an aqueous based microgel in order to understand how a highly anisotropic liquid shape, or a shape which has different physical properties depending on the way it is measured, behaves inside this soft solid.