Functional Micro/Macro Fabrication Combining Multiple Additive Fabrication Technologies: Design and Development off an Improved Micro-Vane Phacoemulsifier used in Cataract Surgery

Abstract

Microstereolithography (µSL) technology can fabricate complex, three-dimensional (3D) microstructures, although µSL has difficulty producing macrostructures with micro-scale features. There are potentially many applications, where 3D micro-features can benefit the overall function of the macrostructure. One such application has been recently identified in cataract surgery where a medical device, called a coaxial phacoemulsifier, is inserted into the eye through a relatively small incision and used to break the lens apart while removing the lens pieces and associated fluid from the eye through a small tube. In order to maintain the eye at a constant pressure, the phacoemulsifier also includes an irrigation solution that is injected into the eye during the procedure. It has been reported, however, that the impinging flow from the irrigation solution on the corneal endothelial cells in the inner eye damages these cells during the procedure. As a result, we are exploring methods for reducing flow velocities during this procedure, and have designed a complex, 3D micro-vane within a sleeve that introduces swirl into the irrigation solution, and thus, produces a flow with rapidly dissipating flow velocities. However, the fabrication of the sleeve could not be accomplished using µSL alone, and thus, a two-part design was accomplished where a sleeve with the micro-vane was fabricated with µSL and a threaded fitting used to attach the sleeve to the phacoemulsifier was fabricated using an Objet Eden 333 rapid prototyping machine. The new combined device was tested in a water container using particle image velocimetry, and the results showed an ejection of the irrigation fluid through the micro-vane in three different radial direction. It is believed that this new device will reduce damage to endothelial cells during cataract surgery and significantly improve patient outcomes from this procedure. This unique application demonstrates the utility of combining µSL with a macro rapid prototyping technology for fabricating a real macro-scale device with functional, 3D micro-scale features that could not be fabricated using conventional methods.