P. Vishnoi, A. Verma, I.H. Karampelas, E.P. Furlani
University at Buffalo,
Keywords: additive manufacturing process, rapid prototyping and manufacturing, numerical simulation, electrical simulations, biofilms, computational fluid dynamics
Summary:We introduced a novel additive manufacturing technique that involves the drop-on-demand (DOD) printing of molten metal droplets to build three dimensional (3D) metal structures of arbitrary shape. Droplet generation in our method is done on the basis of magnetohydrodynamics (MHD). In MHD, a transient magnetic field is generated by an electrically pulsed coil and induces a circulating current in molten aluminum that back couples to the applied field and creates a Lorentz force density (effective pressure) inside the printhead droplet ejection chamber. This effective pressure causes the ejection of a liquid metal droplet through a nozzle. The droplet solidifies on a metal substrate and leads to the printing of arbitrary 3D metal structures in layer-by-layer fashion. We demonstrate a commercial MHD-based printing system under development by Vader Systems (www.vadersystems.com). The underlying physics of droplet generation and the thermos-fluidic aspects of droplet deposition, coalescence and solidification are explained and the results demonstrate good correlation between our computational models and measured data. In addition to the 3D printing, in this paper, we study the Cathodic Voltage Controlled Electrical Stimulation (CVCES), which is a recently developed electrochemical procedure that has provided efficient results in the treatment of biofilm-based prosthetic joint infections. In CVCES, a metal working electrode is implanted in the vicinity of the biofilm, accompanied by a counter electrode and a reference electrode. The electrodes are connected to a potentiostat and a negative potential is applied to the working electrode (cathode) vs the reference electrode. As a result of the applied potential, electrochemical reactions take place on the surface of working electrode and toxic reaction products are formed leading to increased pH and disturbed physiological conditions in the vicinity of cathode. Prior studies have shown that CVCES in combination with standard antibiotics can lead to complete eradication of the infection without any damage to the surrounding tissue. However, many fundamental aspects and the underlying mechanism of this treatment are still unknown. There is also a need for rational design towards optimizing the treatment procedure. In order to tackle these problems, we develop computational models that will stimulate the electrochemical behavior of an in-vivo CVCES procedure. The mathematical models have been developed using the commercial multiphysics software COMSOL.