Light-directed electrophoretic deposition printed objects (EPD) uses photoconductive electrodes and DC electrical fields to dynamically pattern the surface material.

This allows the buildup of material in targeted areas where the light comes in contact with the photoconductor's surface. This enables the creation of arbitrarily patterned 3D multimaterial composites over large areas with fine resolution.

A layer of tungsten nanoparticles (dark brown) was first deposited on areas illuminated through a laser

One of the most common and oldest processes that utilize EPD is the application of a primer coat to new car bodies on a production assembly line. The body of the car is positively charged while the liquid primer in the dunk tank is negatively charged, forcing the attraction of the primer to the metal surface.

Researchers used light-directed EPD to produce an alumina ceramic-tungsten nanoparticle composite. Initially, the tungsten nanoparticles were deposited across the photoconductive surface, then illuminated through a laser cut aluminum mask. A different shaped mask was then substituted along with the new material, to deposit the ceramic material. In the future, the aluminum masks will be replaced by a digitally projected mask, similar to those found in DLP televisions, for a completely automated deposition system.

[phys.org]