Liquid Metal Droplet Impact Dynamics

Droplet on Demand (DOD) is the application of inkjet technology to the realm of additive manufacturing. DOD presents a more affordable alternative to other metal printing methods while still printing full density metal and electrical components. This work focuses on droplet impact, spreading and wetting behavior for room temperature liquid metal on isothermal and non-isothermal substrates,

We conducted the droplet impact at low Weber number O(10^-7) and low Ohnesorge number O(10^-4) indicating capillarity driven spreading resisted by fluid inertia as well as higher Weber numbers up to O(10²) while maintaining O(10^-4) for the Ohnesorge number, leading to impact driven spreading resisted by the fluid inertia.  We studied droplet contact diameter as a function of time until contact line arrest as well as advancing and arrested contact angles. Furthermore, we measured droplet height as a function of time to model oscillation and damping after impact as these parameters are critical for the frequency of droplet deposition. These results are compared between the isothermal, cooled substrate, and heated substrate cases to quantify localized thermal effects on dynamic contact and wetting conditions.