Deposition Offset of Printed Foam Strands in Direct Bubble Writing

Abstract

Direct Bubble Writing is a recent technique to print shape-stable 3-dimensional foams from streams of liquid bubbles. These bubbles are ejected from a core-shell nozzle, deposited on the build platform placed at a distance of approximately 10 cm below the nozzle, and photo-polymerized in situ. The bubbles are ejected diagonally, with a vertical velocity component equal to the ejection velocity and a horizontal velocity component equal to the motion of the printhead. Owing to the horizontal velocity component, a discrepancy exists between the nozzle trajectory and the location of the printed strand. This discrepancy can be substantial, as for high printhead velocities (500 mm/s) an offset of 8 mm (in radius) was measured. Here, we model and measure the deviation in bubble deposition location as a function of printhead velocity. The model is experimentally validated by the printing of foam patterns including a straight line, a circle, and sharp corners. The deposition offset is compensated by tuning the print path, enabling the printing of a circular path to the design specifications and printing of sharp corners with improved accuracy. These results are an essential step towards the Direct Bubble Writing of 3-dimensional polymer foam parts with high dimensional accuracy.

Free‐Boundary Microfluidic Platform for Advanced Materials Manufacturing and Applications

“…Gas-Driven Co-Flow: In addition to flow-focusing configuration, co-flow can also be used for the manufacturing of materials. [62,63,98,[100][101][102][103][104][105][106][107][108][109][110][111][112][113][114][115][116][117][118]128] Using external air flow to drive internal phase liquid flow, high-definition single-cell printing can be realized (Figure 4A). The speed, accuracy, and flexibility of the approach were studied.…”

“…In this section, we focus on four types of FBMM, including hydrodynamics‐based, interfacial tension‐based, acoustics‐based, and electrodynamics‐based ( Figure ). The hydrodynamics‐based FBMM includes the flow focusing, [ 50,58,60,81–97 ] co‐flow, [ 62,63,98–128 ] cross‐flow, [ 61,129–139 ] and free jet channel geometries. [ 56,140–146 ] The interfacial tension‐based FBMM includes single‐axial, oblique, and spinning.…”