Researchers Print Helical Extrusion from Rotating Nozzle

Researchers from Harvard College have revealed a paper detailing their work in 3D printing helical multi supplies from a singular rotating nozzle.

They’ve named the strategy RM-3DP, or rotational multi materials 3D printing.

The method permits for the simultaneous creation and patterning of multimaterial, helically architected filaments with subvoxel management in 2D and 3D motifs utilizing totally different supplies.

Earlier than we get into the nitty-gritty, let’s check out an image as an example the end result.

Twisty extrusion
Twisty extrusion. (Picture credit score: Harvard College)

The RM-3DP course of works by constantly rotating a multimaterial nozzle with a managed ratio of angular-to-translational velocity. The resin tanks are mounted above the nozzle, and likewise rotate with the extrusion head.

This enables for the creation of helical filaments with programmable helix angle, layer thickness, and interfacial space between totally different supplies inside a given cylindrical voxel. The cylindrical voxel is outlined as by the nozzle diameter multiplied by a size of extruded filament equal to 2x the radius of the nozzle, or 2πR^3 for brief. After the extruded helical tracks are laid down, a UV lamp passes over the tracks to remedy them.

You’ll be able to see the entire extrusion and rotating resin tank equipment within the video beneath.

The nozzles have a novel shell-fan-core design using fan components that create an azimuthally heterogeneous construction. They permit for the free rotation of ink reservoirs and the nozzle utilizing a 4-channel rotary union, which directs pressurized air from stationary inlets to rotating shops.


The researchers have defined that there’s extra to this course of than merely printing colourful tracks. These will not be merely totally different colours inside the helix, however they’re certainly multi supplies, and in a single demonstration the group efficiently printed conductive and insulating supplies from the identical nozzle.

The end result was a helical dielectric elastomer actuator (HDEA) filament with discrete, individually addressable helical conductive channels embedded inside a dielectric elastomer matrix.

A HDEA is a kind of electroactive polymer that modifications form when an electrical area is utilized to it. When voltage is utilized, the fabric contracts or expands, inflicting the actuator to alter form. This movement can be utilized to energy mechanical units comparable to robots and synthetic muscle groups. HDEAs are light-weight, low-power, and extremely compliant, making them appropriate for a number of makes use of together with robotics, biomedical units, and good supplies.

Experiment setup
Experiment setup. (Picture credit score: Harvard College)

Earlier strategies of fabricating HDEAs contain helical chopping of a dielectric elastomer tube and deposition of compliant electrodes on the helix faces.

Nonetheless, utilizing RM-3DP, HDEAs will be quickly printed in a single step by co-extruding two viscoelastic inks from the shell-fan-core nozzle to concurrently type each dielectric and conductive elements in a helical geometry. The conductive elements are printed with inks containing carbon.

You’ll be able to see the extrusion and curing course of, together with the completed HDEA functioning within the video beneath.

Springy Filaments

Along with the HDEAs, the researchers demonstrated the fabrication of springy filaments and matrixes. The end result was a structural composite composed of stiff and mushy sub voxelated components. The springy filaments had been fabricated by co-extruding two viscoelastic inks from the fan-core nozzle to embed stiff acrylic springs (blue fan options) inside a mushy acrylic matrix (clear fan-core characteristic).

The researchers demonstrated that the tensile mechanical habits of the springy filaments could possibly be tuned by various ω* (the dimensionless rotation fee). It was proven that as ω* was elevated from 0 to five, the tensile pressure at failure confirmed an roughly 30 to 40 fold improve.

You’ll be able to learn the total paper, and take a look at the opposite fascinating supplemental movies revealed on Nature, over at this hyperlink.


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