The Miracle of 3D Inkjet Printing: Complex Structures at Record Speed

Wednesday - November 29 2023, 02:44 UTC - 11 months ago

The team from ETH Zurich successfully used 3D inkjet printing technology equipped with machine vision to rapidly build complex structures in one go, such as a hand and a human heart-like structure. The 3D printing process is fast, cheaper, and more accurate than traditional methods and is capable of combining materials with different properties for functional structures.

We don’t think twice about using our hands throughout the day for tasks that still thwart sophisticated robots—pouring coffee without spilling when half-awake, folding laundry without ripping delicate fabrics. The complexity of our hands is partly to thank. They are wonders of biological engineering: Hard skeleton keeps their shape and integrity and lets fingers bear weight. Soft tissues, such as muscles and ligaments, give them dexterity. Thanks to evolution, all these "biomaterials" self-assemble. Recreating them artificially is another matter.

Scientists have tried to use additive manufacturing—better known as 3D printing—to recreate complex structures from hands to hearts. But the technology stumbles when integrating multiple materials into one printing process. 3D printing a robotic hand, for example, requires multiple printers—one to make the skeleton, another for soft tissue materials—and the assembly of parts. These multiple steps increase manufacturing time and complexity.

Scientists have long sought to combine different materials into a single 3D printing process. A team from the soft robotics lab at ETH Zurich has found a way. The team equipped a 3D inkjet printer—which is based on the same technology in normal office printers—with machine vision, allowing it to rapidly adapt to different materials. The approach, called vision-controlled jetting, continuously gathers information about a structure’s shape during printing to fine-tune how it prints the next layer, regardless of the type of material.

In a test, the team 3D printed a synthetic hand in one go. Complete with skeleton, ligaments, and tendons, the hand can grasp different objects when it "feels" pressure at its fingertips. They also 3D printed a structure like a human heart, complete with chambers, one-way valves, and the ability to pump fluid at a rate roughly 40 percent of an adult human’s heart. The study is "very impressive," Dr. Yong Lin Kong at the University of Utah, who was not involved in the work but wrote an accompanying commentary, told Nature. 3D inkjet printing is already a mature technology, he added, but this study shows machine vision makes it possible to expand the technology’s capabilities to more complex structures and multiple materials.

The Problem With 3D Inkjet Printing .

Recreating a structure using conventional methods is tedious and error-prone. Engineers cast a mold to form the desired shape—say, the skeleton of a hand—then combine the initial structure with other materials.

It’s a mind-numbing process requiring careful calibration. Like installing a cabinet door, any errors leave it lopsided. For something as complex as a robot hand, the results can be rather Frankenstein. Traditional methods also make it difficult to incorporate materials with different properties, and they tend to lack the fine details required in something as complex as a synthetic hand. All these limitations kneecap what a robotic hand—and other functional structures—can do.

Then 3D inkjet printing came along. Common versions of these printers squeeze a liquid resin material through hundreds of thousands of individually controlled nozzles. The layers build one upon the another until the structure takes its desired shape. The process is relatively fast, cheaper, and more accurate in creating layers than traditional methods.