From TFA:

"“I did my PhD in France on making a spherical shell swim. To make it swim, we were making it collapse. It moved like a [inverted] jellyfish,” says Adel Djellouli, a researcher at Bertoldi Group, Harvard University, and the lead author of the study. “I told my boss, 'hey, what if I put this sphere in a syringe and increase the pressure?' He said it was not an interesting idea and that this wouldn’t do anything,” Djellouli claims. But a few years and a couple of rejections later, Djellouli met Benjamin Gorissen, a professor of mechanical engineering at the University of Leuven, Belgium, who shared his interests. “I could do the experiments, he could do the simulations, so we thought we could propose something together,” Djellouli says. Thus, Djellouli’s rubber sphere finally got into the syringe. And results were quite unexpected."

The paper discussed in the Ars piece can be found here[0].

[0] https://www.nature.com/articles/s41586-024-07163-z.epdf?shar...

The paper and videos are here:

https://bertoldi.seas.harvard.edu/publications/shell-bucklin...

Note that this is not "gripper" like "five-fingered robot hand". A better description might be "vise" (like the kind in a woodworking shop). The egg gets pressed between two linear actuators each with one degree of freedom.

From the title it sounded like the fluid could be given procedural instructions and then carry them out, but after watching the videos, it seems that what is happening is that the pressure/volume curve can be modified in hydraulic systems by adding these spheres to the hydraulic fluid, which collapse at a certain pressure threshold thereby reducing the output pressure of the system around a specific range, to avoid crushing the target object. The spheres can't be given different code. But the pressure/volume curve of the hydraulic fluid can be modified by using spheres with different properties.

> “You can tune pressure at which the spheres activate by changing their radius and thickness of their walls.

I immediately thought this.

The whole thing seems like such an intuitive idea. I really like the idea of mixing sizes to induce multiple pressure “plateaus”.

Also the drama of its inception is delectable.

The paper linked in another comment has some excellent visual aides. Wish we had a video.

Sometimes I wish I had gone into materials science like one of my HS teachers suggested. This is pretty dang cool