PoLS at Georgia Tech

Collision Induced Binding and Transport of Shape Changing Robot Pairs We report in experiment and simulation the spontaneous formation of dynamically bound pairs of shape changing robots undergoing locally repulsive collisions. These physical `gliders' robustly emerge f...

Please check out the full preprint on the arxiv!

arxiv.org/abs/2504.14170

A big thanks to authors Akash Vardhan, Ram Avinery, Hosain Bagheri, Velin Kojohourav, Shengkai Li, Hridesh Kedia, Tianyu Wang, Daniel Soto, Kurt Wiesenfeld, and Dan Goldman for their great work!

These principles—emergent behavior arising from actively-driven, deformable objects—are relevant to many living systems. From single-celled organisms to swarms of insects, "smart" behavior can arise from groups of "dumb" individuals, modulated by simple mechanical interactions.

These dyads form even when the robots have no ability to modulate their gait. However, a force-sensing feedback loop can increase the lifetime of the dyad, and therefore the distance traveled by the pair.

When motion was initiated for seven densely-packed smarticles, it was expected that they would push each other away and expand to a relaxed state. Instead, 64% of trials formed long-lived pairs of robots, called "dyads", which moved together for more than 100 gait periods.

The robots, dubbed "smarticles", are formed from three links and two motors, inspired by Purcell’s three-link swimmer. The motion of the arms causes the smarticles to repel one another, but they are unable to move significant distances on their own.

Actively-driven #robots can produce a rich variety of emergent phenomena, including behaviors that appear counterintuitive at first. In a recent preprint from the Goldman Lab at @gtresearchnews.bsky.social, undulating robots form long-lived pairs mediated solely by repulsive interactions.

Reversible kink instability drives ultrafast jumping in nematodes and soft robots A soft jumping robot inspired by nematodes demonstrates ultrafast jumping using reversible kink instability and stiffness.

Excited to share our new work in @science.org #Robotics that shows how reversible kinks can help nematodes perform jumps 1000 times faster than you can blink! scim.ag/4iDIa1i
🧵:
Work co-led by @chemicalsunnyraj.bsky.social , @itiwari93.bsky.social and Victor Ortega-Jimenez with many other colleagues

Check out these birds, courtesy of Nami Ha! Nami and the
@bhamlalab.bsky.social at Georgia Tech studies the amazing materials that make up living things, including the ultrafast water absorption of sandgrouse feathers.

Today! Come see @sacrozhangt.bsky.social's talk!

Today! Please come see Dr. Shucong Li give an excellent talk!

Please join us this Thursday for the final PoLS Lunch & Learn of the semester! This week's speaker will be @sacrozhangt.bsky.social from the Hammer and @wcratcliff.bsky.social labs.

The @bhamlalab.bsky.social is looking to hire a new lab manager! See the flyer below for details!

Please join us today for another Lunch & Learn seminar! This week's speaker is Maryam Hejri from the Yunker Lab. Lunch will be served at 12:00, with a talk beginning at 12:30!

Neuromechanical Phase Lags and Gait Adaptation in the Nematode $C.$ $elegans$ Mechanical forces from the environment shape how muscle activation translates into movement in C. elegans, revealing that passive mechanics can tune gait through phase lag and wavelength modulation.

To learn more, please check out the full paper—now available in PRX Life! Congratulations to the authors Chris Pierce, Yang Ding, Lucinda Peng, Xuefei Lu, Baxi Chong, Hang Lu, and Dan Goldman.

doi.org/10.1103/PRXL...

They built a mechanical model showing that phase lags result from a combination of internal elastic torques and external resistive forces. The worm's gait pattern is not purely neural—it's shaped by physics!

In low viscosity media, these phase lags are evenly distributed across the body. In viscous buffer, or in agar, the phase lag grows along the body before dropping near the tail.

Using calcium imaging, the Goldman Lab was able to measure the difference in phase between undulatory movements and the activation waves that cause them—called neuromechanical phase lags (NPLs). The NPLs vary with medium, including fluids of different viscosity and agar.

Animals at many length scales move through undulation. In a new paper, Chris Pierce and the Goldman Lab use the nematode 🪱 C. elegans to show how interactions with the environment cause undulating body movements to become desynchronized to the phase of muscle contractions.

Today! Come see Ben's talk!

This week's Lunch & Learn speaker is @doshna.bsky.social from the Sponberg Lab! Please come see his talk tomorrow!

Today! Join us for a PoLS seminar featuring Dr. Abdul Malmi-Kakkada, an Assistant Professor of Physics at Augusta University! Dr. Malmi-Kakkada is a computational biophysicist with expertise in cell-cell signaling and cell-substrate mechanical interactions.

We will begin at 3:00 in Howey N201!

Please join us on April 15 for a PoLS seminar featuring Dr. Shucong Li!

Dr. Li recently became an Assistant Professor at the Georgia Tech School of Materials Science and Engineering. She will be hosted by Dr. Zeb Rocklin.

AAAS Honors Seven Georgia Tech Researchers as Lifetime Fellows Seven faculty members at the Georgia Institute of Technology have been elected 2024 Fellows of the American Association for the Advancement of Science (AAAS), the world’s largest general scientific so...

Dan has been recognized "for distinguished contributions to the field of biological physics and nonlinear dynamics at the interface of #biomechanics, #robotics, and granular #physics."

Read more in the full press release!

news.gatech.edu/news/2025/03...

PoLS faculty Dan Goldman has been named a lifetime fellow of the American Association for the Advancement of #Science (@aaas.org)!

Congratulations to Dan, and also to the six other @gtresearchnews.bsky.social honorees named this year!

Today! Please come see Pablo's talk!

Check out the full preprint, now posted to the arXiv! Thanks to authors R. Sinaasappel, @prathyushakr.bsky.social, Harry Tuazon, E. Mirzahossein, P. Illien, @bhamlalab.bsky.social, and A. Deblais for their wonderful work!

doi.org/10.48550/arX...

In true PoLS fashion, this work bridges #biology and #physics. Evolution has optimized the shape and behavior of worms like T. tubifex for particle aggregation. Engineers can mimic these principles to design soft, flexible robots for tasks like cleaning up microplastics.

Longer, more flexible filaments are more effective at aggregating small particles. Motion is also essential—filaments use an "active swiping" behavior to gather these particles together. The width of this swiping motion is the key parameter that governs clustering.

Their new preprint explores particle aggregation mediated by three kinds of active filaments:

🪱 Living tubifex worms in Petri dishes
💻 Simulated, actively driven filaments
🤖 Robotic filaments made from hexbug robots

The result: flexibility is key

Can wriggling #worms inspire new principles in robot design? A new preprint from the @bhamlalab.bsky.social, in collaboration with the University of Amsterdam and @sorbonne-universite.fr, describes how active filaments—like living worms—can efficiently gather tiny particles in confined spaces.