EMPA and Max Planck Decode Squirrel Tail Scales to Inspire Agile Bionic Robots

EMPA and Max Planck Decode Squirrel Tail Scales to Inspire Agile Bionic Robots

(IN BRIEF) Empa’s Soft Kinetic group and the Max Planck Institute for Intelligent Systems have, for the first time, dissected the physics behind the thorn-covered tail scales of African scaly-tailed squirrels, revealing how these subcaudal spines deliver enhanced grip and stability on smooth bark. Through museum specimen scans, analytical modeling, and 3D-printed physical replicas, the researchers demonstrated the scales’ critical role in secure perching. Under Ardian Jusufi’s leadership, the team is now planning dynamic experiments and field studies to observe emergency landing behaviors. Their findings lay the foundation for biomimetic designs of agile, energy-efficient robots and drones capable of navigating complex, vertical environments for uses in agriculture, environmental monitoring, and disaster response.

(PRESS RELEASE) DÜBENDORF, 2-Jul-2025 — /EuropaWire/ — EMPA’s Soft Kinetic group, in collaboration with the Max Planck Institute for Intelligent Systems, has decoded how African scaly-tailed squirrels leverage thorn-covered scales on the undersides of their tails to secure themselves on smooth rainforest bark. By combining mathematical modeling with physical prototypes, the researchers have, for the first time, elucidated the mechanics of these subcaudal spines—and their insights could drive the creation of agile, energy-efficient bionic robots and drones.

The subcaudal spines were shown to provide stability were found to provide stability whilst perched on tree bark of varying roughness. Image: Empa

Nocturnal gliders measuring between 6 cm and 45 cm in body length, scaly-tailed squirrels owe their name to the sharp, overlapping scales beneath their tails. While biologists suspected these spines aid in gripping, their exact function remained untested. Lead investigator Ardian Jusufi and his team borrowed museum specimens, performed high-resolution 3D scans of the scales, and developed both analytical and physical “squirrel” models outfitted with 3D-printed replicas of the claws and spines. Static experiments showed these structures markedly enhance stability and grip across bark surfaces of varying smoothness.

“Simulations alone can’t capture the unpredictable dynamics of treetop locomotion, so we build moving physical replicas to validate our theories,” says Jusufi. Having previously unveiled gecko tail reflexes with soft-robot studies, his group now aims to conduct dynamic trials and field observations to simulate emergency landings and rapid mid-air course corrections—maneuvers critical for escaping predators without injury.

The researchers replicated the squirrels’ subcaudal scales and claws in order to physically test how the structures aid the animal in perching. Image: Empa / MPG

Beyond advancing our knowledge of arboreal movement, this work provides direct blueprints for biomimetic engineering. By emulating the thorn-like tail scales, future robots and drones could perch, land, and traverse complex vertical terrains—applications vital to agriculture, environmental monitoring, and disaster relief. As the project progresses from static models to real-world filming of wild squirrels, the team intends to refine robotic prototypes that truly mirror the squirrels’ remarkable agility.

Media Contacts:

Prof. Dr. Ardian Jusufi
Empa, Soft Kinetic
Phone +41 58 765 39 47
Ardian.Jusufi@empa.ch

Dr. Andrew K. Schulz
Max Planck Institute for Intelligent Systems
aschulz@is.mpg.de

Anna Ettlin
Communications
Phone +41 58 765 47 33
redaktion@empa.ch

SOURCE: EMPA