The langoustine tails that typically end up in restaurant compost bins have found an unlikely second career. Engineers at Switzerland’s EPFL are building functional robots from discarded crustacean exoskeletons. The grippers can hoist 500-gram objects. The swimmers paddle through water at 11 centimeters per second.

The work tackles a problem most roboticists ignore: what happens when machines wear out. Traditional robots combine metal frames, plastic joints, and electronic components into structures nearly impossible to disassemble or recycle. Josie Hughes, who leads EPFL’s Computational Robot Design and Fabrication Lab, wondered if food industry waste could offer an alternative.

Her team’s answer involves augmenting dead crustacean shells with synthetic tendons and motors, then separating the components when robots reach end-of-life. Biodegradable joints decompose naturally. Actuators get reused.

This circular approach addresses sustainability concerns without sacrificing performance. A three-gram langoustine exoskeleton can support 680-gram payloads in specific configurations. Grippers bend at 8 Hz. Swimming robots built with paired exoskeletal fins operate at speeds comparable to soft robotic alternatives. The biological components cost nothing beyond collection and cleaning.

Why Crustacean Shells Work

Crustacean exoskeletons prove surprisingly well-suited for robotic applications. Each langoustine abdomen contains six articulated segments. Mineralized plates provide rigid structure. Flexible joint membranes allow large bending angles. This architecture, refined over evolutionary timescales for underwater agility, requires minimal modification for mechanical use.

The fabrication process involves strategic augmentation rather than complete redesign. Researchers embed an elastomer along the dorsal shell to create restoring force. They route inextensible tendons through ventral segments that act as natural pulleys. A silicone coating seals the structure to prevent dehydration.

Without coating, joints lasted roughly five hours before drying stiffened the membranes. Ecoflex coating extended operational life to 25 hours. Dragon Skin coating reached 39 hours.

This sidesteps problems inherent to bio-hybrid systems using living tissue, which demand precise temperature control, nutrient supply, and expensive cell-culturing infrastructure. Dead exoskeletons, by contrast, remain stable at room temperature. They require no maintenance beyond occasional moisture.

“To our knowledge, we are the first to propose a proof of concept to integrate food waste into a robotic system that combines sustainable design with reuse and recycling.”

Lead author Sareum Kim’s claim holds up. Researchers have experimented with spider legs as grippers and beetle shells as structural elements. But using crustacean waste from food production represents a genuinely novel material source. The langoustines come from frozen seafood destined for cooking. Supply is effectively unlimited wherever these crustaceans are consumed.

Directional Strength

The exoskeletons exhibit useful directional properties. During flexion, joints move freely with minimal resistance. But extension locks the structure at geometric hard limits where tergite plates contact neighboring grooves. This produces stiffness spikes up to 3.3 Newton-millimeters per degree. The asymmetry lets robots generate directional thrust through symmetric cyclic motion, functioning like a ratchet in resistive media.

For swimming applications, this proves sufficient. Paired fins mounted on a motorized base were tested in a three-meter pool. They achieved speeds from 2 to 11 centimeters per second depending on flapping frequency. Counterintuitively, symmetric power and return strokes outperformed asymmetric patterns. The researchers suggest rapid strokes prevented full fin deployment, reducing thrust differential.

More precise control requires tendon augmentation. A single cable routed through the ventral shell creates an underactuated continuum mechanism. Pulling patterns determine motion sequences. Route the tendon straight from base to tip, you get smooth progressive bending ideal for enveloping grasps. Add intermediate pulley points at alternating segments, the structure curls with mid-section priority suitable for precision grips. Change anchor positions again, different kinematics emerge.

The grippers successfully handled objects ranging from highlighter pens to tomatoes to 500-gram weights. Each object elicited different conformations as the underactuated structure adapted passively to surface geometry. Biological variation means each exoskeleton bends slightly differently, though.

“Exoskeletons combine mineralized shells with joint membranes, providing a balance of rigidity and flexibility that allows their segments to move independently. These features enable crustaceans’ rapid, high-torque movements in water, but they can also be very useful for robotics.”

The Circular Economy Angle

The implications extend beyond clever demonstrations. Circular economy advocates have long argued that products should be designed for disassembly and material recovery rather than eventual landfilling. Electronics and robotics rarely follow this principle. Components get glued, welded, and fastened into integrated assemblies. Separating aluminum from copper from plastic requires industrial shredding.

Hughes’ approach inverts this pattern. Exoskeletons attach to synthetic bases through mechanical fasteners that release easily. Small components like elastomers and fishing line used for tendons can biodegrade or be disposed of as minimal waste. Motors and electronics transfer intact to new exoskeletal structures. The model resembles traditional tool design where handles wear out but blades get resharpened and remounted.

Whether this scales beyond laboratory prototypes remains uncertain. Biological variability complicates manufacturing standardization. No two langoustine tails bend identically. This requires either computational compensation through adaptive controllers or statistical characterization to sort exoskeletons by mechanical properties. The researchers acknowledge these challenges while suggesting that tolerating variability might prove easier than eliminating it.

Cost analysis is conspicuously absent from the published work. Synthetic soft grippers might be more expensive to manufacture initially but offer predictable performance. Exoskeletal systems cost nothing for base materials but require individual characterization and custom augmentation. Which approach proves economically viable depends on application requirements and production scale.

What Comes Next

The structural principles apply across arthropod species at vastly different scales. Beetles measuring 0.3 millimeters, lobsters reaching 60 centimeters, shrimp, crawfish, and crabs all possess segmented exoskeletons with varying mechanical properties. Each represents a potential material source with different load capacities, flexibility ranges, and joint geometries. The researchers suggest this biological diversity offers a design space worth systematic exploration.

Future applications might include biomedical implants where biocompatibility and eventual biodegradability offer advantages over permanent synthetic materials. Environmental monitoring platforms could deploy robots temporarily without creating persistent waste. Whether these remain speculative or find practical implementation depends partly on technical refinements and partly on whether circular design principles gain traction in robotics manufacturing.

For now, the work establishes proof of concept. Discarded seafood shells can be engineered into functional machines, then cleanly disassembled when usefulness expires. That dinner plate waste can grip, bend, swim, and eventually decompose suggests our assumptions about appropriate robotic materials deserve reconsideration. Perhaps other biological structures discarded daily merit similar engineering attention.

Advanced Science: 10.1002/advs.202517712