A 3D-printed robot moth grows UV sensors using its own artificial blood
Researchers at the University of Tartu and the Italian Institute of Technology demonstrate on-demand sensor growth via internal chemical circulation.
Engineers have built a moth-shaped prototype that uses an internal fluid circulation to grow light detectors directly on its wings. The development in soft robotics, carried out by teams at the University of Tartu in Estonia and the Italian Institute of Technology, enables a machine to form new hardware components after manufacturing rather than relying solely on pre-installed parts.
Chemical synthesis inside microfluidic channels
Robots typically operate with a fixed hardware configuration set during assembly. To overcome this constraint, researchers at the University of Tartu and the Italian Institute of Technology (IIT) designed an insect-scale device capable of in situ material synthesis, as reported in New Atlas. The moth-inspired body is produced through 3D printing using transparent plastic embedded with miniature fluidic pathways.
A miniature pump drives roughly 3 ml (0.1 fluid ounces) of carrier liquid through the printed vascular network. The circulating fluid carries pyrrole, a monomer that diffuses approximately one-hundredth of a millimeter into the adjacent polymer walls. When exposed to ultraviolet light alongside a light-activated additive, the pyrrole undergoes polymerization to form polypyrrole, an electrically conductive plastic that appears as a dark patch on the wing surface.
“Growing the receptor on site means the environment itself can pattern the robot, based on what is actually happening at that time.”
— Kadri-Ann Pankratov, doctoral researcher at the University of Tartu
Sensing mechanisms and physical response
Electrical detection relies on pre-installed conductors rather than grown circuitry. Thin gold wires integrated into the structure during printing connect directly to the newly formed conductive site, as detailed in the team's study published in Advanced Science and highlighted by New Atlas.
When ultraviolet rays strike the polypyrrole patch, its electrical resistance drops momentarily. An onboard microprocessor registers this resistance drop and triggers a reaction: an integrated LED blinks or a wire made of nitinol, a shape-memory alloy, contracts to flap the wings. Tests confirmed that the newly grown sensor retained functional conductivity after four months in storage. Because residual monomer continues reacting under subsequent exposures, sensor sensitivity increased over time, though each signal cycle requires roughly five minutes to return to baseline.
Current limits and engineering pathways
The experimental moth remains a laboratory prototype and cannot achieve untethered flight. Wing actuation currently relies on external power to heat the nitinol wire, although the researchers have conducted preliminary trials using chemical reagents in the fluid to power the onboard chip.
Operational limits remain defined by physics and user control. In current tests, a physical stencil placed by researchers dictates where the light hits the wing, and the polymerization reaction cannot be reversed. However, first author Kadri-Ann Pankratov indicated that the fluidic network can be drained, flushed, and refilled with alternative chemistries. The research builds on prior material work, such as IIT's FiloBot and autonomous systems from Cornell University, pointing toward future systems where vascular channels serve both material delivery and energy storage functions, as documented by New Atlas.
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