South Korean team developed a four-day process for printing microbots from sulfur waste that can be moved and recycled

Short on the new development

South Korean scientists have created the world’s first 4‑D printing technology that turns industrial refinery waste—mostly sulfur—into materials for flexible robotics. This solution simultaneously addresses three problems: disposal of hazardous byproducts, sourcing suitable raw material for robots, and recycling them after use.

What is it?

- 4‑D printing differs from conventional 3‑D in that the modeling process takes “time” into account—objects can autonomously change shape under external stimuli (heat, light, electromagnetic fields).

- In this case sulfur is converted into PSNs (poly(phenylene polysulfide)) polymers that have shape memory and respond to temperature, light or magnetic field.

How the technology works

1. Printing: microrobots slightly larger than 1 cm are produced.

2. Shape and motion: when heated or illuminated they deform according to their programmed shape memory; adding about 20 % magnetic powder allows them to be controlled in a magnetic field.

3. Assembly: parts are joined with an infrared laser, seam‑free—simply melted into a single structure.

Scientists have already fabricated a model of the Sagrada Família using this technology.

Why it matters

- Environmental friendliness. Waste is turned into useful material; after the robots are used they can be fully remelted and reused without loss of properties.

- Versatility. Robots can navigate hard‑to‑reach areas, deliver medication inside the body, and perform many tasks.

- Cost reduction. No need for motors or continuous power, and traditional flexible robot durability issues are solved.

Support

The research grant was provided by the U.S. military, which is interested in advancing flexible robotics.

Thus this technology combines solving an environmental problem with creating new opportunities for robotics and potentially opens the way to a fully closed‑loop production cycle.