Exploding polymer-coated gold nanoparticles in nano-engine. Image source: Yi Ju/University of Cambridge

New nanoscale engines powered by light may one day propel microrobots in biomedical or other nanomachinery applications. The actuating nano-transducers (ANTs) developed by University of Cambridge researchers are a few billionths of a meter in size. But they are capable of a force per unit-weight nearly 100 times higher than many motors or muscles.

The prototype device is composed of charged gold nanoparticles combined with temperature-responsive gel polymers. Large amounts of elastic energy are stored in a fraction of a second as the nano-engine is heated with a laser and the polymer expels water. The nanoparticles aggregate into tight clusters and rapidly absorb water upon cooling, resulting in explosive expansion.

The ANTs are characterized as bio-compatible, cost-effective to manufacture, fast to respond, and energy efficient. The university researchers are working to advance this technology for microfluidics bio-applications.