Kunli Xiong – Soft Matter Lab

Microscopic Geared Metamachines published in Nature Communications

Top: single gear; Bottom: the second gear from the right has an optical metamaterial that react to laserlight and makes the gear move. All gears are made in silica directly on a chip. Each gear is about 0.016 mm in diameter. *(Image by G. Wang)*

Microscopic Geared Metamachines
Gan Wang, Marcel Rey, Antonio Ciarlo, Mohanmmad Mahdi Shanei, Kunli Xiong, Giuseppe Pesce, Mikael Käll and Giovanni Volpe
Nature Communications 16, 7767 (2025)
doi: 10.1038/s41467-025-62869-6
arXiv: 2409.17284

The miniaturization of mechanical machines is critical for advancing nanotechnology and reducing device footprints. Traditional efforts to downsize gears and micromotors have faced limitations at around 0.1 mm for over thirty years due to the complexities of constructing drives and coupling systems at such scales. Here, we present an alternative approach utilizing optical metasurfaces to locally drive microscopic machines, which can then be fabricated using standard lithography techniques and seamlessly integrated on the chip, achieving sizes down to tens of micrometers with movements precise to the sub-micrometer scale. As a proof of principle, we demonstrate the construction of microscopic gear trains powered by a single driving gear with a metasurface activated by a plane light wave. Additionally, we develop a versatile pinion and rack micromachine capable of transducing rotational motion, performing periodic motion, and controlling microscopic mirrors for light deflection. Our on-chip fabrication process allows for straightforward parallelization and integration. Using light as a widely available and easily controllable energy source, these miniaturized metamachines offer precise control and movement, unlocking new possibilities for micro- and nanoscale systems.

After the article was published, it was reported by many media outlets, University of Gothenburg, New Scientist, Optics.org, Phys.org, ScienceDaily, Discover Magazine, among others.

Featured in:
GU: Light powered motor fits inside a strand of hair.
New Scientist: Microscopic gears powered by light could be used to make tiny machines and video on Youtube.
Optics.org: University of Gothenburg makes micron-scale light-powered gears
Phys.org: New light-powered gear fits inside a strand of hair
ScienceDaily: Scientists build micromotors smaller than a human hair
Discover Magazine: The Smallest Motors in History Can Fit Inside a Strand of Hair
@DrBenMiles: Scientists Create Micro Machines Powered by Light

Retina electronic paper with video-rate-tunable 45000 pixels per inch on ArXiv

High-resolution display of “The Kiss” on Retina E-Paper vs. iPhone 15: Photographs comparing the display of “The Kiss” on an iPhone 15 and Retina E-paper. The surface area of the Retina E-paper is ~ 1/4000 times smaller than the iPhone 15. *(Image by the Authors of the manuscript.)*

Retina electronic paper with video-rate-tunable 45000 pixels per inch
Ade Satria Saloka Santosa, Yu-Wei Chang, Andreas B. Dahlin, Lars Osterlund, Giovanni Volpe, Kunli Xiong
arXiv: 2502.03580

As demand for immersive experiences grows, displays are moving closer to the eye with smaller sizes and higher resolutions. However, shrinking pixel emitters reduce intensity, making them harder to perceive. Electronic Papers utilize ambient light for visibility, maintaining optical contrast regardless of pixel size, but cannot achieve high resolution. We show electrically tunable meta-pixels down to ~560 nm in size (>45,000 PPI) consisting of WO3 nanodiscs, allowing one-to-one pixel-photodetector mapping on the retina when the display size matches the pupil diameter, which we call Retina Electronic Paper. Our technology also supports video display (25 Hz), high reflectance (~80%), and optical contrast (~50%), which will help create the ultimate virtual reality display.

Kunli Xiong appointed at Uppsala University

Kunli Xiong has been appointed as an assistant professor at Uppsala University, Department of Material Science and Engineering. Congrats!

He will start his new appointment on May 6th 2024. His research will focus on nanooptics technology for electronic paper, optical neural networks, and intelligent microparticles.

Kunli Xiong joins the Soft Matter Lab

Kunli Xiong started his research position at the Physics Department of the University of Gothenburg on 16th June 2022.

Kunli received a Ph.D. degree in Material Science from the Chalmers University of Technology, Sweden. In his research, he focuses on developing novel plasmonic E-paper technology.