The precise control of tiny droplets on surfaces is essential for advanced manufacturing, pharmaceuticals, and next-generation lab-on-a-chip diagnostics. However, once droplet volume reaches pico- and nanoliter scales, the droplets become extremely sensitive to microscopic surface irregularities, and friction at the solid–liquid interface becomes a major obstacle to smooth transport.
Against this backdrop, a study led by Dr. Mizuki Tenjimbayashi and his colleagues at Materials Nanoarchitectonics (MANA) proposed a novel strategy that involved coating the droplet with a repellent material instead of engineering a perfectly smooth surface. This study published in the journal ACS Nano has been selected as the “Supplementary Cover Article.”
Using an ultrasonic spray, the team coated picolitre droplets with fluorocarbon-modified fumed titania particles of 20 nanometers diameter, forming a dynamic nano–micro coating around them. Once coated, the droplets no longer experienced high friction at a solid–liquid interface. Instead, they moved over the particle layer via solid–solid contact, which dramatically reduced the force required for sliding, down to a subnanonewton level.
When the team compared sliding behavior across different droplet volumes, they found that this technique reduced the droplet-repellent volume by three to four orders of magnitude compared to that of classical liquid-repellent interfaces. Importantly, the particle coating preserves the droplet’s ability to change shape, allowing droplets to merge, split, or reshape when stimulated, displaying capabilities that are crucial for microfluidic applications.
The ability to control droplets at such tiny scales could transform pico- and nanofluidics, soft microrobotics, and systems where droplets behave collectively like particles. It could then be possible to miniaturize chemical and biomedical procedures. Experiments, diagnostic tests, and sensing tasks could be performed using only picolitre amounts of liquid, reducing reagent consumption and chemical waste and facilitating more sustainable scientific and industrial practices.
***
Source: Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS)
Research Highlights Vol. 94
https://www.nims.go.jp/mana/research/researchactivities/highlights/vol94.html
About Research Center for Materials Nanoarchitectonics (MANA)
The Research Center for Materials Nanoarchitectonics (MANA) is one of the core research centers of the National Institute for Materials Science (NIMS). Established in 2007 under the World Premier International Research Center Initiative (WPI) by Japan’s Ministry of Education, Culture, Sports, Science and Technology (MEXT), MANA pioneers the concept of Nanoarchitectonics to design innovative materials at the nanoscale level. MANA promotes world-class research, fosters global collaboration, and supports the development of young scientists. With a strong international presence and interdisciplinary approach, MANA continues to lead in advancing materials science for a more sustainable and innovative future.
Website: https://www.nims.go.jp/mana/index.html
MANA Research Highlights
MANA independently selects and publishes its exceptional research achievements as “Research Highlights,” which are different from the official ‘Press releases’ disseminated by NIMS, with the purpose of showcasing its research outcomes.
https://www.nims.go.jp/mana/research/researchactivities/highlights/index.html
About the World Premier International Research Center Initiative (WPI)
The WPI was launched in 2007 by Japan’s Ministry of Education, Culture, Sports, Science and Technology (MEXT), to foster globally visible research centers exhibiting the highest standards and outstanding research environments. With over a dozen centers that operate at several institutions throughout the country, these centers are given a high degree of autonomy, allowing them to pursue innovative modes of management and research. This program is supported by the Japan Society for the Promotion of Science (JSPS).
See the latest research news from the centers at the:
WPI News Portal: https://www.eurekalert.org/newsportal/WPI
WPI program website: https://www.jsps.go.jp/english/e-toplevel/index.html
ACS Nano
Manipulating Pico- to Nanoliter Droplets on Surfaces without Sticking
6-Nov-2025