Successful Installation of MCA-4
— Microscopic Contact Angle Meter at Chongqing University
| 2026/2/13 |
Professor Xiao Yan: School of Energy and Power Engineering, Chongqing University |
Professor Xiao Yan of Energy and Power Engineering, Chongqing University (Second from right), the interviewer from Kyowa Interface Science, and our distributor's staff.
Professor Xiao Yan holds a Ph.D. in Engineering from Tsinghua University and currently serves as a supervisor for Master's and Doctoral students at the School of Energy and Power Engineering, Chongqing University.
After graduating with his doctorate, he conducted postdoctoral research at the University of Illinois Urbana-Champaign (UIUC) and the Hong Kong University of Science and Technology.
Microdroplets Open the Door to Energy Management
――― What specific applications and directions is your research related to?
Prof. Yan: I primarily research fluid and heat transfer in the energy field, with a particular focus on the energy and momentum transport processes of micro-
scale fluids and their regulation. The relevant research results can support the development of technologies such as advanced cooling. My specific research
method involves observing the behavior of tiny water droplets sprayed onto sample materials; on one hand, to characterize surface properties and structures,
and on the other, to utilize surface properties to control the fluid transport process. The droplets ejected by the precision inkjet system are extremely small and
almost unaffected by gravity, which creates ideal conditions for me to conduct research on micro-scale fluid and heat transfer.
Precision Operation Makes Experiments Handy
――― Do you have any evaluation or feedback after using the MCA measurement system?
Prof. Yan: The inkjet system allows for precise adjustment of the dispensing position and control of the liquid volume. This offers a high degree of freedom in
setting conditions for experiments and is very convenient to operate. Although I have used inkjet systems from other manufacturers, the MCA's inkjet system
performs exceptionally well in terms of dispensing stability.
――― Do you have any suggestions or comments regarding the measuring instrument?
Prof. Yan: If the system could dispense multiple droplets, it might open up more possibilities for experiments.
――― Thank you for your suggestion. We will consider incorporating it into future product design and development.
The Moment of Fluid Motion in Microdroplets
――― Did you have any impressive experiences while conducting research experiments with the MCA?
Prof. Yan: As part of our exploration, the MCA accidentally captured an interesting droplet phenomenon during an experiment. In 2018, we named this recorded
image "Swimming Jellyfish" and submitted it to Nikon, where it won a global scientific photography award. Because of this award, the image was exhibited in
museums across the United States and was also rated by the journal Nature as one of the most beautiful science photos of September.
The moment this image was recorded occurred due to interface phenomena; a small amount of alcohol added to the droplet caused evaporation at the interface,
and the phenomenon was caused by the difference in surface tension.
This image was also the only non-living subject among the Nikon award-winning works at that time, yet its swimming motion within the droplet evoked the
imagination as if it possessed life.
The Research Applications Using MCA
――― In your opinion, what significance and possibilities does the MCA hold for academic research and applications?
Prof. Yan: The MCA has profound significance for me; it could be said that it guided my research direction. Besides measuring contact angles, the MCA can
also be used for other observational studies. Beyond my research field—energy control technology— I believe there are other research uses and possibilities in
research institutions, such as in micro-science and aerospace science.
While conducting research at an American university, I shared this instrument with domestic researchers, who were very interested. Now that this equipment
has finally entered domestic universities, it is something to look forward to very much. I am also curious to see how other researchers will use this instrument
(and what research they will do). When I used this equipment in the past, I wrote several papers with my co-advisor, Professor Nenad Miljkovic, and the details
regarding the use of the MCA are included in them.
――― Thank you very much for taking your valuable time to share these experiences regarding the research use of the MCA.
About the Photography Work "Swimming Jellyfish
- Yan, X., Sett, S., Feng, L., Zhang, L., Huang, Z., Chen, F., & Miljkovic, N. (2019).
“Swimming Jellyfish “: Visualizing Jet-Like Internal Flow in Coalescing Droplets. Journal of Heat Transfer, 141(10).
https://www.nature.com/immersive/d41586-020-02720-8/index.html
Representative Papers by Prof. Yan on MCA / Microdroplet Interface Research
“Swimming Jellyfish “: Visualizing Jet-Like Internal Flow in Coalescing Droplets. Journal of Heat Transfer, 141(10).
- Xiao Yan, Zhiyong Huang, ..., Daniel Orejon, Feng Chen, Nenad Miljkovic (2019).
Atmosphere-mediated superhydrophobicity of rationally designed micro/nanostructured surfaces. ACS Nano, 13(4), 4160-4173.
- Xiao Yan, Feng Chen, ..., Zhiyong Huang, Nenad Miljkovic (2019).
Hierarchical condensation. ACS Nano, 13(7), 8169-8184.
- Xiao Yan, Yimeng Qin, ..., Jie Feng, Nenad Miljkovic (2020)
Laplace pressure driven single droplet jumping on structured surfaces. ACS Nano,14(10), 12796-12809.
- Xiao Yan, Feipeng Chen, ..., Jie Feng, Nenad Miljkovic (2022)
Micro-Scale Confinement and Wetting Contrast Enable Enhanced and Tunable Condensation. ACS Nano,16(6), 9510
- Xiao Yan, Bingqiang Ji, Lezhou Feng, Xiong Wang, Daolong Yang, Kazi Fazle Rabbi, …, Nenad Miljkovic (2022).
Particulate–droplet coalescence and self-transport on superhydrophobic surfaces. ACS nano, 16(8), 12910-12921.
[Instruments Used] Microscopic Contact Angle Meter MCA-4
The evolution of micro-droplets on material surfaces usually occurs within very short timeframes and at extremely small scales. Therefore, during
the experimental process, the stability of droplet generation, the accuracy of volume control, and the clarity of image recording are critical. For scholars
engaged in fluid and heat transfer research, the ability to observe the behavior of single microdroplets on material surfaces under repeatable
conditions is an important foundation for experimental research.
MCA-4 combines a precision inkjet dispensing system with high-speed image recording capabilities, enabling researchers to stably generate
microdroplets and observe and analyze their behavior on material surfaces. In Professor Yan's related research work, the MCA-4 is used for contact
angle measurement and experimental observation of micro-droplets, providing reliable support for the acquisition of experimental data.