RSC Applied Interfaces publishes interdisciplinary work with an applied focus, which can be read for free here. To celebrate the excellent articles that have been published so far in our journal, we asked some of our authors to discuss their work in more detail.
In this post, we hear from Andrew Tunell and Chih-Hao Chang at The University of Texas at Austin, USA, as they discuss their recently published article entitled ‘Nanoparticle dispersion and separation in superhydrophilic nanostructures‘.
An introduction from Andrew Tunell and Chih-Hao Chang
This research explores the dispersion, assembly, and size-selective separation of nanoparticles when suspended in a droplet and wicked through a superhydrophilic nanostructure. A wicking nanostructured surface was fabricated using interference lithography on a silicon wafer to create periodic structures with a gap spacing of 300 nm. Through optical, electron, and fluorescent microscopy, dispersion patterns of particles larger and smaller than the structure’s gap were investigated. Particles smaller than the structure’s gap assembled in the valleys of the surface structures and extended into the wicking region. Conversely, larger particles were confined to the wetted region and in some cases demonstrated assembly patterns directed by the structures. At high concentrations, these dispersion patterns were visible to the naked eye due to thin-film interference. This study establishes a passive, geometry-driven approach for particle filtering and separation, with potential application in cost-effective particle analysis and environmental contamination detection.
Additional investigations extending this work are ongoing within our group. Through the fabrication of additional structures, the separation of virus- and exosome-scale particle analogs has been demonstrated. The addition of contact transfer using polydimethylsiloxane (PDMS) has enabled the complete separation of particles of different sizes onto independent substrates. These early results support the potential advancement of this approach toward passive separation of biological nanoparticles and micro- and nanoplastic contaminants.
Meet the authors
Andrew Tunell
Andrew Tunell is a Mechanical Engineering PhD candidate within the University of Texas at Austin under the supervision of Prof. Chih-Hao Chang. His research focuses on particle interactions with periodic nanostructured surfaces. In addition to exploring particle wicking and separation in superhydrophilic surfaces, he also works closely with superhydrophobic surfaces for applications in dust and contamination resistance. His current work centers on minimizing nanoscale adhesion by studying and designing surfaces to mitigate electrostatic and van der Waal forces.
Chih-Hao Chang
Dr. Chih-Hao Chang is a Professor in the Walker Department of Mechanical Engineering and holds the Earl N. & Margaret Brasfield Endowed Faculty Fellowship in Engineering at the University of Texas at Austin. He received his B.S. (2002) from Georgia Institute of Technology and his M.S. (2004) and Ph.D. (2008) from Massachusetts Institute of Technology (MIT), all in Mechanical Engineering. He received the inaugural Early Career Faculty Award from National Aeronautics and Space Administration (NASA) in 2012, the Ralph E. Powe Junior Faculty Award from the Oak Ridge Associated Universities (ORAU) in 2013, and the Faculty Early Career Development (CAREER) Award from the National Science Foundation (NSF) in 2016. His research focuses on nanomanufacturing and the design and fabrication of 2D/3D multifunctional nanostructures with novel physical properties. His research group have demonstrated engineered nanostructures such as self-cleaning, anti-glare, anti-scratch glass, light-weight ultra-stiff nanolattice material with near-unity refractive index, stretchable transparent conductors, and responsive materials with dynamic iridescence. He is a Topical Editor for the journal Applied Optics.
Find out more about Prof. Chang’s Lab here.
Nanoparticle dispersion and separation in superhydrophilic nanostructures
Andrew Tunell, Kun-Chieh Chien, Samuel Lee, Nirmalay Barua, Alexandra Paul, Sapun H. Parekh, Tanya Hutter and Chih-Hao Chang
RSC Appl. Interfaces, 2025,2, 1199-1208. DOI: 10.1039/D5LF00089K
RSC Applied Interfaces is a dedicated, interdisciplinary reference journal for cutting-edge research on the applications of surfaces and interfaces. In addition to the applied focus, work considered for publication in RSC Applied Interfaces is expected to be highly original and of top quality. The journal seeks to report major scientific advances beyond the state of the art, at the cutting edge of this interdisciplinary field.