Research

Ongoing Project I: Nanoconfined Wet Etching and Interfacial Reaction Kinetics

Wet etching remains an essential process for material removal, surface preparation, and sacrificial-layer release in micro- and nanoelectronic fabrication. As device dimensions continue to decrease and three-dimensional architectures become increasingly complex, wet chemical reactions often occur inside nanoscale gaps, channels, and high-aspect-ratio structures. Under these conditions, etching kinetics can deviate substantially from those measured on conventional open surfaces, leading to feature-size-dependent removal rates and challenges in process uniformity.

Our research investigates how nanoconfinement modifies wet-etching kinetics and interfacial reaction environments. We use horizontal and vertical nanochannel platforms to study chemically distinct systems, including alkaline etching of silicon and HF-based etching of silicon dioxide. 

Refs:

  1. Y. Zhong, D. Park, S. Xiao, S. Hu, L. Zheng, C. Duan#. “Wet etching of silicon in planar nanochannels.” Langmuir 40(18), 9501–9508 (2024). DOI: 10.1021/acs.langmuir.4c00056.
  2. Y. Zhong, D. Park, S. Xiao, L. Zheng, C. Duan. “Confinement-dependent wet etching kinetics in Si nanochannels.” Proceedings of SPIE: Advanced Etch Technology and Process Integration for Nanopatterning XIII 12958, 129580C (2024). DOI: 10.1117/12.3010881.

 

Ongoing Project II: Nanopore Platforms for Bioanalytical and Biomedical Applications

Solid-state nanopores provide a unique interface for manipulating and detecting ions, molecules, and nanoscale particles because transport through an individual pore can be strongly influenced by surface charge, particle–pore interactions, applied voltage, and pressure. Our earlier work established single-nanopore platforms in which nanoparticle blockage produces rapid and reversible gating, mechanosensitive ionic transport, and electrical signatures that can be used to characterize individual nanoparticles. These systems provide a foundation for bio-inspired transport control, single-particle analysis, chemical delivery, and sensing.

Our current research extends these concepts from individual nanopores to parallel nanopore arrays for higher-throughput bioanalytical detection. Nanopore-array blockage enables rapid capture and quantification of extremely dilute nanoparticles, while the spatially resolved array architecture can also support single-particle optical readout. More recently, we have integrated nanopore arrays with isothermal amplification and CRISPR-Cas detection to create low-input, highly sensitive single-bead fluorescence assays for pathogen detection. By combining the mechanistic control available in single nanopores with the parallelism and scalability of nanopore arrays, we aim to develop compact platforms for nanoparticle characterization, biomolecular diagnostics, pathogen detection, and other biomedical and bioanalytical applications.

Refs:

  1. J. Xu*, X. Jiang*, M. K. Dashtarzhaneh*, Y. Zhong, B. Sharma, R. Peng, L. Zheng, F. Khodadadi#, K. Du#, C. Duan#. “Ultrasensitive, low-input detection of avocado sunblotch viroid via RPA-CRISPR and nanopore-array single-bead fluorescence readout.” Microsystems & Nanoengineering 12(1), 187 (2026). DOI: 10.1038/s41378-026-01312-2.
  2. R. Yazbeck*, J. Xu*, Y. Zhong, Y. Xu, L. Zheng, B. Xu, C. Duan#. “Rapid detection and quantification of ultralow-concentration nanoparticles based on nanopore array blockage.” Droplet 4(4), e70020 (2025). DOI: 10.1002/dro2.70020.
  3. R. Yazbeck*, Y. Xu*, T. Porter, C. Duan#. “Nanoparticle-blockage-enabled rapid and reversible nanopore gating with tunable memory.” Proceedings of the National Academy of Sciences 119(27), e2200845119 (2022). DOI: 10.1073/pnas.2200845119.
  4. R. Yazbeck, M. A. Alibakhshi, J. von Schoppe, K. L. Ekinci, C. Duan#. “Characterization and manipulation of single nanoparticles using a nanopore-based electrokinetic tweezer.” Nanoscale 11(47), 22924–22931 (2019). DOI: 10.1039/C9NR08476B.

 

Ongoing Project III: Patterned Micro/Nano Structures for Phase-Change Heat Transfer

About 40% of the total power generated in the United States by heat engines is through the Rankine cycle, where water vapor is used to drive steam turbines. Boiling heat transfer plays an important role in these energy-conversion devices because the critical heat flux (CHF) in the pool-boiling curve limits the achievable power density and efficiency.

Although enhancing CHF can have a major impact on many energy-conversion and thermal-management systems, significant challenges remain because of the complex mechanisms governing boiling heat transfer. Far-field hydrodynamic limits have traditionally been considered important in determining CHF, while studies of micro- and nanostructured surfaces have demonstrated that near-surface effects—including nucleation-site density, surface wettability, capillary transport, and bubble dynamics—can also strongly influence heat-transfer performance.

We are developing patterned micro/nano structures to systematically investigate and improve phase-change heat transfer. These structures provide controlled platforms for studying the interplay between near-surface and far-field transport and are being explored for both boiling and evaporation applications.

 

Ongoing Project IV: Micro/Nano-structured Materials for Energy Conversion and Storage

Batteries have been widely used in portable electronic devices, urgent power supply and vehicle starting-lighting-ignition. Recent increasing concerns on energy and environment further expand their applications in renewable energy storage and electric vehicles. Although the theoretical energy density of current batteries is high enough to satisfy these new demands, their practical energy density (which is around 30% percent of the theoretical energy density) is generally too low for such new applications due to the usage of inactive components (e.g. cover and separator ) and internal energy loss.

To improve practical energy density, one needs to either develop new batteries with higher theoretical energy density or optimize the structure of current batteries. It has been shown that controlled nanostructures have potential applications on both aspects. We propose to design and synthesize new controlled nanostructures for two separate projects: new light nanostructured materials as current collectors and separators and new air cathode for Lithium-Air batteries.