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Decoupling Geometry and Surface Chemistry in 3D-Printed ALD-Functionalized Porous Ceramic Channels
Antoine E Jimenez1, Diego R Gomes1, Carina Hedrich2
1Karlsruhe Institute of Technology, Institute for Applied Materials, Ceramic Materials and Technology, Haid-und-Neu Straße 7, Karlsruhe 76131, Germany.
ACS Omega
|July 28, 2026
Summary
This study reveals that aluminum oxide (Al2O3) ceramic channels exhibit faster capillary-driven transport than titanium dioxide (TiO2) due to rapid surface relaxation, enabling programmable fluid flow in porous materials.
Area of Science:
- Materials Science and Engineering
- Chemical Engineering
- Surface Science
Background:
- Capillary-driven transport in porous media is traditionally linked to static pore geometry and wettability.
- The dynamic surface energy of metal oxides, particularly in high-surface-area porous structures, is a critical but understudied factor influencing fluid transport.
- Existing manufacturing methods often couple macroscopic geometry with surface chemistry, limiting independent control.
Purpose of the Study:
- To introduce a novel manufacturing route that decouples macroscopic geometry from surface chemistry for porous ceramic fabrication.
- To investigate the influence of time-dependent surface properties on capillary-driven transport in engineered aluminum oxide (Al2O3) and titanium dioxide (TiO2) channels.
- To establish a platform for programmable capillary transport by independently tuning geometric and chemical properties.
Main Methods:
- Additive manufacturing combined with colloidal assembly (AMCA) was used to create porous ceramic structures.
- Atomic layer deposition (ALD) was employed for surface functionalization.
- Spontaneous imbibition experiments and time-resolved contact-angle measurements were conducted on Al2O3 and TiO2 channels at various times post-fabrication.
Main Results:
- A transition from Lucas-Washburn to a resistance-limited transport regime was observed, dominated by evaporation and viscous drag.
- Both Al2O3 and TiO2 surfaces became superhydrophilic post-burnout, followed by hydrophobic recovery.
- Al2O3 channels demonstrated faster imbibition rates and higher liquid rise than TiO2, attributed to reduced contact-line friction and pinning from rapid surface relaxation.
Conclusions:
- The AMCA-ALD method successfully decouples geometric and chemical factors in capillary transport, with geometry influencing volume but not height.
- Rapid surface relaxation in Al2O3 enhances fluid uptake, outperforming TiO2 despite TiO2's intrinsic hydrophilicity.
- This approach provides a versatile platform for designing porous ceramics with tailored transport properties for applications in microfluidics, diagnostics, and catalysis.
