NanoBioSystems and
Manipulation Lab

Various promising applications using self-assembly of nanostructures. Self-assembly of nanostructures opens up a number of exciting possibilities, including batteries, solar cells, photonic crystals, nanoplasmonics, and so on. When an assembly is highly organized and can be controlled locally and timely, not only is quality performance improved, but new opportunities and functions — such as genotyping, diagnosis, printing, or display — can be realized.

Our approach: Spatio-temporal control of nanostructure self-assembly using microfluidics and electrokinetics

For localized positioning in the microchannel or on the substrate, we use microfluidics and electrokinetics. Microfluidic phenomena, surface functionalization, inkjet printing, electrospinning, and other chemistry, physics, and tools are studied.
These well-organized structures enable the realization of energy harvesting, iontronics, optoelectronics, and biomedical microdevices.

We fabricate three-dimensional nanochannel network membranes (3D NCNMs) by combining capillary-guided nanoparticle confinement with evaporation-driven self-assembly. Nanoparticle suspensions are selectively trapped at predefined microchannel interfaces by a Laplace pressure barrier and subsequently self-assembled into highly ordered 3D structures, forming interconnected nanoscale pores. The resulting nanochannels exhibit ion-selective transport through electrical double-layer (EDL) overlap at the charged nanoparticle surfaces. By tailoring nanoparticle size, surface charge, and material properties, the ionic transport characteristics of the NCNM can be readily controlled. This versatile platform enables a wide range of applications in iontronics, energy harvesting and conversion, optoelectronics, and nanofluidic devices.

Iontronics for Neuromorphic Computing


Iontronics uses ions, rather than electrons, as information carriers, offering a natural bridge between artificial devices and biological systems. Inspired by biological ion channels, artificial nanochannels and nanopores can reproduce key ionic functions such as ion selectivity, gating, and rectification, enabling applications in sensing, energy conversion, and information processing.


Our research focuses on the memristive behavior of fluidic nanochannels, in which transient ion redistribution and concentration polarization provide history-dependent ionic transport. These dynamics closely resemble the short-term plasticity of biological synapses and enable fluidic devices to function as neuromorphic computing elements. By integrating ion transport, memory, and computation within an aqueous medium, we aim to develop brain-inspired computing systems that more closely mimic both the operating principles and the physical environment of the brain.


Representative work
Brain-inspired computing with fluidic iontronic nanochannels, PNAS (2024)

High-Performance Ionic Diodes Based on 3D Nanochannel Networks

We develop high-performance ionic diodes using three-dimensional nanochannel network membranes (3D NCNMs) with tailored geometry and surface charge. A homogeneously charged asymmetric NCNM enables unipolar ionic rectification through microscale geometric asymmetry while maintaining high ionic current through the interconnected 3D nanochannel network. Building on this concept, we further developed an asymmetric bipolar ionic diode by combining oppositely charged nanochannel regions with optimized microchannel geometry, achieving an ionic current rectification ratio of approximately 1,600. The strong rectification also enables efficient ion accumulation at the heterogeneous junction without electroconvective instability, which was utilized for highly sensitive Hg²⁺ detection down to 10 pM. These studies demonstrate the versatility of 3D NCNMs for controlling directional ion transport and enabling applications in ionic circuits, sensing, and energy conversion.

Representative works
High Current Ionic Diode Using Homogeneously Charged Asymmetric Nanochannel Network Membrane, Nano Letters (2016)
Asymmetric Nanochannel Network-Based Bipolar Ionic Diode, ACS Nano (2022)

Nanoelectrokinetically Enhanced Photocatalysis for Sustainable Water Treatment

We develop high-performance photocatalytic and photoelectrocatalytic platforms by integrating nanofluidic electrokinetics, plasmonics, and microfluidic transport for sustainable water treatment. Our ion-concentration-polarization-assisted photocatalytic reactor generates a nonlinear electric field that enhances charge separation across the photocatalyst layer, increasing photocatalytic reaction rates and enabling effective degradation of plastic contaminants. Building on this concept, we further developed a plasmon-enhanced photoelectrocatalytic microreactor using Au/TiO₂ nanofibers, where localized surface plasmon resonance (LSPR), electric-field enhancement, and efficient mass transport synergistically accelerate pollutant degradation. The system achieved 89% degradation of microcystin-LR within 12.9 min and demonstrated effective removal of both the toxin and its degradation intermediates. These approaches provide a versatile platform for treating emerging water contaminants, including microplastics, organic pollutants, and cyanotoxins, with potential for scalable and sustainable wastewater purification.

Representative works
Ion-concentration-polarization-assisted photocatalytic reactor, Lab on a Chip (2022)
Water purification of organic pollutants using photocatalytic microreactors integrating Au/TiO₂/carbon cloth under solar irradiation,
Chemical Engineering Journal Advances (2025)

Nanofluidic Energy Harvesting

We develop nanofluidic energy-conversion platforms that harvest electrical energy from salinity gradients by controlling selective ion transport through three-dimensional nanochannel network membranes (3D NCNMs). Inspired by the electric eel, we first demonstrated a high-voltage nanofluidic generator by alternately stacking cation- and anion-selective NCNMs, enabling the direct conversion of Gibbs free energy from ion-concentration gradients into electricity. The interconnected 3D nanochannel architecture provides high ionic conductance while maintaining strong ion selectivity, offering a scalable route toward clean and sustainable power generation.

Building on this concept, we further developed a plasmon-enhanced osmotic energy-conversion platform that combines light-induced surface-charge modulation with structurally optimized ion transport. Plasmonic excitation enhances the effective surface charge and ion selectivity of the NCNM, while a physics-informed genetic algorithm coupled with multiphysics simulations optimizes the bipolar nanochannel geometry for asymmetric ion transport. The synergistic combination of plasmonic enhancement and structural optimization significantly improves voltage, current, and power generation under both monochromatic and broadband solar illumination. Integration into a scalable series–parallel NCNM array further demonstrates the potential of this platform for high-performance blue-energy harvesting and sustainable power generation.

Representative works
High-voltage nanofluidic energy generator, Nano Energy (2018)
Plasmon-Enhanced Osmotic Energy Conversion via Physics-Informed Evolution of Nanochannel Networks, ACS Appl. Mater. Interfaces (2026)

This work was featured in news including YTN (link)

Wearable Biofuel Cells for Self-Powered Devices

We develop flexible and sustainable biofuel cells that harvest energy directly from glucose in bodily fluids such as sweat and tears. A textile-based biofuel cell integrated with moisture-management fabric enables continuous fuel transport without an external pump, generating sufficient power from sweat to operate wearable electronics. By stacking multiple cells in series and parallel, the system achieved an open-circuit voltage of 1.08 V and a maximum power output of 80.2 μW, demonstrating its potential for integration into sportswear and other wearable platforms.

Extending this concept to ocular devices, we developed a safe and durable self-powered smart contact lens with fully embedded glucose fuel cells. The lens maintains stable power generation under repeated deformation and long-term storage, while integration with electroresponsive hydrogel capacitors enables visual differentiation of tear-glucose levels. These platforms demonstrate the potential of biofuel cells as self-sustaining power sources for next-generation wearable and biomedical devices.

Representative works
Sustainable and high-power wearable glucose biofuel cell using long-term and high-speed flow in sportswear fabrics, Biosensors and Bioelectronics (2020)
Safe, Durable, and Sustainable Self-Powered Smart Contact Lenses, ACS Nano (2022)

This work was featured in many news including Chosun (link)

Colorimetric sensors using photonic crystals. Many animals and plants display structural colors in their epidermis, based on nanostructures that respond visually to environmental cues. Photonic crystals (PCs) built from regular dielectric nanostructures reflect light at particular wavelengths by diffraction/interference (Bragg equation); when the periodic spacing changes, the bandgap shifts and the color change is visible to the eye.

• Colorimetric VOCs sensing using photonic crystals - Real-Time Monitoring of Hazardous VOCs via Polymer Swelling in Opal Structures

• Virus sensing based on optical guidance using photonic crystals — Real-time visualization of influenza virus using Qdot-aptamer beacon and photonic crystals, RSC Advances 2018

• Smart contact lens using a PC-based strain sensor — The photonic crystal-based smart contact lens for continuous intraocular pressure monitoring, Lab on a Chip 2020.

• Actively tunable structural color — Flexible All-Solid-State Electrically Tunable Photonic Crystals, Advanced Optical Materials 2018.        

A new class of flexible all-solid-state electrically tunable photonic crystals (ETPCs) is realized via chemically induced polymer swelling and lattice control using dielectric elastomer actuators, showing a wide color range (red→blue-green) with low hysteresis and long-term stable operation.   Featured in donga science (link)

AI-Driven Inverse Engineering of Phononic Crystals —  We combine artificial intelligence with multiphysics simulations to inversely design phononic crystals with tailored bandgaps and defect modes, enabling rapid optimization of acoustic and elastic-wave control for sensing, vibration suppression, and other wave-engineering applications.

• Lego-inspired reconfigurable PnC platform

• Active-Learning-Guided Acoustic Metamaterial Resonators