Jiseok's Lab
Project l 01
Polymeric holograms
Polymeric materials have been used to realize optical systems that interact with holographic signals through periodic variations of their structural or optical properties.
The conjugated polymers display three different holographic modes in a single architecture. Using dithering mask lithography, we realized two-dimensional patterns with varying cross-linking densities on a conjugated polymer, forming 2D periodic refractive index variations that displayed structural colour via diffraction. Anisotropic shrinkage causes optical and structural heterogeneities along the third dimension, displaying three-dimensional full parallax signals.
Unlike typical optical systems displaying a single-mode hologram, our system realizes multimodal holograms in a cost-effective and scalable manner. Our study presents a next-generation hologram manufacturing method for multilevel anti-counterfeiting and encryption technologies.
Project | 02
Maskless flow lithography (micofluidics)
Low-cost and high-resolution on-chip microscopes are vital for reducing cost and improving efficiency for modern biomedicine and bioscience. Despite the needs, the conventional microscope design has proven difficult to miniaturize. The optofluidic microscope design, readily fabricable with existing microfluidic technologies, offers low-cost and highly compact imaging solutions. More functionalities, such as encoding microparticles and fluorescence bioassay, can also be readily adapted into industrial systems. We anticipate that the our low cost optofluidic micro particle fabrication system can significantly address a range of biomedical and bioscience needs, and engender new microscope applications.
Project | 03
Upconversion Nanocrystals
Spectrally tunable microarchitectures are effective information media because they act as carriers of luminescent materials. Among them, upconversion nanocrystals(UCNs) are materials that attract attention due to the unique optical properties(e.g., anti-Stokes effect, high photochemical stability, and low toxicity). In this project, we are trying to develop UCNs-embedded smart functional 3D microstructure using opto-fluidics. In previous research, UCNs-based encoding systems with exponentially scalable encoding capacities and an ultralow decoding false-alarm rate, and luminescence color transition based on the crystal phase control. These systems can be applicable in barcoding of pharmaceutical packaging, multiplexed microRNA detection or a high temperature industrial thermal process.
Project | 04
Behavioral Optical Tactile Sensors
Tactile sensor system is a recognition and expression of external stimuli like as pressure, heat, torsion, and so on. Different from conventional electronic signal based tactile sensor, we investigated optical nanoparticles based optical tactile sensor. This system can detect various stimuli with quick, intuitive, and precise visible range signals. We also focus on types of nanoparticles, luminescence method, detection signal type. Our research will be applied to e-skin, smart devices, and new generation displays.
Project | 05
Polydiacetylene Chemosensors
Conjugated polymers recently have drawn much attention as an emerging sensory material due to their meritorious signal amplification, convenient optical detection, readily tunable properties, and easy fabrication. We review the molecular design principles of sensory conjugated polymer recognition events, which can trigger conformational change of the conjugated polymer, induce intermolecular aggregation, or change the distance between the conjugated polymer as an energy donor and the reporter dye molecule as an energy acceptor. These recognition/detection mechanisms result in mainly three types of measurable signal generation: turn on or turn off fluorescence, or change in either visible color or fluorescence emission color of the conjugated polymer. In this article, we highlight recent advances in fluorescent and colorimetric conjugated polymer-based biosensors.
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