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Research Fields

Flexible optoelectronics
Self-powered energy
Flexible drug delivery
Laser-material interaction
Flexible LSI & Memristor
Flexible Piezo Sensor


      Flexible biomedical optoelectronics


    Flexible biomedical optoelectonic system is very useful since they can be conformally placed on the heart, brain and rolled upon the blood vessels of the spine to diagnose or even treat various diseases. LEDs have been actively studied as therapeutic and diagnostic tools for medical treatment. Our flexible inorganic LED (e.g GaAs and GaN)enables implantable, flexible biomedical optoelectronic devices. Flexible inorganic biomedical optoelectronic system could be utilized in the human body for biomedical sensing of disease and even control of neural optogenetic signals simultaneously. We have developed high performance flexible vertical ILEDs (f-VLEDs) using anisotropic conductive films, for extremely efficient and highly aligned f-LED arrays.

    We have developed unique flexible electrocorticogram (ECoG) system, called iWEBS (insertable wrapping electrode array beneath the skull), for spatiotemporal mapping of neural interactions. Our invivo flexible electrodes is used to be inserted through a small cranial slit and wraps onto the cortical brain surface in living animals. This technology facilitates not only minimizing brain damage but also keeping the stable intact of flexible electrodes, which is essential for measuring functional connectivity across the wide-range cortical areas. Using our flexible iWEBS, we could record dynamic changes of optogenetic signals across major cortical brain domains of freely moving mice. Our flexible iWEBS represents a significant improvement over conventional ECoG recording, therefore, is a competitive recording system for mapping wide-range brain connectivity under various behavioral conditions.

    Flexible Inorganic LED display

  Flexible inorganic LED display has been spotlighted as a powerful medium of visual communication system that can be attached to any places for the wearable and portable applications. Prof. Lee's group has developed the ACF interconnected inorganic LEDs (e.g.gallium nitride (GaN) and gallium arsenide (GaAs) LEDs) on flexible substrate for an active-matrix display. Using these advanced technologies, we can build the flexible inorganic LED display for wearable and flexible application.

  • Related References

"Optogenetic Mapping of Functional Connectivity in Freely Moving Mice via iWEBS" ACS Nano,10, 2791, 2016  PDF  [IF=13.9]

"Self-powered Fully-Flexible Light Emitting Systems enabled by Flexible Energy Harvester", Energy Environ. Sci., 7(12), 4035, 2014, PDFCover Article. [IF=29.5]

"Water-resistant Flexible GaN LED on a Liquid Crystal Polymer Substrate for Implantable Biomedical Applications", Nano Energy, 1 , 145 (2012). PDF  [Movie]  [IF=12.3]

"Bio-Integrated Flexible Inorganic LED", Nanobiosensors in Disease Diagnosis, 1, 5, 2012  PDF

"Laser Lift-Off of GaN Thin Film and its Application to the Flexible Light Emitting Diodes",  Proc. of SPIE, 8460, 846011-1, (2012) PDF