신소재공학과

Research Highlight

A Korea Advanced Institute of Science and Technology (KAIST) research team led by Professor Keon Jae Lee from the Department of Materials Science and Engineering and Professor Daesoo Kim from the Department of Biological Sciences has developed flexible vertical micro LEDs (f-VLEDs) using anisotropic conductive film (ACF)-based transfer and interconnection technology. The team also succeeded in controlling animal behavior via optogenetic stimulation of the f-VLEDs.


                           


Flexible micro LEDs have become a strong candidate for the next-generation display due to their ultra-low power consumption, fast response speed, and excellent flexibility. However, the previous micro LED technology had critical issues such as poor device efficiency, low thermal reliability, and the lack of interconnection technology for high-resolution micro LED displays.

The research team has designed new transfer equipment and fabricated a f-VLED array (50x50) using simultaneous transfer and interconnection through the precise alignment of ACF bonding process. These f-VLEDs achieved optical power density (30 mW/mm2) three times higher than that of lateral micro LEDs, improving thermal reliability and lifetime by reducing heat generation within the thin film LEDs.
These f-VLEDs (thickness: 5 micrometre, size: below 80 micrometre) can be applied to optogenetics for controlling the behavior of neuron cells and brains. In contrast to the electrical stimulation that activates all of the neurons in brain, optogenetics can stimulate specific excitatory or inhibitory neurons within the localized cortical areas of the brain, which facilitates precise analysis, high-resolution mapping, and neuron modulation of animal brains. (Refer to the author's previous ACS Nano paper "Optogenetic Mapping of Functional Connectivity in Freely Moving Mice via Insertable Wrapping Electrode Array Beneath the Skull")

In this work, they inserted the innovative f-VLEDs into the narrow space between the skull and the brain surface and succeeded in controlling mouse behavior by illuminating motor neurons on two-dimensional cortical areas located deep below the brain surface.


                              이건재 교수 기사 4.jpg


Comparison of micro-LEDs Technology. (IMage: KAIST)


Professor Lee said, "The flexible vertical micro LED can be used in low-power smart watches, mobile displays, and wearable lighting. In addition, these flexible optoelectronic devices are suitable for biomedical applications such as brain science, phototherapeutic treatment, and contact lens biosensors."
He recently established a startup company (FRONICS Inc.) based on micro LED technology and is looking for global partnerships for commercialization. This result was published in the February 2018 issue of Nano Energy ("Optogenetic Control of Body Movements via Flexible Vertical Light-Emitting Diodes on Brain Surface").

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40 Hyper-stretchable elastic piezoelectric energy harvester file ADMINI 2015.04.29 9523
39 The Way towards Commercialization of Highly Efficient Nanogenerator file admin 2015.02.17 9171
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37 Best Paper Award at 2014 Pan Pacific Microelectronic Symposium file admin 2015.02.17 8983
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34 Making Graphene Using Laser-induced Phase Separation file ADMINI 2016.12.07 4423
33 Mobile Sensor Array Platform & its Circuit Development. file admin 2015.02.17 4046
32 Intel Best Paper Award at Electronic Components and Technology Conference file admin 2015.02.17 4021
31 Excellent Paper Award at the 2014 Conference on Next Generation Lithography file admin 2015.02.17 4021
30 Seon-Jin Choi, Jinsup Lee Prize Winner at the “9th 1nside” Edge International Thesis Competition from Samsung Electro-mechanics. file admin 2015.02.17 3979
29 Grand Prize at the Dow Chemical Korea Award 2014 file admin 2015.02.17 3937
28 One of 2013 KAIST Top 10 Representative R&D Outcomes. file admin 2015.02.17 3920
27 3D Free Standing Structure Made of Graphene. file admin 2015.02.17 3915
26 The Convergence New Technology Fair Silver Award file admin 2015.02.17 3910
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24 Review article from Prof. Sang Ouk, Kim group was published in 25th anniversary of Advanced Materials. file admin 2015.02.17 3784
23 Excellent paper Award at the Optical Society of Korea. file admin 2015.02.17 3622
22 New Nanocomposite Catalyst applied for Li-O2 Batteries with improved High-capacity and Long-cycle file admin 2015.02.17 3604