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2-6. Research on novel soft devices and integrated circuit architectures

| Participants

member
member_detail
Name :Yongtaek Hong
Affiliation :Seoul National University
Tel :+82-02-880-9567
E-mail :yongtaek@snu.ac.kr
Homepage :http://axel.snu.ac.kr

| Research Purpose

Development of patch-like stretchable temperature/pressure/displacement/shear force/3-axis force sensor sheet and integration with stretchable display, control technology with microprocessor, and signal processing for real-time monitoring. Development of large-area multi-modal smart sensor sheet for robot skin applications, which could monitor in real-time.

| Contents

Topic 1. Development of temperature/pressure/displacement integrated sensor

(1) Temperature sensor
- Development of improved temperature sensor based on conductive composite of aligned nickel fillers by external magnetic field.
- Temperature can be measured by the change of electrical characteristics, which result from change of distance between conductive nickel fillers by external temperature variation.
(2) Pressure sensor
- Development of piezo-resistive type pressure sensor based on conductive composite of aligned nickel fillers
- Pressure can be measured by the change of electrical characteristics, which result from change of distance between conductive nickel fillers by external pressure.


Electrical characteristics according to external stimuli (pressure/temperature)


- Development of multiscale wavy structured electrode with silver nanowires (AgNWs) embedded in PDMS
- Capacitive pressure sensor based on AgNWs embedded in PDMS


Capacitive pressure sensor based on wavy structured AgNWs


(3) Strain Sensor
- Development of stretchable strain sensor based on single-walled carbon nanotubes (SWCNTs) using inkjet printing
- Showing highly sensitive (guage factor > 10), excellent linearity (R2>0.99), and good stability under repetitive stretching and bending tests


Schematic image and electrical characteristics of inkjet-printed strain sensor


(4) Temperature/pressure/displacement integrated sensor - Development of passive electronic skin that could sense various stimuli of temperature, pressure, and displacement by integration of piezoelectric temperature/pressure sensor array based on conductive composite, highly-sensitive capacitive pressure sensor array, and inkjet-printed strain sensor


Temperature/pressure/displacement integrated sensor


Topic 2. Development of shear and 3-axis force sensor

- Fabrication of multiscale wavy structured electrode with silver nanowires (AgNWs) embedded in PDMS
- Capacitive shear and 3-axis force sensor based on AgNWs embedded in PDMS
- Development of bump design for shear and 3-axis force sensor


Schematic image of capacitive shear and 3-axis force sensor


Topic 3. Stretchable display with microcontroller based on inkjet printing

- Bonding LED chips on inkjet-printed stretchable electrodes forming stretchable LED arrays
- Integrating microcontroller with stretchable LED arrays
- Integrated system where the microcontroller can process data from sensor arrays and display on stretchable LED array


(a) A LED chip bonded on inkjet-printed stretchable electrodes (b) I-V curve of LED chip on stretched elastomer



Detailed technologies and operation of stretchable LED array


| Expected Contribution

- Providing fundamental technologies to demonstrate novel soft electronics applications through development of stretchable electronic systems beyond flexible electronic devices
- Improving device uniformity and being large-area processable using in situ process, in contrast to previously reported transfer based stretchable electronic devices
- Realizing stretchable electronic systems with ultra-low-cost, large-area and environmentally friendly process using solution process and printing process
- Providing high value added technology through opening a new electronics/biotechnology/medical market such as robot skins, body-attachable biosensors, environment sensors, stretchable displays, control technologies with microprocessor, and signal processing

| Representative Research Achievement

1. S. Chung, M. Jang, S.-B. Ji, H. Im, N. Seong, J. Ha, S.-K. Kwon, Y.-H. Kim, H. Yang, Y. Hong, Adv. Mater. 2013, 25, 4772. (Frontispiece Highlight Paper) (Wiley Hot Topics)
2. S. Kim, J. Byun, S. Choi, D. Kim, T. Kim, S. Chung, Y. Hong, Adv. Mater. 2014, 26, 3094. (Front Cover Paper)
3. Y. Joo, J. Byun, N. Seong, J. Ha, H. Kim, S. Kim, T. Kim, H. Im, D. Kim, Y. Hong, Nanoscale 2015, 7, 6208.
4. S. Park, G. Giri, L. Shaw, G. Pitner, J. Ha, J. H. Koo, X. Gu, J. Park, T. H. Lee, J. H. Nam, Y. Hong, Z. Bao, Proc. Natl. Acad. Sci. 2015, 112, 5561.
5. S. Kim, S. Choi, E. Oh, J. Byun, H. Kim, B. Lee, S. Lee, Y. Hong, Sci. Rep. 2016, 6, 34632.
6. 홍용택, 변정환, 김상우, KOR 10-1541618 (07-28-2015) (미국 특허 출원 진행 중)