2018 SPIE Photonics West, San Francisco, United States

January 29 - February 1, 2018 (Mon - Thur), The Moscone Center

<Oral Session>

Energy-harvesting metamaterial based wireless chemical sensor system

Wonwoo Lee, Yonghee Jung, Hyunseung Jung, and Hojin Lee

 Abstract

In this paper, we propose a new wireless chemical sensor system through energy-harvesting metamaterial at microwave frequencies. The effective dielectric constant change, arises from the chemical compounds and their mixtures, leads to the resonance shift of our metamaterial sensor and thus causes spectral change of it energy-harvesting properties. With this variation of energy-harvesting rate of our sensor system that provides intuitive sensing results, the chemical components of the various solutions can be identified. Finally, we expect that our system can offer not only great accessibility but also simplicity for sensor systems including biochemical and dynamic dielectric environment sensing systems.

SPIE Photonics West 2020, San Francisco, USA

February 1 - 6, 2020 (Sun. - Thur.), Moscone Centor

High-Performance Ionic Polymer Mechanotransducer for Soft Tactile Feedback

Yongchan Kim, Changhyeon Cho, So Young Kim, Hanbin Choi, Do Hwan Kim, and Hojin Lee

Abstract

  In this talk, we propose an i-EAP actuator with wide bandwidth of over 200 Hz and high blocking force based on PEDOT:PSS electrode with additives and ionic-polymer with nanofibrillary network for effective haptic feedback. In particular, we developed an actuator that improves the interfacial properties between electrodes and an ionic-polymer as well as electrical conductivity of electrodes by simple and effective way through spray-coating of PEDOT:PSS solution with additives. As a result, the proposed i-EAP actuator was successfully operated with a large displacement up to 2.7 mm at an operating frequency of 20 mHz under an applied voltage of 2 V. These our actuator is capable of driving up to a high frequency of 200 Hz and shows an improved blocking force up to 0.4 mN. We believe our i-EAP actuator will provide a rational guide to future haptic feedback.

IDW '23, Niigata, Japan

December 6 - December 8, 2023 (Wen. - Fri.), TOKI MESSE Niigata Convention Center

Adaptive Frequency Driving Scan Driver for Low Power Display based on a-InGaZnO TFTs

Jinho Moon, Hyunwoo Kim, Yongchan Kim, and Hojin Lee

Abstract

 In this paper, a scan driver combined with logic circuit using amorphous indium-gallium-zinc-oxide (a-InGaZnO) thin-film transistors (TFTs) is proposed. Logic circuit masks the output signal from the scan driver in order to control the driving frequency. Proposed frequency adaptive scan driver is expected to reduce power consumption depending on the display contents.

AMSM 2019, Incheon, Korea

October 16 - 19, 2019 (Tue. - Fri.), Sheraton Grand Incheon Hotel

Wireless Powered VOC Sensor Based on Wi Fi Energy Harvesting Metamaterial with i-TPU

Wonwoo Lee, Heejoo Park, Hyunseung Jung, So Young, Kim, Do Hwan Kim, and Hojin Lee

Abstract

  In this paper, we propose a novel wireless powered VOC sensor system based on energy harvesting metamaterial combined with ionic thermoplastic polyurethane (i TPU) gas sensing channel at microwave frequency . The sensor consists of the SRR, rectifier circuit t o harvest the RF energy by converting electromagnetic energy into DC voltage, and i TPU gas sensing channel to detect VOC with the variation of resistance. For the practical wireless sensing system, we utilized widespread and easily accessible commercial 2 .4 GHz Wi Fi source as external electromagnetic wave energy, and the energy harvesting metamaterial was designed and optimized to resonate at 2.4 GHz. When i TPU was exposed to VOC , the diffusivity of ionic liquid (IL) increases leading to decrease of the resistance of i TPU that can be identified with the differential harvested energy induced from variation of resonance property for the energy harvest ng metamaterial sensor . As a result, by analyzing the differential harvested energy , the proposed sensor c ould provide the highly sensitive wireless VOC sensor system without bulky and complicated measurement system offering great accessibility and simplicity for the practical sensor applications Also, the wireless powered VOC sensor showed high stability and repeatability representing the rapid restoring to the initial resistance value of the i TPU gas sensing channel. Finally , it is expected that the proposed system can be applied to not only for VOC sensors but also for dynamic environmental sensing systems