https://scholar.dgist.ac.kr/handle/20.500.11750/860 2026-04-24T18:39:28Z https://scholar.dgist.ac.kr/handle/20.500.11750/60234 Title: A Duty-Cycled Continuous-Time Delta-Sigma Modulator for ExG Biopotential Acquisition Author(s): Chun, Woo Yub; Lee, Junghyup Abstract: This paper introduces a continuous-time (CT) delta-sigma analog-to-digital converter (ADC) integrated with a capacitively-coupled chopper instrumentation amplifier (CCIA) for ExG biopotential recording. The design features a duty-cycled operation that enhances power efficiency by minimizing unnecessary power dissipation during low-frequency signal acquisition. The system is optimized to meet key requirements such as low noise, low power, high input impedance, and sufficient input range for various biopotential signals. Fabricated in a standard 0.18 μm CMOS process, the ADC achieves FoMSNDR of 170.1 dB for a 10 kHz bandwidth, consuming 4.5 μW at 0.6 V. The active area is 0.138 mm². 2025-12-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58326 Title: Hexagonal metal complex based mechanically robust transparent ultrathin gold μECoG for electro-optical neural interfaces Author(s): Kim, Duhee; Bissannagari, Murali; Kim, Boil; Hong, Nari; Park, Jaeu; Lim, Hyeongtae; Lee, Junhee; Lee, Jungha; Kim, Yoon Kyoung; Cho, Youngjae; Lee, Kwang; Lee, Junghyup; Yoon, Jong-Hyeok; Jang, Jae Eun; Tsai, David; Lee, Sanghoon; Kwon, Hyuk-Jun; Choe, Han Kyoung; Kang, Hongki Abstract: Transparent electro-optical neural interfacing technologies offer simultaneous high-spatial-resolution microscopic imaging, and high-temporal-resolution electrical recording and stimulation. However, fabricating transparent, flexible, and mechanically robust neural electrodes with high electrochemical performance remains challenging. In this study, we fabricated transparent (72.7% at 570 nm), mechanically robust (0.05% resistance change after 50k bending cycles) ultrathin Au microelectrodes for micro-electrocorticography (mu ECoG) using a hexadentate metal-polymer ligand bonding with an EDTA/PSS seed layer. These transparent mu ECoG arrays, fabricated with biocompatible gold, exhibit excellent electrochemical properties (0.73 Omega<middle dot>cm2) for neural recording and stimulation with long-term stability. We recorded brain surface waves in vivo, maintaining a low baseline noise and a high signal-to-noise ratio during acute and two-week recordings. In addition, we successfully performed optogenetic modulation without light-induced artifacts at 7.32 mW/mm2 laser power density. This approach shows great potential for scalable, implantable neural electrodes and wearable optoelectronic devices in digital healthcare systems. 2025-03-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58214 Title: Transparent Temperature Sensors for Photothermal Neuromodulation: Advances, Challenges, and Future Directions Author(s): Lee, Jee Woong; Lee, Junhee; Lee, Jungha; Kim, Duhee; Hong, Woongki; Lee, Junghyup; Song, Minyoung; Kang, Hongki Abstract: Photothermal neuromodulation, a rapidly advancing technique in neuroscience, has been introduced as an incredibly versatile platform for the in-depth study of neural electrophysiological signals and the development of treatments for various neurological disorders. Particularly, nanomaterial-based photothermal neuromodulation technologies have advantages compared to optogenetic stimulation methods, such as non-genetic modification, minimally invasive, and reduced immune response. Photothermal neuromodulation research has introduced various nanomaterials and stimulation methods to regulate thermosensitive ion channels or modify cell membrane capacitance, enabling excitation and inhibition of neural activity. Recent advances in nanomaterials have significantly improved the precision and efficiency of photothermal neuromodulation, expanding its potential applications in neuroscience research. In the photothermal neuromodulation studies, different temperature measurement methods have been used but do not satisfy all the requirements necessary to analyze this phenomenon. An ideal temperature sensor for a photothermal neuromodulation study must have high transparency, high thermal sensitivity, and high spatial and temporal resolution. This review aims to cover the current status of thermally induced neuromodulation studies and the transparent temperature sensing methodologies that can be used for photothermal neuromodulation. 2025-06-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/57679 Title: Wireless System Miniaturization Solutions for Ingestible Sensors Author(s): Kim, Chanyoung; Lee, Junghyup; Song, Minyoung Abstract: Ingestible sensors are pivotal in monitoring the gastrointestinal (GI) tract and enhancing comprehension of complex gastrointestinal processes, propelled by sensor technology advancements. They must ensure robust wireless communication from deep within the body while maintaining longevity for comprehensive monitoring. Wireless system miniaturization stands as a promising solution to these challenges. This paper introduces the current state and technical challenges ingestible sensors and their solutions for wireless system miniaturization. The key techniques for further miniaturization include the antenna miniaturization, integration of adaptive impedance matching networks, and the replacement of crystal. Additionally, the paper explores future directions for wireless communication systems to support the continued advancement of ingestible sensor technology. 2024-11-30T15:00:00Z