https://scholar.dgist.ac.kr/handle/20.500.11750/9934 2026-10-03T22:38:18Z https://scholar.dgist.ac.kr/handle/20.500.11750/60896 Title: A Substrate-Aware CMOS Micromagnetic Stimulation SoC with a Bent Micro-Coil and Programmable Triangular Current Driver Author(s): Kim, Ji Won; Cha, Dong Hun; Lee, Seung Hwan; Eom, Kyungsik; Lee, Sanghoon; Lee, Seung Woo; Park, Jeong Hoan Abstract: Microscopic magnetic stimulation (MSTI) induces electric fields without direct charge injection and can shape localized field gradients with asymmetric micro-coils. Most demonstrations still rely on external drivers, off-chip hardware, or separated coil validation, so the CMOS integration boundary remains poorly characterized. This work presents a fabricated 2 & times;1 mm(2 ) 0.18 mu m CMOS magnetic-stimulation SoC that co-integrates ASK-compatible command decoding, FSM and register-based parameter control, a programmable current-voltage-current triangular driver, and a bent top-metal micro-coil, and it characterizes the on-chip driver-to-coil path together with a substrate-aware field model. Sensing-load reconstruction confirms command-to-waveform programmability, including duration-window decoding, burst-count control, and polarity reversal, with measured slew targets that give a peak current of I-pk=3.72 - 21.6 mA . A quantitative comparison contrasts the current-mode triangular driver with conventional electrode stimulators, a coil-impedance measurement shows the coil stays resistive across 1 to 10 MHz, and the measured total SoC power is about 41 mW. Substrate-aware simulation at a 15 mu m target plane shows that the grounded p-substrate retains 35.1 - 40.5% of the no-substrate peak x-directed field-gradient metric. The prototype establishes this electrical programmability and the substrate-aware gradient-transfer loss as a compact design-margin metric for CMOS-integrated magnetic stimulation. Direct biological activation is not claimed and is left to future in vitro validation. 2026-06-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60227 Title: Toward virtual bladder: real-time bladder volume monitoring with flexible AuCNT strain sensors Author(s): Cho, Youngjun; Jo, Yujin; Kang, Minseok; Shin, Heejae; Cho Jeongmok; Jeong Hyunghwa; Suh Hyunsuk Peter; Pak Changsik John; Park, Jeonhyeong; Kwon Soonchul; Choi Hongsoo; Yu, Jaesok; Kim, Hoe Joon; Lee, Sanghoon Abstract: Digital twin technology holds considerable potential for personalized diagnostics and treatment of bladder dysfunction, particularly neurogenic conditions such as underactive bladder (UAB). In this study, to address the need for precise monitoring, we introduce a flexible, stretchable strain sensor composed of gold-coated carbon nanotubes (AuCNTs) embedded in Ecoflex. We specifically designed a three-channel configuration to capture anisotropic expansion and evaluated the sensor's performance using both two-dimensional balloon models and ex-vivo three-dimensional porcine bladder models. As a result, the AuCNT sensor demonstrated high sensitivity, and the three-channel design significantly enhanced spatial accuracy compared to single-channel approaches. Based on these measurements, we created a preliminary "Virtual Bladder" model that provides dynamic, real-time visualization of bladder volume changes. While our current model requires further development to incorporate multimodal data and anatomical variability, it serves as a foundational step towards developing advanced digital twin frameworks and closed-loop neuromodulation systems for bladder dysfunction. 2025-12-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59332 Title: Contrast agent-free 3D ultrasound deep-depth vascular imaging with a 2D row column addressed Array: In vivo human clinical feasibility study Author(s): Guezzi, Nizar; Lee, Sangheon; Nam, Sangwoo; Jung, Dongkyu; Noman, Muhammad; Seong, Hyojin; Lee, Sanghoon; Kim, Hoe Joon; Yu, Jaesok Abstract: Three-dimensional (3D) imaging of vascular networks is essential for accurately diagnosing deep organ diseases. However, current ultrasound imaging methods are primarily limited to visualizing 2D cross-sections, which restricts the ability to evaluate the full structure of vascular networks. Although several 3D ultrasound techniques have been proposed to overcome this limitation, most struggle to achieve deep penetration and a wide field of view due to their high resource requirements. Row-column addressed arrays (RCAs) have emerged as a promising solution, enabling 3D imaging with significantly reduced hardware complexity. Nevertheless, the limited image quality achievable with RCAs has hindered their broader application. In this study, we propose a coded plane-wave-based, contrast-free 3D imaging system using RCAs for in vivo imaging of deep human vasculature. To validate the method, we imaged the liver and spleen of two healthy adult volunteers and successfully visualized vascular structures without contrast agent injection. Flow dynamics were captured at a frame rate of 27 Hz. Additionally, we demonstrated contrast-to-noise ratio (CNR) improvements of approximately 9 dB and 10 dB in the z-y and z-x planes, respectively, compared to non-coded excitation. This approach offers strong potential for in vivo 3D visualization and assessment of complex, deeply located vascular networks. 2026-01-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59061 Title: Optimized Coil Design for Enhanced Electric Field Induction in Peripheral Nerve Stimulation Author(s): Park, Jaeu; Lee, Kyeong Jae; Nagwade, Pritish; Jeong, Jinwoong; Park, Jeong Hoan; Choi, Hongsoo; Kim, Sohee; Lee, Sanghoon Abstract: Peripheral nerve electrical stimulation is widely used for the treatment of neuropathic pain and neural regeneration. However, it often induces adverse biological reactions and unintended activation of surrounding neural tissues. As an alternative, peripheral nerve magnetic stimulation offers a promising, less invasive approach that enables targeted nerve stimulation without direct tissue contact. Despite its potential, it is constrained by the bulkiness of coils and excessive heat generation due to the high currents required. To address these limitations, we conducted a study on coil design optimized for peripheral nerve modulation. Our approach, supported by simulations and animal experiments, focused on optimizing coil geometry to maximize the induced electric field gradient. Among various designs, a four-leaf rhombus-shaped coil demonstrated the highest gradient at the center of the interface. In rat sciatic nerve experiments, this coil, driven by a rectangular pulse with a 200 μs rise time and 25 V amplitude, successfully elicited compound muscle action potentials in both the tibial anterior and gastrocnemius muscles. This study presents design guidelines for peripheral nerve stimulation (PNS) coils based on magnetic stimulation as an alternative to conventional electrical stimulation. The proposed approach may serve as a foundation for the development of advanced, miniaturized, and energy-efficient neural stimulation coils. © 2025 Elsevier B.V., All rights reserved. 2025-07-31T15:00:00Z