https://scholar.dgist.ac.kr/handle/20.500.11750/807 2026-04-04T17:17:31Z https://scholar.dgist.ac.kr/handle/20.500.11750/56750 Title: Modulating the molecular orbitals of matter through tailoring at the nanoscale using a topographic interface to enable versatile colloidal current devices Author(s): Ali Abbas; 김현설; 강유민; 임병화; 김건목; 김철기 Abstract: In this study, we present a novel approach for colloidal particle manipulation that leverages the topographic effect generated by micro-hills and surface gradients around a micro-magnet. We demonstrate that the magnetic landscape, or matter orbital, created by periodically arranged circular micro-magnets induces a symmetric orbit of magnetic particle flow under a rotating magnetic field. However, the presence of irregular topographic structures on the surface can disrupt the intended control of particle manipulation. By controlling the distance between the source of the driving force and the target particles with sub-nanometer precision on the surface morphology, we can break the symmetry of the energy distribution and distort the symmetric orbit of colloidal flow. This can be achieved without changing the driving force, but by modifying the symmetry in the energy landscape at the switching point. Furthermore, we show that the enhancement of the magnetic effect of the micro-magnet array can restore the symmetry of the orbit. We also demonstrate the application of this technique on on-chip-based devices configured by symmetry control, showcasing its potential for selective manipulation, trapping, recovery, and altering the direction of colloidal particles using a time-dependent magnetic field. This novel approach could find applications in precise lab-on-a-chip systems where the topographic effect is required as an additional variable without disrupting the existing control methods. Overall, our findings highlight the potential of this innovative approach for precise micro-particle manipulation in biomedical and lab-on-a-chip applications, offering new possibilities for manipulating particles with intricate topographic structures. 2023-05-23T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/56746 Title: Low-Frequency Noise and Detectivity Analysis of Planar Hall Magnetoresistance Sensors for Applications Author(s): 김진우; 전태형; 전창엽; Sharma Pranita; Ruzmetov Khujabek Nodirbek ugli; 김혜지; 이성혁; 임병화; 김철기 Abstract: We studied noise and detection performance of planar Hall magnetoresistance (PHMR) sensors, specifically cross-junction and multi-ring sensors. The sensors were characterized in 0.5 Hz-200 Hz, and their ability to detect magnetic field in an unshielded environment was evaluated. The external magnetic field was applied parallel and perpendicular to the easy axial direction, and the resulting spectrum was measured. By optimizing the sensor structure, the resolution was enhanced at low frequencies, indicating good detection values. The results demonstrate that PHMR sensors are universal, high-performance magnetometers that can applies to a variety of applications. Moreover, the field resolution of the PHMR sensor can open new opportunities for biomagnetic signal detection, and the sensor can have industrial applications in harsh environments. 2023-05-23T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/56741 Title: Recent Advances and Applications in Planar Hall Magnetoresistive Sensors Author(s): 전태형; 전창엽; 임병화; 김철기 Abstract: Recent advances in nano/micro technology have resulted in the widespread adoption of magnetoresistive sensors in storage media and other applications. Magnetoresistive sensors have high performance that satisfies the demands of advanced applications that require smart sensing performance, such as the Internet of Things, mobile devices, space and aviation, as well as the smart home, environment, and health care application. In this discussion, I will talk about magnetoresistive sensors based on the planar Hall effect exhibit high sensitivity, low noise characteristics, and wide temperature range suitability for ultra-low magnetic field detection. Additionally, their simple structure makes them cost-effective, easy to fit and miniaturize, and easy to integrate, rendering them a promising sensor for various new applications. 2023-05-24T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/56740 Title: Development of current sensor with 0.1% precision applicable to automotive electronic components Author(s): Sung-Min Hong; 김철기; Dae-Sung Lee Abstract: This study is a smart current sensor that can protect and control the power system by predicting and analyzing power demand through accurate current measurement and detecting not only rated current but also accident current through accurate measurement of abnormal and fault current. In this study, a low-power current sensor with 0.1% precision was designed and manufactured using Planar Hall Resistance (PHR), a magnetic sensing device compatible with the CMOS process. The current sensor is largely composed of a current sensing unit, a current path, and a smart signal processing ROIC, and was manufactured and packaged in the form of an all-in-one ROIC to enable a post-CMOS compatible process on the CMOS ROIC. The current sensor has a driving range of 0 to 10A, has a sensor precision characteristic of 0.1%, and is applied to automotive flasher units as an application field. 2023-05-24T15:00:00Z