Study of Microelectrode Array Probe for Simultaneous Detection of Glutamate and Local Field Potential during Brain Death / 分析化学

High extracellular potassium can induce spreading depression-like depolarizations, elevations of extracellular glutamate and even neuronal death in normal brain. To investigate the contribution of high potassium in vivo, a microelectrode arrays ( MEAs ) probe integrated with recording sites for glutamate concentration (50í150 μm) and local field potential ( LFP) ( diameter=15 μm) was fabricated by Micro-electro-mechanical-systems ( MEMS) technologies. We implanted the MEA probe acutely in the rat brain and exposed the brain to a high potassium solution. During these multi-modal recordings, it was observed that high potassium elevated extracellular glutamate while suppressing the LFP irreversibly. This is one of the first studies in which a dual mode MEA probes is applied in vivo for neuronal death, and it is concluded that our MEA probes are capable of examining specific spatiotemporal relationships between electrical and chemical signaling in the brain.

Development of Implantable Medical Devices: From an Engineering Perspective / 대한배뇨장애요실금학회지

From the first pacemaker implant in 1958, numerous engineering and medical activities for implantable medical device development have faced challenges in materials, battery power, functionality, electrical power consumption, size shrinkage, system delivery, and wireless communication. With explosive advances in scientific and engineering technology, many implantable medical devices such as the pacemaker, cochlear implant, and real-time blood pressure sensors have been developed and improved. This trend of progress in medical devices will continue because of the coming super-aged society, which will result in more consumers for the devices. The inner body is a special space filled with electrical, chemical, mechanical, and marine-salted reactions. Therefore, electrical connectivity and communication, corrosion, robustness, and hermeticity are key factors to be considered during the development stage. The main participants in the development stage are the user, the medical staff, and the engineer or technician. Thus, there are three different viewpoints in the development of implantable devices. In this review paper, considerations in the development of implantable medical devices will be presented from the viewpoint of an engineering mind.

Micro-Electro-Mechanical Systems-based Gas Chromatography Columns with High Performance / 分析化学

The fabrication and experimental test results were presented for a micro-electro-mechanical systems (MEMS)-based gas chromatography column. Compared with conventional column, this micro-gas chromatography column is suitable for on-line analysis and monitoring because of the small size, rapid analysis and other characteristics. These 0.5, 1 and 3 m GC columns were fabricated using a deep reactive-ion etching (DRIE) and were coated the stationary phase via a dynamic coating procedure. These GC columns perfectly separated the mixture of benzene, toluene and o-xylene in less than 200 s, where, the 3.0 m of the GC column achieved) a high resolution of 14.3 between toluene and o-xylene and yielded approximately 6160 plates. Moreover, the effect of separation performance for different column length were examined and compared. These GC columns are suitable for the application of a variety of disciplines, including environmental analysis, methane gas probes and homeland security.

Development of Micro/Nano Devices for Cancer Diagnosis / 대한소화기학회지

In order to rapidly detect and analyze the presence of a target ligand of interests in environmental or industrial fluids as well as biological samples, numerous test systems have been designed and developed, which have been based on the combination of a test reagent and absorbing paper or membrane. The main limitations of these conventional devices are the difficulty of quantitative or semi-quantitative detection and poor detection limit (around nanogram/ml range detection capability). In this paper, new approaches and research trends which use nano/MEMS (micro electro mechanical systems) technology is introduced, which has a concept of fast, precise, and massive diagnosis and analysis of target molecules using very small amount of samples.