We are studying and developing biosensing techniques in order to analyze and monitor simply and easily biological phenomena such as DNA recognition events antigen-antibody interaction, and cell functions in vitro. Particularly, we focus on the direct detection of ions or ionized molecules with charges, because most of biological phenomena are closely related to ionic or ionized molecular behaviors such as sodium or potassium ions through ion channel at cell membrane which are based on cell-cell communication for example, and DNA molecules also have intrinsic molecular charges based on phosphate groups. Our research activities contain interesting information not only for researchers in biology and molecular biology, but also researchers in electronics and physics. We believe that novel tool and method based on material and device sciences should be studied and developed for discovery of unknown biological phenomenon in the interdisciplinary field.