This paper reports a microfluidic device that allows us to measure the effect of local differentiation stimulation on embryoid bodies for the purpose of elucidating the role of the cell-cell interaction of iPS cells in differentiation induction. We developed the local stimulation device having two chambers separated by thin polydimethyl siloxane (PDMS) membrane with through-holes of the diameter smaller than single cell. Embryoid bodies of iPS cells are formed on the membrane and seal the holes, separating the aqueous environments of 2 chambers without leakage. This configuration brings localized exposure to chemicals for differentiation induction at the area defined by the holes. In this paper, we demonstrated the function of local stimulation using fluorescent solution.

Improving the performance of power devices is necessary to perform highly efficient power conversion. Therefore, better power devices made of wide bandgap semiconductors have come to be used. However, most of the complicated structures of GaN-HEMT as high-speed operating devices have not been analyzed in detail. In this study, we clarified the structures of GaN-HEMT by analyzing with the SEM, TEM, EDS, and the multifunctional SPM. We have clarified the existence of fine electrodes and p-type GaN layers near the source and drain electrodes by using SEM. We have clarified the composition of the superlattice strain relief layer of about 5 nm and the AlGaN layer for carrier generation of about 20 nm by using TEM and EDS. We have clarified the dopant polarity of a p-type GaN layer with a thickness of about 300 nm under the gate electrode for normally-off function by using the multifunctional SPM.

In this study, an insulator-based dielectrophoresis device using a track-etched membrane was developed for selective trapping of living yeast cells. A high electric field was formed in cylindrical pores of 8-µm diameter within the insulating membrane between two transparent plate electrodes. At a frequency of 20 MHz, only a living cell could be drawn into the pore and trapped strongly by dielectrophoresis. For non-spherical cells with a diameter and length of 5 µm and 14 µm, respectively, it was found that a cell longer than the pore diameter was drawn into the pores with electro-orientation if the minor axis of the cell was shorter.