Evaluation of Microfluidic Channels With Thin Si Windows and Trapping Structures

We present the fabrication and evaluation of a microchannel with thin Si windows and a trapping structure for injected liquid samples, including an evaluation using tubing methods of polydimethylsiloxane eyelets, and Kovar. Yeast cells and latex particles were observed using a fluorescence microscope under atmospheric conditions and a scanning electron microscope (SEM) under vacuum. As moving and flowing liquid samples cannot be observed for a long time, a trapping structure in the microchannel is required. In our experiment using pole structures under a thin Si window in microchannels to trap liquid samples, we successfully observed them using the SEM under an accelerating voltage of 15 kV and an emission current of $75~\mu \text{A}$ . This result indicates the possibility of using higher accelerating voltages of electrons for higher observation resolutions at a lower power density of 2.3 kW/cm2. Microfluidic channels with a thin window would be a useful technique for monitoring liquid samples under vacuum. [2020-0367]