Observation of microorganisms is currently a challenging subject for cell biologists, since most of them are composed of a unit cell and thereby it is very important to explore their dynamic movement and physiologic energy generation mechanisms to understand the potential ability and function of the unit cells composing organisms including human beings. We proposed to use microchips 3D microfludic structures fabricated by femtosecond (fs) laser for dynamic observation of microorganisms. We referred to such microchips as nanoaquariums. The nanoaquarium has several advantages over conventional observation methods using a glass slide with a coverslip or a Petri dish, such as great reduction of observation times, ability of 3D observations, easy integration of functional microcomponents into the observation site for highly functional observations, etc.

Our technique for fabrication of nanoaquarium consists of (1) 3D direct writing of the photosensitive glass by fs laser (1045nm, 370fs, 200kHz), (2) baking to form the modified regions at the laser exposed regions, (3) wet chemical etching in dilute HF solution to selectively remove the modified regions, and (4) post annealing to smooth the etched surfaces. By this procedure, embedded microfluidics integrated with some functional microcomponents can be fabricated inside the photosensitive glass.

In this talk, we demonstrate to fabricate several kinds of nanoaquariums integrated with functional microcomponents such as a micropump and an optical attenuator for exploration of dynamics and functions of some microorganisms by fs laser 3D micromachining of photosensitive glass. Applications of the fabricated nanoaquariums include analysis of flagellum motion of Euglena gracilis, understanding the information transmission process in Pleurosia leavis, observations of rheotaxis behavior of aquatic microorganisms in flowing water, and Phormidium assemblage to seedling root for growth promotion of Komatsuna vegitable..

Troy Anderson