Controllable alignment of elongated microorganisms in 3D microspace using electrofluidic devices manufactured by hybrid femtosecond laser microfabrication

Abstract

This paper presents a simple technique to fabricate new electrofluidic devices for the three-dimensional (3D) manipulation of microorganisms by hybrid subtractive and additive femtosecond (fs) laser microfabrication (fs laser-assisted wet etching of glass followed by water-assisted fs laser modification combined with electroless metal plating). The technique enables the formation of patterned metal electrodes in arbitrary regions in closed glass microfluidic channels, which can spatially and temporally control the direction of electric fields in 3D microfluidic environments. The fabricated electrofluidic devices were applied to nanoaquariums to demonstrate the 3D electro-orientation of Euglena gracilis (an elongated unicellular microorganism) in microfluidics with high controllability and reliability. In particular, swimming Euglena cells can be oriented along the z-direction (perpendicular to the device surface) using electrodes with square outlines formed at the top and bottom of the channel, which is quite useful for observing the motions of cells parallel to their swimming directions. Specifically, z-directional electric field control ensured efficient observation of manipulated cells on the front side (45 cells were captured in a minute in an imaging area of~160 × 120 μm), resulting in a reduction of the average time required to capture the images of five Euglena cells swimming continuously along the z-direction by a factor of~43 compared with the case of no electric field. In addition, the combination of the electrofluidic devices and dynamic imaging enabled observation of the flagella of Euglena cells, revealing that the swimming direction of each Euglena cell under the electric field application was determined by the initial body angle.

Ultrafast Mid-IR Laser Pulses Generation via Chirp Manipulated Optical Parametric Amplification

“…The low requirement on a multi-plate scheme allows BBP generation with a wide variety of initial laser energy of only several tens to hundreds µJ. With the reported conversion efficiency, µJ-level few-cycle Mid-IR pulses can be directly obtained from a single-stage BBP-OPA pumped by a laser system with moderate pulse energy, which can benefit applications that do not require the ultrahigh energy of femtosecond laser pulses [115][116][117][118][119].…”

Lab-on-Chip Platform for Culturing and Dynamic Evaluation of Cells Development

“…All-glass lab-chips were fabricated utilizing commercially available borosilicate glass slides (Borofloat 3.3, Schott, Mainz, Germany). In the literature on the subject, a variety of techniques ensuring fabrication of microstructures in glass substrates can be distinguished, for example, laser ablation [27,28] or sandblasting; nevertheless, in this study, typical micromachining processes including xurography, wet chemical etching, mechanical drilling of via holes, and thermal bonding were applied to achieve final LOC structures ( Figure 2). The pattern of the microchannels/microchambers was formed by submerging the glass slides in a solution of 50% HF/69% HNO 3 (10:1 v/v), etching speed: 3 µm/min.…”

Mimicking Intravasation–Extravasation with a 3D Glass Nanofluidic Model for the Chemotaxis‐Free Migration of Cancer Cells in Confined Spaces

“…[ 12 ] Furthermore, the integration of microelectronic components in the fabricated microfluidic channels by the subsequent femtosecond laser‐induced selective metallization has been applied for the electrical manipulation of biological samples in nano‐aquariums. [ 13 ] Through the combination of FLAE with successive two‐photon polymerization (TPP), which is an additive processing technology, complex 3D shapes of polymeric structures with submicrometer dimensions have been successfully integrated inside glass microfluidic devices. This novel hybrid FLAE‐TPP technique has been applied to build a multi‐functional filter‐mixer applied for simultaneous rapid fluid mixing and particle filtering within a short channel distance [ 14 ] and to fabricate an optofluidic unit combined with a 3D microlens array and center pass units for counting Euglena cells.…”