Two-dimensional optical feedback control of Euglena confined in closed-type microfluidic channels

Abstract

We examined two-dimensional (2D) optical feedback control of phototaxis flagellate Euglena cells confined in closed-type microfluidic channels (microaquariums), and demonstrated that the 2D optical feedback enables the control of the density and position of Euglena cells in microaquariums externally, flexibly, and dynamically. Using three types of feedback algorithms, the density of Euglena cells in a specified area can be controlled arbitrarily and dynamically, and more than 70% of the cells can be concentrated into a specified area. Separation of photo-sensitive/insensitive Euglena cells was also demonstrated. Moreover, Euglena-based neuro-computing has been achieved, where 16 imaginary neurons were defined as Euglena-activity levels in 16 individual areas in microaquariums. The study proves that 2D optical feedback control of photoreactive flagellate microbes is promising for microbial biology studies as well as applications such as microbe-based particle transportation in microfluidic channels or separation of photo-sensitive/insensitive microbes.

Device and programming abstractions for spatiotemporal control of active micro-particle swarms

“…The synergistic integration of global and local stimulus modalities (side LEDs, projector, and microfluidic chip mazes) combinatorically increased the possibilities to manipulate and interact with microscopic swarms compared to previous systems. 7,30,31,[37][38][39]50 Having multiple stimulus modalities can also greatly accelerate specific tasks compared to single modality stimulation, e.g. the command fastCompress, which combines the LED stimulus with a projected barrier, is at least an order of magnitude faster than the command compress, which only uses a shrinking projected barrier (Fig.…”

“…All three stimulus modalities have been demonstrated individually with Euglena before, but they have not yet been combined in one device. 31,37,39 Note that Euglena have an inherent degree of variability, which makes complete characterization of all possible Euglena behaviours difficult. Here, we focus on the most robust and consistently observed Euglena responses.…”

“…2D). These cells are ∼50 μm long, swim at about 100 μm s −1 , and exhibit avoidance responses to changes in strong light stimuli within ∼1 s. 7,37,[40][41][42] The cells are kept in the upper Euglena reservoir ( Fig. 2A and C) where they live stably for weeks without stringent maintenance needs besides daylight.…”

“…1). We combined several existing biotic processing units (BPUs 30,38 ) from other experimental 7,37 and interactive biology 31,39 setups to create a single highly expressive BPU (Fig. 2).…”

“…1,27,30,[34][35][36] Other setups capitalize on local stimuli (e.g. projection of images 31,37 ) to control individual Fig. 1 Schematic of the device and swarm programming.…”