Controlled regular locomotion of algae cell microrobots

Abstract

Algae cells can be considered as microrobots from the perspective of engineering. These organisms not only have a strong reproductive ability but can also sense the environment, harvest energy from the surroundings, and swim very efficiently, accommodating all these functions in a body of size on the order of dozens of micrometers. An interesting topic with respect to random swimming motions of algae cells in a liquid is how to precisely control them as microrobots such that they swim according to manually set routes. This study developed an ingenious method to steer swimming cells based on the phototaxis. The method used a varying light signal to direct the motion of the cells. The swimming trajectory, speed, and force of algae cells were analyzed in detail. Then the algae cell could be controlled to swim back and forth, and traverse a crossroad as a microrobot obeying specific traffic rules. Furthermore, their motions along arbitrarily set trajectories such as zigzag, and triangle were realized successfully under optical control. Robotize algae cells can be used to precisely transport and deliver cargo such as drug particles in microfluidic chip for biomedical treatment and pharmacodynamic analysis. The study findings are expected to bring significant breakthrough in biological drives and new biomedical applications.

A Micromanipulator and Transporter Based on Vibrating Bubbles in an Open Chip Environment

“…In addition, the manipulation method can be used for trapping swimming pandorina morum cells. It is a promising application in biology, chemistry, physics, and medicine to manipulate cells with intrinsic motility, as the precise manipulation of the mobile microorganisms (such as bacterial and algal cells) remains difficult [ 49 ]. The feasibility and effectiveness of utilizing this technology to manipulate swimming pandorina morum cells was investigated, as shown in Figure 9 .…”

Incorporation of Terbium into a Microalga Leads to Magnetotactic Swimmers

“…The strong permanent magnet‐based setup was selected for three reasons: 1) Unlike an electromagnetic coils‐based setup, permanent magnets do not generate heat, which is necessary to avoid a temperature‐induced influence on the behavior of the biohybrid microswimmers (20–32 °C optimum for C. reinhardtii ) . 2) The microalgae containing a small amount of Tb 3+ could only be controlled by a strong magnetic field.…”

“…In this study, we present a proof‐of‐concept that by incorporation of terbium into a microalga magnetotactic behavior can be achieved. In addition to the steering of innately photosensitive C. reinhardtii based on phototactic guidance reported previously, here we wanted to control the movement of the microswimmers by magnetization. For this purpose, we incubated the microalgae in terbium (Tb 3+ )‐enriched media.…”

“…Photosynthetic microalgae need light for the production of energy, because of this, they swim toward the light (phototaxis) and can be steered by it. But C. reinhardtii shows also a forward motion in the dark, which is crucial for the application inside the human body. In addition, it can be easily cultivated in the laboratory.…”

Mobile Microrobots for Active Therapeutic Delivery

“…For example, the unicellular freshwater green microalga Chlamydomonas reinhardtii (CR) has been investigated as a model organism and potential platform for physiological and genetic studies as well as for the production of human therapeutic proteins . Microalgae also attracted the attention of the microrobotics community due to its perception and driving skills, along with the natural motility by converting chemical energy to mechanical movement by its flagella …”