The Transport Behavior of a Biflagellated Microswimmer before and after Cargo Loading

Abstract

The changes in the transport behavior of a microswimmer before and after cargo loading are crucial to understanding and control of the motion of a biohybrid microbot. In this work, we show the change in swimming behavior of biflagellated microalgae Chlamydomonas reinhardtii picking up a 4.5 μm polystyrene microbead upon collision. The microswimmer changed from linear forward motion into helical motion upon the attachment of the cargo and swam with a decreased swimming velocity. We revealed the helical motion of the microswimmer upon cargo loading due to suppression of flagella by image analysis of magnified timelapse images of C. reinhardtii with one microbead attached at the anterior end (between the flagella). Furthered suppression on the flagellum imposed by the loading of the second cargo has led to increased oscillation per displacement traveled and decreased swimming velocity. Moreover, the microswimmer with a microbead attached at the posterior end swam with swimming velocity close to free swimming microalgae and did not exhibit helical swimming behavior. The experimental results and analysis showed that the loading location of the cargo has a great influence over the swimming behavior of the microswimmer. Furthermore, the work balance calculation and mathematical analysis based on Lighthill's model are well consistent with our experimental findings.

Navigating the microenvironment with flip and turn under quadrupole magnetophoretic steering control: Nanosphere‐ and nanorod‐coated microbead

“…The kinematic results recorded under bright field imaging of an optical microscope (connected to cellSens Imaging Software) were then processed accordingly using ImageJ. During the processing stage of the raw kinematic motion results, the $$v$$ evaluated at each time frame was further decomposed into $${v_\parallel }$$, the $$v$$ of IONPs‐PS parallel to the main reference axis of direction of $$\nabla {\bf{B}}$$ where the IONPs‐PS experiences $${{\bf{F}}_{mag,\;IONPs - PS}}$$ (see Figure 2C), and $${v_ \bot }$$, the $$v$$ perpendicular to it [28]. The $${v_\parallel }$$ is the combination of magnetophoresis and viscous drag, whereas $${v_ \bot }$$ is mainly dominated by Brownian diffusion.…”