Modeling, control and experimental characterization of microbiorobots

Abstract

In this paper, we describe how motile microorganisms can be integrated with engineered microstructures to develop a micro-bio-robotic system. SU-8 microstructures blotted with swarmer cells of Serratia Marcescens in a monolayer are propelled by the bacteria in the absence of any environmental stimulus. We call such microstructures with bacteria MicroBioRobots (MBRs) and the uncontrolled motion in the absence of stimuli self actuation. Our paper has two primary contributions. First, we demonstrate the control of MBRs using self actuation and DC electric fields, and develop an experimentally validated mathematical model for the MBRs. This model allows us to use self actuation and electrokinetic actuation to steer the MBR to any position and orientation in a planar micro channel. Second, we combine our experimental setup and a feedback control algorithm to steer robots with micrometer accuracy in two spatial dimensions. We describe the fabrication process for MBRs and show experimental results demonstrating actuation and control.

Swimming microorganisms acting as nanorobots versus artificial nanorobotic agents: A perspective view from an historical retrospective on the future of medical nanorobotics in the largest known three-dimensional biomicrofluidic networks

“…During the same year, phototactic directional control of a relatively large structure propelled by attached flagellated bacteria was demonstrated 28 followed by the DC electric field directional control of the same bacteria-propelled structure in 2011. 29 These demonstrations extended further the list of possible directional control methods for microorganism-based nanorobotic agents.…”

Bacterial Biohybrid Microswimmers

“…Unlike the few Gram-positive bacteria listed above, many Gram-negative bacteria have been widely used in the development of hybrid microswimmers. This includes Vibrio alginolyticus (Sowa et al, 2003;Nogawa et al, 2010;Kojima et al, 2013;Zhang et al, 2013), Serratia marcescens (Darnton et al, 2004;Behkam and Sitti, 2006;Steager et al, 2007Steager et al, , 2011Park et al, 2010;Traoré et al, 2011;Kim and Kim, 2016), Magnetococcus marinus MC-1 (Felfoul et al, 2011(Felfoul et al, , 2016, Salmonella typhimurium (Cho et al, 2012;Park et al, 2013a;Li et al, 2015) and Escherichia coli (Di Leonardo et al, 2010;Singh and Sitti, 2016;Stanton et al, 2016;Suh et al, 2016;Park et al, 2017). The different strategies applied to couple a cargo to the bacterial surfaces will be further discussed in section Binding Strategies for the Preparation of BacteriaBots.…”

“…Differently shaped flat fragments of this bacterial carpets, termed "auto-mobile chips, " moved above the surface of the microscope slide in two dimensions (Darnton et al, 2004). Many other works have used S. marcescens swarming cells (Behkam and Sitti, 2006;Steager et al, 2007Steager et al, , 2011Park et al, 2010;Traoré et al, 2011;Kim and Kim, 2016), as well as E. coli swarming cells (Singh and Sitti, 2016;Park et al, 2017) for the development of hybrid microswimmers.…”

“…A similar approach of control by electric fields was followed by Steager et al (2011), and later on further investigated to elucidate the mechanism of motion and the observed prevalence of clockwise motion (Wong et al, 2014). By comparing squares and gear structures, the authors found that bacteria that adhered to the surface walls of large microstructures were influenced much less by the shape of the structure than expected, at least for the large microstructure/bacterium size ratio that was considered.…”

Thrifty Swimming With Shear-Thinning: A Note on Out-of-Plane Effects for Undulatory Locomotion Through Shear-Thinning Fluids

“…Finally, sperm cells, which also use an undulatory swimming gait, move through viscoelastic and shear-thinning cervical mucus [5,7,13,28,33]. This biomedical relevance, improvements in analytical and numerical techniques, and recent experimental work towards using artificial [9,17,23] and biological propulsion [22,26] for disease detection and drug delivery has driven recent increased interest in modelling swimming at small length scales.…”