Abstract
Untethered microrobots provide the prospect for performing minimally invasive surgery and targeted delivery of drugs in hard-to-reach areas of the human body. Recently, inspired by the way the prokaryotic flagella rotates to drive the body forward, numerous studies have been carried out to study the swimming properties of helical swimmers. In this study, the resistive force theory (RFT) was applied to analyze the influence of dimensional and kinematical parameters on the propulsion performance of conventional helical swimmers. The propulsion efficiency index was applied to quantitatively evaluate the swimming performance of helical swimmers. Quantitative analysis of the effect of different parameters on the propulsion performance was performed to optimize the design of structures. Then, RFT was modified to explore the tapered helical swimmers with the helix radius changing uniformly along the axis. Theoretical results show that the helical swimmer with a constant helix angle exhibits excellent propulsion performance. The evaluation index was found to increase with increased tapering, indicating that the tapered structures can produce more efficient motion. Additionally, the analysis method extended from RFT can be used to analyze the motion of special-shaped flagella in microorganisms.
Highlights
High-precision interventional small-scale continuum robots have shown great potential in biomedical applications [1]
The analysis in this paper focused on the transition from the tapered swimmers to the helical swimmers with a constant helix radius
Two tapered helical swimmers are proposed, and resistive force theory (RFT) is extended to get a new method for analyzing the propulsion performance of them
Summary
High-precision interventional small-scale continuum robots have shown great potential in biomedical applications [1]. In order to achieve non-invasive surgery or targeted drug delivery in hard-to-reach areas of the human body, numerous untethered microrobots have been proposed to perform diverse tasks at the microscale level [2,3,4,5,6], ranging from diagnostic and therapeutic tasks in vivo to probing, analyzing, and transporting micro-objects in biology, to fluidic applications in lab-on-a-chip devices. Since the flow around them is at a low Reynolds number, executing a geometrically reciprocal motion will lead to no net displacement according to the scallop theorem [7]. Small scale organisms or artificial microrobots must perform complex non-reciprocal motions to realize propulsion at a low Reynolds number. The propulsion mechanism of prokaryotic bacteria has attracted significant attention [11,12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
