EAGER: Numerical and Experimental Study of Purcell-Like Locomotion for Microswimmers

Kansas State University, Manhattan KS

Investigators

Abstract

Untethered microswimmers have attracted many interests in recent years due to their great potential in various applications such as minimally invasive medicine and active environment monitoring. One of the most famous locomotion by micro-swimmers is the so-called “Purcell swimmer” which was first proposed by and later named after Nobel laureate Edward Purcell. The Purcell swimmer geometrically presents the simplest segmented structure for one-dimensional locomotion on microscale where the Reynolds number is small. Earlier numerical and theoretical studies were universally based on the same assumption of Stokes flow, which neglects the nonlinear and inertial contributions. However, under a more careful examination, actual flow conditions of many microswimmers do not satisfy the criterion to ignore those contributions. On the other hand, experimental demonstrations of untethered Purcell swimmers and associated flow dynamics were scarce due to the challenge of implementing individually-driven hinges in a non-invasive manner with existing fabrication methods for microscale. The success of this study will broaden the understanding of flow physics in micro-swimmers and experimentally demonstrate a new approach to fabricate and control untethered micro-swimmers for the study of their locomotion and flow dynamics. Education components such as graduate education and class teaching are integrated in this project. Demonstration of microswimmer locomotion is included in outreach events to promote public interests in STEM. There are two main goals in this research. First, a unique electromicrofluidic printing technique will position and assemble multiple droplets containing cross-linkable prepolymers and particle embedded hydrogels to fabricate micro-swimmers with individually driven hinges, thus it will allow to manufacture and optically drive untethered Purcell swimmers for the first time. Second, high-fidelity numerical simulation solving Navier-Stokes equations will be used to study Purcell-like locomotion of micro-swimmers to exam the nonlinear and inertial impact on the involved flow physics at the Reynolds number of interests. Both parts of the research involve the study of a newly proposed X-swimmer as a micro-swimmer capable of three-dimensional Purcell-like locomotion. The outcome of this study for three-dimensional locomotion will change the scope of Purcell-like locomotion and enable new possibilities in the study of microswimmer locomotion and flow dynamics. The success of the proposed research will lead to future interdisciplinary collaborations in a broader community for research in micro-swimmers and their various applications. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.