Michael Alemayehu

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Faculty Mentor: Alfredo Alexander-Katz

Direct Supervisor: Joshua Steimel

Home University: Morehouse College

Major: Applied Physics and Electrical Engineering

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Biography

Born in Atlanta, Georgia with an Ethiopian upbringing, I am a first generation college student attending Morehouse College. I am in the Dual Degree Engineering Program majoring in Applied Physics and Electrical Engineering. In graduate school, I aspire to conduct research with the electrical engineering department. I specifically hold interest in electronic systems and/or electromagnetic.

Abstract

Synthetic Creation of a Chemotactic System via Utilization of Magnetically Actuated Microrobotic Walkers

Chemotaxis is a fundamental biological process that plays an important role in disease, reproduction, and many biological functions. Here, we present a novel method to create a synthetic chemotactic system, which utilized magnetically actuated microrobotic walkers. The system used a rotating magnetic field that once actuated induced the magnetic beads to self-assemble into microrobots and walk on surfaces. To mimic chemotaxis a biological receptor-ligand pair was utilized to couple the microbots to the surface. The presence of free binding sites on the surface was required to obtain chemotactic motion as these binding sites modulated walker velocity. Placing a droplet of concentrated streptavidin on a biotynlated slide and letting the droplet evaporate created sufficient gradients in the density of binding sites to achieve chemotaxis. The “coffee-ring” deposition effect upon evaporation created differentials in the density of binding sites. A series of continuous velocity measurements were conducted across the sample to map the walker velocity profile. Walkers were then placed on a random walk path and chemotactic directed motion was observed as the walkers drifted towards regions with a high density of binding sites. Walkers in an area with a high density of binding sites experienced a significant amount of “sticking” followed by hinge-like motion, while walkers in a low density area exhibited virtually no “sticking” and tended to slip much more frequently. The drift velocities that were extracted from the random walk path illustrated the discrepancy between the chemical gradients present in this synthetic chemotactic system.