Advisor: Saad Bhamla, Ph.D. (Georgia Institute of Technology)

Committee:

David Hu, Ph.D. (Georgia Institute of Technology)

Sunghwan ‘Sunny’ Jung, Ph.D. (Cornell University)

Sheila Patek, Ph.D. (Duke University)

Simon Sponberg, Ph.D. (Georgia Institute of Technology)

Fast, furious, and frugal: Principles of drops, jets, and damping in extreme invertebrates

and design of low-cost scientific tools

Sharpshooter insects (Hemiptera: Cicadellidae) are pierce-sucking insects that feed on plant’s xylem fluid. Due to the poor nutritious content of the xylem sap, sharpshooter insects extract almost 300 times their body weight worth in plant fluids. To prevent fluidic buildup, these insects discharge their liquid excreta in the form of discrete water droplets before flinging them away using a resilin-based biological spring found in their anal stylus. In this thesis, we consider this distinctive droplet-catapulting phenomenon observed in sharpshooter insects during excretion. Through an experimental, mathematical and computational approach, we explore the physical limits of such a unique droplet propulsion strategy and show why it is energetically favorable for these insects to fling their droplet excreta instead of using other mechanisms such as ‘jetting’ and ‘dripping’. Using dimensionless analysis, we show how biological organisms living in a world governed by surface tension develop exquisite strategies to overcome capillary adhesion during fluidic ejection. 

In parallel, we present a mathematical framework for the arrest and damping of ultra-fast movements in biological organisms. We consider the behavior of two organisms: the rapid launch of slingshot spiders (Araneae: Theridiosomatidae) and the controlled landing springtails (Arthropoda: Collembola) at the water-air surface. 

Finally, we define the principles of curiosity-driven frugal science. We discuss two open-hardware devices: Trackoscope, a low-cost microscope for autonomously tracking micro-organisms; and Opencell, a low-cost platform for synthetic biology that reproduces the functionality of three ubiquitous devices - a cell disruptor, microcentrifuge, and vortex mixer.