Description
- Abstract:
- This dissertation presents a new technique to increase the accessible noise range in micro and nanofluidics using electrokinetics. We show that the application of voltage noise with the same statistical properties as fundamental thermal noise controllably amplifies the Brownian motion of lambda DNA molecules suspended in solution inside a nanoslit. We analyzed the trajectories of single molecules and found that their self-diffusivity in the direction of the applied electric field increased in proportion with the variance of the voltage noise. However, unlike thermal noise, the voltage noise causes correlated fluctuations of different molecules and their segments. Therefore, this technique unlocks a previously inaccessible effective temperature regime for studies and applications of noise-dependent phenomena. Using this new technique, we significantly increased the back and forth hopping of a DNA between neighboring nanopits inside a nanofluidic device. The second half of this dissertation presents observation, analysis, theory, and simulation of a new nanofluidic transport phenomenon where a gradient in liquid viscosity causes transport of nanoparticles inside a glass nanofluidic channel. Viscosity gradient results in multiplicative (state-dependent) noise, which refers to the dependence of a particle’s thermal fluctuations on its position. To investigate the motion of particles in viscosity gradient we measured the drift and the flux of nanoparticles as well as the ionic current inside the nanochannel with no applied voltage, pressure, or salinity gradient. We show that the resulting dynamics agrees with the isothermal description for Brownian particles. We discuss the origins of the ionic current, the dynamics of the nanoparticles, and the role of the boundary conditions for the ions and the nanoparticles.
- Notes:
- Thesis (Ph. D.)--Brown University, 2023
Citation
Lameh, Shady Shayan,
"Electrokinetic noise driven dynamics of DNA molecules and dynamics of nanoparticles in diffusivity gradients."
(2023).
Physics Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://repository.library.brown.edu/studio/item/bdr:tj262ceq/
