Carbon nanotube (CNT) arrays are emerging as versatile nanostructures that can be used in many applications including gene transfection technology. To understand the transport of molecules through an array of CNTs, diffusion of molecules was studied experimentally and analytically. A procedure using fluorescent spectroscopy was developed to measure the concentration change of fluorescein salt in a two-reservoir system separated by a CNT array. Experiments were conducted to measure how changing the initial concentration gradient and reservoir volume size impacted the diffusivity of the system. For 2 mL reservoirs, diffusivities were measured between 2.56*10^(-11) m^2/s and 3.51*10^(-11) m^2/s. Diffusivities were measured between 2.5*10^(-11) m^2/s and 7.91*10^(-11) m^2/s for reservoirs of 5 mL volume. Changing the starting concentration in the range of 4.29 to 100.1 μM did not significantly affect the value of diffusivity for a given reservoir size. Using the Stokes-Einstein equation and Fick’s laws of diffusion, an analytical model was developed to estimate the diffusivity of fluorescein salt to be 5.17*10^(-11) m^2/s. The results of experimentation and modeling provide a method to predict the time needed for concentrations of molecules to diffuse through the CNT array. The use of a fluorescent spectroscopy device can be applied to study diffusion of other molecules and properties of carbon nanotubes.

Library of Congress Subject Headings

Carbon nanotubes--Mechanical properties; Diffusion--Measurement; Fluorescence spectroscopy; Fluorescein

Publication Date


Document Type


Student Type


Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)


Michael Schrlau

Advisor/Committee Member

Michael Schertzer

Advisor/Committee Member

Patricia Taboada-Serrano


RIT – Main Campus

Plan Codes