From Chip-in-a-lab to Lab-on-a-chip: The Development of a Prototype for Acoustofluidic Nanoparticle Separation

Open Access
Rufo, Joseph Michael
Graduate Program:
Engineering Science and Mechanics
Master of Engineering
Document Type:
Master Thesis
Date of Defense:
April 30, 2015
Committee Members:
  • Jun Huang, Thesis Advisor
  • Microfluidics
  • Acoustofluidics
  • Dynamic Light Scattering
  • Nanoparticle
  • Separation
Dynamic Light Scattering (DLS) is a commonly used analytical technique for measuring the size distribution of particles in solution. DLS is an attractive technique because it is non-invasive (a low power laser is used so as not to damage the samples), requires very little sample preparation, and can extract information from small volume samples with relatively low particle concentrations. For these reasons, DLS has become a widely used analytical technique in many industries. For example, in the development of new biopharmaceuticals, one of the major limitations is the large number of tests that must be performed on limited amounts of sample. DLS allows researchers to extract size distribution information from as little as 2 μL of sample, saving the rest of the sample for other required tests. Although the size range of particles that can be analyzed via DLS is large (ranging from .03 nm to 10 μm), careful attention must be paid to the concentration of particles larger than 500 nm. If the concentration of larger particles is too high, it can prevent accurate measurement of the smaller sized particles. However, many applications produce samples containing particles above and below 500 nm (i.e. proteins and protein aggregates). The goal of this thesis was to develop an acoustic-based separation technique that could establish a tunable cutoff diameter and remove all particles larger than the cutoff diameter. The concept of acoustic-based separation was initially demonstrated in a laboratory setting with polystyrene beads. First, mixed samples were analyzed by DLS. The samples were then passed through our acoustic filter, and the smaller fraction was again analyzed by DLS and compared to both the initial measurements and samples of known concentrations. Results showed that our acoustic filter drastically improved the quality of the DLS measurements. Finally, we replaced the expensive lab equipment with custom electronics and constructed a prototype for acoustic nanoparticle separation.