Optofluidics

From OLEG

Contents 1 Funding 2 Project Summary 3 Motivation for Approach 4 Anticipated Benefits 5 Project Publications

Funding

• US Department of Education, GAANN Fellowship (Graduate Assistance in Areas of National Need)
• NCSU Faculty Start-up Funds, College of Engineering and Department of Electrical & Computer Engineering

Project Summary

This project concerns the methods of trapping, sorting, mixing, and aligning nano- and micro-scale dielectric particles of arbitrary shape using electromagnetic fields within microfluidic environments. We are currently approaching this on two fronts:

1. Theoretical - mathematical modeling of spheroidal particle response to optically-induced forces and torques;
2. Experimental - investigating the influence of optical traps and periodic optical interference patterns on spheroidal particles.

Motivation for Approach

Several other prominent research groups and companies are engaged in similar projects implementing spatial light modulators and holographic optical trapping. Our approach (in theory and experiment) complements the need for specific optical elements, and instead relies on simple holography to form the optical fields of interest.

Such an approach holds several potential advantages: on-the-fly alteration of the interference field to any arbitrary pattern, a wavelength-independent manipulation system, an area of impact limited only by the primary laser power, and, because no specialty optical elements are required, a lower overall cost.

Anticipated Benefits

Our mathematical model will allow designers of optical trapping and manipulation systems access to several novel techniques, or "knobs to turn". Perhaps most importantly, because many particles of interest are not perfect spheres, our model accepts particles of arbitrary shape (e.g., blood and tissue cells, nanowires, microrotors), and finds that they behave much differently in an optofluidic system.

Our physical system will not only provide validity to our mathematical model, but will also allow for non-invasive and highly dynamic particle manipulation, alignment, mixing, sorting, etc. Due to our interest in sorting living cells, we currently employ infrared light at 1064nm. However, our system is easily tuned for a wide range of optical wavelengths.

Project Publications

• B. L. Conover and M. J. Escuti, "Anisotropic particle motion in optical landscapes modeled via the T-matrix optical scattering approach," Proceedings of the SPIE – Optics & Photonics Conference, vol. 7038, num. 703847, 2008.

• R. W. Going, B. L. Conover, and M. J. Escuti, "Electrostatic force and torque description of generalized spheroidal particles in optical landscapes," Proceedings of the SPIE – Optics & Photonics Conference, vol. 7038, num. 703880, 2008.

• B. L. Conover and M. J. Escuti, "Modeling anisotropic particle behavior within optical landscapes in microfluidic systems," 82nd ACS Colloid & Surface Science Symposium, 2008.

• B. L. Conover, "Analytical Model of Particle Motion in Optical Interference Landscapes and Laminar Flow," M.S. thesis, Dept. Elect. Comp. Eng., North Carolina State Univ., Raleigh, 2006.

• B. L. Conover and M. J. Escuti, "Modeling microfluidic motion of particles with anisotropic shape within optical landscapes," OSA Optics in the Southeast & HONET, num. SE03-B5, 2006.

• B. L. Conover and M. J. Escuti, "The response of particles with anisotropic shape within an optical landscape and laminar flow," Proceedings of the SPIE – Optics & Photonics Conference, vol. 6326, num. 632614, 2006.

• B. L. Conover and M. J. Escuti, "The response of particles with anisotropic shape within an optical landscape and laminar flow," CLEO/IQES and PhAST Technical Digest, num. JTuD41, 2006.