Optical Particle Trapping

Single molecule detection and analysis has rapidly grown into an important and vibrant field. The ability to trap a single particle for analysis has improved knowledge of a vast number of disciplines including, biomedicine, biophysics, physiology, molecular biology, immunology and analytical chemistry. Optical traps use light to manipulate nanoparticles using the radiation pressure from a focused laser beam. Optical traps allow for a non-invasive manipulation of micro and nanoscale particles over extended periods of time with high accuracy. This advantage provides a main advantage over other particle traps in use today. Despite the advantage over other methods, optical traps tend to suffer from the need of high optical powers and the potential danger of damaging the object under study. Thus our research group has developed an ABEL (anti-Brownian electrokinetic) trap, an active trapping method proposed by Enderlein that can trap particle with low optical excitation power [Publication 1]. A one dimensional version of this device has already been proven to work (Figures 1-4). We are now developing a 2D version of this device. 

Figure 1 - Top view of 1D ABEL trapping a microbead

Figure 2 - (a) Bright-field top view of the intersection region with boundary outline. (b-d) Fluorescence
micrographs of the excitation beams with the right, left and both beams activated

Figure 3 - Cross-section as indicated in b-d

Figure 4 - Fluorescent profile

Along with optical trapping in the ABEL trap, we will also integrate this trap with a nanopore gate. Integrating the ABEL trap with the nanopore gate will allow us to trap only one specific particle at a time. We have already demonstrated the ability to move an individual nanoparticle through a nanopore at a controlled rate on older ARROW device structures (Figures 5, 6) [Publications 2, 3]. 
Figure 5 - Illustration of nanopore integrated on ARROW device

Figure 6 - Cross section of nanopore


  1. "Ultralow power trapping and fluorescence detection of single particles on an optofluidic chip", Sergie Kuhn, Philip Measor, Evan J. Lunt, Brian S. Phillips, David W. Deamer, Aaron R. Hawkins, and Holger Schmidt, Lab on a Chip 132, 071011, (2010).
  2. "Controlled gating and electrical detection of single 50S ribosomal subunits through a solid-state nanopore in a microfluidic chip", Mikhail I. Rudenko, Matthew R. Holmes, Dmitri N. Ermolenko, Evan J. Lunt, Sarah Gerhardt, Harry F. Noller, David W. Deamer, Aaron Hawkins, and Holger Schmidt, Biosensors and Bioelectronics 29, 34-39, (2011).
  3. "Micropore and Nanopore Fabrication in Hollow ARROW Waveguides", Matthew R. Holmes, Mikhail Rudenko, Philip Measor, Tao Shang, Holger Schmidt, Aaron R. Hawkins, Journal of Micro/Nanolithography, MEMS, and MOEMS 9, 023004, (2010).

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