- Orthogonal optical forces offers sorting
One strategy that we have reported to accomplish optical nanoscale manipulation is to incorporate restricted spatial input location, orthogonal sort and movement direction features, with particle sorting achieved using an asymmetric potential cycled on and off, while movement is accomplished using photophoresis. This approach offers high throughput sorting. We have also been able find the optimal conditions for the sorting of multiple size particles.
T.W. Ng, A. Neild, P. Heeraman, Continuous and fast sorting of Brownian particles, Optics Letters. 33 (2008) 584-586.
A. Neild, T.W. Ng, T. Woods, Optimizing photophoresis and asymmetric force fields for grading of Brownian particles. Applied Optics. 48 (2010) 6820-6826. - Scattering and standing wave optical forces offers sorting
We have described an approach that applies optical scattering forces to translate varied sized particles differentially from a surface followed by the introduction of an optical standing wave to maintain and tighten the positional tolerance of the differentiated particles in the medium. We found that the workability of this scheme is highly dependent on Brownian forces typically dominant at this length scale. It also shows the significant impact of temperature and medium viscosity on the operation of this technique.
A. Neild, T.W. Ng, W.M.S. Yii, Optical sorting of dielectric Rayleigh spherical particles with scattering and standing waves. Optics Express. 17 (2009) 5321-5329.
- Plasmon waves from tailored surfaces offers trapping (NEW)
Optical forces available on a chip that possess features of strong trapping at the subwavelength scale, in a coplanar geometry, and at specific and selective locations portend many useful applications. Surface plasmons are a strong candidate. We advanced a concept that comprised a two pronged approach to accomplish this. Firstly, the plasmon fields emanating from a subwavelength aperture are manipulated so that it leaks maximally to the sides on a surface through the use of tailored corrugations. Secondly, the location of secondary corrugation at some distance permits reflection of these leaky waves, which with the coherence property of light used, generated optical standing wave fields capable of strong optical trapping.
M. Muradoglu, T.W. Ng, A. Neild, I. Gralinski, Tailored leaky plasmon waves from a subwavelength aperture for optical particle trapping on a chip. Journal of the Optical Society of America B. 28 (2011) 602-607.
Major Research Thrusts
Biochemical Analysis TechniquesWe seek to develop better methods, assays, and procedures that enable analysis of substances found in living organisms and the chemical reactions underlying life processes.
Particle/Cell ManipulationOur quest to find novel methods to move particles and cells around to accomplish important functions.
Instrumentation DevelopmentThe natural outcome of experimentation where we produce more advanced sensors, actuators, processors, and software.