Large scale arrays of tunable microlenses

Varshney, Atul; Gohil, Smita; Tadavani, Somayeh Khajehpour; Yethiraj, Anand; Bhattacharya, Sarbari; Ghosh, Sibasish

doi:10.1039/c3lc51170g

Cited by 9 publications

(10 citation statements)

References 24 publications

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“…Increasing the frequency decreases the strength of the electrohydrodynamic flows, but does not change significantly the dipolar contribution. The silicone oil drops coalesce, and are attracted to the nearest ITO-free regions by negative dielectrophoresis and an array of hexagonal silicone oil droplets, in castor oil, is created on the top of patterned ITO slide [31].…”

Section: Pattern Formation and Flow Visualizationmentioning

confidence: 99%

Anomalous dynamics in tracer-particle motions in an electrohydrodynamically driven oil-in-oil system

Tadavani

Yethiraj

2018

Phys. Rev. E

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We characterize the superdiffusive dynamics of tracer particles in an electrohydrodynamically driven emulsion of oil droplets in an immiscible oil medium, where the amplitude and frequency of an external electric field are the control parameters. In the weakly driven electrohydrodynamic regime, the droplets are trapped dielectrophoretically on a patterned electrode, and the driving is therefore spatially varying. We find excellent agreement with a 〈x^{2}〉∼t^{1.5} power law and find that this superdiffusive dynamics arises from an underlying displacement distribution that is distinctly non-Gaussian and exponential for small displacements and short times. While these results are comparable with a random-velocity field model, the tracer particle speeds are in fact spatially varying in two dimensions, arising from a spatially varying electrohydrodynamic driving force. This suggests that the important ingredient for the superdiffusive t^{1.5} behavior observed is a velocity field that is isotropic in the plane and spatially correlated. Finally, we can extract, from the superdiffusive dynamics, a experimental length scale that corresponds to the lateral range of the hydrodynamic flows. This experimental length scale is non zero only above a threshold ion mobility length.

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Section: Pattern Formation and Flow Visualizationmentioning

confidence: 99%

Anomalous dynamics in tracer-particle motions in an electrohydrodynamically driven oil-in-oil system

Tadavani

Yethiraj

2018

Phys. Rev. E

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“…Although PDMS is optically transparent and has low losses in the visible range, light scattering through the polymer is not always negligible due to nanoparticles of silica within commercially available products (52). Alternatively, nanoliter-size droplets can be easily, robustly, and precisely formed in microfluidic devices whose focal length can be tuned by altering the surface tension at the droplet interface or electrical field within the microfluidic device (43,49). Environmentally responsive lenses, such as hydrogels, have also been used to adjust focus in a passive manner (see Fig.…”

Section: On-chip Lens Systemsmentioning

confidence: 99%

“…The creation of arrays of these lenses on-chip is simplified by the ability to address individual droplets to spatial locations, either hydrodynamically or through the use of electrophoresis or electrowetting on dielectrics (EWOD). Temporal modulation of an electric field has recently been used to both create two-dimensional (2D) monodisperse droplet arrays for use as microlenses and to achieve large deformation of microlenses for variable-focus tunability over millisecond timescales, a speed similar to that of the inertial response limit that can be affected by a common piezoelectric z-stepper (49,55).…”

Section: On-chip Lens Systemsmentioning

confidence: 99%

Optics-Integrated Microfluidic Platforms for Biomolecular Analyses

Bates

2016

Biophysical Journal

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Compared with conventional optical methods, optics implemented on microfluidic chips provide small, and often much cheaper ways to interrogate biological systems from the level of single molecules up to small model organisms. The optical probing of single molecules has been used to investigate the mechanical properties of individual biological molecules; however, multiplexing of these measurements through microfluidics and nanofluidics confers many analytical advantages. Optics-integrated microfluidic systems can significantly simplify sample processing and allow a more user-friendly experience; alignments of on-chip optical components are predetermined during fabrication and many purely optical techniques are passively controlled. Furthermore, sample loss from complicated preparation and fluid transfer steps can be virtually eliminated, a particularly important attribute for biological molecules at very low concentrations. Excellent fluid handling and high surface area/volume ratios also contribute to faster detection times for low abundance molecules in small sample volumes. Although integration of optical systems with classical microfluidic analysis techniques has been limited, microfluidics offers a ready platform for interrogation of biophysical properties. By exploiting the ease with which fluids and particles can be precisely and dynamically controlled in microfluidic devices, optical sensors capable of unique imaging modes, single molecule manipulation, and detection of minute changes in concentration of an analyte are possible.

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“…Microlenses are lenses with dimensions smaller than 1mm. It can be used, either individually or as microlens arrays, in a various applications such as: wavefront sensors, medicine, quantum computer research and so on [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%