The document provides an overview of optofluidic devices, which integrate microfluidics and optical technology to manipulate fluids and light at the microscale. It highlights the unique properties of fluids for device design, applications in lab-on-a-chip systems, and mentions the advantages of integration and reconfigurability. The conclusion notes the rising interest in this field, despite a limited number of successfully commercialized devices.

1. OPTOFLUIDIC DEVICES
By,
Prathul Nath P P
15PH62R06
M.Tech in SST
Dept of Physics
IIT Kharagpur

2. Contents
 Introduction to Optofluidics.
 What makes it special?
 Physics of Optofluidics.
 Device fabrication.
 Applications.
 Conclusion.

3. Introduction to Optofluidics
 Manipulating fluids and light at the micro
scale and exploiting their interaction.
 It combines Micro fluidics and Optical
technology.
 Enables real time tunability of optical
properties that are difficult to reconfigure in
conventional solid state optical systems.
 A notable application of this technology is
in so-called lab-on-a-chip devices:
miniature systems for analyzing and sorting
particles and cells.
Courtesy: Carlos Lopez

4.  The oil-immersion microscope, liquid mirrors for telescopes, liquid
crystal displays and electrowetting lenses are good examples.
Courtesy: Heather Montgomery
 Integration and reconfigurability are two major advantages
associated with optofluidics.

5. What makes it so special ?
 Fluids have unique properties that cannot be found in solid
equivalents, and these properties can be used to design devices.
 Ability to change the optical property of the fluid medium within a
device by simply replacing one fluid with another.
 Optically smooth interface between two immiscible fluids and the
ability of flowing streams of miscible fluids to create gradients in
optical properties by diffusion.
 Chip optical manipulation of Nano /micro-sized objects in micro
fluidic channels, thereby providing a non-intrusive method to
optically manipulate micro particles in a small fluidic sample
volume.

6.  These devices use active species dissolved in a liquid solution as the
gain medium.
 Integration offers significant advantages to these systems including
minimized consumption of reagents, portability, increased
automation and reduced costs.
 The integration of monolithic or hybrid optical and optoelectronic
devices (light sources, filters or photo detectors) into the lab-on-a-
chip is being investigated at present to improve the performance
and portability of these systems.

7. Physics of Optofluids
 Laminar flow : For flows confined on the such scale, viscous forces
in the fluid dominate over inertial forces and the flow has damping
nonlinearity thereby never turbulent and always laminar.
 Diffusion driven mixing occurs as a consequence of laminar flow, a
lack of turbulent flow means that all mixing is driven by diffusion
of the species.
 Capillarity phenomena :The surface tension (strongest forces at this
scale) at the phase boundary of a fluid dominates over the viscous
forces inside the fluid. It can be used to introduce a fluid into a void
but similarly renders the same fluid difficult to remove.

8. Device Fabrication
 Optofluidic systems is carried out
in PDMS (soft lithography) and
other polymers.
 PDMS has attractive properties
such as elasticity, optical
transparency and a biocompatible
surface chemistry, low Young’s
modulus has allowed the
construction of thin flexible
membranes that are exploited to
build microvalves or adaptive
lenses. Source: Anagha A V, Dept of PHYSICS,
CUSAT

9. L square Lens
Source : Anagha A V, Dept of Physics , CUSAT
L lens is formed by laminar flow of three streams of fluids; the index
of refraction of the central (“core”) stream is higher than the index of
the sandwiching (“cladding”) streams. The streams enter a
microchannel containing an “expansion chamber”—a region in which
the width of the channel expands laterally.

10.  Various microfluidic components, such as micromechanical valves,
microchannels, micropumps, microfluidic mixers and other
elements to handle and control fluids at the microscale have been
realized.
 The reported optofluidic lasers emit light in the visible range. By
exploiting other kinds of dissolved active medium, such as quantum
dots or colloidal nanocrystals, near-infrared emission could be
achieved with equally good performance.

11. Optical Micro cavities fabricated for different applications
Source: C. MONAT*, P. DOMACHUK AND B. J. EGGLETON School of Physics, University
of Sydney, Sydney, New South Wales 2006, Australia

12. Lab On A Chip
 Lab-on-a-chip refers to
technologies which allow
operations which normally
require a laboratory -
synthesis and analysis of
chemicals - on a very
miniaturized scale, within a
portable or handheld device.
 Analysis of samples can take
place in situ, exactly where
the samples are generated,
rather than being transported
around to a large laboratory
facility.
Source: Azonano.com

13. Applications
 Displays.
 Biosensors and Imaging.
 Lab On a Chip.
 Energy.
 Dye Laser.

14. Conclusion
 Optofluidics is a rapidly growing field. The permutations of optics
and micro fluidic combinations are numerous and exciting to
explore It is full of promise, but few devices have been successfully
commercialized as of yet.
 Optofluidic devices are good complements to micro-
electromechanical systems (MEMS) reconfigure themselves
through fluidic controls. Such controls can dramatically simplify
fluid manipulation by completely removing the need for on-chip.

15. Acknowledgement
I would like to thank the Head of the department and
Professor A.Dhar for giving me this opportunity. I
would also like to thank my seniors and fellow
classmates for all the support they have given.

16. References
 Integrated Optofluidics: A new river of light, C. MONAT*, P.
DOMACHUK AND B. J. EGGLETON Centre for Ultrahigh
Bandwidth Devices for Optical Systems (CUDOS), School of
Physics, University of Sydney, Sydney, New South Wales 2006,
Australia.
 Optofluidics: An Emerging Technology for Reconfigurable
Architectures, Anagha A1, Anjitha V2, Gnana Sheela K3,
Department of Electronics and Communication Engineering, TIST,
CUSAT, Kerala,India.
 Wikipedia.org
 http://www.azonano.com/
 http://ieeexplore.ieee.org/

17. THANK YOU