SOME RESEARCH INNOVATIONS, DISCOVERIES AND BREAKTHROUGHS
Superfluidity in Microchannels
and Nanochannels: The Rough Makes
it Smooth!
Would you believe that we should
design rough surfaces to make them behave in the smoothest possible way? In
other words, would you ever imagine that a rough surface may help in inducing a
motion on the top of it, instead of inhibiting the same? That, as a
possibility, would indeed sound unachievable, until we discovered from our
recent study that specially designed tiny water-transport channels (or pores)
may achieve this apparently impossible task by two simple mechanisms. First,
confining rough surfaces made of water-disliking materials may trigger the
formation of tiny bubbles adhering to the walls of narrow channels. This
incipient vapor layer acts as an effective
smoothening blanket, by disallowing the liquid on the top of it to be directly
exposed to the rough surface asperities. In such cases, the liquid is not
likely to feel the presence of the wall directly and instead may smoothly sail
over the intervening vapor layer shield. Thus,
instead of ‘sticking’ to a rough channel surface, the liquid may effectively
‘slip’ on the same. Secondly, the spontaneous formation of an electrically
charged layer adhering to the channel surface amplifies this tendency of
slippage to a large extent, by pumping the layer of fluid even more effectively
along with the movable charges. Based on this novel conjecture, we may design
miniaturized super-fluidic systems with an unimaginably high rate of liquid
pumping, without actually using any pumping device.
Digital Opto-fluidic Valve (
“Opto-fluidics”, referring to the integration of optics with
fluidics, has recently emerged to offer with a novel paradigm for the dynamic
manipulation of optical properties at length scales both greater than and
smaller than the wavelength of light, for actuating and manipulating fluid
flows. We have designed and fabricated a novel system in which we may
selectively ‘switch’ the movement of microdroplets in
different directions by using a light source (move liquid droplets selectively
by light!). Through the use of a photosensitive surface coating that senses the
energy incident from a light source; our system directly converts optical form
of energy to surface energy, and creates a consequent gradient in surface
tension for controlling the movement of tiny droplets in a selective manner.
Lab on a CD
The
recent advancements in CD-based microfluidics (lab-on-a-CD) have opened up the
possibilities of implanting complicated bio-microfluidic arrangements on
relatively inexpensive rotating platforms. Besides being advantageous because
of their versatility in handling a wide variety of sample types, the ability to
gate the flow of liquids (non-mechanical valving),
simple rotational motor requirements, economized fabrication methods, large
ranges of flow rates attainable, and the possibility of performing simultaneous
and identical fluidic operations has made the CD an attractive platform for
multiple parallel assays. The CD platform (including microchannel
arrays embedded within the same), coupled with automated liquid reagent loading
systems, indeed appears to be ideal for the future commercial introduction of
more compact and inexpensive lab-on-a-chip devices. Moreover, typical polymeric
materials of the CD-based microfluidic substrates are
excellently conducive to the standard micro-fabrication techniques and are also
extremely bio-compatible in nature, rendering their suitability of being
employed in biomedical diagnostics and sample detection systems of the future
generation.
Our technology development has lead to the simple design and
inexpensive fabrication of CD-based systems, in which liquid droplets may be
transported in a controllable manner with the aid of centrifugal effects and
under the simultaneous control of surface tension forces. The CD-based system
also acts like a mixing platform and reaction chamber for bio-chemical
analysis. Such systems may be potentially used for rapid, accurate,
inexpensive, and portable bio-diagnostic platforms.
DNA Hybridization through Microfluidics
A
remarkable advancement in the technology of the micro Total Analysis Systems
(µ-TAS) over the past few years has made it possible to organize and combine
the processes of sample handling, analysis and detection in stand-alone
integrated microfluidic platforms. This allows rapid
biochemical analyses to be carried out over length scales that are several
orders of magnitudes below the conventional practice. Overall, bio-microfluidics has provided great promises in improving the
sensitivity, specificity and the processing time required for a sample
analysis, which are the key requirements for advanced biomedical applications.
In order to appreciate the significance of bio-microfluidics
in advanced biomedical and biotechnological applications, it needs to be appreciated
first that different methods, in principle, can be employed to detect eventual
abnormalities or illnesses in patients. For viral infections or blood-related
pathologies, for example, immunoassays can be performed to determine the nature
of organisms that are responsible to disturb the inherent immunological
defensive systems in the living beings. One way of performing this is to use
homogeneous systems in which the sample and detection molecules are both in a
liquid system. Another way is to employ a heterogeneous system, in which one
type of molecules involved is bound to the solid substrate. The DNA or the
Deoxyribonucleic acid happens to play a critical role towards achieving this
goal, in many of the related applications. As such, DNA is found within the
nucleus of each cell. DNA carries the genetic information that encodes proteins
and enables cell to reproduce and perform their functions.
Structurally, the DNA is a linear polymer made up of
repeating sub-units (monomers) known as nucleotides that are covalently bonded
together. The sequence of these nucleotides forms the hereditary information.
Each monomer consists of a phosphate group that is responsible for the negative
charge on the DNA, a de-oxyribose sugar and a
nitrogen containing base. The backbone of a single stranded DNA molecule
contains a series of alternating sugar and phosphate groups, with one base
attached to each sugar molecule. The double-helical DNA strands essentially
contain linked nucleotides with one of the four bases adenine (A), thymine (T),
guanine (G) and cytosine (C). One oxygen atom is missing in the sugar content
of the nucleotide - thus the prefix “deoxy”. In the
sequence of their nucleotides, and thus their bases, both strands are
complementary to each other - in each case an A is opposed by a T and a G by a
C; this base pairing holds it together. For genetic ailments, DNA analysis can be
performed to know whether a patient possesses a mutation in a specific gene. One
of the methods to analyze this condition is to perform a gel-phase electrophoretic separation of fragments formed from the DNA
under question. Differences in fragment lengths from the patient’s DNA and a
healthy reference indicate the possibilities of certain genetic ailments.
Another method for accomplishing this purpose is to introduce many different
known single stranded (ss) DNA sequences bound
together with particles or gels in a reactive microsystem.
The DNA sample under investigation can be ‘hybridized’ with these different
sequences. By identifying the specific DNA sequence with which this sample
reacts (note that there is only one complementary sequence with which such
selective reaction becomes possible), one can determine the DNA sequence of the
unknown sample. It has been well appreciated that this kind of hybridization of
the DNAs to their complementary sequences plays a
major role in replication, transcription and translation, where specific
recognition of nucleic acid sequences by their complementary strands is
essential for the propagation of information content. In practice, microchip
based nucleic acid arrays presently permit the rapid analysis of genetic
information by hybridization. The DNA chips have gained wide usage in
bio-analytical chemistry, with applications in important areas such as gene
identification, genetic expression analysis, DNA sequencing and clinical
diagnostics.
We have attempted to utilize optimal combinations of various
actuating mechanisms in microfluidics and the critical
system parameters to achieve a faster yet inexpensive methodology of DNA
hybridization than the state-of-the-art affairs (mostly diffusion controlled),
and practically implement the same through the design and fabrication of novel
bio-microfluidic devices. Fundamental studies on the
mathematical description of the underlying fluid dynamic and bio-chemical
transport mechanisms, indeed, are likely to play vital roles towards achieving
this goal, without attempting for too many ‘hit-and-miss’ type of expensive
experimental trials. More extensive and detailed simulation studies, therefore,
need to be executed to map the variations in the microfluidic
system parameters/configurations with the DNA hybridization rates, for a wide
range of practical conditions in order to come up with the most optimal
solution.
Tracking the Dynamics of a Biological Cell in a Microfluidic
Environment
Understanding
the dynamics of biological cells in micro-scale conduits, in response to either
chemically changing environment or shear stress imparted by the background
flow, turns out to be of profound importance in designing and optimizing
advanced lab-on-a-chip based biomicrofluidic devices.
From several biological research endeavours, the traction force imparted by a
cell on the adhering surface has been identified to be one of the most
important parametric markers of its biophysical states. Change in the strength
of cell adhesion is a well-established scenario under diseased conditions,
apoptosis, exposure to unfavorable environment, shear
stress etc. For all of these cellular events, the activation
of intracellular signaling pathways results in either
over-expression or degradation of the adhering molecules, thus affecting the
cellular adhesion strength.
We
have developed a microfabrication compatible and high
resolution force measurement technique termed as Ultrasoft-Polydimethylsiloxane
based Traction Force Microscopy (UPTFM), for analyzing the dynamics of
biological cells in a micro-environment. This technique has been devised for
mapping the cellular traction forces imparted on the adhering substrate, so as
to depict the physiological state of the cells, surviving in the
micro-confinement. We have subsequently integrated the technique with a microfluidic platform for evaluating different states of
stress in adherent cancer and cells. Utilizing this technique, we may monitor
the spatio-temporal evolution of cellular traction
forces for static incubation periods with no media replenishment as well as for
dynamic flow conditions that inherently induce cell deformation and detachment.
The biophysical state of the cell can be quantified towards designing better
lab-on-a-chip devices with pharmaceutical and biomedical applications. Point of
drug administration can be effectively determined using this technology. In
fact, a major concern is drug screening technology is frequent occurrence of
false-positive results where actual cellular response is not because of the
drug administration but because of pre-existing neighboring
environmental conditions. Respectively, with relevance to the aforementioned
issue, exact biophysical state of cell can be monitored before the
drug-treatment and by selecting the appropriate cellular state, false positive
results can be significantly eliminated.
Micro Heat Pipe
for Chip Cooling
It is
well known that high temperature induces mechanical, chemical and electrical
changes, which impair the performance reliability of electronic devices. As a
design constraint, higher heat build-up impedes the miniaturization (lowering
form factor) of electronic devices, which is otherwise a critical need from the
industry.
Our technology innovation has lead to the development of a
novel miniaturized chip-cooling strategy for electronics packaging
applications. The design involves micro-grooved heat pipes, which may act as
extremely efficient heat sinks. Two-phase heat transfer with its associated
highest values of transfer coefficients are effectively utilized in small grooved
heat pipes for effective dissipation of the generated heat in the electronic
components. The system transfers heat through phase change (evaporation and
condensation), thereby reducing the possibilities of overheating through
unwarranted temperature rises in the system.
Painless Microneedle for Blood Extraction and
Drug Delivery (Painless needle mimics mosquito's bite!)
In
diabetes mellitus, routine pathological examination of extracted blood samples
becomes extremely critical for its diagnosis and effective management. As such,
a number of diabetes patients have to check their blood glucose level several
times a day as a part of self health-monitoring process and inject insulin in
tune with the observed levels, as per medical protocols. A frequent repetition
of this monitoring, however, gives rise to several physiological hazards,
including the development of insertion pains.
We have designed a biocompatible painless microneedle by mimicking the blood sampling system of a
female mosquito, as a part of a compact medical device that comprises a
shape-memory alloy indentation actuator (providing with the initial driving
force), a blood sugar sensor (immobilized glucose oxidase)
attached to the gate electrode of a Metal-Oxide-Semiconductor Field Effect
Transistor (MOSFET), and in integrated micropump for
injecting insulin that is actuated in accordance with the blood glucose level
being measured. For more details, please read the news articles linked below.
http://technology.newscientist.com/article/dn14348
http://www.zeenews.com/articles.asp?aid=456438&sid=env&ssid=28
http://news.softpedia.com/news/Microneedle-Offers-Painless-Solution-to-Injections-90272.shtm
http://in.news.yahoo.com/139/20080718/981/tsc-now-a-painless-microneedle-that-mimi.html
http://www.twocircles.net/2008jul18/engineers_develop_painless_needle_mimics_mosquito_bite.html
http://www.newstin.co.uk/tag/uk/70505270?commentFilter=all-from-group
http://www.download222.com/thread-926-1-1.html
http://www.mumbaimirror.com/net/mmpaper.aspx?page=article§id=7&contentid=20080719200807190311217825a79273
http://www.newindpress.com/NewsItems.asp?ID=IE320080718015723&Title=Health&rLink=0
http://technorati.com/posts/S%2FToJJfVKD2E%2BCxz0f7XTv191wjiLlaJb1kwxhhTFgk%3D
http://www.healthjockey.com/2008/07/21/scientists-inspired-by-mosquitoes-to-develop-painless-needles/
http://www.medindia.net/news/view_main_print_new.asp
http://dailytimes.com.pk/default.asp?page=2008\07\21\story_21-7-2008_pg6_11
http://www.in-pharmatechnologist.com/news/ng.asp?n=86695-microneedle-insulin-drug-delivery
http://www.fundazone.com/
http://www.samachaar.in/Science/Engineers_develop_painless_needle_that_mimics_mosquito_bite_47984/
http://epaper.sakaaltimes.com/Default.aspx?selpg=85&BMode=100&selDt=07/27/2008#
http://derstandard.at/druck/?id=1216325296169
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For
Research Publications click here
SELECTED SPONSORED RESEARCH AND CONSULTANCY PROJECTS
(The
list below is only indicative of the Projects undertaken but by no means is a
comprehensive one)
·
Associated with the
Research Project (2007-2010) “Cell Culture inside Microfluidic
Channels with Extended Air-water Interface” (funded by DBT) as the principal investigator
·
Associated with the
Research Project (2007-2010) “A Study Of Microscale Transport Processes Leading To The
Development Of A Cooling Strategy For Electronic Components”, (funded by DIT) as the principal
investigator
·
Associated with the
Research Project (2008-2010) “Rapid DNA Hybridization in Microfluidic Channels”, (funded by DBT) as the principal investigator
·
Associated with the Indo-US Project (2008-2011) on
“Fabrionics” (supported by the Indo-US Science
and Technology Forum) as the Institute coordinator (PI from IIT Kharagpur)
·
Completed the Indo-US Project (2006-2007) on
“Futuristic Manufacturing” (supported by the Indo-US Science and Technology
Forum) as an investigator
·
Associated with the DST-NSF Project (2006-2008)
“Experimental and Theoretical Studies on DNA Hybridization in Microchannels with Electrokinetically
driven Flow”, as principal investigator
·
Completed the DST-JSPS Project (2006-2008)
“Development of an advanced Micro-Manufacturing Technology characterized by
Micro Surface Quality Control for Bio-MEMS devices”, as principal
investigator
·
Associated with the Research Project (2005-2008)
“IRES: U.S.-India Fast DNA Hybridization
in Microfluidic Platforms” (funded by the NSF,
·
Associated with the Research Project (2008-2010)
“High throughput Glycomics
with Lectin Microarray”
(funded by DBT) as a co-principal
investigator
·
Completed the Research Project (2005-2007) “Development of A Window Based Interactive
Software with User Friendly GUI for Time Dependent Numerical Simulation of
Transport Phenomena During Laser Surface Treatment of Materials” (funded by
BRNS) as the principal investigator
·
Completed the Research Project (2004-2007) “Modeling and Simulation of Momentum, Heat and
Mass Transfer in Laser Surface Alloying” (funded by Department of Science
and Technology, Govt. of
·
Associated with the Research Project (2003-2007)
“Modelling and Simulation of photothermal
interaction of laser beam with living biological tissues” (funded by ISIRD,
SRIC, IIT Kharagpur, and subsequently by the
Department of Science and Technology, Govt. of
·
Completed the Project (2001-2002) on “Mathematical Modelling of Heat Transfer and
Fluid Flow during Laser Surface Alloying” (funded by DMRL,
·
Associated with the Consultancy Project (2006-2007) “Characterization of Surface Roughness for
Pressure-Driven and/or Electro-osmotic Liquid Flow in Microchannel”
(funded by
·
Associated with the Consultancy cum R&D Project
(2006-2009) “Development of a fundamental
model for characterizing solidification transport in the mushy region ”
(funded by General Motors Research and Development Center,
USA) as the consultant-in-charge
·
Completed the Consultancy cum R&D Project
(2003-2006)“An Integrated Micro-Macro
Solidification Algorithm for Direct Numerical Simulation of Large Scale
Solidification Structures ” (funded by General Motors Research and
·
Completed the Consultancy Project (2002-2003)“Development of a Mathematical Model for
describing the flow field in liquids/melts agitated by an impinging gas jet and
submerged gas stirring in LD converter ” (funded by TISCO) as the consultant-in-charge
·
Completed the Consultancy Project (2006) “Genetic Algorithms in hydrocyclones
” (funded by Tata Steel,
·
Completed the Project (1999-2001)“A Personal Computer Based Real-time Power
Plant Simulator Using Parallel Processing Technology” (funded by AICTE) as
a co-investigator
SOME RECENT INVITED LECTURES DELIVERED IN INTERNATIONAL AND
NATIONAL ARENA OF IMPORTANCE
- “Fundamentals
of Bio-Microfluidics: Present Trends and Future
Challenges”, International Conference on Advanced Materials (ICAM); under
the auspices of the International
- “Towards
an Improved Understanding of Surface Effects in Microscale
Liquid Flows”, Special Physical Mathematics Seminar, Department of
Mathematics, MIT, USA, June 26, 2007 (also presented at the University of
California, Berkeley, USA, July 5,
2007)
- “Novel Mechanisms for Rapid DNA Hybridization
through Microfluidics”, Indo-US Workshop, Northwestern University,
- “Effects of Micromanufacturing
Process Parameters on Fluid Flow in Microchannels”,
University of
- “Effects of Micromilling
Process Parameters on Fluid Flow in Microchannels”,
Japan-India Joint Seminar on Micro and Nano
scale Manufacturing Processes, IIT
- “Turbulence Modelling Strategies for Molten Pool
Convection in Laser-Aided Surface Processing of Materials”, Japan-India
Joint Seminar on Micro and Nano scale
Manufacturing Processes,
- “Some
Interesting Fluid-Dynamic Apects in Solidication Phase Change of Binary Systems”, CBI-Colloqium,
- “An Enthalpy based Micromodel
for Dendritic Solidification of a Pure Melt”,
Indo-Japan Joint Seminar on Advanced Manufacturing, IIT
- “Fundamentals of Microfluidics:
Some Biotechnological Applications and Beyond”, Indo-USA Workshop on MEMS
and Microsystems, IIT
- “Modeling and Simulation of Transport Phenomena in Micromanufacturing Applications: Issues of Microscale Fluid Flow and Heat Transfer”, for the
occasion of 7th India-Japan Joint Seminar on Advanced Manufacturing
Systems, Tokyo, Japan, February 16-21, 2004
- “Mathematical Modeling
of Laser Surface Alloying”, for the occasion of DAE-BRNS national Laser
Symposium (NLS-2003), Kharagpur,
- “Some Issues on Momentum, Heat and Mass Transfer
in Binary Alloy Solidification Processes”, ACCESS e.V,
RWTH
- “Computational Fluid Dynamics and Heat Transfer
in Manufacturing and Materials Processing: Current Issues and Future
Challenges”, for the occasion of Asia Youth Forum on Advanced
Manufacturing, Tokyo, Japan, March 1-8, 2003 (Invited by JSME)
RECENT VISITING POSITIONS (RESEARCH/ TECHING) ABROAD
- Visiting Professor,
- Visiting Scientist,
- Guest Scientist, LSTM, University of Erlangen, Germany, May-December, 2005 May-July, 2006,
and May-June 2007
- Visiting Scientist,
5.
Visiting Scientist, Aachen University , Germany
EDITORSHIP AND PEER REVIEW ACTIVITIES
Editorial Board Member of: International Journal of Micro and Nano Systems, Open Journal of Thermodynamics
Reviewer of the Following Journals: Journal of Fluid Mechanics, Lab on a Chip, Physics
Letters A, International Journal of Heat and Mass Transfer, Analytica
Chimica Acta, Journal of
Colloidal and Interface Science, Journal
of non Newtonian Fluid Mechanics, International Journal of Heat and Fluid Flow,
Microfluidics and Nanofluidics,
ASME Journal of Heat Transfer, Numerical Heat Transfer, Journal of
Biomechanics, Materials Science and Engineering, Science and Technology of
Welding and Joining, Materials and Manufacturing Processes, Journal of
Biomechanics, Applied Thermal
Engineering, International Communications in Heat and Mass Transfer, Acta Materialia, International
Journal of Multiphase Flow, Fluid Dynamics and Materials Processing, Chaos, Solitons and Fractals, IEEE Transactions on Components and
Packaging Technologies, Biomedical Microdevices,
Medical and Biological Computing, etc.
Microfluidics @IITKGP: A Perspective & Outlook
