Download Abstract: The first part of the seminar will be on a microsystem for

Abstract:
The first part of the seminar will be on a microsystem for flow cytometry in
marine life sensing. Measurements of plankton distribution, abundance and
structure have important contributions in studying climate change. A robust,
accurate and reliable microsystem to be deployed deep-sea for in-situ
monitoring of phytoplankton is under development. The various aspects of the
system include a chip, fluidics, optics, electronics and mechanical design.
The chip employs 2D hydrodynamic flow focusing to maintain the cells move
single-file and the optical detection technique is based on light scattering.
The fluidics employs a cross-flow filtration system for continuous filtration
of sheath flow directly from the sea and an expansion chamber to reduce flow
pulsations. A combined filtration-concentration mechanism has been devised
and demonstrated. The fluidics has been tested using cultured yeast solution
and optics is validated using polystyrene bead mixture. The bench-top model
of the system has been tested and the deployable system is under
construction.
The second part of the seminar will focus on a microsystem for detection of
bacteria. Presence of pathogenic bacteria like E-Coli 0157:H7 in soil (or
food) may result in serious health conditions. Therefore, accurate monitoring
of pathogenic bacteria is crucial in food and agriculture industries.
Detection platforms based on microsystems have advantages in terms of speed,
accuracy and sensitivity. We have developed a platform that can extract, mix,
capture, incubate and detect bacteria directly from soil sample. The
bacterial solution is extracted from soil sample and mixed with beads in an
extractor chip, captured (magnet), purified and mixed with reagents on a
second chip, finally detected on a third chip based on fluorescence
measurements. Design and fabrication of the chips, micro-valves, system
integration and tests are presented and results discussed. Bacteria detection
has been demonstrated and the limit of detection (LOD) of the system is
evaluated.
Biography:
Ashis Sen is currently an Assistant Professor in the department of Mechanical
Engineering at IIT Guwahati. Earlier, he was working as a Research Associate
and R&D Engineer in the Sensors Development Group with joint appointment
between the National Oceanography Centre (Nat. Environmental Research
Council) and ECS, Univ. of Southampton, UK. Prior to this, he worked as a
Senior Microfluidics Engineer at Epigem Ltd., UK for nearly one-and-half
years.
Ashis received his Ph.D. degree in Mechanical Engineering from the
Univ of South Carolina- Columbia USA.
During 2003-2004, he worked as a
Thermal Engineer at Applied Thermal Technologies in the areas of electronics
cooling. Ashis received his ME degree from the Indian Institute of Science,
Bangalore and BE from the National Institute of Technology, Rourkela.
His
current research interests are microfluidics, microfabrication, lab-on-chip
and micro-fuel cells. Ashis is a member of ASME and received the USC
Outstanding Graduate Student award in 2007.