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after the microscope and on both sides
of the channel. These heating elements
create steam bubbles that push the
cells into the right channel. Sorting
with these jet flow generators takes
about 100 microseconds per cell. This
speed is unique, and is also the result
of not using any moving elements.
Our scientists have performed an
experiment in which the cell sorter had
to isolate monocytes from a PMBC-
sample (Peripheral Blood Mononuclear
Cell) with monocytes and lymphocytes.
The sorter, using the jet flow generators,
was able to move 88% of the cells to
the correct output channel. The purity
of the collected monocytes at the chip’s
exit was 99%. These are exceptional
results proving that the cell sorter does
what it has been designed for. One way
of further improving the accuracy of the
jet flow generators is adding a sensor
that communicates the exact position
and speed of a passing cell to the jet
flow generators.
The power of parallelization
This concept and prototype of a cell
sorter becomes extremely powerful if
you consider the parallelization that is
possible with the silicon technology.
The first prototype has one microfluidic
channel with a lens-free microscope
and with jet flow generators on both
sides of the channel – but it is fairly
straightforward to extend this design
to hundreds of channels that function
in parallel and thus can sort hundred
Figure 3: Silicon wafer holding 20 prototypes of the high-
throughput ‘cell sorter’ chip
Figure 4A: Lens free
digital holographic
microscopy captures the
interference of direct
laser light with light that
has passed through the
cell
Figure 4B: Demo
setup of the lens free
microscope
Figure 5: With the help of lens-free microscopy, three types of white
blood cells may be recognized in a blood sample
thousands and even millions of cells.
That way, it becomes possible to
attain an unseen throughput for cell
analysis and isolation. In our design,
the number of channels we can add
is limited by the chip area and related
cost (we estimate that a hundred
channels will take up a square
centimeter of silicon); by the power of
the laser of the lensfree microscope;
and by the computations needed
for the image recognition. Currently,
the researchers work to fabricate
a 5-channel sorter as a proof-of-
concept for the improved throughput
and parallel sorting.
About the author
Liesbet Lagae - R&D manager lifescience
technologies, imec
Liesbet Lagae is co-founder and currently
R&D program manager of the life science
technologies activities in imec. In this role,
she oversees the emerging R&D of all the
life science technologies activities at imec.
She holds a PhD degree from the KU
Leuven, Belgium for her work on Magnetic
Random Access Memories obtained under
an IWT grant. As a young group leader,
she has initiated the field of molecular
and cellular biochips based on magnetic,
plasmonic, electrical sensing principles
intelligently combined with fluidics to do
full diagnostic analysis at IMEC, Belgium.
She is also appointed as a professor in
nanobiophysics at the KU Leuven. She has
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