New-Tech Magazine - Europe | January Digital edition

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 3: Silicon wafer holding 20 prototypes of the high- throughput ‘cell sorter’ chip

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

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

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

Figure 5: With the help of lens-free microscopy, three types of white blood cells may be recognized in a blood sample

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