Biomedical Engineering Reference
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Fig. 2.13 The hybrid integrated circuit/microfluidic chip splits a droplet and subsequently merges
it. The droplets are composed of oil submerged in a water medium
pixel using DEP, after which the electric field was switched to a lower frequency,
triggering electroporation. After 40 s, the trypan blue had entered and stained the
cell, confirming that electroporation had indeed occurred.
2.4.4
Merge
Figures 2.13 and 2.14 demonstrate how a simple fluid droplet can be split into two,
with one individually manipulated, and then rejoined into one. Merging droplets
is an essential function for performing chemical reactions on the chip. A sample
and multiple reagents are each contained in individual droplets. The reaction is
instigated by merging the droplets together, bringing the different reagents into
contact with the sample. Droplet merging is performed by moving the active pixels
under each droplet together, as seen in Fig. 2.13 [ 10 , 12 ]. When the two neighboring
droplets come into contact, they merge into a single, larger drop. After completion
of a reaction, the analytes are transported to an area of the chip with sensing
capabilities.
Cell fusion is a critical technique enabling cellular reprogramming, cloning, and
hybridoma formation [ 25 - 31 ]. A method for fusing cells using a hybrid integrated
circuit/microfluidic chip was developed and is shown in Fig. 2.15 . The chip traps and
moves cells using dielectrophoresis, positioning the cells into pairs in preparation
for cellular fusion. Fusion was performed using electroporation or by introducing
PEG (polyethylene glycol) into the system. Our technique has the advantage of
precise control over every cell, allowing perfect pairing of cells every time and
thus significantly increasing the yield. Fusion was performed in three different
configurations: An individual pair of cells was isolated and fused, several pairs of
cells were isolated and fused, and thousands of cell pairs were fused simultaneously.
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