Biomedical Engineering Reference
In-Depth Information
Fig. 2.7 Virtual microfluidic channels are created using trains of moving pixels. Every tenth pixel
in a line is active, with each one transporting several cells. Linear channels can also be combined
with junctions to create the branching configurations seen on the right
shows (a) two similar cells being moved by the second-generation integrated circuit
and (b) two different strains of cells moving over the integrated circuit. An active
pixel potentiated to 5 V creates approximately 5 pN of force on a cell, transporting
it at up to 300m=s. The cells are exposed to electric fields of up to 50 kV/m at
1 MHz, well within the range where they remain healthy. Thousands of cells were
also positioned simultaneously to form a complex and well-defined structure, as
seen in Fig. 2.6 c. The phrase “lab on a chip” is spelled using yeast cells.
Virtual microfluidic channels were created using the hybrid integrated circuit/
microfluidic chip. Figure 2.7 shows two such arrangements where three channels
are run in parallel and where one channel is branched into four. Cells are carried
by trains of pixels where active pixels are separated by several inactive pixels. In
Fig. 2.7 , every tenth pixel was active. The active pixels each move in the same
direction and each one carries several cells. Virtual microfluidic channels are created
similarly to videos on the chip. A video file contains a number of frames where a
train of pixels moves one position with each subsequent frame. Each video encodes
a different configuration of channels, allowing a single chip to perform many tasks
simply by playing a different video.
Thousands of cells can also be moved simultaneously on the chip. Figure 2.8
shows frames from a video where thousands of yeast cells were positioned to move
like a dancer. The dancer is approximately 1.5 mm tall. Active pixels are located
inside the dancer, drawing cells to the edge of the dancer where the electric field is
strongest. This video was created by sending a GIF video file to the chip. A new
frame is displayed on the chip several times every second, moving the cells as each
new frame is displayed. Figure 2.8 shows frames 5 s apart with one additional frame
inserted at 0:17 s to show the dancer's full range of motion.
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