Biomedical Engineering Reference
In-Depth Information
Figure 4.76
The inverse of the frequency 1/
fr
varies linearly with the device dimension.
4.4.4.2 Encapsulating a Single Cell
Encapsulation of single cell has been identified as an important process for the study
of cells. It is also important for in vivo applications where capsules are reimplanted
in the human body. In order to perform a single-cell encapsulation, incoming cells
must be spaced by a time difference synchronized with the droplet formation fre-
quency (Figure 4.77).
4.4.4.3 Gelling, Polymerization, Biocompatibility, and Viability
For encapsulation purposes, gelling of the capsules is mandatory. Conventional
methods polymerize capsules in microwells or beakers. Gelling inside a microsystem
remains a difficult problem, because it usually occurs quickly and gelled capsules
clog microchannels. Chemicals used to perform the polymerization process must
be totally biocompatible, or else the viability of the cells may drop drastically. This
research area is somewhat outside the scope of this topic, and we refer the reader to
the abundant literature in this domain.
4.5
Conclusions
This chapter was devoted to the physics of droplets and two-phase flows in micro-
channels. The applications of these different types of flows are extremely important
in biotechnology. Droplets are the smallest containers that can be imagined, and
mastering their manipulation is the key to new developments.
Figure 4.77
Single-cell encapsulation: a spacing of the incoming cell according to the droplet for-
mation frequency leads to the formation of capsules containing at most one cell each [88].
