4
1 Introduction
Fig. 1.1 Droplet microfluidics based on closed channels [55]
In order to implement a microfluidic device, a large variety of microfluidic
platforms is available, which are based on different principles of driving and
controlling the phases. Here, particularly droplet microfluidics is a well-established
and highly potential platform, as droplets are especially suited to encapsulate
biological samples like cells, proteins, or DNA [117]. These droplets are injected
into a second immiscible phase (i.e., the so-called continuous phase). Figure 1.1
shows the formation of droplets using a T-junction. Here, both phases are driven
by a pump and when they meet at the T-junction, droplets are formed out of the
dispersed phase. The arrows in Fig. 1.1 depict the flow direction of the continuous
and dispersed phases. Then, these discrete droplets flow inside the immiscible
continuous phase through closed microchannels (called channels throughout the
book).
Note that, besides droplet microfluidics based on closed channels, digital
microfluidics also uses droplets. In digital microfluidics, droplets are moved on
a planar-surface using electrowetting or dielectrophoresis [56, 96]. Here, activated
electrodes generate electric fields, which allow to “hold” droplets on particular cells
within the grid. By assigning time-varying voltage values to turn electrodes on and
off, droplets can be moved around the grid and, by this, can be merged, split, and
mixed.
This book considers droplet microfluidics based on closed channels. Here,
the injected droplets confine the samples and reagents, which are transported by
the continuous flow through the microfluidic device. If this microfluidic device
contains multiple paths through which the droplets can flow, it is a so-called droplet
microfluidic network. Figure 1.2 shows a droplet microfluidic network proposed
in [13], which contains multiple paths through which the droplets can flow.
Along these paths, the droplets are manipulated by unit operations, which,
eventually, realize the desired (bio-)chemical experiment. These unit operations
for manipulating droplets can be realized with active as well as passive modules [55, 117], e.g., active and passive modules for droplet generation, merging,
splitting, and trapping exist. Active modules use, e.g., valves or electric fields
1 Introduction
Fig. 1.1 Droplet microfluidics based on closed channels [55]
In order to implement a microfluidic device, a large variety of microfluidic
platforms is available, which are based on different principles of driving and
controlling the phases. Here, particularly droplet microfluidics is a well-established
and highly potential platform, as droplets are especially suited to encapsulate
biological samples like cells, proteins, or DNA [117]. These droplets are injected
into a second immiscible phase (i.e., the so-called continuous phase). Figure 1.1
shows the formation of droplets using a T-junction. Here, both phases are driven
by a pump and when they meet at the T-junction, droplets are formed out of the
dispersed phase. The arrows in Fig. 1.1 depict the flow direction of the continuous
and dispersed phases. Then, these discrete droplets flow inside the immiscible
continuous phase through closed microchannels (called channels throughout the
book).
Note that, besides droplet microfluidics based on closed channels, digital
microfluidics also uses droplets. In digital microfluidics, droplets are moved on
a planar-surface using electrowetting or dielectrophoresis [56, 96]. Here, activated
electrodes generate electric fields, which allow to “hold” droplets on particular cells
within the grid. By assigning time-varying voltage values to turn electrodes on and
off, droplets can be moved around the grid and, by this, can be merged, split, and
mixed.
This book considers droplet microfluidics based on closed channels. Here,
the injected droplets confine the samples and reagents, which are transported by
the continuous flow through the microfluidic device. If this microfluidic device
contains multiple paths through which the droplets can flow, it is a so-called droplet
microfluidic network. Figure 1.2 shows a droplet microfluidic network proposed
in [13], which contains multiple paths through which the droplets can flow.
Along these paths, the droplets are manipulated by unit operations, which,
eventually, realize the desired (bio-)chemical experiment. These unit operations
for manipulating droplets can be realized with active as well as passive modules [55, 117], e.g., active and passive modules for droplet generation, merging,
splitting, and trapping exist. Active modules use, e.g., valves or electric fields