Figure 1. Ultrasonically drilled hole

Figure 3. Schematic of electrode arrangement
in microfluidic channel


Figure 4. Reconstructed images of objects
in the channel

A vast majority of microfluidic devices are simple planar microchips fabricated by photolithography on substrates such as glass, silicon or polymers. Current commercial interest is in plastic fabrication for single-use disposable microfludic devices.

There are several suggested advantages of microfluidic systems including; reduced inventory of reagent and sample consumption, improved separation efficiency, reduced power consumption and portability.

A subsection of microfluidics is the emergence of droplet-based microfluidics with droplets as discrete fluidic volumes created by two
immiscible phases. Droplets can be seen as micro-reactors that can be transported, sorted, mixed and individually analyzed.

Droplets in small channels (Fig 3 & 4.) also allow fluid flows with no dispersion, which is a general problem with single-phase fluids. In addition, when such droplets are surrounded by an immiscible fluid it can prevent contact between the surface of the chip and the sample within the droplet, eliminating adverse effects due to the large surface to volume ratios.

Since identical droplets are produced with a very high rate in one
experiment, parallel processing is achievable to produce large data sets. These advantages offer the potential of higher throughput and the possibility to create new products.