Editing Digital microfluidics (section)

==== Biological extraction ====
Biological separations usually involve low concentration high volume samples. This can pose an issue for digital microfluidics due to the small sample volume necessary.<ref name="Shah_2009" /> Digital microfluidic systems can be combined with a macrofluidic system designed to decrease sample volume, in turn increasing analyte concentration.<ref name="Shah_2009" /> It follows the same principles as  the magnetic particles for separation, but includes pumping of the droplet to cycle a larger volume of fluid around the magnetic particles.<ref name="Shah_2009" />
Extraction of drug analytes from dried urine samples has also been reported. A droplet of extraction solvent, in this case methanol, is repeatedly flowed over a sample of dried urine sample then moved to a final electrode where the liquid is extracted through a capillary and then analyzed using mass spectrometry.<ref name="Kirby_2014">{{cite journal | vauthors = Kirby AE, Lafrenière NM, Seale B, Hendricks PI, Cooks RG, Wheeler AR | title = Analysis on the go: quantitation of drugs of abuse in dried urine with digital microfluidics and miniature mass spectrometry | journal = Analytical Chemistry | volume = 86 | issue = 12 | pages = 6121–9 | date = June 2014 | pmid = 24906177 | doi = 10.1021/ac5012969 }}</ref>