TABLE I.

Summary of the literature regarding droplet dispensing in DMF devices.

Number of dispensed droplets	Volume variation	Off-chip pressure source?	Feedback control?	Oil?	Dielectric layer	Comments
NDP	<3%	No	No	Yes	Parylene	No experimental details provided15
42	13%	No	No	Yes	Parylene	Devices were construced using multi-layer PCB and the reservoir was surrounded by a retaining wall and had two electrode areas, to increase the backpressure on the droplet when dispensing. In addition, an external pump with a three-way valve was used to dispense droplets. The volume variation of the dispensed droplets was only under 10% when also using feedback control16
79	12%	Yes	No
42	5-6%	Yes	Yes
48	0.4%	No	No	Yes	Si3N4	The reservoir was walled-in and had an extra electrode within; increasing the pressure from the reservoir when dispensing17
NDP	0.2–4%	Yes	No	Yes	Si3N4	The reservoir was walled-in and had an extra electrode within, increasing the pressure from the reservoir when dispensing18
12	1 or 5%	No	See comments	Yes	Parylene	Multilayer PCB electrondes were used to avoid problems with the deformation of droplets due to contact lines on the same plane of the device. Volume variation was 1% with feedback control and 5% without; however only 12 droplets were measured in each case, as this was the maximum that could be dispensed from a reservoir without re-filling13
NDP	∼1–3%	No	No	No	Parylene	Volume variation is cited as an estimate and no experimental details were provided3