Related Experiment Video
Updated: Aug 11, 2026

High Speed Droplet-based Delivery System for Passive Pumping in Microfluidic Devices
Published on: September 2, 2009
Electrical discharge in capillary breakup: controlling the charge of a droplet
Jean-Christophe Baret1, Frieder Mugele
1Philips Research Laboratories Eindhoven, Prof. Holstlaan 4, 5656AA Eindhoven, The Netherlands.
Abstract:
We studied the detachment of sessile droplets of conductive liquids from an immersed wire by reducing the contact angle using ac electrowetting. Upon detachment, the droplets acquire a certain amount of charge, which is shown to be controlled by a dimensionless parameter alpha. Alpha describes the interplay between the diverging Ohmic resistance of the breaking capillary neck and the ac frequency. In the specific configuration of the present experiment, discharging at high frequency leads to self-excited oscillations in which the droplets periodically detach from and reattach to the wire.
Related Concept Videos
Van de Graaff Generator
Van de Graaff uses both smooth and pointed surfaces, conductors, and insulators to generate large static charges and, hence, large voltages. A substantial excess charge can be deposited on the sphere because it moves...
Electric Field of a Charged Disk
The system's symmetry is in the cylindrical directions across the plane of the charge. As a result, the electric fields created by various surface charge elements nullify each other in the direction parallel to the surface. Thereby, the resulting electric field is perpendicular to the plane. Since the disk is...
DC Battery
Capillary Electrophoresis: Instrumentation
Electrochemical Systems
The Electrical Double Layer

