  Recently, our group reported that an any aqueous droplet dispensed from a
pipette tip has considerable amount of electrical charge. This natural
electrical charge of a droplet could cause undesired, unfamiliar experimental
results. Since the origin of the charge of a droplet is related to the pipette
tip material, we modified the inside material of the pipette tip with
poly(dimethylsiloxane)-graphene nanocomposites. The droplets dispensed from the
modified pipette tip has lower electrical charge than that from the common
pipette tip. We compare the experimental results with the droplets from common
pipette tip and modified pipette tip. This fluid dynamics video includes the
principle of the spontaneous electrification of the droplet and the results of
the droplet in oil experiments.
