Context

• Scientists spot piezoelectric effect in liquids for the first time

What is piezoelectric effect

• In the piezoelectric effect, a body develops an electric current when it is squeezed.
•  Quartz is the most famous piezoelectric crystal
• Such crystals are also used in cigarette lighters, electric guitars, TV remote controls, audio transducers, and other instruments where converting mechanical stress to a current is useful.

How it works

• The quartz crystal consists of silicon and oxygen atoms at the four vertices of a three-sided pyramid; each oxygen atom is shared by two pyramids. These pyramids repeat themselves to form the crystal.
• The effective charge of each pyramid is located slightly away from the centre. 
• When a mechanical stress is applied – i.e. when the crystal is squeezed – the position of the charge is pushed further from the centre, giving rise to a small voltage. This is the source of the effect.

Piezoelectric effect in liquid

• The effect has been known for 143 years and in this time has been observed only in solids.
• Now, the effect was found in pure 1-hexyl-3-methylimidazolium, bis (trifluromethylsulfonyl)imide, both ionic liquids at room temperature.

https://www.thehindu.com/sci-tech/science/scientists-spot-piezoelectric-effect-in-liquids-for-the-first-time/article66671337.ece