Shear-thickening fluids - which increase in stiffness when zapped with a vibrating force - could be useful for making better body armour, researchers at the Massachusetts Institute of Technology (MIT) have said.
The idea is to fill an armoured vest or helmet with shear-thickening liquid and surround it with an array of piezoelectric transducers, they say.
Normally, the protective garment would be soft and flexible, giving the wearer maximum freedom of movement.
But, at the first sign of danger, the transducers could be activated with the flick of a switch.
They would vibrate the fluid, increasing its overall stiffness and boosting the protective strength of the body armour.
According to New Scientist, switching the transducers off again would return the fluid to its normal state, making the armour soft and easy to remove.
The team has said the same technique could also be used for vehicle suspension systems and medical devices such as splints.