What can a resistor remember?

Human skin acts like a memristor, a device that alters its resistance in response to the last potential difference applied. Memristors were proposed in the 1970s but the first physical device wasn’t built until 2008. Researchers have found that human skin acts as memristor – it seems to ‘remember’ the last potential difference applied. When a negative potential difference was applied to various parts of a human arm, the area of skin displayed a low resistance; when a positive potential difference was applied before the negative, the negative potential produced a much higher resistance. This effect arises as sweat contains positively charged ions, which are drawn upwards from sweat pores by a negative potential difference, lowering skin resistance.

Researchers believe that memristors may, one day, replace transistors in computers. In 2012, researchers built a device using memristors which had an access time 100 times faster than the available flash solid-state memory technology used in USB drives while consuming only one percent of the energy.