http://news.bbc.co.uk/2/hi/science/nature/8504373.stm

 

What's really going on? This explanation seems pretty bad, IMO.

Simply put, quantum mechanics says that there is a tiny probability that a particle shot at a wall will pass through it in an effect known as tunnelling.

 

Similarly, the material that surrounds the spiky balls acts like a wall to electric current. But as the balls draw closer together, when squashed or deformed by a finger's pressure, the probability of a charge tunnelling through increases.

 

I think that's a decent explanation. The tunneling probability depends on the barrier height and thickness. You press on the material and each barrier gets thinner. More current flows because the electrons can more readily tunnel.

It syas in that article as well that slowly increasing the pressure causes a smooth increase in the tunneling current. But isn't the tunelling current an exponetial function...so as you get closer it gets alot bigger a lot faster?

smooth ≠ linear