A New Discovery in an Old Field

As scientific discovery advances it would appear to require ever more complex machinery and processes to implement ever smaller improvement. How refreshing therefore to have the opportunity to participate in the application of a truly new piece of science that is simple to understand and even simpler to use.

Metal-filled polymers have been around since the early 20th century and many hundreds of learned papers have been written about their properties. It is surprising then, that in the last few years of that century, a non-scientist should discover a unique combination of constituent properties and manufacturing processes that produce a whole new class of materials. These materials are named Quantum Tunnelling Composites or QTCs and the company formed to exploit them is called Peratech.

QTC's have the unique capability of transformation from a virtually perfect insulator to metal like conductor when deformed. That deformation can result from the compression, twisting or stretching of the material and QTC's response can be tuned appropriately to the spectrum of forces applied. The transition from insulator to conductor follows a smooth and repeatable curve, with the resistance dropping exponentially.

Using this capability, Peratech has introduced totally new classes of components for switching and sensing applications, with potential uses across a wide range of industries.

What Makes QTC Different?

What is it that gives QTCs their unique properties? The clue is in the name. Standard composites are usually made from polymers filled with carbon. In these some carbon particles always contact one another creating a conduction path. As pressure is applied, more come into contact and therefore more conduction pathways build up. This conduction process is known as percolation.

In QTCs the conduction process is fundamentally different. In QTCs the metal particles never come into contact. They do however get very close. So close that Quantum Tunnelling is possible between the metal particles.

Quantum Tunnelling is a phenomenon that derives from Quantum Mechanics. In quantum mechanics an electron is not viewed as a solid particle but more like a wave. You can think of the wave as describing the probability that the electron would happen to be at that location. When the wave meets a barrier, for instance a non-conductive material, the wave doesn't instantly go to zero, but decays exponentially. If the wave hasn't reached zero by the time it has reached the other side of the barrier then it emerges on the other side. In other words there is a probability that the electron could be found on the other side of the barrier; the electron has effectively "tunnelled" through the non-conductive barrier.