Sensor Solution

Sensor technology: Quantum Tunneling Composite (QTC)

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Technology overview:

QTC is a new type of material consists of Nickel particles embedded in a nonconducting pressure sensitive polymer. (Invented in 1997 by Peratech Ltd). Its electrical characteristic can be explain using the concept of quantum tunneling effect. This is a quantum mechanical effect of particles transitioning through a classical-forbidden energy state.
Since QTC is a mixture of nonconducting polymer and Nickel particles, it acts as a near perfect insulator when there is no mechanical stress. However, when we apply pressure to the material, the conductive Nickel particles will come closer to each other and a certain close distance will enable the quantum tunneling effect. Subsequently, with enough pressure, the material is able to turn to a near perfect conductor.

Commercial product used: QTC Sheet from Peratech Ltd.

This is product designed specifically for sensing force at finger touch level. It consists of 3 layers: a plastic backing, a conductive aluminum layer, a QTC layer. QTC Sheet is very thin, light and flexible. This make it an ideal sensing material for small and portable application. More at Peratech website...

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Sensor design:

In order to enable a small and portable design, one side of the printed circuit board (Pcb) is utilized as the sensing interface. QTC sheet is attached directly on top of the Pcb electrode so that no wire is needed. This design provides a flat sensing surface which is ideal when working with QTC sheet because there will be no mechanical stress other than user's input.

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