Does QTC behave like a regular resistor?

[flatline]

At any particular level of compression, does QTC behave identically to an equivalent resistor?

Specifically, does it consume power like a resistor does (R*I^2)?

I've been wondering about this ever since I first read about QTC.

--flatline

 

[tolkaze]

Wikipedia states:

Quantum tunnelling composites (or QTCs) are composite materials of metals and non-conducting elastomeric binder, used as pressure sensors. They utilise quantum tunnelling: without pressure, the conductive elements are too far apart to conduct electricity; when pressure is applied, they move closer and electrons can tunnel through the insulator. The effect is far more pronounced than would be expected from classical (non-quantum) effects alone, as classical electrical resistance is linear (proportional to distance), while quantum tunnelling is exponential with decreasing distance, allowing the resistance to change by a factor of up to 1012​ between pressured and unpressured states.[1]​

So my understanding is that while it does alter current through resistance, it does it in a different fashion to a resistor, in that a regular resistor would halve resistance with half the length (imagine high resistance wire) whereas QTC would rapidly reduce resistance as the material was compressed, in a non-linear fashion. As for power consumption, I suspect that it would passively create heat at higher resistance, and decreasing amounts of heat as it was compressed, so like the resistance, the power converted to heat would change in a non-linear fashion.

So while you can't easily calculate the resistance at a given compression of QTC, you would probably be able to calibrate a particular piece of QTC material and map the curve of distance v resistance. This may actually be the same for all material, but I guess it would depend on thickness, binding agent, concentration of metals etc. We were looking at using them in various geophysical logging equipment to replace extensiometer based calipers, but found that the calibration changed...

My findings while playing with it are that thickness (i.e. we needed more than 1mm compression with out current setup), compression, heat, and amount of wear and tear tend to have an effect on the material and resistance. For use a pressure sensor (on or off at a given threshold) or in a flash light (where slight variations may not be noticed) it is fine, but having to calibrate each time was not that easy for us.

Edit: I should mention that when new, QTC material used as a variable resistance switch does have a good, repeatable curve.

 

[Mr Happy]

At any particular level of compression, does QTC behave identically to an equivalent resistor?

Specifically, does it consume power like a resistor does (R*I^2)?--flatline

Yes to both questions.