QTC vs. Force-Sensing Resistors: How the Sensors Differ
QTC vs FSR sounds like a comparison between two different sensor families. The important correction is that quantum tunnelling composite (QTC) is itself used to build force-sensitive resistive sensors. An FSR describes a broad function: an electrical resistance that changes when force is applied. QTC describes a particular pressure-sensitive composite and its underlying physics.
What changes when you press each sensor?
In a typical polymer-based force-sensing resistor, applied pressure changes the conductive pathways between particles or layers. Resistance generally drops as force increases. In QTC, conductive particles dispersed in an elastic material are arranged so close that electron tunnelling is important to its electrical response. Pressure changes particle separation, often creating a steep resistance change.
Both can be read with an electronic circuit that converts resistance into a measurable voltage. Neither is automatically a precise digital scale.
QTC versus a conventional FSR: quick comparison
| Question | QTC-based sensor | Other FSR designs |
|---|---|---|
| What is it? | A pressure-responsive composite used inside a force sensor | A broad category of force-dependent resistive devices |
| Typical response | Resistance falls under pressure, potentially very sharply | Resistance also generally falls under force |
| Best description | Material and mechanism | Sensor function; several material mechanisms exist |
| Needs calibration? | Yes, for quantitative force estimates | Yes, for quantitative force estimates |
| Possible limitations | Mechanical history, temperature and time dependence | Nonlinearity, hysteresis, drift and actuator dependence |
Does QTC measure force more accurately?
Not necessarily. A large change in resistance makes a sensor sensitive, but sensitivity is not the same as accuracy. Accuracy depends on repeatability, shape and placement of the load, temperature, electronics and calibration. A 2017 comparison of five flexible force sensors evaluated QTC alongside several other FSR products for pressure monitoring. It is a useful real-world reminder that performance must be judged in the intended application rather than by the technology name alone.
Which should you choose for a project?
- Detecting a touch or squeeze: either approach may work; prioritize the usable force range and mechanical packaging.
- Measuring a changing load: look for calibration curves, repeatability and loading-versus-unloading differences.
- Wearable or textile prototypes: test the actual bending, temperature and contact conditions, not just bench-top pressure.
- Educational demonstrations: compare resistance readings before and after applying a consistent load; avoid claiming to measure exact newtons without calibration.
Why do product comparisons get confusing?
“FSR” is sometimes used informally to mean a familiar thin printed force sensor, while QTC is marketed by its material name. In scientific writing, both can be discussed as resistive pressure-sensing technologies. The narrower distinction is which structure and conduction mechanism a particular device uses.
Read next
For the material science, see our introduction to quantum tunnelling composites. To interpret the response of an individual sensor, check the force–resistance curve, test setup and the differences between loading and unloading.
Sources: Sensors (2017), flexible force-sensor comparison; Sensors and Actuators A, QTC characterization and modelling.
