Which term refers to a polymer-based material that is a flexible conductor under pressure, used in smart sensing?

• A. Smart fibres
• B. Composite materials
• C. Quantum-tunnelling composite (QTC)
• D. Micro encapsulation

Answer: (C)

A polymer-based material that becomes a flexible conductor when pressed is exemplified by a Quantum-tunnelling composite. In this material, conductive particles are embedded in a flexible polymer matrix. When nothing is pressing it, the particles sit apart, so little or no electrical current can pass and the material behaves as an insulator. Apply pressure and the particles are pushed closer together, creating conducting paths and enabling electrons to tunnel across the small gaps. This rapid drop in resistance in response to applied force is what makes it useful for smart sensing, such as touch or pressure sensors. The whole thing remains flexible and can be made into films, coatings, or integrated into wearables. Other terms describe broader ideas (like smart fibres or general composites) or different techniques (like micro encapsulation), but they don’t capture the specific pressure-activated conduction mechanism that defines this material.