Negative Gauge Factor Piezoresistance in Soft Strain and Pressure Sensors: Mechanisms, Materials, and Emerging Applications

Soft strain and pressure sensors underpin wearable electronics, soft robotics, and human‐centered healthcare, yet most piezoresistive devices rely on a positive gauge factor (pGF), in which resistance increases as deformation disrupts conductive pathways and continuous power is needed to register an event. Negative‐gauge‐factor (nGF) materials, whose resistance decreases under deformation, offer a fundamentally different route. Importantly, a negative gauge factor does not by itself imply low power: continuously conducting nGF devices still require an applied bias and constant monitoring, whereas near‐zero‐standby‐power, event‐triggered operation is enabled specifically by switch‐type nGF devices that are insulating at rest and turn on only under strain. This review classifies reported nGF systems into four mechanistic categories: intrinsic nGF from strain‐induced band‐structure modulation (Si, MoS 2 , PtSe 2 /PdSe 2 , SiC); composite nGF that transfers this response into polymer matrices and textiles; polymer‐reorganization nGF in conducting polymers; and architecture‐induced nGF engineered through tunneling barriers, contact closure, and compliant geometries. We discuss how these mechanisms enable low‐power switch‐type sensors, wearable health and motion monitoring, electronic skins, and smart textiles, and outline the challenges to establishing nGF piezoresistance as a design principle for energy‐efficient soft electronics.