This paper introduces a cost-effective and eco-friendly paper-based self-inductive folding displacement sensor (PSIFS) for measuring human respiration and motion signals. The sensor boasts a displacement resolution of 20 µm and a wide measurement range of 43.2 mm, achieving sensitivity up to 4.44% mm⁻¹. Its sensing mechanism relies on inductance variation due to the 3D deformation of a planar inductor coil. A folding method is proposed to triple the sensitivity. The sensor successfully recognizes various breathing and joint motion states.
