Compact polymer-coated FBGs enabling physiological pressure sensing

Accurate, continuous pressure monitoring is crucial in managing conditions such as intracranial hypertension and cardiovascular disease. While Fiber Bragg Gratings (FBGs) offer benefits such as MR-compatibility and catheter integration, their native pressure sensitivity (<0.4 fm/mmHg) limits biomedical use. We present a polymer-mediated strain-transfer method using PDMS jacketing that enhances FBG sensitivity by over 200 times, enabling compact (<600 µm) probes suitable for minimally invasive deployment. Finite-element modeling and tests confirm a 212-fold gain without added optical loss or reduced durability. The sensor achieves a responsivity of 0.84 dB/mmHg and a detection limit of 1.1 mmHg, rivaling state-of-the-art devices while retaining the advantages of FBG sensors. The soft, biocompatible coating also enables applications in gait analysis, soft robotics, and wearable rehab systems.