Porous PDMS-Based Flexible Capacitive Sensor with Integrated Guyt on Chamber for Hydrostatic Pressure Measurement

Continuous monitoring of hydrostatic and interstitial fluid pressures within biological tissues is essential for diagnosing and managing a wide range of medical conditions, including hydrocephalus, glaucoma, compartment syndrome, and tumor progression. However, conventional pressure sensors are typically rigid and invasive, limiting their applicability for long-term implantation in soft tissue environments. In this study, we present a flexible, capacitive pressure sensor based on a porous polydimethylsiloxane (PDMS) matrix embedded with barium titanate (BaTiO3, BTO) nanoparticles. The incorporation of BTO enhances the dielectric constant, while NaCl-induced porosity improves mechanical compliance, enabling the sensor to detect subtle pressure changes with high sensitivity. The sensor is integrated with a cylindrical Guyton chamber for accurate hydrostatic pressure transmission and implantation feasibility. Optical characterization confirmed effective porosity modulation, and electrical measurements demonstrated a pressure sensitivity of 0.0518 pF/mmHg with excellent linearity (R2=0.9943) and minimal hysteresis across the physiological pressure range (0–14 mmHg). Compared to previously reported flexible sensors, the proposed device achieves a favorable balance of sensitivity, simplicity, and repeatability, making it highly suitable for intra-organ pressure monitoring and other biomedical applications requiring minimally invasive, real-time pressure sensing.