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

Abstract

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.