Ultra-Sensitive Wireless Capacitive Nanocomposite-Based Pressure Sensors for Health Monitoring

Wireless pressure sensing plays a crucial role in a wide range of applications, including robotics, wearables, and health monitoring. These sensors are of particular interest in healthcare, especially for monitoring physiological pressures such as intraocular, blood, bladder, and intracranial pressure (ICP), offering significant potential for clinical use. However, improving the sensitivity and in vivo performance of these sensors remains a key challenge. In this paper, a novel approach is introduced to enhance the sensitivity of wireless capacitive pressure sensors by utilizing a nanocomposite dielectric layer. Biocompatible zinc oxide (ZnO) nanoparticles are incorporated into styrene-ethylene-butylene-styrene (SEBS) at different concentrations to fabricate a nanocomposite pyramid-structured dielectric layer. Sensors with a 0.7%-ZnO (v/v) nanocomposite dielectric layer exhibit a 4.3-fold improvement in sensitivity compared to ones with a pure SEBS dielectric layer. The sensitivity of the fabricated sensors reaches a notably high value of 45 MHz mmHg^-1 within the pressure range of up to 25 mmHg. Additionally, a new pickup probe is developed that extends the wireless reading distance by 40% over conventional probes. Furthermore, in vivo studies are conducted, demonstrating reliable detection of ICP changes in murine models. This design enables wireless sensing without complex electronics, offering enhanced sensitivity, stability, and clinical potential.