A Hybrid Chitosan-BaTiO₃ Composite-Based Flexible and Self-Powered Pressure Sensor for Wearable Healthcare...

Wearable pressure sensors are key to many applications, such as those for Internet of Things (IoT), implantables in healthcare, soft robotics, insoles, and prosthetics, where the demands for flexible, self-powered, and highly sensitive pressure sensors are significantly growing. These requirements necessitate the development of flexible and high-performance piezoelectric materials, where current embodiments can be limited, requiring compromises between properties such as sensitivity, output voltage, biocompatibility, and response time. Here, a biopolymer composite-based piezoelectric material using chitosan-BaTiO₃ nanoparticles (NPs) is produced, showing significant promise for wearable healthcare pressure sensors. To demonstrate this, a piezoelectric-based dynamic pressure sensor and its array (5 × 5) are fabricated using a hybrid composite material by varying different concentrations of BaTiO₃ NPs (5, 10, 15 wt %). The sensors demonstrate relatively high pressure and frequency sensitivities for three different concentrations of the hybrid composite (5, 10, 15 wt %), constituting 105 mV/kPa, 233 mV/kPa, 276 mV/kPa; and 448.57 mV/Hz, 1703 mV/Hz, 2564 mV/Hz, respectively. The results show that the sensitivity increases linearly with an increase in the BaTiO₃ NP concentration, and the 15 wt % shows a maximum of 11-fold increase in the pressure and frequency sensitivities compared to pure chitosan. The mechanical flexibility of the pressure sensor is validated for 10⁴ cycles and demonstrates excellent long-term stability. This class of hybrid organic-inorganic composite-based pressure sensor will be a pathway toward highly flexible, sensitive, and biocompatible wearable electronic devices for healthcare applications.