Millable polyurethane/cellulose acetate/nanohydroxyapatite composite film as a flexible ferro-piezoelectric nanogenerator for innovative applications in physiological motion sensing

The advancement of piezoelectric nanogenerators capable of converting mechanical energy into electrical energy holds the potential for remarkable progress in biomedical devices and wearable consumer electronics. The current research work delves into the development of innovative polymeric piezoelectric composites intended for applications in energy harvesting and physiological motion sensing. The study explores the feasibility of a system composed of a millable polyurethane (MPU)/cellulose acetate (CA) blend reinforced with nanohydroxyapatite (nHA) to create a flexible ferro-piezoelectric polymer composite material. MPU and CA have been blended to create a polymer blend matrix, which has subsequently been embedded with nHA quantitatively. Morphology, mechanical strength, chemical features, and crystalline characteristics have also been systematically analyzed. The composite films exhibit piezoelectric properties, as evidenced by butterfly-shaped amplitude curves obtained from dynamic contact electrostatic force microscopy. Polarization measurements corresponding to the applied electric field validate the presence of ferroelectric domains in the resulting P-E hysteresis curves. An assessment of dielectric property variation has also been conducted as a function of frequency. A device prototype is manufactured, and tribo-piezoelectric responses, along with the resulting voltage generated in response to human finger tapping, have been evaluated using a digital oscilloscope. The outcomes offer valuable insights into the promising potential of creating efficient piezoelectric nanogenerators from this novel system, applicable across a spectrum of commercial utility.