Three-Dimensional Multistack-Printed, Self-Powered Flexible Pressure Sensor Arrays: Piezoelectric Composites with...

Recently, the development of pressure sensor devices composed of mechanically flexible materials has gained a tremendous attention for emerging wearable electronics applications. Compared with various sensing materials, piezoelectric composite materials provide a characteristic advantage of enabling energy unit-free integration of sensor compartments. In this study, we develop a new chemical method of synthesizing highly functioning piezoelectric composite materials with electrostatically reinforced heterogeneous interfaces to improve the voltage output signal in all-printed sensor arrays. The surfaces of piezoelectric oxide nanoparticles are decorated subsequently with a cationic polyelectrolyte, polyethyleneimine, and a tri-block copolymer, styrene-ethylene/butylene-styrene grafted with maleic anhydride. To elucidate the factors determining the performance of pressure sensor devices, both the electrical properties and piezoelectric characteristics are investigated comprehensively for various compositional composite materials prepared from chemical and physical rubbers. The resulting device exhibits a sensitivity of 0.28 V·kPa^-1 with a linear increment of output voltage in a pressure range up to 30 kPa. It is also demonstrated that the all-printed sensor array is fabricated successfully by a multistack-printing process of conductive, insulating, and piezoelectric composite materials in an additive manufacturing fashion.