Optimization of a flexible piezoelectric module structure based on a lead-free piezoceramic embedded in nanofiber composites

[Display omitted] •The flexible module structures based on piezoceramic nanofibers were optimized.•Energy harvesting single modules were optimized according to electrode structure.•Dual modules were optimized electrode structure according to arrayed x- and z-axis, and connected in series or in parallel.•The energy harvesting properties and the structural health monitoring sensing capabilities were analyzed. To realize flexible piezoelectric materials with energy harvesting properties and vibrational characteristics, a piezoelectric module structure based on a lead-free piezoceramic embedded in a nanofiber composite was optimized according to the electrode structure and the module array arrangement. Lead-free piezoceramic particles embedded in nanofiber composites were prepared by an electrospinning process and then modularized by adding upper and lower electrodes via lamination. The energy harvesting properties of the flexible piezoelectric single modules with electrode structures consisting of top and bottom electrodes or interdigitated electrodes with various electrode widths and electrode intervals were characterized according to the oscillation frequency and the bending motion. The displacement and vibrational mode shapes of the flexible single modules were analyzed using a laser scanning vibrometer. Based on the optimized electrode structures of the flexible single modules, flexible piezoelectric dual modules were fabricated according to x- and z-axis array arrangements and to serial and parallel connection methods. The energy harvesting properties were measured and structural health monitoring sensor tests were conducted for several simulated situations. Among the examined modules, the flexible piezoelectric dual module with a serially connected x-axis array showed the best performance. This work provides a new guideline for using module structure design to enhance the piezoelectric effect in flexible modules.