Piezoelectric performance testing of PLLA Films: Each strained film was initially cut at a 45-degree angle relative to the strain direction, which was experimentally determined using THz spectroscopy as described in our previous work . Electrodes were then fabricated on both sides of the film using a blade-coating method with stretchable silver flake paste (CI-1036), followed by curing at 60°C for 2 hours per side. The cyclic strain and tapping tests were conducted using an ESM303 MARK-10 tension/compression test stand. Each sample was subjected to 30 strain cycles, maintaining a consistent strain of 10%. The open-circuit voltage and short-circuit current were measured using a Keithley 6517B electrometer. The voltage sensitivity of the samples was characterized by applying an oscillatory force to the samples using a piezometer (PiezoMeter PM300, Piezotest), which includes frequency and force sweeps. Simultaneously, the open-circuit voltage and short-circuit current were measured with a Keithley 6517B electrometer.