shows increased output voltage (Voc) from 2 V to 6.24 V (peak to peak) as the external force (Fz) increased from 10 N to 125 N, respectively. The application of higher magnitudes of Fz, up to 125 N, resulted in linear voltage increments in the device. In the Figure , we present a single pulse, where the positive part corresponds to external force/bend and negative part corresponds to the relaxation (back to original position) of the device. The response time of operation shows a sensitivity of 5 ms (Figure ) for the device. The internal resistance (RI) of the cell was also calculated (inset Figure ). A maximum voltage of ~2.9 V across the externalload resistance of 1 MΩ was obtained. The sensitivity of the NG device experienced due to external force was used to characterize the device response. A maximum sensitivity of 108 mV kPa -1 (< 10 N) was recorded for the device with Mn3O4 membranes (Figure ). This is higher than the sensitivity of 90 mV kPa -1 recorded till date for a lower-dimensional ZnO NG, which is a widely used as a triboelectric nanogenerator material. With increasing external load, the sensitivity of our device decreases to a minimum of 20 mV kPa -1 . This high sensitivity makes our device sensitive to detect small mechanical perturbations. The power density and current density was mapped for the force based measurements. Power density of 7.99 mW m -2 and current density of 3.4 mA m -2 were obtained for a minimum force of 10 N as seen in Figure . Our results compare favorably to other Mn-based NGs reported recently (see Table in Supporting Information for a comparison).