Recently, various energy transducers driven by the relative motion of solids and liquids have been demonstrated. However, in relation to the energy transducer, a proper understanding of the dynamic behavior of ions remains unclear. Moreover, the energy density is low for practical usage mainly due to structural limitations, a lack of material development stemming from the currently poor understanding of the mechanisms, and the intermittently generated electricity given the characteristics of the water motion (pulsed signals). Here, we demonstrate a method by which to generate continuous electrical energy with the flow of a water droplet through an electrolyte-insulator-semiconductor (EIS) structure. The output power and energy conversion efficiency of the transducer are 0.373 uW/g and 29.8 %, respectively, where v is the speed of the water droplet. We propose and verify a hypothesis pertaining to the ion-dynamic operation mechanism of the transducer which holds that the electron flow is induced by the adsorption and desorption of ions. Further, we describe ion specificity and bio-functionality, an important characteristic of electrical signals generated by macroscopic droplet motion, in relation to the potential profile of electric double layer, which is determined by the characteristics of microscopic ion properties.