The well-known Marangoni effect perfectly supports the dynamic mechanism of organic solvent -swollen gels on water. On this basis, we report a series of energy conversion processes of concentrated droplets of polyvinylidene fluoride/dimethyl formamide (PVDF/DMF) that can transfer chemical-free energy to kinetic energy to rapidly rotate itself on water. This droplet (22.2 mg) is capable to offer kinetic energy of 0.099 mu J to propel an artificial paper rocket of 31.8 mg to move over 560 cm on water at an initial velocity of 7.9 cm As the droplet increases to 35.0 mg, a paper goldfish of 10.6 mg can be driven to swim longer at a 'higher initial velocity of 20 cm s(-1). The kinetic energy of the droplet can be further converted to electrical energy through an electromagnetic generator, in which as a 0.5 M Omega resistor is loaded, the peak output reaches 6.5 mV that corresponds to the power density of 0.293 mu W kg(-1). We believe that this report would open up a promising avenue to exploit energies for applications in miniature robotics.