High-voltage nanofluidic energy generator based on ion-concentration-gradients mimicking electric eels

Although rapid advances have been made in micro/nano-scale devices, there is still a lack of clean and sustainable power source for them. Here we propose a high voltage nanofluidic energy generator inspired by electrical eel using ion-concentration gradients, which converts Gibbs free energy into electricity without any pollutants. The high voltage can be induced by alternatively multi-stacking cation and anion-exchange nanochannel network membranes (CE-NCNMs and AE-NCNMs) in a confined microscale space. These membranes were constructed by in situ self-assembled nanoparticles with hydroxyl and amine groups, respectively. The multiple stacks of CE-NCNMs & AE-NCNMs were successfully realized by precisely guiding the nanodrops with the suspended positively or negatively charged nanoparticles into the desired positions in the multilayered microchannel platform. The performance of the proposed nanofluidic energy generator was quantitatively investigated by changing nanoparticle species, intermembrane distance (IMD), and environmental temperature. Interestingly, we found that our optimized IMD (similar to 80 mu m) is very similar to the inter-cell membrane distance of electrocytes in natural electric eels and the diffusion potential of a single full cell at this IMD (similar to 138 mV) is also similar to the net potential across a single electrocyte (similar to 150 mV). This optimized IMD is verified through not only electrical measurement but also by fluorescent tracing and numerical analysis using multiphysics simulation. The high voltage of up to 1 V achieved by stacking 20 full cells is, to the authors' knowledge, the highest value yet obtained by microfluidic systems harnessing ion-concentration gradients.