Energy conversion from external fluctuating signals based on asymmetric nanopores

Electrical transduction from fluctuating external signals is central to energy conversion based on nanoscale electrochemical devices and bioelectronics interfaces. We demonstrate theoretically and experimentally a significant energy transduction from white noise signals using the electrical rectification of asymmetric nanopores in polymeric membranes immersed in aqueous electrolyte solutions. Load capacitor voltages of the order of 1 V are obtained within times of the order of 1 min by means of nanofluidic diodes which convert zero time-average potentials of amplitudes of the order of 1 V into average net currents. We consider single-nanopore and multipore membranes to show that the conversion processes can be significantly increased by scaling. The results concern a wide range of operating electrolyte concentrations. Because these concentrations dictate the pore resistance, the tuning of the load capacitance to optimize the system response at each concentration is also addressed. Finally, the experimental results are described theoretically by using simple equivalent circuits with a voltage-dependent resistance in series with a load capacitance. (C) 2015 Elsevier Ltd. All rights reserved.