0000000000162191
AUTHOR
Vicente Gomez
showing 19 related works from this author
Fabrication of Single Cylindrical Au-Coated Nanopores with Non-Homogeneous Fixed Charge Distribution Exhibiting High Current Rectifications
2014
We have designed and characterized a cylindrical nanopore that exhibits high electrochemical current rectification ratios at low and intermediate electrolyte concentrations. For this purpose, the track-etched single cylindrical nanopore in polymer membrane is coated with a gold (Au) layer via electroless plating technique. Then, a non-homogeneous fixed charge distribution inside the Au-coated nanopore is obtained by incorporating thiol-terminated uncharged poly(N-isopropylacrylamide) (PNIPAM) chains in series to poly(4-vinyl pyridine) (PVP) chains, which are positively charged at acidic pH values. The functionalization reaction is checked by measuring the current–voltage (I–V) curves prior …
Charging a Capacitor from an External Fluctuating Potential using a Single Conical Nanopore
2015
We explore the electrical rectification of large amplitude fluctuating signals by an asymmetric nanostructure operating in aqueous solution. We show experimentally and theoretically that a load capacitor can be charged to voltages close to 1 V within a few minutes by converting zero time-average potentials of amplitudes in the range 0.5–3 V into average net currents using a single conical nanopore. This process suggests that significant energy conversion and storage from an electrically fluctuating environment is feasible with a nanoscale pore immersed in a liquid electrolyte solution, a system characteristic of bioelectronics interfaces, electrochemical cells, and nanoporous membranes.
Ion transport and selectivity in nanopores with spatially inhomogeneous fixed charge distributions
2007
Polymeric nanopores with fixed charges show ionic selectivity when immersed in aqueous electrolyte solutions. The understanding of the electrical interaction between these charges and the mobile ions confined in the inside nanopore solution is the key issue in the design of potential applications. The authors have theoretically described the effects that spatially inhomogeneous fixed charge distributions exert on the ionic transport and selectivity properties of the nanopore. A comprehensive set of one-dimensional distributions including the skin, core, cluster, and asymmetric cases are analyzed on the basis of the Nernst-Planck equations. Current-voltage curves, nanopore potentials, and tr…
Voltage-controlled current loops with nanofluidic diodes electrically coupled to solid state capacitors
2016
[EN] We describe experimentally and theoretically voltage-controlled current loops obtained with nanofluidic diodes immersed in aqueous salt solutions. The coupling of these soft matter diodes with conventional electronic elements such as capacitors permits simple equivalent circuits which show electrical properties reminiscent of a resistor with memory. Different conductance levels can be reproducibly achieved under a wide range of experimental conditions (input voltage amplitudes and frequencies, load capacitances, electrolyte concentrations, and single pore and multipore membranes) by electrically coupling two types of passive components: the nanopores (ionics) and the capacitors (electr…
Concatenated logic functions using nanofluidic diodes with all-electrical inputs and outputs
2018
[EN] Nanopore-based logical schemes in ionic solutions typically involve single gates and chemical inputs. The design of computer-like functions requires the consecutive concatenation of several gates and the use of electrical potentials and currents to facilitate the downstream transfer of electrochemical information. We have demonstrated the robust operation of concatenated logic functions using biomimetic nanofluidic diodes based on single pore membranes. To this end, we have implemented first the logic functions AND and OR with combinations of single nanopores using all-electrical input and output signals. The concatenation of these gates allows the output of the OR gate to act as one o…
Surface charge regulation of functionalized conical nanopore conductance by divalent cations and anions
2019
Abstract The surface charge regulation in nanoscale volumes is a subject of wide interest to biological and chemical soft matter systems. Also, electrolyte mixtures with monovalent and divalent ions are commonplace in practical applications with micro and nanoporous ion-exchange membranes. We have studied experimentally and theoretically the conductance of conical nanopores functionalized with negative and positive surface charges that are bathed by electrolyte mixtures of the monovalent ions K+ and Cl− and the divalent ions Mg2+, Ba2+, Ca2+, and SO42−. Small concentrations of these ions can modulate the nanopore selectivity and conductance because of their interaction with the charged grou…
Energy transduction and signal averaging of fluctuating electric fields by a single protein ion channel
2016
[EN] We demonstrate the electrical rectification and signal averaging of fluctuating signals using a biological nanostructure in aqueous solution: a single protein ion channel inserted in the lipid bilayer characteristic of cell membranes. The conversion of oscillating, zero time-average potentials into directional currents permits charging of a load capacitor to significant steady-state voltages within a few minutes in the case of the outer membrane porin F (OmpF) protein, a bacterial channel of Escherichia coli. The experiments and simulations show signal averaging effects at a more fundamental level than the traditional cell and tissue scales, which are characterized by ensembles of many…
Hybrid Circuits with Nanofluidic Diodes and Load Capacitors
2017
[EN] The chemical and physical input signals characteristic of micro- and nanofluidic devices operating in ionic solutions should eventually be translated into output electric currents and potentials that are monitored with solid-state components. This crucial step requires the design of hybrid circuits showing robust electrical coupling between ionic solutions and electronic elements. We study experimentally and theoretically the connectivity of the nanofluidic diodes in single-pore and multipore membranes with conventional capacitor systems for the cases of constant, periodic, and white-noise input potentials. The experiments demonstrate the reliable operation of these hybrid circuits ove…
Optimizing Energy Transduction of Fluctuating Signals with Nanofluidic Diodes and Load Capacitors
2018
[EN] The design and experimental implementation of hybrid circuits is considered allowing charge transfer and energy conversion between nanofluidic diodes in aqueous ionic solutions and conventional electronic elements such as capacitors. The fundamental concepts involved are reviewed for the case of fluctuating zero-average external potentials acting on single pore and multipore membranes. This problem is relevant to electrochemical energy conversion and storage, the stimulus-response characteristics of nanosensors and actuators, and the estimation of the accumulative effects caused by external signals on biological ion channels. Half-wave and full-wave voltage doublers and quadruplers can…
Ionic transport characteristics of negatively and positively charged conical nanopores in 1:1, 2:1, 3:1, 2:2, 1:2, and 1:3 electrolytes
2019
We study experimentally the current (I)-voltage (V) curves of 1:1, 2:1, 3:1, 2:2, 1:2, and 1:3 electrolytes in positively and negatively charged conically-shaped pores of nanoscale dimensions. The positive charges are poly(allylamine hydrochloride) chains functionalized on the pore surface by electrostatic interactions while the negative charges are carboxylic acid groups. Under physiological conditions, these fixed-charge groups are ionized and strongly interact with the different monovalent, divalent, and trivalent ions in the pore solution. The current rectification of the I-V curves and the membrane potentials provide fundamental information on the interaction of the pore charge groups …
Nanopore charge inversion and current-voltage curves in mixtures of asymmetric electrolytes
2018
[EN] We consider the screening of the negative charges (carboxylic acid groups) fixed on the surface of a conical-shaped track-etched nanopore by divalent magnesium (Mg2+) and trivalent lanthanum (La3+). The experimental current (I)-voltage (V) curves and current rectification ratios allow discussing fundamental questions about the overcompensation of spatially-fixed charges by multivalent ions over nanoscale volumes. The effects of charge inversion or reversal on nanopore transport are discussed in mixtures of asymmetric electrolytes (LaCl3 and MgCl2 with KCl). In particular, pore charge inversion is demonstrated for La3+ as well as for mixtures of this trivalent ion at low concentrations …
Converting external potential fluctuations into nonzero time-average electric currents using a single nanopore
2015
The possibility of taking advantage of a fluctuating environment for energy and information transduction is a significant challenge in biological and artificial nanostructures. We demonstrate here directional electrical transduction from fluctuating external signals using a single nanopore of conical shape immersed in an ionic aqueous solution. To this end, we characterize experimentally the average output currents obtained by the electrical rectification of zero time-average input potentials. The transformation of external potential fluctuations into nonzero time-average responses using a single nanopore in liquid state is of fundamental significance for biology and nanophysics. This energ…
Electrical network of nanofluidic diodes in electrolyte solutions: Connectivity and coupling to electronic elements
2016
[EN] We consider a nanopore network with simple connectivity, demonstrating a two-dimensional circuit (full-wave rectifier) with ensembles of conical pores acting as nanofluidic diodes. When the bridge nanopore network is fed with an input potential signal of fluctuating polarity, a fixed output polarity is obtained. The full-wave rectification characteristics are demonstrated with square, sinusoidal, and white noise input waveforms. The charging of a load capacitor located between the two legs of the bridge demonstrates that the nanofluidic network is effectively coupled to this electronic element. These results can be relevant for energy transduction and storage procedures with nanopores …
Energy conversion from external fluctuating signals based on asymmetric nanopores
2015
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 convers…
Multipore membranes with nanofluidic diodes allowing multifunctional rectification and logical responses
2016
[EN] We have arranged two multipore membranes with conical nanopores in a three-compartment electrochemical cell. The membranes act as tunable nanofluidic diodes whose functionality is entirely based on the pH-reversed ion current rectification and does not require specific surface functionalizations. This electrochemical arrangement can display different electrical behaviors (quasi-linear ohmic response and inward/outward rectifications) as a function of the electrolyte concentration in the external solutions and the applied voltage at the pore tips. The multifunctional response permits to implement different logical responses including NOR and INHIBIT functions.
Designing voltage multipliers with nanofluidic diodes immersed in aqueous salt solutions.
2016
[EN] Membranes with nanofluidic diodes allow the selective control of molecules in physiological salt solutions at ambient temperature. The electrical coupling of the membranes with conventional electronic elements such as capacitors suggests opportunities for the external monitoring of sensors and actuators. We demonstrate experimentally and theoretically the voltage multiplier functionality of simple electrical networks composed of membranes with conical nanopores coupled to load capacitors. The robust operation of half and full wave voltage multipliers is achieved in a broad range of experimental conditions (single pore and multipore membranes, electrolyte concentrations, voltage amplitu…
Modulation of current-time traces by two-pore arrangements of polyimide nanofluidic diodes
2019
Liquid state arrangements of two polymeric membranes with single conical nanopores constitute nanofluidic diodes that allow a rich electrical functionality based on the modulation of individual conductances in aqueous electrolyte solutions. In particular, the prescribed sequences of current-time traces can be obtained by preprogramed switching between series and parallel pore connection arrangements. Hybrid nanopore-solid-state circuits are also possible. The basic applied physics of the nanofluidic diode arrangements can be understood from simple circuit theory concepts and should be of widespread interest to sensing and actuating procedures, controlled release dispensers, and energy conve…
Membrane potential of single asymmetric nanopores: Divalent cations and salt mixtures
2019
We study the electric potential difference (membrane potential) that arises across a single-pore membrane which separates two aqueous solutions at different salt concentrations. This potential difference is obtained here as the reversal potential of a conical nanopore, defined as the applied voltage needed to obtain a zero current through the membrane. To this end, different monovalent (LiCl, NaCl, KCl, and CsCl) and divalent (CaCl2, MgCl2, and BaCl2) cations are considered over a wide range of concentrations and salt mixtures for the two asymmetric nanostructure directionalities. The experimental data allows discussing fundamental questions on the interaction of the charges fixed to the po…
Net currents obtained from zero-average potentials in single amphoteric nanopores
2013
We have studied experimentally and theoretically the rectifying properties of a single asymmetric nanopore functionalized with amphoteric lysine groups and characterized the net current obtained with zero-average time dependent potentials. The pH-controlled rectification phenomena may be relevant to bio-electrochemistry, pH sensing and regulation, and energy conversion. (C) 2013 Elsevier B.V. All rights reserved.