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Nanofluidics-based energy harvesting and generation for low-power consumption devices

Prof. Gilad Yossifon

School of Mechanical Engineering, Tel-Aviv University

Department of Biomedical Engineering

Micro- and Nano-Fluidics and Robots Laboratory

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30/6/24

www.micronanofluidics.sites.tau.ac.il

Email: gyossifon@tauex.tau.ac.il

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Our lab’s main research activities

Micro and Nano-fluidics
Lab-on-chip devices
Non-Linear Electro-Kinetics
Electrokinetic manipulation of � bioparticles
Active (self-propelling) particles
Micro/Nano-Robots
Microfluidic cooling of � high-power chips

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Electric-Double-Layer (EDL)

Electrolyte (dissolved ions)
EDL - screens surface charge
Diffuse layer - mobile ions, net charge�

-

+

Diffuse layer

+

Bulk solution

-

+

-

+

-

It is a well known fact, for over two centuries, that upon immersion of a charged solid surface into an electrolyte consisting of dissolved ions a spontaneous charge separation takes place within the fluid to form a charged layer with an excess of counterions – so as to screen the surface charge.
Outside this charged layer exists an electro-neutral bulk solution.
The length scale of this thin layer is inversely proportional to the square root of the electrolyte concentration – commonly on the order of 10nm.
The potential drop across this layer is termed zeta-potential and its importance becomes evident in the following.

Solid-liquid interfaces tend to develop surface charge, which attracts oppositely charged counterions and repels similarly charged co-ions.
The resulting ionic double layer screens the surface charge over a characteristic Debye length => net ionic charge. With the exception of these charged double layers, the fluid is charge neutral.
The EDL consists of two layers: a compact layer of immobile adsorbed ions and a diffuse layer of mobile ions.
The diffuse part of the double layer is established when diffusive transport tending to smooth ion gradients balances electrostatic transport driving counterions towards the interface.
Ions in solution with number density ci and charge zi set up an electrostatic field obeying Poisson’s equation.
In equilibrium, each ion is statistically distributed according to the Boltzmann distribution.
Combining these two equations, we arrive at the nonlinear Poisson-Boltzmann equation, which can be linearized for small potentials to obtain the expression showing an exponential decay of the potential.
λ is the screening length which typically is on the order of tens of nanometer. It depends inversely on the ionic bulk concentration.
The potential drop across the charge cloud is called the zeta-potential.

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Yossifon, Mushenheim, Chang & H.-C. Chang, PRE (2009)

Membrane

+

-

+

~ 100 nm

λ_d~ 50 nm

-

+

-

+

Electric field

anode

+

cathode

-

Depletion �layer

Enrichment layer

C₀

-

+

Rubinstein & Sthilman, J. Chem. Soc. (1979)

Levich (1962)

EDLs overlap ⇒ ion permselectivity (counterions)
Applied electric field ⇒ Concentration-polarization (CP)
Complete depletion at the interface ⇒ limiting current
Molecule preconcentration (orders of magnitude)

Limiting resistance

L

Electro-dialysis (ED)

Rubinstein & Zaltzman, PRE (2000)

S. M. Rubinstein, G. Manukyan, A. Staicu, I. Rubinstein, B. Zaltzman, R. G. H. Lammertink, F. Mugele, and M. Wessling, Phys. Rev. Lett. (2008)

Yossifon & Chang, Phys. Rev. Lett. (2008)

A. Abu-Rjal, N. Leibowitz , S. Park, B. Zaltzman, I. Rubinstein and G. Yossifon, Phys. Rev. Fluids (2019)

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Green, Park & Yossifon, PRE. (2013)

Electro-dialysis (ED) in Microscale Device

Cathode

-

Anode

+

Nanoslot

Microchannel

Depletion layer

Preconcentrated plug

Green, Eshel, Park & Yossifon, Nanoletters (2016)

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Reverse electro-dialysis (RED)

Salinity Gradient Power Generation (Blue Energy)
Also termed Osmotic energy harvesting

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Sci. Rep.| 7: 14068 (2017)

Example -

Ionic Circuits Powered by Reverse Electrodialysis

Sabbagh, Fraiman, Fish, Yossifon, ACS Appl. Mater. Interfaces (2023)

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Theoretical model of RED

Green, Edri and Yossifon, PRE (2015)

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Adv. Funct. Mater. 27, 1603623 (2017)

Example -

Tandem GOM-RED stacks power electronic devices

graphene oxide membrane (GOM)

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Onsager reciprocity

Electro-osmotic flow (EOF):

Surface charge (-)

-

λ_d

-

Electric field

y

U

Helmholtz-Smoluchowski slip velocity

Schiffbauer and Yossifon, Phys. Rev. E 86:056309-1-9 (2012)

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Onsager reciprocity

Streaming current:

PRL 95, 116104 (2005)

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Example -

Capillary-driven streaming current

Nano Lett. 19, 7191−7200 (2019)

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Streaming potential:

=0

Onsager reciprocity

I_c

I_s

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Example - Moisture-driven fabric-based

generator for powering wearable electronics

Device 2, 100316 (2024)

Fabric moist-electric generators (F-MEGs)

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Electro-wetting on dielectric (EWOD)

Hillman and Yossifon, Int. Conf. on electrokinetics (2022)

Glass slide

Hydrophobic layers

Air

Control Electrodes

Dielectric layer

Droplet

off

on

Ground electrode

F

off

Young-Lippman equation:

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Reverse electro-wetting on dielectric (REWOD)

Nat. Comm., 2:448 (2011)

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Reverse electro-wetting on dielectric (REWOD)

Nat. Comm., 2:448 (2011)

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Water-TENG (TriboElectric NanoGenerators)

Adv. Mater. Technol. 8, 2201029 (2023)

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A wide variety of micro/nano-fluidic based generation of power modes:
Reverse electro-dialysis (Osmotic Power Generation)
Streaming current / potential
Reverse electro-wetting on dielectrics (REWOD)
Water-TENG (TriboElectric NanoGenerators)
Others: Pressure Retarded Osmosis (PRO), Thermoelectric Nanofluidic Systems, Capacitive Energy Harvesting, Fuel Cells …
Unique advantages:
Simplicity
In some modes of operation -- no moving parts !
In some modes of operation -- continuous DC electric field/current

Summary