multifunctional probes for simultaneous stimulation and recording of neural activity

Institut Mines-Télécom

Multifunctional Probes for Simultaneous Stimulation and Recording of Neural Activity

Sahika Inal

Department of Bioelectronics, Microelectronics Center of Provence, France

[email protected]

100 µm

Stimulation Sensing


Organic electronics offer unique opportunities

• Mechanical Properties: Similar to tissue, improved implant stability

• Ideal surfaces/interfaces: biocompatible

• Processing: low cost- easy fabrication

• Tunability of electronic properties: tailor for specific applications

• Ionic conductivity: signal transmission with biological systems

Organic electronic materials provide a new toolbox for interfacing with biology

Living Systems + Biomaterial

s

Electronic Elements

electronic input (control)

biological input (monitoring)

cellsenzymesDNA

electrodestransistorsSTM

An enzymatic reaction changes current in a transistor

Application of voltage bias triggers cell growth

10μm

Department of Bioelectronics – www.bel.emse.fr2

Institut Mines-Télécom3

Our research at a glance

Department of Bioelectronics – www.bel.emse.fr

Neuroengineering In vitro Diagnostics Cell Actuators e-Textiles

Fundamentals of Conducting Polymer

Devices

Integration with cells forin vitro toxicology or with enzymes for metabolite

detection

Electrical control of cell adhesion and growth

Textile electrodes for electrocardiography

In vitro and implantable neuroprobes for sensing and

stimulation

100 µm


Multifunctional Neuroprobes


→ Non-specific delivery - low amounts- side effects

→ Deviation from optimal therapeutic level over time

→ No control over when or at which amount they should be delivered

Miniaturized device for spatial control

Electronic control of release for temporal resolution

Multifunctional probe for feedback regulated release

The nervous system coordinates the functions in the body.Neurological disorders are treated with pills or via injection of drugs.


J. Isaksson, P. Kjall, D. Nilsson, N. D. Robinson, M. Berggren, and A. Richter-Dahlfors, Nat. Mater, 6, 673 (2007)K.C. Tybrandt, S. Larsson, S. Kurup, D.T. Simon, P. Kjall, J. Isaksson, M. Sandberg, E.W.H. Jager, A. Richter-Dahlfors, M. Berggren, Adv. Mater, 21, 4442 (2009)

Oxidation/reduction at Source/Target drives cations through the membrane.→ Good spatio and temporal resolution→ Dosage control by duration and magnitude of applied bias- electrically switchable→ Good ON/OFF ratio- low leakage→ Flow free

5 Department of Bioelectronics – www.bel.emse.fr

The ion pump: electronic control of ion releaseSource Target

++++

+++ +

++

PEDOT:PSS

SO3H SO3H SO3H SO3H SO3- SO3H SO3H SO3H

S

O O

S

O O

S

O O

S

O O

S

O O

S

O O

S

O O

S

O O

+ *

Ion exchange membrane

+

PEDOT:PSS

+

PEDOT:PSS

+++

++++ +

++ +

VST

+ -

+ + + + + + + ++


Conducting polymer electrodes for sensing


Arrays for in vitro monitoring Arrays for in vivo recordings

→ Low impedance – low noise→ Easy to fabricate at small size and density→ Good interface with biological systems


Multimodal Device

7 Department of Bioelectronics – www.bel.emse.fr

Target

Source 1

Source 2

Ion exchange Gold

PEDOT:PSS

Sensing electrodeIon pump nozzle

++

Bioelectronic pixel


Bioexperiment design: Hippocampus slice on top of the device


A pathological activity: Low Mg2+ concentration in the perfusion produces epileptiform activity: high rate of spiking

Firing of neurons is affected in the presence of GABA.

The net effect is the decrease in the firing probability of the cells.

GABA solution

GABA “inhibitory neurotransmitter”

>e-


Time trace of a recording site with brain slice on top


Evoked activity Abolishment of the hyperexcitability

GABA pump offLow Mg2+

Recovery phase

GABA pump on


Implantable multimodal probe


24 electrodes (15x15 µm)

100 µm

Integration of the multimodal device on a flexible substrate


Summary

Ion pump and PEDOT:PSS electrodes are integrated into an in vitro device structure.

Ion pump operates efficiently in the presence of sensing electrodes at the nozzle.

Electrodes are not disturbed by the delivered ions. Electrodes record the local biological activity in response to

chemical stimulation. in vivo release/record platforms are currently tested.



AcknowledgmentsDepartment of BioelectronicsIlke Uguz, Nathan Schäfer, Vincenzo Curto, Adel Hama, Marc Ferro, Sébastien Sanaur, Seiichi Takamatsu, Pierre Leleux, Marcel Brandlein, Mary Donahue, Susan Daniel, Mohammed El Mahmoudy, Dimitrios Koutsouras, Xenofon Strakosas, Thomas Lonjaret, Eloise Bihar, Margaret Brennan, Michel Fiocchi, Esma Ismailova, Jonathan Rivnay, Julie Oziat, Yi Zhang, Anna Maria Pappa, Liza Klots, Shahab Rezaei Mazinani, Jolien Pas, Patrick Fournet, Gaëtan Scheiblin, Esma Ismailova, Roisin M. Owens, George G. Malliaras


Linkoping University, Sweden Amanda Jonsson, Loig Kergoat, Daniel T. Simon, Magnus Berggren

Aix-Marseille University, FranceAdam Williamson, Christophe Bernards

Institut Mines-Télécom Department of Bioelectronics – www.bel.emse.fr13


Implantable multimodal probe


source waste

24 electrodes (15x15 µm)

Cation exchange

membrane 100 µm

Integration of the multimodal device on a flexible substrate


Controlling epileptiform activity with an ion pump


hyperexcitability

activity stops

pump on


Integration of ion pumps and electrodes-photolith


Sensing electrodeIon pump “nozzle”

CEM: PSSA-co-MA

Substrate

Gold

Insulation

PEDOT:PSS

Cation exchange membrane (CEM)

+ +

Bioelectronic pixel


0.0 0.5 1.0 1.5

0.0005

0.0010

0.0015

0.0020

0.0025

Cur

rent

[mA

]

time [h]

Characterization of the device


Transport of cations between the source and target (VST = 20V)

Ca2+

K +

Na+

101 102 103 104

104

105

Impe

danc

e [O

hm]

Frequency [Hz]

Stable current during S-T biasing µM range delivery of various cations

including neurotransmitters

ca. 20-30kΩ @1kHz Not affected when the pump is

operated!


Characterization of the device


CaCl2

KCl

NaCl

OFF K+ pumping OFF GABA pumping

1 2 3 4

Electrode recordings during ion delivery

GABA “inhibitory neurotransmitter”


Why organic electronic materials for bio-interfacing?


Mixed conduction Efficient ion transport

2D 3D interfacing Oxide-free interface Mechanical

properties match to tissue

J. Rivnay, R.M. Owens, G.G. Malliaras, Chem. Mater. 2013


Photolithographic patterning allows for micron-scale device arrays


1 μA resulting in a delivery rate of 10 nanomol/second. Assuming that the delivery is equally distributed between the 32 outlets in our device, 1 µA yields a delivery rate of 0.3 pmol second-1 outlet-1. To be able to run a direct current through the device for extended times, we need a nonpolarizable electrode, that is an electrode that can transfer charge between the electrode and the electrolyte.


Metal lift-off

2× parylene deposition

Lithography

Peel-off

Sensing electrodeIon pump

Ion bridge coating

Substrate

Gold

Ion bridge material

Parylene C

Anti-adhesive

Photoresist

PEDOT:PSS

Etching

PEDOT:PSS coating


Similarities of the Devices


Ion PumpCP Electrode

Both based on patterned conducting polymer (PEDOT:PSS)

Both use plastic supports and ion barrier layers (PaC)

Both are fabricated to allow for direct contact of the active material with aqueous media


Microscopy image of a hippocampus slice on top of the device

Notice the gold lines and hippocampus slice sitting on top of the device active area.

corte

x

CA

1

CA

3

harp

Stri

atum

pump outlets

“dark line” or “c-shape” = the pyramidal layer (the somas of the big pyramidal neurons) of CA

200 µm200 µm

23


Validation of sensing of and inhibition of neural network activity with co-localized device

Time trace of the recording site with brain slice on top, recording a) from t= ca. 600s on: Spontaneous activity

b) from t= ca.1200s on: Abolishment of the neuronal hyperexcitability due to local delivery of GABA This shows the ability of the recording site to record physiological activity both when the pump is on and when it is not. The delivery of GABA was estimated to be 0.3 picomol/second/outlet.

24


3D-Conducting Scaffolds

A. M.-D. Wan and S. Inal et. al. , J. Mater. Chem. B, in press (2015).


Control over Cell Growth and Fn conformation


Precise control of protein conformation and major cell functions

Enhanced effects in 3D

Compact conformation of Fn in oxidized film, promoting stronger adhesion of 3T3-L1 preadipocytes.


Redox devices or OECTs using CP scaffolds


multifunctional probes for simultaneous stimulation and recording of neural activity

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