Institut Mines-Télécom
Multifunctional Probes for Simultaneous Stimulation and Recording of Neural Activity
Sahika Inal
Department of Bioelectronics, Microelectronics Center of Provence, France
100 µm
Stimulation Sensing
Institut Mines-Télécom
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
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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
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Multifunctional Neuroprobes
Department of Bioelectronics – www.bel.emse.fr4
→ 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.
Institut Mines-Télécom
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
+ -
+ + + + + + + ++
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Conducting polymer electrodes for sensing
Department of Bioelectronics – www.bel.emse.fr6
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
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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
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Bioexperiment design: Hippocampus slice on top of the device
Department of Bioelectronics – www.bel.emse.fr8
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-
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Time trace of a recording site with brain slice on top
Department of Bioelectronics – www.bel.emse.fr9
Evoked activity Abolishment of the hyperexcitability
GABA pump offLow Mg2+
Recovery phase
GABA pump on
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Implantable multimodal probe
Department of Bioelectronics – www.bel.emse.fr10
24 electrodes (15x15 µm)
100 µm
Integration of the multimodal device on a flexible substrate
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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.
Department of Bioelectronics – www.bel.emse.fr11
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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
Department of Bioelectronics – www.bel.emse.fr12
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
Institut Mines-Télécom
Implantable multimodal probe
Department of Bioelectronics – www.bel.emse.fr14
source waste
24 electrodes (15x15 µm)
Cation exchange
membrane 100 µm
Integration of the multimodal device on a flexible substrate
Institut Mines-Télécom
Controlling epileptiform activity with an ion pump
Department of Bioelectronics – www.bel.emse.fr15
hyperexcitability
activity stops
pump on
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Integration of ion pumps and electrodes-photolith
Department of Bioelectronics – www.bel.emse.fr16
Sensing electrodeIon pump “nozzle”
CEM: PSSA-co-MA
Substrate
Gold
Insulation
PEDOT:PSS
Cation exchange membrane (CEM)
+ +
Bioelectronic pixel
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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
Department of Bioelectronics – www.bel.emse.fr17
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!
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Characterization of the device
Department of Bioelectronics – www.bel.emse.fr18
CaCl2
KCl
NaCl
OFF K+ pumping OFF GABA pumping
1 2 3 4
Electrode recordings during ion delivery
GABA “inhibitory neurotransmitter”
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Why organic electronic materials for bio-interfacing?
Department of Bioelectronics – www.bel.emse.fr19
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
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Photolithographic patterning allows for micron-scale device arrays
Department of Bioelectronics – www.bel.emse.fr20
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.
Institut Mines-Télécom Department of Bioelectronics – www.bel.emse.fr21
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
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Similarities of the Devices
Department of Bioelectronics – www.bel.emse.fr22
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
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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
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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
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Institut Mines-Télécom Department of Bioelectronics – www.bel.emse.fr26
3D-Conducting Scaffolds
A. M.-D. Wan and S. Inal et. al. , J. Mater. Chem. B, in press (2015).
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Control over Cell Growth and Fn conformation
Department of Bioelectronics – www.bel.emse.fr
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.
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Redox devices or OECTs using CP scaffolds
Department of Bioelectronics – www.bel.emse.fr