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Minimal-Traumatic Peripheral Nerve Cuff Electrodes

Cuff Closure Mechanisms
Different closure mechanisms for different applications
buckle- and belt
buckle- and belt
Fabrication Technology
Cuff electrodes produced in a layer-by-layer process
resulting in very soft and flexible devices:
1. Start with a silicone rubber foil (50 to 200µm thickness)
2. Laminate 25µm Platinum/Iridium (PtIr) foil
3. Localized laser-evaporation of PtIr where it is not
required, leaving PtIr contacts, pads and tracks behind.
4. Deposition of silicone layer (30 to 200µm thick)
5. Laminate a pre-stretched silicone foil
6. Localized laser-evaporation of silicone, exposing PtIr
contacts, pads and cutting the contour of the planar
electrode array.
Minimal-Traumatic Peripheral Nerve Cuff Electrodes
M.Schuettler1, R.Pfeifer1, J.Ordonez2, C.Bierbrauer1, C.Henle1,
M.Dautrebande3, G.Thiebaut3, P.Doguet3
1: CorTec GmbH, Freiburg, Germany, 2: Lab. for Biomed. Microtechnology, Dept. of Micro-
systems Engineering, Univ. of Freiburg, 3: Synergia Medical, Mont-Saint-Guibert, Belgium
Abstract: Cuff electrodes are used since the 1970s for excitation of, and recording from peripheral nerves. They consist of
electrically insulating tubing placed around the nerve. The tubing holds electrical contacts facing towards the nerve, establishing
the electrical interface. Although cuff electrodes have the potential to provide a long-term stable electrical interface to the
peripheral nerve, they also come with the risk of mechanical nerve irritation or even nerve damage.
We developed cuff electrodes that minimize these risks by selecting very soft silicone as basis material in which bendable,
twistable and stretchable metal contacts are embedded. Our self-spiraling nerve cuffs show excellent mechanical robustness and
apply pressure well below the hazardous level of peripheral nerve venal blood pressure.
© CorTec GmbH May 2017. All rights reserved
buckle- and belt
Buckle and Belt
down to 100µm Ø
1.5mm – 6mm Ø
self-adjustable diameter
Split Cylinder
200µm 10mm Ø
various sealing concepts
Tripolar self-spiraling nerve cuff electrodes with an inner
(target) diameter of 2.5 mm and a length of 16.5 mm
where mechanically characterized as follows.
Nerve Constriction Pressure
Venal blood pressure: 20 mmHg
Cuff pressure on average: 5 mmHg
Cuff pressure at max.: 9 mmHg
Material Softness (Youngs Modulus)
Peripheral Nerve: 0.5 0.6 MPa
25A-Shore Silicone: 0.8 1.0 MPa (used her)
Polyimide (PI 26xx): 2 10 Gpa (used elsewhere)
Liquid Cristal Polymer: 11 24 Gpa (used elsewhere)
Mechanical Robustness
Complete opening and closing cycles: 60
Design Features
Self-Spiraling Cuff
1. Inner diameter (at rest): 2.5 mm
2. Wall thickness: 0.5 mm
3. Cuff Length: 16.5 mm
4. Spiral: 2.5x wraps
5. Metal contacts: 1.5 mm wide meandered rings
Meander Contacts*
Shaping the metal contact to a meander dramatically
changes its mechanical properties
Mechanics of silicone dominate over that of PtIr contacts
25µm PtIr contacts are + Stretchable
+ Bendable
+ Twistable
* Meander Contacts: US Patent Pending
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