TY - JOUR
T1 - Stability of flexible thin-film metallization stimulation electrodes
T2 - analysis of explants after first-in-human study and improvement of in vivo performance
AU - Čvančara, Paul
AU - Boretius, Tim
AU - López-Álvarez, Víctor M
AU - Maciejasz, Pawel
AU - Andreu, David
AU - Raspopovic, Stanisa
AU - Petrini, Francesco Maria
AU - Micera, Silvestro
AU - Granata, Giuseppe
AU - Fernandez, Eduardo
AU - Rossini, Paolo Maria
AU - Yoshida, Ken
AU - Jensen, Winnie
AU - Divoux, Jean-Louis
AU - Guiraud, David
AU - Navarro, Xavier
AU - Stieglitz, Thomas
N1 - Creative Commons Attribution license.
PY - 2020/7/8
Y1 - 2020/7/8
N2 - OBJECTIVE: Micro-fabricated neural interfaces based on polyimide (PI) are achieving increasing importance in translational research. The ability to produce well-defined micro-structures with properties that include chemical inertness, mechanical flexibility and low water uptake are key advantages for these devices.APPROACH: This paper reports the development of the transverse intrafascicular multichannel electrode (TIME) used to deliver intraneural sensory feedback to an upper-limb amputee in combination with a sensorized hand prosthesis. A failure mode analysis on the explanted devices was performed after a first-in-human study limited to 30 d.MAIN RESULTS: About 90% of the stimulation contact sites of the TIMEs maintained electrical functionality and stability during the full implant period. However, optical analysis post-explantation revealed that 62.5% of the stimulation contacts showed signs of delamination at the metallization-PI interface. Such damage likely occurred due to handling during explantation and subsequent analysis, since a significant change in impedance was not observed in vivo. Nevertheless, whereas device integrity is mandatory for long-term functionality in chronic implantation, measures to increase the bonding strength of the metallization-PI interface deserve further investigation. We report here that silicon carbide (SiC) is an effective adhesion-promoting layer resisting heavy electrical stimulation conditions within a rodent animal trial. Optical analysis of the new electrodes revealed that the metallization remained unaltered after delivering over 14 million pulses in vivo without signs of delamination at the metallization-PI interface.SIGNIFICANCE: Failure mode analysis guided implant stability optimization. Reliable adhesion of thin-film metallization to substrate has been proven using SiC, improving the potential transfer of micro-fabricated neural electrodes for chronic clinical applications. (Document number of Ethical Committee: P/905/CE/2012; Date of approval: 2012-10-04).
AB - OBJECTIVE: Micro-fabricated neural interfaces based on polyimide (PI) are achieving increasing importance in translational research. The ability to produce well-defined micro-structures with properties that include chemical inertness, mechanical flexibility and low water uptake are key advantages for these devices.APPROACH: This paper reports the development of the transverse intrafascicular multichannel electrode (TIME) used to deliver intraneural sensory feedback to an upper-limb amputee in combination with a sensorized hand prosthesis. A failure mode analysis on the explanted devices was performed after a first-in-human study limited to 30 d.MAIN RESULTS: About 90% of the stimulation contact sites of the TIMEs maintained electrical functionality and stability during the full implant period. However, optical analysis post-explantation revealed that 62.5% of the stimulation contacts showed signs of delamination at the metallization-PI interface. Such damage likely occurred due to handling during explantation and subsequent analysis, since a significant change in impedance was not observed in vivo. Nevertheless, whereas device integrity is mandatory for long-term functionality in chronic implantation, measures to increase the bonding strength of the metallization-PI interface deserve further investigation. We report here that silicon carbide (SiC) is an effective adhesion-promoting layer resisting heavy electrical stimulation conditions within a rodent animal trial. Optical analysis of the new electrodes revealed that the metallization remained unaltered after delivering over 14 million pulses in vivo without signs of delamination at the metallization-PI interface.SIGNIFICANCE: Failure mode analysis guided implant stability optimization. Reliable adhesion of thin-film metallization to substrate has been proven using SiC, improving the potential transfer of micro-fabricated neural electrodes for chronic clinical applications. (Document number of Ethical Committee: P/905/CE/2012; Date of approval: 2012-10-04).
KW - electrode
KW - neural interfaces
KW - polyimide
KW - stability
KW - thin-film
UR - http://www.scopus.com/inward/record.url?scp=85088205599&partnerID=8YFLogxK
U2 - 10.1088/1741-2552/ab9a9a
DO - 10.1088/1741-2552/ab9a9a
M3 - Journal article
C2 - 32512544
SN - 1741-2560
VL - 17
JO - Journal of Neural Engineering
JF - Journal of Neural Engineering
IS - 4
M1 - 046006
ER -