Investigation of the Stability and Biocompatibility of Commonly Used Electrode Materials in Organic Neurooptoelectronics

Falco, Aniello; Matarèse, Bruno F. E.; Feyen, Paul; Benfenati, Fabio; Lugli, Paolo; Mello, John C. de

doi:10.1109/tnano.2016.2536946

Cited by 12 publications

(8 citation statements)

References 25 publications

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“…ITO is a well-known n-type semiconductor material that is often utilized in transparent microelectrodes. ITO has high conductivity, excellent transparency over the entire visible spectrum due to a large bandgap of around 4 eV, as well as confirmed biocompatibility (Falco et al, 2016). ITO can be grown on either solid or flexible substrates using welldeveloped physical vapor deposition techniques (e.g., sputtering).…”

Section: Semiconductorsmentioning

confidence: 99%

A Review: Electrode and Packaging Materials for Neurophysiology Recording Implants

Yang

Gong

2021

Front. Bioeng. Biotechnol.

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To date, a wide variety of neural tissue implants have been developed for neurophysiology recording from living tissues. An ideal neural implant should minimize the damage to the tissue and perform reliably and accurately for long periods of time. Therefore, the materials utilized to fabricate the neural recording implants become a critical factor. The materials of these devices could be classified into two broad categories: electrode materials as well as packaging and substrate materials. In this review, inorganic (metals and semiconductors), organic (conducting polymers), and carbon-based (graphene and carbon nanostructures) electrode materials are reviewed individually in terms of various neural recording devices that are reported in recent years. Properties of these materials, including electrical properties, mechanical properties, stability, biodegradability/bioresorbability, biocompatibility, and optical properties, and their critical importance to neural recording quality and device capabilities, are discussed. For the packaging and substrate materials, different material properties are desired for the chronic implantation of devices in the complex environment of the body, such as biocompatibility and moisture and gas hermeticity. This review summarizes common solid and soft packaging materials used in a variety of neural interface electrode designs, as well as their packaging performances. Besides, several biopolymers typically applied over the electrode package to reinforce the mechanical rigidity of devices during insertion, or to reduce the immune response and inflammation at the device-tissue interfaces are highlighted. Finally, a benchmark analysis of the discussed materials and an outlook of the future research trends are concluded.

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Section: Semiconductorsmentioning

confidence: 99%

A Review: Electrode and Packaging Materials for Neurophysiology Recording Implants

Yang

Gong

2021

Front. Bioeng. Biotechnol.

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“…We recently demonstrated the photophysical stability of light emitting polymers after extensive immersion to cell-culture medium (Matarèse, 2017). In addition, we have demonstrated the stability and biocompatibility of key OLED electrodes (ITO, gold, aluminum, and silver) when exposed to the physiological milieu (Falco et al, 2016; Matarèse et al, 2018). Nonetheless, the difficult challenge of implantable fully biocompatible OLEDs remain on the electrode injection materials used in devices that are inherently very sensitive to moisture and oxygen (Matarèse, 2017).…”

Section: Resultsmentioning

confidence: 99%

Sub-millisecond Control of Neuronal Firing by Organic Light-Emitting Diodes

Matarèse

Feyen

Mello

et al. 2019

Front. Bioeng. Biotechnol.

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Optogenetics combines optics and genetics to enable minimally invasive cell-type-specific stimulation in living tissue. For the purposes of bio-implantation, there is a need to develop soft, flexible, transparent and highly biocompatible light sources. Organic semiconducting materials have key advantages over their inorganic counterparts, including low Young's moduli, high strain resistances, and wide color tunability. However, until now it has been unclear whether organic light emitting diodes (OLEDs) are capable of providing sufficient optical power for successful neuronal stimulation, while still remaining within a biologically acceptable temperature range. Here we investigate the use of blue polyfluorene- and orange poly(p-phenylenevinylene)-based OLEDs as stimuli for blue-light-activated Sustained Step Function Opsin (SFFO) and red-light-activated ChrimsonR opsin, respectively. We show that, when biased using high frequency (multi-kHz) drive schemes, the OLEDs permit safe and controlled photostimulation of opsin-expressing neurons and were able to control neuronal firing with high temporal-resolution at operating temperatures lower than previously demonstrated.

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“…Previous reports 32 , 33 involving the use of SU8 as an adhesion layer have typically entailed full processing of the SU8 film before the metal layer is deposited in accordance with protocol A. Figure 5a–d shows a series of transmission spectra recorded at 168-hour intervals for a sample prepared in this way (SU8/Au-A).…”

Section: Stability Of Su8 and Su8/au Films In Culturing Mediummentioning

confidence: 99%

“…SU8 has the further advantage of being photo-patternable, allowing patterned electrodes with feature sizes down to a few microns to be readily fabricated using a simple two-step expose/develop procedure 31 . We have previously reported preliminary data 32 , 33 , showing SU8-supported gold electrodes to have favourable and moderately stable electro-optical characteristics in cell culturing medium, making them a potentially attractive choice for bioelectronics. Unfortunately, we found that, after prolonged periods of immersion in culture medium, gold deposited on SU8 had a tendency to develop wrinkles and cracks on the surface, reducing electrode durability and performance 32 , 33 .…”

Section: Introductionmentioning

confidence: 99%

“…We have previously reported preliminary data 32 , 33 , showing SU8-supported gold electrodes to have favourable and moderately stable electro-optical characteristics in cell culturing medium, making them a potentially attractive choice for bioelectronics. Unfortunately, we found that, after prolonged periods of immersion in culture medium, gold deposited on SU8 had a tendency to develop wrinkles and cracks on the surface, reducing electrode durability and performance 32 , 33 . Here we show that the adhesion of Au to SU8 can be controlled by varying the relative amounts of thermal annealing before and after Au deposition, and report an optimized processing protocol that reduces the tendency for wrinkling and cracking.…”

Section: Introductionmentioning

confidence: 99%

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Use of SU8 as a stable and biocompatible adhesion layer for gold bioelectrodes

Matarèse

Feyen

Falco

et al. 2018

Sci Rep

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Gold is the most widely used electrode material for bioelectronic applications due to its high electrical conductivity, good chemical stability and proven biocompatibility. However, it adheres only weakly to widely used substrate materials such as glass and silicon oxide, typically requiring the use of a thin layer of chromium between the substrate and the metal to achieve adequate adhesion. Unfortunately, this approach can reduce biocompatibility relative to pure gold films due to the risk of the underlying layer of chromium becoming exposed. Here we report on an alternative adhesion layer for gold and other metals formed from a thin layer of the negative-tone photoresist SU-8, which we find to be significantly less cytotoxic than chromium, being broadly comparable to bare glass in terms of its biocompatibility. Various treatment protocols for SU-8 were investigated, with a view to attaining high transparency and good mechanical and biochemical stability. Thermal annealing to induce partial cross-linking of the SU-8 film prior to gold deposition, with further annealing after deposition to complete cross-linking, was found to yield the best electrode properties. The optimized glass/SU8-Au electrodes were highly transparent, resilient to delamination, stable in biological culture medium, and exhibited similar biocompatibility to glass.

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Investigation of the Stability and Biocompatibility of Commonly Used Electrode Materials in Organic Neurooptoelectronics

Cited by 12 publications

References 25 publications

A Review: Electrode and Packaging Materials for Neurophysiology Recording Implants

A Review: Electrode and Packaging Materials for Neurophysiology Recording Implants

Sub-millisecond Control of Neuronal Firing by Organic Light-Emitting Diodes

Use of SU8 as a stable and biocompatible adhesion layer for gold bioelectrodes

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