Carbon nanotube electrodes for effective interfacing with retinal tissue

Abstract

We have investigated the use of carbon nanotube coated microelectrodes as an interface material for retinal recording and stimulation applications. Test devices were micro-fabricated and consisted of 60, 30 μm diameter electrodes at spacing of 200 μm. These electrodes were coated via chemical vapor deposition of carbon nanotubes, resulting in conducting, three dimensional surfaces with a high interfacial area. These attributes are important both for the quality of the cell-surface coupling as well as for electro-chemical interfacing efficiency. The entire chip was packaged to fit a commercial multielectrode recording and stimulation system. Electrical recordings of spontaneous spikes from whole-mount neonatal mouse retinas were consistently obtained minutes after retinas were placed over the electrodes, exhibiting typical bursting and propagating waves. Most importantly, the signals obtained with carbon nanotube electrodes have exceptionally high signal to noise ratio, reaching values as high as 75. Moreover, spikes are marked by a conspicuous gradual increase in amplitude recorded over a period of minutes to hours, suggesting improvement in cell-electrode coupling. This phenomenon is not observed in conventional commercial electrodes. Electrical stimulation using carbon nanotube electrodes was also achieved. We attribute the superior performances of the carbon nanotube electrodes to their three dimensional nature and the strong neuro-carbon nanotube affinity. The results presented here show the great potential of carbon nanotube electrodes for retinal interfacing applications. Specifically, our results demonstrate a route to achieve a reduction of the electrode down to few micrometers in order to achieve high efficacy local stimulation needed in retinal prosthetic devices.

Carbon Nanotube Scaffolds Tune Synaptic Strength in Cultured Neural Circuits: Novel Frontiers in Nanomaterial–Tissue Interactions

“…Single-walled and multiwalled carbon nanotubes (SWCNTs and MWCNTs, respectively) have attracted tremendous attention as potential scaffolds for reestablishing the intricate connections between neurons (Mattson et al, 2000;Hu et al, 2005;Lovat et al, 2005;Ni et al, 2005; Galvan-Garcia et al, 2007; Cellot et al, 2009); they are an ideal material for long-term neural implants, as they enhance electrical recording of neurons in culture and in living animals (Keefer et al, 2008;Shoval et al, 2009) by reducing the impedance between devices and cell membranes (Kotov et al, 2009).…”

One-to-one neuron–electrode interfacing

“…Thus, larger electrodes are in fact less advantageous and smaller electrodes (provided the noise level is within the noise level of the amplification system) are preferred. When using high cell densities and in particular when performing MEA recordings from a tissue, significantly higher signals can be obtained (Shoval et al, 2009). In these cases the culture or the tissue may contribute to better electrode sealing.…”

Multi-walled carbon nanotube based multi-electrode arrays for the detection of the emergent activity in the cortical network

“…These calculations are supported by the comparison of the voltammograms at 200 mV/s scan rate (Fig. 4c) that show that the charge accumulation is the highest for the electrode modified by MWCNTs [5,6,31,4,32].…”

“…Thus, the difficulties are related to the electrode material and to its planarity. In this frame, the use of carbon nanotube (CNT) coatings has been demonstrated extensively in the literature to improve neuronal recordings [4][5][6].…”