1. A method for electrically stimulating a retina of an eye to induce visual perception, said method comprising the steps of:
placing an electrode within the eye in proximity to a retinal ganglion cell (RGC) layer; and
applying a biphasic, asymmetrical, charge-balanced waveform to at least a portion of the RGC layer,
said biphasic, asymmetrical, charge-balanced waveform comprising:
a pre-pulse phase having a first polarity, a sub-threshold first amplitude, and a first duration to change the excitability of at least one cell related to the at least the portion of the RGC layer; and
a stimulation-pulse phase following the pre-pulse phase having a second polarity opposite the first polarity, a supra-threshold second amplitude, and a second duration less than the first duration to induce visual perception.
2. The method of claim 1, wherein said stimulation-pulse phase follows said pre-pulse phase.
3. The method of claim 1, wherein the first polarity is a cathodic polarity and the second polarity is an anodic polarity to induce visual perception of a circular shape.
4. The method of claim 3, wherein the first duration is of a duration sufficient to increase excitability of a passing region of an axon in a nerve fiber layer adjacent to the portion of the RGC layer.
5. The method of claim 1, wherein the first polarity is an anodic polarity and the second polarity is a cathodic polarity to induce perception of an elongated shape.
6. The method of claim 5, wherein the first duration is sufficient to increase excitability of an approximately 90\xb0 bending region of the at least one cell.
7. The method of claim 1, wherein said step of placing an electrode within the eye adjacent a RGC layer further includes placing said electrode within the eye adjacent an approximately 90\xb0 bending region of the RGC layer.
8. The method of claim 1, wherein a charge delivered by said stimulation-pulse phase balances a charge delivered by said pre-pulse phase.
9. The method of claim 1, wherein said first duration of said pre-pulse phase is approximately ten times longer than said second duration of said stimulation-pulse phase.
10. The method of claim 1, wherein said biphasic, asymmetrical, charge-balanced waveform further comprises an interphase delay between said pre-pulse phase and said stimulation-pulse phase.
11. A method for electrically stimulating a retina of an eye to induce visual perception, said method comprising the steps of:
placing an electrode within the eye in proximity to a retinal ganglion cell (RGC) layer; and
selecting a first polarity and a second polarity of a biphasic, asymmetrical, charge balanced waveform, wherein the second polarity is opposite to the first polarity, wherein the first polarity and the second polarity are selected to induce a visual perception;
applying the biphasic, asymmetrical, charge balanced waveform to at least a portion of the RGC layer,
said biphasic, asymmetrical, charge-balanced waveform comprising:
a pre-pulse phase comprising the first polarity, a sub-threshold first amplitude, and a first duration to change the excitability of at least one cell related to the at least the portion of the RGC layer; and
a stimulation-pulse phase comprising the second polarity, a supra-threshold second amplitude, and a second duration less than the first duration to induce the visual perception.
12. The method of claim 11, wherein the first polarity is cathodic, the second polarity is anodic, and the visual perception comprises the perception of a circular shape; or
wherein the first polarity is anodic, the second polarity is cathodic, and the visual perception comprises the perception of an elongated shape.
13. A method for electrically stimulating a retina of an eye to induce visual perception, said method comprising the steps of:
placing an electrode within the eye in proximity to a retinal ganglion cell (RGC) layer; and
selecting parameters to balance the charge of a biphasic, asymmetrical waveform, wherein the parameters include:
first parameters of a pre-pulse phase comprising a first polarity, a sub-threshold first amplitude, and a first duration, and
second parameters of a stimulation-pulse phase comprising a second polarity opposite to the first polarity, a supra-threshold second amplitude, and a second duration at least ten times shorter than the first duration;
applying the biphasic, asymmetrical waveform with the charge balanced according to the selected parameters to at least a portion of the RGC layer,
said biphasic, asymmetrical waveform comprising:
the pre-pulse phase comprising the first polarity, the sub-threshold first amplitude, and the first duration to change the excitability of at least one cell related to the at least the portion of the RGC layer; and
the stimulation-pulse phase comprising the second polarity, the supra-threshold second amplitude, and the second duration to induce the visual perception;
wherein the first polarity is cathodic, the second polarity is anodic, and the visual perception induced is of a circular shape; or
wherein the first polarity is anodic, the second polarity is cathodic, and the visual perception induced is of an elongated shape.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An aqueous carbon nanotube dispersion comprising:
carbon nanotube particles present in an amount of at least about 1 weight percent on a total solids basis, wherein the carbon nanotube particles comprise a plurality of carbon nanotubes and have a mean particle size that ranges from about 250 nm to about 2 \u03bcm; and
a polymeric carrier, the polymeric carrier comprising an aqueous dispersion of one or more polymeric species;
wherein the aqueous carbon nanotube dispersion has a viscosity of 1100 to 4500 cP at 5 RPM and 25\xb0 C.
2. The aqueous carbon nanotube dispersion of claim 1, wherein the carbon nanotube particles are present in the carbon nanotube dispersion in an amount of at least about 2 weight percent on a total solids basis.
3. The aqueous carbon nanotube dispersion of claim 1, wherein the carbon nanotube particles are present in the carbon nanotube dispersion in an amount of at least about 5 weight percent on a total solids basis.
4. The aqueous carbon nanotube dispersion of claim 1, wherein the carbon nanotube particles are present in the carbon nanotube dispersion in an amount of at least about 10 weight percent on a total solids basis.
5. The aqueous carbon nanotube dispersion of claim 1, wherein the one or more polymeric species comprises a polyvinylpyrrolidone, a polyurethane, an epoxy or combinations thereof.
6. The aqueous carbon nanotube dispersion of claim 1, wherein the carbon nanotubes comprise single-walled carbon nanotubes, multi-walled carbon nanotubes or mixtures thereof.
7. The aqueous carbon nanotube dispersion of claim 1, wherein the aqueous carbon nanotube dispersion has a rating on the Hegman scale of 8.
8. The aqueous carbon nanotube dispersion of claim 1, further comprising at least one additional component, the at least one additional component comprising a film former, a coupling agent, a lubricant, a surfactant, a biocide, an anti-foaming agent or mixtures thereof.
9. The aqueous carbon nanotube dispersion of claim 8, wherein the at least one additional component comprises a film former, the film former comprising polyurethane, epoxide, polyvinylpyrrolidone, polyacrylate, polyester, polyvinylacetate, polyvinyl alcohol or combinations thereof.
10. The aqueous carbon nanotube dispersion of claim 9, wherein the film former is present in the aqueous carbon nanotube dispersion in an amount of at least about 50 weight percent on a total solids basis.
11. The aqueous carbon nanotube dispersion of claim 9, wherein the film former is present in the aqueous carbon nanotube dispersion in an amount ranging from about 60 weight percent to about 80 weight percent on a total solids basis.
12. The aqueous carbon nanotube dispersion of claim 8, wherein the at least one additional component comprises a coupling agent, the coupling agent comprising one or more organosilanes.
13. The aqueous carbon nanotube dispersion of claim 12, wherein the one or more organosilanes comprise aminofunctional silanes, non-aminofunctional silanes or combinations thereof.
14. The aqueous carbon nanotube dispersion of claim 12, wherein the one or more organosilanes are present in the aqueous carbon nanotube dispersion in an amount up to about 10 weight percent on a total solids basis.
15. The aqueous carbon nanotube dispersion of claim 12, wherein the one or more organosilanes are present in the aqueous carbon nanotube dispersion in an amount ranging from about 1 weight percent to about 5 weight percent on a total solids basis.
16. A method of making an aqueous carbon nanotube dispersion comprising:
providing a polymeric carrier;
mixing carbon nanotube particles in an amount of at least about 1 weight percent on a total solid basis with the polymeric carrier, wherein the polymeric carrier comprising an aqueous dispersion of one or more polymeric species and wherein the carbon nanotube particles comprise a plurality of carbon nanotubes; and
reducing the mixed carbon nanotube particles in size such that the carbon nanotube particles have a mean particle size that ranges from about 250 nm to about 2 \u03bcm;
wherein the aqueous carbon nanotube dispersion has a viscosity of 1100 to 4500 cP at 5 RPM and 25\xb0 C.
17. The method of claim 16, wherein the carbon nanotube particles are mixed with the polymeric carrier in an amount ranging from about 1 weight percent to about 30 weight percent on a total solids basis.
18. The method of claim 16, wherein the carbon nanotube particles are mixed with the polymeric carrier in an amount ranging from about 1 weight percent to about 15 weight percent on a total solids basis.
19. The method of claim 16, wherein the one or more polymeric species comprises polyvinylpyrrolidone, polyurethane, epoxy or combinations thereof.
20. The method of claim 16, wherein the mixed carbon nanotube particles are reduced in size by milling.
21. The method of claim 16, further comprising providing at least one additional component and adding the at least one additional component to the aqueous carbon nanotube dispersion, the at least one additional component comprising a film former, coupling agent, lubricant, surfactant, biocide, anti-foaming agent or mixtures thereof.
22. The method of claim 21, wherein the at least one additional component comprises a film former, the film former comprising polyurethane, epoxide, polyvinylpyrrolidone, polyacrylate, polyester, polyvinylacetate, polyvinyl alcohol or combinations thereof.
23. The method of claim 22, wherein the film former is present in the aqueous carbon nanotube dispersion in an amount of at least about 50 weight percent on a total solids basis.
24. The method claim 22, wherein the film former is present in the aqueous carbon nanotube dispersion in an amount ranging from about 60 weight percent to about 80 weight percent on a total solids basis.
25. The method of claim 21, wherein the at least one additional component comprises a coupling agent, the coupling agent comprises one or more organosilanes.
26. The method of claim 25, wherein the one or more organosilanes comprises aminofunctional silanes, non-aminofunctional silanes or combinations thereof.
27. The method of claim 25, wherein the one or more organosilanes are present in the aqueous carbon nanotube dispersion in an amount ranging from about 1 weight percent to about 5 weight percent on a total solids basis.
28. An aqueous carbon nanotube dispersion consisting essentially of:
carbon nanotube particles present in an amount of at least about 1 weight percent on a total solids basis, wherein the carbon nanotube particles comprise a plurality of carbon nanotubes and have a mean particle size that ranges from about 250 nm to about 2 \u03bcm; and
a polymeric carrier selected from the group consisting of a polyvinylpyrrolidone, a polyurethane, an epoxy, and combinations thereof;
wherein the aqueous carbon nanotube dispersion has a viscosity of 1100 to 4500 cP at 5 RPM and 25\xb0 C.