1.-14. (canceled)
15. An implantable device for detecting a triggering signal within tissue and generating an output signal therefrom, the device comprising:
an array of nanowires having a predetermined spatial distribution, density, size and shape implanted in a location within the tissue within which the triggering signal is received;
an electrical conductor disposed at a first end of all nanowires in the array of nanowires;
a bias source in electrical communication with the electrical conductor for biasing the array;
a plurality of electrodes disposed on a second end of each of one nanowire or a bundle of nanowires in the array of nanowires, wherein each nanowire produces a current at a corresponding electrode in response to detection of the triggering signal, wherein the array of nanowires generates an output signal corresponding to the currents produced in response to the triggering signal.
16. The implantable device as in claim 15, wherein the triggering signal comprises light impinging on the tissue and the output signal comprises a signal for stimulating one or more photoreceptor neurons.
17. The implantable device as in claim 15, further comprising a recording device comprising an amplifier and a memory device, wherein the wherein the output signal is communicated to the recording device for amplification and storage in the memory device.
18. The implantable device as in claim 15, further comprising an electrically-reactive membrane having a plurality of openable cells for retaining a neurotransmitter, wherein the electrically-reactive membrane is in electrical contact with the plurality of electrodes, and wherein the output signal activates the electrically-reactive membrane to release at least a portion of the neurotransmitter in response to detection of the signal.
19. The implantable device of claim 15, wherein each nanowire has a diameter ranging between 10 nm-5 \u03bcm and a height ranging between 1-50 \u03bcm.
20. The implantable device of claim 15, wherein a spacing between nanowires in the array is on the order of 2nm or more.
21. The implantable device of claim 15, wherein the predetermined spatial distribution mimics a distribution of rods and cones in a normal eye.
22. The implantable device of claim 15, wherein the array of nanowires includes a plurality of nanoridges having lengths of approximately 5 \u03bcm to 400 \u03bcm, each nanoridge having a plurality of stimulation electrodes disposed along its length for selectively activating local ganglion cells.
23. The implantable device of claim 22, wherein the plurality of nanoridges is disposed at a central area of the array corresponding to a fovea in the eye.
24. The implantable device of claim 15, wherein the array of nanowires is disposed on a flexible substrate comprising a biocompatible material.
25. The implantable device of claim 24, wherein the biocompatible material is poly(p-xylylene or polydimethylsiloxane.
26. The implantable device of claim 15, wherein spaces between the nanowires in the array of nanowires are filled with a biocompatible material.
27. The implantable device of claim 26, wherein the biocompatible material has channels formed therethrough, the channels adapted to pass nutrients to the retina tissue.
28. The implantable device of claim 26, wherein the biocompatible material is poly(p-xylylene or polydimethylsiloxane.
29. The implantable device of claim 15, further comprising:
a first inductive coil disposed adjacent the eye and in electrical communication with the bias source; and
a second inductive coil disposed outside of the eye for inducing a magnetic field at the first inductive coil.
30. The prosthetic implantable device of claim 15 adapted for epiretinal implantation, wherein the electrodes are placed in contact with a vitreous fluid in the eye.
31. The implantable device of claim 15 adapted for subretinal implantation, wherein the electrodes are disposed between photoreceptors and a retinal pigment epithelium in the eye.
32. An implantable device for detecting an electrical potential within a tissue and generating an output therefrom, the device comprising:
an array of nanowires;
an electrical conductor disposed at a first end of all nanowires in the array of nanowires;
a bias source in electrical communication with the electrical conductor for biasing the array;
a plurality of electrodes disposed on a second end of each individual nanowire or each bundle of nanowires in the array of nanowires, wherein one or more pairs of individual nanowires or bundles of nanowires, when implanted within tissue, detects an intracellular or extracellular action potential within the tissue and generates an output signal at the electrical conductor; and
a recording device comprising an amplifier connected to the electrical conductor for receiving and storing a signal corresponding to an amplified intracellular or extracellular action potential.
33. The implantable device as in claim 32, further comprising an electrically-reactive membrane having a plurality of openable cells for retaining a neurotransmitter, wherein the electrically-reactive membrane is in electrical contact with the electrical conductor, and wherein the output signal further activates the electrically-reactive membrane to release at least a portion of the neurotransmitter in response to detection of light.
34. The implantable device of claim 32, wherein the array of nanowires is disposed on a flexible substrate comprising a biocompatible material.
35. The implantable device of claim 34, wherein the biocompatible material is polyp-xylylene or polydimethylsiloxane.
36. The implantable device of claim 32 wherein spaces between the nanowires in the array of nanowires are filled with a biocompatible material.
37. The implantable device of claim 36, wherein the biocompatible material has channels formed therethrough, the channels adapted to pass nutrients to the tissue.
38. A method for forming a prosthetic retina, comprising:
forming an semiconductor layer on a substrate;
coating an upper surface of the semiconductor layer with a photoresist;
imprinting a pattern in the photoresist with a mold adapted to define a plurality of features with a predetermined spatial distribution, density, size and shape;
anisotropically etching the photoresist to expose areas of the semiconductor layer surrounding the plurality of features;
coating the photoresist and exposed areas of the semiconductor layer with a conductive coating;
removing the photoresist to define conductive areas corresponding to the plurality of features and to selectively lift the conductive coating from areas of the semiconductor layer surrounding the conductive areas;
anisotropically etching the semiconductor layer surrounding the conductive areas to define an array of vertical nanowires separated by channels;
filling the channels with a biocompatible insulating material, wherein the insulating material is adapted to permit nutrients to be conducted therethrough;
forming electrical contacts on an upper end of each nanowire of the array of vertical nanowires, wherein the electrical contacts are adapted to stimulate neurons for visual perception; and
removing the substrate to expose a lower end of each nanowire of the array of vertical nanowires.
39. The method of claim 38, further comprising:
attaching the array of vertical nanowires to a flexible substrate.
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. A method for determining a direction of arrival of a first signal in a plurality of signals generated by a source in a plurality of sources, comprising:
a processor estimating a first direction of arrival for a previous signal generated by the source prior to the first signal with a particle filter operating in a time-frequency domain;
receiving by a plurality of receivers at a time t the plurality of signals from the plurality of sources, at least two of the received plurality of signals being correlated;
the processor determining a regularization factor and a weighting factor for each of a plurality of frequency components of the first signal;
the processor determining a likelihood for the direction of arrival for each of the plurality of frequency components of the first signal based on the regularization factor and the weighting factor;
the processor determining a global likelihood for the direction of arrival of the first signal based on the likelihood for the direction of arrival for each of the plurality of frequency components of the first signal;
the processor updating a plurality of weights of the particle filter; and
the processor generating an estimate of the direction of arrival of the first signal by applying the updated weights of the particle filter.
2. The method of claim 1, wherein the global likelihood L(\u03b8) is determined by an expression:
L
\u2061
(
\u03b8
)
=
\u2211
n
=
1
N
\u2062
L
n
reg
\u2061
(
\u03b8
)
\u2062
\u03bb
n
,
with \u03b8 representing a vector of all directions-of-arrivals for all the sources in the plurality of sources, n represents a frequency component, N represents a total number of frequency components, Lnreg(\u03b8)\u03bbn is a regularized likelihood of all directions-of-arrivals for all the sources adjusted by a normalized weighting factor \u03bbn for a frequency component n.
3. The method of claim 1, wherein the weighting factor for a frequency component n is a normalized weighting factor \u03bbn that is determined by an expression:
\u03bb
n
=
\u03c4
n
\u2211
n
=
1
N
\u2062
\u03c4
n
,
wherein
\u03c4
n
=
\u03c6
(
\uf605
P
^
n
\u2061
(
\u03b8
)
\u2062
X
n
\uf606
\uf605
X
n
\uf606
,
with
\u03c4n representing an un-normalized weighting factor, {circumflex over (P)}n(\u03b8) representing a regularized projector for a frequency component n on a signal subspace, \u03b8 representing a vector of all directions-of-arrivals for all the sources in the plurality of sources, Xn representing a vector of frequency components n of the plurality of signals received by the plurality of receivers and \u03c6 representing a non-negative non-decreasing weighting function.
4. The method of claim 1, further comprising the processor determining a Maximum A Posteriori likelihood (MAP) estimate of a frequency component of the first signal.
5. The method of claim 4, wherein the MAP estimate represented by \u015cn(\u03b8) is determined by an expression:
\u015cn(\u03b8)=(AnHA\u03bbnI)\u22121+AnHXn,
with \u03b8 representing a vector of all directions-of-arrivals for all the sources in the plurality of sources, A representing a steering matrix, AnH representing a Hermitian of a steering matrix for a frequency component n, \u03bbn representing a regularization factor for a frequency component n, I representing an identity matrix and Xn representing a vector of frequency components n of the plurality of signals received by the plurality of receivers.
6. The method of claim 1, wherein the updated weights wik of the particle filter are determined by an expression:
w
i
k
=
w
i
k
–
1
\u2062
p
\u2061
(
X
1
:
N
|
\u03b8
i
k
)
\u2211
i
=
1
P
\u2062
w
i
k
–
1
\u2062
p
\u2061
(
X
1
:
N
|
\u03b8
i
k
)
,
with k representing an update time, i representing a particle index, p representing a probability distribution function, P representing a total number of particles, X1:N representing a vector of frequency components at moment k, and \u03b8ik representing a direction of arrival estimates of particle i at moment k.
7. The method of claim 6, wherein the global likelihood is adjusted with a scaling parameter.
8. The method of claim 1, wherein at least one source in the plurality of sources is a moving source.
9. The method of claim 1, wherein the first signal is an acoustic signal.
10. The method of claim 1, wherein at least one source in the plurality of sources is associated with a power generator.
11. A system to determine a direction of arrival of a first signal in a plurality of signals generated by a source in a plurality of sources, comprising:
a memory enabled to store data and instructions;
a processor enabled to retrieve and execute instructions from the memory to perform the steps:
estimating a first direction of arrival for a previous signal generated by the source prior to the first signal with a particle filter operating in a time-frequency domain;
processing the plurality of signals from the plurality of sources received at a time t by a plurality of receivers, at least two of the received plurality of signals being correlated;
determining a regularization factor and a weighting factor for each of a plurality of frequency components of the first signal;
determining a likelihood for the direction of arrival for each of the plurality of frequency components of the first signal based on the regularization factor and the weighting factor;
determining a global likelihood for the direction of arrival of the first signal based on the likelihood for the direction of arrival for each of the plurality of frequency components of the first signal;
updating a plurality of weights of the particle filter; and
generating an estimate of the direction of arrival of the first signal by applying the updated weights of the particle filter.
12. The system of claim 11, wherein the global likelihood L(\u03b8) is determined by an expression:
L
\u2061
(
\u03b8
)
=
\u2211
n
=
1
N
\u2062
L
n
reg
\u2061
(
\u03b8
)
\u2062
\u03bb
n
,
with \u03b8 representing a vector of all directions-of-arrivals for all the sources in the plurality of sources, n represents a frequency component, N represents a total number of frequency components, Lnreg(\u03b8)\u03bbn is a regularized likelihood of all directions-of-arrivals for all the sources adjusted by a normalized weighting factor \u03bbn for a frequency component n.
13. The system of claim 11, wherein the weighting factor for a frequency component n is a normalized weighting factor \u03bbn that is determined by an expression:
\u03bb
n
=
\u03c4
n
\u2211
n
=
1
N
\u2062
\u03c4
n
,
wherein
\u03c4
n
=
\u03c6
(
\uf605
P
^
n
\u2061
(
\u03b8
)
\u2062
X
n
\uf606
\uf605
X
n
\uf606
,
with
\u03c4n representing an un-normalized weighting factor, {circumflex over (P)}n(\u03b8) representing a regularized projector for a frequency component n on a signal subspace, \u03b8 representing a vector of all directions-of-arrivals for all the sources in the plurality of sources, Xn representing a vector of frequency components n of the plurality of signals received by the plurality of receivers and \u03c6 representing a non-negative non-decreasing weighting function.
14. The system of claim 11, further comprising the processor determining a Maximum A Posteriori likelihood (MAP) estimate of a frequency component of the first signal.
15. The system of claim 14, wherein the MAP estimate represented by \u015cn(\u03b8) is determined by an expression:
\u015cn(\u03b8)=(AnHA\u03bbnI)\u22121+AnHXn,
with \u03b8 representing a vector of all directions-of-arrivals for all the sources in the plurality of sources, A representing a steering matrix, AnH representing a Hermitian of a steering matrix for a frequency component n, \u03bbn representing a regularization factor for a frequency component n, I representing an identity matrix and Xn representing a vector of frequency components n of the plurality of signals received by the plurality of receivers.
16. The system of claim 11, wherein the updated weights wik of the particle filter are determined by an expression:
w
i
k
=
w
i
k
–
1
\u2062
p
\u2061
(
X
1
:
N
|
\u03b8
i
k
)
\u2211
i
=
1
P
\u2062
w
i
k
–
1
\u2062
p
\u2061
(
X
1
:
N
|
\u03b8
i
k
)
,
with k representing an update time, i representing a particle index, p representing a probability distribution function, P representing a total number of particles, X1:N representing a vector of frequency components at moment k, and \u03b8ik representing a direction of arrival estimates of particle i at moment k.
17. The system of claim 16, wherein the global likelihood is adjusted with a scaling parameter.
18. The system of claim 11, wherein at least one source in the plurality of sources is a moving source.
19. The system of claim 11, wherein the first signal is an acoustic signal.
20. The system of claim 11, wherein at least one source in the plurality of sources is associated with a power generator.