U.S. patent application number 15/642097 was filed with the patent office on 2017-10-19 for methods and apparatuses for configuring artificial retina devices.
The applicant listed for this patent is Long-Sheng FAN. Invention is credited to Long-Sheng FAN.
Application Number | 20170296819 15/642097 |
Document ID | / |
Family ID | 54929408 |
Filed Date | 2017-10-19 |
United States Patent
Application |
20170296819 |
Kind Code |
A1 |
FAN; Long-Sheng |
October 19, 2017 |
METHODS AND APPARATUSES FOR CONFIGURING ARTIFICIAL RETINA
DEVICES
Abstract
Methods and apparatuses to detect configuration commands from
waveforms received at a retina prosthesis device for calibrating
the device are described. The device can comprise an array of pixel
units to receive light to stimulate neuron cells to cause an effect
of visual sensation from the light. The pixel units may have
configurable parameters for the stimulation to the neuron cells.
The configurable parameters may be updated according to the
configuration commands detected without requiring micro processor
and non-volatile memory in the device. The stimulation may be
generated according to the updated configurable parameters to
improve the effect of visual sensation from the light including
compensation for the physiological and environmental variations and
drifts.
Inventors: |
FAN; Long-Sheng; (Hsinchu,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FAN; Long-Sheng |
Hsinchu |
|
TW |
|
|
Family ID: |
54929408 |
Appl. No.: |
15/642097 |
Filed: |
July 5, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14320398 |
Jun 30, 2014 |
9737710 |
|
|
15642097 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 2924/0002 20130101;
A61N 1/37223 20130101; H01L 23/4985 20130101; A61N 1/0543 20130101;
A61N 1/36046 20130101; H01L 2924/0002 20130101; H01L 2924/00
20130101 |
International
Class: |
A61N 1/36 20060101
A61N001/36; A61N 1/05 20060101 A61N001/05; A61N 1/372 20060101
A61N001/372 |
Claims
1. A machine-implemented method to calibrate a retina prosthesis
device, the method comprising: receiving diagnostic commands from
an interface at the a retina prosthesis device, wherein the device
comprises an array of pixel units to receive light to stimulate
neuron cells to cause an effect of visual sensation from the light,
and wherein the pixel units have configurable parameters for the
stimulation to the neuron cells; sending data related to electric
characteristics of the neuron cells via the interface according to
the diagnostic commands; detecting configuration commands received
at the interface subsequent to sending the data; updating the
configurable parameters according to the configuration commands
detected; and generating the stimulation according to the updated
configurable parameters to improve the effect of visual sensation
from the light.
2. The method of claim 1, wherein the interface is based on
wireless signals carrying power to wireles sly power the device and
wherein the configuration commands are embedded within the wireless
signals.
3. The method of claim 1, further comprising detecting mode change
commands at the interface for the device to enter a neuron
identification mode.
4. The method of claim 1, wherein the diagnostic commands includes
at least one sampling command during the neuron identification
mode.
5. The method of claim 4, wherein the electrical characteristics
are sensed a plurality of times according the sample command.
6. The method of claim 5, wherein the data includes the electrical
characteristics sensed for the plurality of times.
7. The method of claim 6, wherein the configuration commands are
received subsequent to sending the data in the neuron
identification mode.
8. The method of claim 7, wherein the configuration commands depend
on the data sent in the neuron identification mode.
9. A non-statutory machine-readable medium having instructions
stored therein, which when executed by a processor, cause the
processor to perform a method of calibrating a retina prosthesis
device, the method comprising: receiving diagnostic commands from
an interface at the a retina prosthesis device, wherein the device
comprises an array of pixel units to receive light to stimulate
neuron cells to cause an effect of visual sensation from the light,
and wherein the pixel units have configurable parameters for the
stimulation to the neuron cells; sending data related to electric
characteristics of the neuron cells via the interface according to
the diagnostic commands; detecting configuration commands received
at the interface subsequent to sending the data; updating the
configurable parameters according to the configuration commands
detected; and generating the stimulation according to the updated
configurable parameters to improve the effect of visual sensation
from the light.
10. The machine-readable medium of claim 9, wherein the interface
is based on wireless signals carrying power to wireles sly power
the device and wherein the configuration commands are embedded
within the wireless signals.
11. The machine-readable medium of claim 9, wherein the method
further comprises detecting mode change commands at the interface
for the device to enter a neuron identification mode.
12. The machine-readable medium of claim 9, wherein the diagnostic
commands includes at least one sampling command during the neuron
identification mode.
13. The machine-readable medium of claim 12, wherein the electrical
characteristics are sensed a plurality of times according the
sample command.
14. The machine-readable medium of claim 13, wherein the data
includes the electrical characteristics sensed for the plurality of
times.
15. The machine-readable medium of claim 14, wherein the
configuration commands are received subsequent to sending the data
in the neuron identification mode.
16. The machine-readable medium of claim 15, wherein the
configuration commands depend on the data sent in the neuron
identification mode.
17. A retina prosthesis device, comprising: a processor; and a
memory coupled to the processor to store instructions, which when
executed by the processor, cause the processor to perform a method
of calibrating the retina prosthesis device, the method comprising:
receiving diagnostic commands from an interface at the a retina
prosthesis device, wherein the device comprises an array of pixel
units to receive light to stimulate neuron cells to cause an effect
of visual sensation from the light, and wherein the pixel units
have configurable parameters for the stimulation to the neuron
cells, sending data related to electric characteristics of the
neuron cells via the interface according to the diagnostic
commands, detecting configuration commands received at the
interface subsequent to sending the data, updating the configurable
parameters according to the configuration commands detected, and
generating the stimulation according to the updated configurable
parameters to improve the effect of visual sensation from the
light.
18. The device of claim 17, wherein the interface is based on
wireless signals carrying power to wireles sly power the device and
wherein the configuration commands are embedded within the wireless
signals.
19. The device of claim 17, wherein the method further comprises
detecting mode change commands at the interface for the device to
enter a neuron identification mode.
20. The device of claim 17, wherein the diagnostic commands
includes at least one sampling command during the neuron
identification mode.
Description
FIELD OF INVENTION
[0001] This application is a divisional application of U.S. patent
application Ser. No. 14/320,398, filed Jun. 30, 2014. The
disclosure of the above applications is incorporated by reference
herein in their entirety.
FIELD OF INVENTION
[0002] The present invention relates generally to micro devices,
and more particularly to flexible integrated circuit devices
capable of stimulating neural cells.
BACKGROUND
[0003] Age-related macular disease (AMD) and the retinitis
pigmentosa (RP) disease have been identified as major causes of
blindness, especially for senior people worldwide. Retinal
prosthesis device offers possible restoration of part of the vision
to the blindness. Typically, the device includes electrodes
requiring separate wiring implant to control each electrode.
However, field of view provided by such devices, which depends on
the number of electrodes included in the device, may be severely
limited because of size limitation on the wiring implant.
[0004] Furthermore, the image resolution of a retina prosthesis
device may be related to density of electrodes in the device.
Conventional devices for retina prosthesis may include driving
circuit chips separate from electrode or image sensor chips
implanted to retina tissues. Thus, the required number of
electrical interconnections between the electrode chips and the
driving circuit chips can increase significantly to impose
unnecessary ceilings on possible image resolution achievable.
[0005] In addition, existing retina prosthesis devices may be based
on electrodes made of planner chips not conforming to non-planar
shapes of retina tissues. As a result, additional interferences
among the electrodes may occur because of the mismatch in shapes to
further limit possible image resolution of the device.
[0006] Thus, traditional retina prosthesis devices are inherently
limited to provide levels of image resolutions, field of views or
other visual characteristics to achieve levels close to a real
retina to help patients recover from impaired vision
capabilities.
SUMMARY OF THE DESCRIPTION
[0007] In one embodiment, a flexible integrated device can provide
high resolution of electrical excitations (e.g. down to individual
retina cell level) over at least one mm (million meter) to several
mm field of view for retina prosthesis. The flexible integrated
device may be capable of tuning and calibration for adjusting
excitation to target retinal neurons. In one embodiment, the
flexible integrated device may be implanted using either an
epi-retinal (e.g. from the front side of retina or on the retina)
approach or a sub-retinal (e.g. behind the retina) approach.
[0008] In another embodiment, a single flexible CMOS (complementary
metal-oxide-semiconductor) chip can integrate an array of pixel
units. Each pixel may comprise an electrode, photo sensor, signal
processor and driver circuitry. The flexible chip can be fabricated
thin enough to conform to the shape of a retina. For example, the
flexible chip about 3 mm in diameter may be bendable to about 90
.mu.m (micro meter) along the edge of the chip to form a two
dimensional curved spherical device.
[0009] In another embodiment, a flexible integrated device may
include a mosaic of sub-modules divided via boundaries. Device
material except some conducting lines (e.g. metal lines) between
these sub-modules may be removed from the boundaries to increase
moldability (e.g. flexibility to conform to different shapes) of
the device. In some embodiments, the flexible integrated device may
be perforated (e.g. with perforation holes) to maintain some
fluidic flow across the device. Optionally or alternatively, the
flexible integrated device may include a thin substrate to allow a
portion of light (e.g. when not obstructed by metals) to penetrate
through the chip to be applicable in epi-retinal prosthesis.
[0010] In another embodiment, a flexible integrated device may
include electrodes fitted with local return paths (or "guard ring")
to shorten the total distance of electric flows from the
electrodes. As a result, the amount of electricity lost in transit
of the electric flows can be lowered to prevent unwanted
stimulation of sensory cells other than target neuron cells, such
as the bipolar cells and ganglion cells situated behind the retina.
The electrodes may be positioned in three dimensions with multiple
electrode heights from surfaces of the device to differentially
stimulate different types of neuron cells, such as strata of ON and
OFF cells.
[0011] In another embodiment, a flexible integrated device may
include on-chip signal processing circuitry capable of generating
appropriate stimulus waveforms for a pixel unit by taking inputs
from multiple pixel units, such as nearby neighboring pixel units.
The flexible integrated device may include electrical sensing
circuitry capable of identifying specific types of target neural
cells for each pixel unit through receptive field and firing
patterns from the target neural cells (e.g. located close to the
pixel unit).
[0012] In another embodiment, a provision system including a
flexible integrated retina chip implanted to a user as retina
prosthesis may allow fine tuning of the chip via external commands.
For example, each pixel unit in the chip may include specific
receivers and/or circuitry for receiving optical and/or wireless
communication signals for the external commands to select and/or
configure portions of the chip according to the user's visual
perception. The provision system may include a remote control to
issue the external commands optically or wirelessly.
[0013] In another embodiment, an implantable device to interface
with retina cells may comprise an array of pixel units capable of
stimulating the retina cells. The pixel units may operate in a mode
of operation selected from a plurality of modes including a normal
mode and a calibration mode. A control circuitry of the device may
be configured to switch the mode of operation for the pixel units.
In one embodiment, the pixel units may be configured to receive
light for stimulating the retina cells during the normal mode to
enable perception of the images of the lights. During the
calibration mode, the pixel units may be configured to adjust
amount of stimulation (strength or amplitude, duration, duty cycle,
repetition rate of a waveform, or spike sequences representing the
stimulation etc.) to the retina cells.
[0014] In another embodiment, a method to calibrate a retina
prosthesis device may comprise detecting predetermined pre-amble of
light patterns (in space and time) or RF signal sequence to cause
the device into a calibration mode. The device may comprise an
array of pixel units to receive light to enable perception of
vision of the images of the lights. The pixel units may be
configurable via electrical parameters. Light patterns or RF (Radio
Frequency) signal sequence may be received to select one or more
pixel units from the array. In one embodiment, the light patterns
may be associated with known effect of visual sensation. Stimuli
may be generated from the selected pixel units to stimulate neuron
cells to cause actual effect of visual sensation via the light
patterns captured by the selected pixel units. In response to
receiving external commands, the electrical parameters may be
updated for the selected pixel units to improve the actual effect
of visual sensation for the known effect of visual sensation.
[0015] In another embodiment, a system for retina prosthesis
calibration may comprise a retina prosthesis device to interface
with retina cells and a remote control device capable of sending
external commands to the device. The device may include a plurality
of photo sensors to receive light, a plurality of electrodes to
stimulate the retina cells, a configurable processing circuitry to
generate stimuli for the electrodes based on the light received,
and control circuitry to configure the configurable processing
circuitry according to the external commands. A known visual
perception may be projected via the light. In one embodiment, the
external commands may be capable of selecting one or more of the
photo sensors and the electrodes. Optionally or alternatively, the
external commands may be capable of selecting a configuration of
the configurable processing circuitry via a comparison between an
actual perception of vision from the stimulated neuron cells and
the known perception of vision. The configurable processing
circuitry may generate the stimuli according to the
configuration.
[0016] In another embodiment, configuration commands can be
detected from waveforms received at a retina prosthesis device for
calibration. The device can comprise an array of pixel units to
receive light to stimulate neuron cells to cause an effect of
visual sensation from the light. The pixel units may have
configurable parameters for the stimulation to the neuron cells.
The configurable parameters may be updated according to the
configuration commands which are detected without requiring
processor logic (e.g. a micro processor and/or associated memory
components) in the device. The stimulation may be generated
according to the updated configurable parameters to improve the
effect of visual sensation from the light.
[0017] Other features of the present invention will be apparent
from the accompanying drawings and from the detailed description
that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The present invention is illustrated by way of example and
not limitation in the figures of the accompanying drawings, in
which like references indicate similar elements and in which:
[0019] FIGS. 1A-1B are block diagrams illustrating embodiments of
integrated flexible devices for retina prosthesis;
[0020] FIGS. 2A-2B are relationship diagrams illustrating effects
of flexible devices which are curved according to one embodiment of
the present invention.
[0021] FIG. 3 is a schematic diagram illustrating an exemplary
device with perforation holes according to one embodiment of the
present invention;
[0022] FIGS. 4A-4B are block diagrams illustrating cross sectional
views of flexible devices in one embodiment of the present
invention;
[0023] FIGS. 5A-5J are block diagrams illustrating a sequence of
fabrication processes for flexible devices in one embodiment of the
present invention;
[0024] FIGS. 5.1A-5.1F are block diagrams illustrating a sequence
of fabrication processes for flexible devices in another embodiment
of the invention.
[0025] FIGS. 6A-6D are block diagrams illustrating exemplary
layered structures of flexible devices for different approaches to
implant retina prosthesis;
[0026] FIGS. 7A-7B are block diagrams illustrating guard rings to
confine electric flows in exemplary embodiments of the present
invention;
[0027] FIG. 8 is a block diagram illustrating layered structures
for flexible devices with protruding electrodes in one embodiment
of the present invention;
[0028] FIG. 9 is a block diagram illustrating layered structures in
flexible devices with multi-level electrodes in one embodiment of
the present invention;
[0029] FIGS. 10A-10B are schematic diagrams illustrating exemplary
signal processing circuitry in flexible devices according to one
embodiment of the present invention;
[0030] FIG. 10C is a schematic diagram illustrating an exemplary
configuration of pixel units for processing signals according to
one embodiment of the present invention;
[0031] FIG. 10D is a block diagram illustrating a flexible device
wirelessly configured, calibrated, and tested via an external
device according to one embodiment of the present invention;
[0032] FIG. 10E is a schematic diagram illustrating another example
of a signal processing circuitry in flexible devices according to
one embodiment of the present invention;
[0033] FIGS. 11A-11B are block diagrams illustrating operations of
configured flexible devices in one embodiment of the present
invention;
[0034] FIG. 12 is a block diagram illustrating a system to
configure flexible devices in one embodiment of the present
invention;
[0035] FIG. 13 is a flow diagram illustrating a method to configure
flexible devices in one embodiment described herein.
[0036] FIG. 14 is a block diagram illustrating a system to
configure flexible devices in another embodiment of the present
invention;
[0037] FIG. 15 is a perspective diagram illustrating an exemplary
configuration of a flexible retina device coupled with a control
device;
[0038] FIG. 16 is a flow diagram illustrating another method to
configure flexible devices in one embodiment described herein.
DETAILED DESCRIPTION
[0039] Methods and apparatuses for configuring artificial retina
devices are described herein. In the following description,
numerous specific details are set forth to provide thorough
explanation of embodiments of the present invention. It will be
apparent, however, to one skilled in the art, that embodiments of
the present invention may be practiced without these specific
details. In other instances, well-known components, structures, and
techniques have not been shown in detail in order not to obscure
the understanding of this description.
[0040] Reference in the specification to "one embodiment" or "an
embodiment" means that a particular feature, structure, or
characteristic described in connection with the embodiment can be
included in at least one embodiment of the invention. The
appearances of the phrase "in one embodiment" in various places in
the specification do not necessarily all refer to the same
embodiment.
[0041] A flexible IC (integrated circuit) device can integrate an
array of "pixels" in a sing chip. Each pixel can comprise an
electrode, sensors (e.g. photo sensors, electric sensors or other
applicable sensors), a signal processor and/or driver circuitry.
The integration can simplify wiring, fan out, multiplexing or other
requirements to enable intended functions of the device. Costly
signal transmission, for example, via EM (electromagnetic) waves,
between processing circuitry and sensor/electrode arrays may be
eliminated. Each pixel can be accessible within the device to allow
thousands or tens of thousands of pixels in the device to interface
with neuron cells. For example, the flexible integrated device may
provide required density to restore 20/80 vision corresponding to
about a two to three mm-sized, high density array with
10,000.about.20,000 pixel units.
[0042] In one embodiment, flexibility of an integrated device may
be based on controlled thickness of the device. For example, the
device can be thin enough to bend .about.90 .mu.m to conform to the
shape of a retina (e.g. a human eye ball). In some embodiments, the
device may be made (e.g. according to a fabrication process) thin
enough to be bent to a radius of curvature smaller than 12 mm,
about the average radius curvature of a human retina, still within
the safety margin of the material strength of the device.
[0043] As a device is bendable to conform to the curvature of a
retina, the neuron-to-electrode distance between electrodes of the
device and target neuron cells of the retina can be minimized.
Consequently, the power required in the device to excite or
stimulate the neuron cells can be reduced to enable a higher pixel
density and improve resolution of images perceived via the neuron
cells using the device implanted to a patient. In certain
embodiments, the device can meet the conformity requirements for
exciting individual retinal neuron (e.g. targeting an individual
neuron cell per electrode).
[0044] In one embodiment, a flexible integrated circuit (or device)
for retina prosthesis may be fabricated based on an 180 nm
(nanometer) CMOS technology using 1.about.30 micrometer thick Si
device layer sandwiched between two biocompatible polymer and
barrier layers (such as Polyimide/SiC, Parylene/SiC). Both
biocompatible polymer and barrier layer may be compatible (e.g.
biocompatible) with ISO (International Organization for
Standardization) 10993 standards to provide mutual protection
between the flexible integrated device and surrounding tissues when
the device is implanted within the tissues. The barrier layer may
be denser than the biocompatible layer to strengthen the
protection.
[0045] The fabrication approach of a flexible integrated device may
enable integration of high density CMOS image sensors and signal
processing circuitry together with neuron stimulating electrode
arrays on the same flexible patch needed for medical implants. In
some embodiments, semiconductor substrate may be used in the device
to allow inclusion of necessary optical and/or electronic
components for sensing optical images and producing electrical
stimulus as a function of the sensed optical images.
[0046] In an alternative embodiment, a flexible integrated device
may be applicable in different manners of retina implantation. For
example, the device may be manufactured to be thin enough to allow
light to pass through the device. Sensors and electrodes may be
positioned in the same side (or surface) or opposing sides of such
a translucent device. As a result, the device may be implanted in
an epi-retina manner to stimulate retinal ganglion cells (RGC)
directly via electrodes of the device without utilizing a retinal
neural network before the RGC layer. Alternatively, the device may
be implanted in a sub-retinal manner to stimulate the retina from
the bipolar cell side via the electrodes, for example, to work
together with the remaining neural network formed by a variety of
neuron cells, such as bipolar cells, horizontal cells, amacrine
cells etc.
[0047] In one embodiment, a flexible integrated device may be
capable of igniting target neuron cells or nerves according to
characteristics of the neuron cells responding to light stimuli.
For example, the characteristics may indicate the target neuron
cells are ON type cells, OFF type cells or other types of cells. An
ON type cell may respond substantially synchronous with onset of
light stimuli. An OFF type cell may respond substantially
synchronous with offset of the light stimuli. The flexible
integrated device may include processing capability to generate
stimuli from received light to properly ignite the targeted neuron
cells (e.g. as if the neuron cells are directly stimulated by the
received light), for example, via special stimulation pattern (or
waveforms), time delays, ignition, suppression, or other applicable
stimulation manners, etc. In one embodiment, the flexible
integrated device may include multiple layers of electrodes (e.g.
distributed in a three dimensional manner) to allow physical
selection (e.g. based on proximity) of different layers of neuron
cells (e.g. due to neuron connection stratification) to communicate
(or stimulate).
[0048] A flexible integrated device may be configurable to provide
customized functionalities for different retina implant needs. For
example, manual and/or self (automatic) calibration operations may
be applied in vitro (e.g. subsequent to implantation into a
patient) to identify types of targeted neuron cells and/or
adjusting sensor/electrode array parameters of the device according
to actual visual perception of the receiving patient. Processing
functions may be activated or programmed (e.g. through programmable
circuitry) to provide equivalent signal processing effects, for
example, to replace damaged neuron cell networks to improve
impaired vision of the receiving patient.
[0049] The flexible integrated device or chip may be wireles sly
coupled with a near by wearable device, such as eyeglasses.
Availability of two-way wireless communication between the flexible
device and the wearable device may allow the flexible device to
operate in different modes to increase its effectiveness. For
example, the flexible device may enter a test mode (e.g. before
implantation) to enable chip probing without a need for additional
pad openings to ensure quality of the device. After implantation of
the flexible device, diagnostic tests on the device may be
conducted wirelessly when the device is operating in the test
mode
[0050] In some embodiments, the flexible device may operate in a
calibration mode to allow determination of optimum stimulation
waveform (e.g. generated via a pixel array of the device) via
wireless calibration of electrode to neuron interface
characteristics. External computation power may be leveraged to
perform operations via sophisticated algorithms for the
determination which may not be feasible within the implantable
flexible device constrained by both size and power. During the
calibration mode, repeated measurements of neural responses may be
conducted according to external commands. Electrodes can send
stimulating signals and switch to sensing mode to detect the
correlated responses that might be smaller than the noise
background. Since the neurons responses is correlated to the
stimulation, but noise are not, multiple samples of measurement
data (e.g. sensed responses) may be wirelessly transmitted
externally to allow application of the oversampling techniques
(e.g., by repeating this N time and averaging the sum, the signal
to noise ratio will increase sqrt(N) time) to enhance weak/noisy
neural responses to more accurately identify load characteristics
for determining the optimum stimuli waveforms.
[0051] When the flexible device operates in a usage mode or
operating mode, configuration parameters (e.g. for pixel unit
array) for stimulation waveforms may be received (e.g. wirelessly)
at power on. When the flexible device operates in a test or
diagnostic mode, test or electrical parameters (e.g. impedance,
injection current, voltage to reference electrode etc. of each
electrode) of each pixel unit or selected pixel unit(s) may be
accessed and sent out (e.g. wirelessly) to external devices.
[0052] In some embodiments, when the flexible device is switched to
neuron identification mode, test or diagnostic commands may be
received to apply testing stimuli to determine interface neuron
characteristics. For example, electrodes may by using the
oversampling technique as described above to electrically stimulate
the neurons (repeated several times) and send sensed signals to
external components or devices for processing. As a result, the
types of neuron cells interfaced to each electrode can be
identified. In certain embodiments, the flexible device may operate
in an external assist mode to wirelessly receive parameters (e.g.
for generating stimuli) continuously from an external camera or
glasses which processes incoming images via processing operations
requiring significant processing resources (e.g. using
sophisticated algorithms to supplement any lost retinal neural
network functions to the implanted chip, identify potential
hazardous hindrance objects and send signal to the implanted chip
to highlight the objects, or zonal gain controls to the implanted
chip for high dynamic range scenes).
[0053] FIGS. 1A-1B are block diagrams illustrating embodiments of
integrated flexible devices for retina prosthesis. Device 100A of
FIG. 1 may include a two dimensional array of pixel units. Each
pixel unit may include similar structures. For example, pixel unit
107 may comprise a photo sensor 101 to receive incoming light,
processing circuitry 105 to perform operations, and electrode 103
to stimulate target neuron cells to allow perception of vision
projected by the incoming light. In one embodiment, processing
circuitry 105 may include digital, analog or other applicable
circuits to process sensed light from photo sensor 101 for
generating a stimulus or waveform, activation patterns, etc. to
drive electrode 103 to stimulate the targeted neuron cells.
[0054] Alternatively, device 100B of FIG. 1B may include pixel unit
109 comprising photo sensors 111, electrode 113 and circuitry 115.
Electrode 113 may interface with target neuron cells to deliver
stimulus to and/or sense electric activities from targeted neuron
cells. The stimulus may be derived from light captured by photo
sensor 111. In one embodiment, circuitry 115 may provide processing
(e.g. signal processing) functions for receiving, processing,
and/or driving electric signals. For example, electric signals may
be received via sensed light from photo sensor 111 or sensed
electrical fields from electrode 113. Circuitry 115 may drive
stimulus as electric signals via electrode 113.
[0055] The incorporation of electrical sensing circuit 115 in the
retinal prosthesis chip device 100B may enable automatic type
identification of neuron cells through sensed receptive field (e.g.
electrical field) and neuron spiking patterns in time domain.
Examples may be functional asymmetries in ON and OFF ganglion cells
of primate retina that receptive fields of ON cells is 20% larger
than those of OFF cells, resulting in higher full-field
sensitivity, and that On cells have .about.20% faster response
kinetics than OFF cells. A large array of cell-sized micro
electrodes conforming to the retina and capable of both sensing and
stimulating may allow selective stimulating or suppress ON and OFF
retina retinal ganglion cells.
[0056] FIGS. 2A-2B are relationship diagrams illustrating effects
of flexible devices which are curved according to one embodiment of
the present invention. Typically, image resolution and required
driving power (e.g. threshold current density) of a retina
prosthesis device may depend on curvature of the device. In one
embodiment, a flexible integrated device for retina prosthesis may
include cell-pitched electrode array (e.g. each electrode is about
the size of a single neuron cell) fabricated by planar IC
lithography technology. FIG. 2A shows distribution diagram 200A of
neuron-to-electrode distances for implementing an mm-sized planner
electrode array chip in contact with a retina curved according to a
human eye ball, which is roughly spherical with an average diameter
of 25 mm.
[0057] As shown in distribution diagram 200A, an mm-sized planar
electrode array chip 203 in contact with the retina 201 at the chip
center may quickly separate from the retina by about 90 microns at
distance 1.5 mm from the center toward the edge of the chip. This
increase of neuron-to-electrode distance can imply, for example,
increase in the threshold current needed for an electrode to
depolarize target neurons. As shown in relationship diagram 200B of
FIG. 2B, the increase in the threshold current required can be
1.about.2 orders in magnitude according to curve 205. Additionally,
the increase of neuron-to-electrode distance may reduce the
resolution to depolarize particular neurons since the field lines
and electrical currents (e.g. for sending stimulus signals) from
the electrodes may spread out with distance and cover a large area
to reach distant neurons. In one embodiment, a flexible integrated
device of the present invention may be implanted without the
distance or separate implications shown in FIGS. 2A and 2B.
[0058] FIG. 3 is a schematic diagram illustrating an exemplary
device with perforation holes according to one embodiment of the
present invention. Device 300 may be flexible in multiple
dimensions to curve with at least about a curvature of average
human eye ball (e.g. 25 mm in diameter). In one embodiment, device
300 may include multiple hexagonally packed modules with boundaries
between adjacent modules perforated with perforation holes.
[0059] Each module, such as module 301, may include a group of
pixel units in a partition of a device. The partition may be
fabricated in a hexagonal shape, rectangular shape, circular shape
or other applicable shapes. In one embodiment, perforation holes
may allow fluid to exchange between different surfaces of device
300. Boundaries between adjacent modules, such as boundary 303 may
include metal trance (or other conductive trance or conductive
lines) as signal lines for the adjacent modules to directly
communicate with each other. Metal trances may provide power
distribution among the modules. Perforation can maintain some
fluidic flow between tissues of both sides of the device (e.g.
implanted within the tissues) through the perforation holes. The
complete removal of integrated circuit material (e.g. silicon)
except metal lines along the boundaries can increase the
moldability of the device.
[0060] FIGS. 4A-4B are block diagrams illustrating cross sectional
views of flexible devices in one embodiment of the present
invention. Cross section 400A of FIG. 4A may indicate a flexible
integrated device having multiple pixel units 417, 419, 421, 425
with layered structures, such as silicon layer 407, oxide layer 409
or biocompatible layers including polymer 401 and parylene 415.
Unit 417 may include transistors 403, photo sensor 405 in silicon
layer 407 and electrode 413 coupled with circuitry (e.g. including
transistors 403) via aluminum 411. Perforation hole 403 may be
formed across the device along a boundary between adjacent modules.
For example, units 417, 419 may be grouped in one module adjacent
to a separate module including units 421, 425.
[0061] Cross section 400B may indicate a cross sectional view
between adjacent modules (or pixel units) of a flexible integrated
device with a cutting plane across a boundary of the modules
without cutting through perforation holes. Passivated metal lines
or other flexible, conductive lines, such as metal wire 423, can
run across the boundary (e.g. between the perforations holes) to
bring electrical signals from unit to unit.
[0062] FIGS. 5A-5J are block diagrams illustrating a sequence of
fabrication processes for flexible devices in one embodiment of the
present invention. In one embodiment, CMOS and integration of photo
sensors with electrode arrays in structure 500A of FIG. 5A may be
fabricated using a standard or slightly modified CMOS technology or
a CMOS image sensor (CIS) technology on silicon wafer. Preferably,
the silicon wafer may comprise an SOI (Silicon On Insulator) wafer
with a silicon epitaxial layer a few micrometers in thickness. A PN
junction diode may be used via the modified CMOS technology as a
photo sensor. Alternatively, photo sensors with optimized doping
profiles may be used via the CIS technology. In certain
embodiments, CMOS-compatible conducting films such as TiNi might be
deposited on top of electrode layers (e.g. aluminum 511) before
patterning electrodes. The electrodes may be exposed in the final
pad opening step of a conventional CMOS process.
[0063] In one embodiment, structure 500A of FIG. 5A may comprise
layered structures for a flexible integrated device including
transistors 505, photo sensor 507, aluminum 511 for pixel unit 513
over silicon layer 503, oxide/metal layers 509, and Si substrate
501. Structure 500A may include pixel units 515, 517, 519 having
similar components as in pixel unit 513. Structure 500A may have a
front side (or front surface, transistor side) 537 and a back side
535 opposite to the front side 537. Front side 537 may correspond
to the chip surface of a wafer or a silicon chip.
[0064] Subsequently, as shown in FIG. 5B, the front surface of a
layered structure may be passivated by adhesion/barrier thin films
based on, for example, SiC or DLC (Diamond-Like-Carbon) material or
layers. In one embodiment, structure 500B of FIG. 5B may include
barrier layer 525 as a result of the passivation. The
adhesive/barrier thin films may cover already opened pad and
electrode areas for a flexible integrated device, for example, at
the final step of a CMOS process.
[0065] After the passivation process, pad and electrode areas may
be reopened by photolithography and etching with a smaller pad size
and electrode size than previously opened ones via, for example, a
CMOS process. As a result, the exposed side walls surround the pads
and electrodes may be protected by the adhesive/barrier layer
deposited during the passivation process. The exposed side walls,
if not protected or covered, may expose materials of the standard
CMOS passivation layers such as PECVD (Plasma-Enhanced Chemical
Vapor Deposition) silicon dioxides and silicon nitrides.
[0066] In one embodiment, a metal electrode, such as aluminum 511,
may be covered by another layer of metallization (IrOx, Pt, TiN,
FeOx etc.), such as electrode 521, for a better
electrode-to-electrolyte interface. Afterwards, a biocompatible
polymer deposition, such as biocompatible polymer (I) 523, may be
applied over a barrier layer, such as barrier layer 525. The
biocompatible polymer may be based on Polyimide, PDMS
(Polydimethylsiloxane), Parylene, or other applicable biocompatible
material. In one embodiment, the biocompatible material may be
selected according to standards specified via ISO 10993 standard.
After applying the biocompatible layer, in one embodiment, a first
handle wafer may be bonded to the front side of the device wafer,
such as handle substrate (I) 525 in FIG. 5C. Structure 500C may be
ready for thinning treatment from the back side. In some
embodiments, electrodes can be opened right after the biocompatible
polymer layer, such as biocompatible polymer (I) 523, is
deposited.
[0067] Turning now to FIG. 5D, silicon substrate of a device wafer,
such as substrate 501 of FIG. 5C, can by thinned down to a proper
thickness by a combination of lapping and chemical etching steps.
After bonding to the carrier substrate, such as handle substrate
(I) 525 of FIG. 5C, the Si wafer substrate, such as substrate 501,
may then be mechanically thinned to a thickness of about 50
micrometers or other proper thickness size by a wafer lapping
machine. The resulting surface may include micro-crack damages
induced during the lapping process. In one embodiment, a silicon
chemical etching process, such as SF6 plasma etching, dry XeF2
etching, or other applicable etching processes, may be applied to a
controlled thickness to remove these damages. Alternatively,
etching over a substrate using SOI may stop at the buried oxide
layer as etching stop. Typically, the thickness may be controlled
to be from several microns to several tens of microns such that the
photo sensors can effectively absorb photons through the thickness
and the substrate is still bendable to the desirable curvature.
Structure 500D of FIG. 5D may include a wafer substrate which has
been substantially thinned down via the thinning process.
[0068] Turning now to FIG. 5E, adhesion/barrier thin films may be
deposited on a polished and/or etched surface after the thinning
process. For example, barrier layer 527 may be deposited over the
back side of structure 500E of FIG. 5E. Subsequently, perforation
holes (or via holes) between device front and back surfaces may be
patterned and opened by, for example, lithography and RIE (Reactive
Ion Etching) processes or other applicable processes. For example,
structure 500F of FIG. 5F may include perforation hole 531. In some
embodiment, edges of a flexible device may be similarly opened as
shown in open 539 of FIG. 5F.
[0069] Turning now to FIG. 5G, a polymer layer may be further
etched through to a handle substrate for perforation holes. For
example, structure 500G may include perforation hole 531 etched
through biocompatible polymer (I) 523 to handle substrate (I) 525.
Subsequently, a second biocompatible polymer layer may be deposited
and patterned to open up the perforation holes. For example,
biocompatible polymer (II) 529 may be deposited over the backside
of structure 500G and opened for perforation hole 531. Two
biocompatible layers may seal together to wrap around a device as
similarly shown in seal 535 of FIG. 5G.
[0070] Subsequently, a second handle substrate may be bonded to a
device on the opposite side of a first handle substrate which has
already been boned to the device. The first handle substrate may be
removed from the device. For example, structure 500H of FIG. 5H may
include a newly bonded handle substrate (II) 533 over the back side
with the first handle substrate, such as handle substrate (I) 525,
removed from the front side.
[0071] After removing a handle substrate from the front surface,
electrodes may be exposed by applying lithography and RIE process
or other applicable processes. For example, structure 5001 of FIG.
5I may include an opening through biocompatible polymer (I) 523 for
electrode 521 on the front side. In one embodiment, an electrode
may include an optional dielectric layer, such as dielectric 535 of
FIG. 5I. Finally, a second handle wafer may be removed to complete
the fabrication process of a flexible integrated device. For
example, structure 500J of FIG. 5J may represent a flexible
integrated device without a second handle substrate, such as handle
substrate (II) 533 of FIG. 5I. FIGS. 5.1A-5.1F are block diagrams
illustrating a sequence of fabrication processes for flexible
devices in another embodiment of the invention.
[0072] FIGS. 6A-6D are block diagrams illustrating exemplary
layered structures of flexible devices for different approaches to
implant retina prosthesis. In one embodiment, a flexible integrated
device for retina prosthesis can include a thin substrate to allow
a portion of light to penetrate through the device (or chip) when
not obstructed by metals. Thus, the monolithic chip can to be used
for epi-retinal prosthesis even when the photo sensors and
electrodes are fabricated on the same side (e.g. either the front
side or the back side of the device).
[0073] For example, device 600A of FIG. 6A may include photo sensor
607 and electrode 615 fabricated on the front side (or transistor
side) of the device. Device 600A may be implanted in an epi-retinal
manner with light 623 coming from the back side of the device. In
one embodiment, electrodes and photo sensors of device 600A may
face the side towards retina ganglion cells 621. Device 600A may
include layered structures including silicon 603 having
transistors/sensors 605, oxide layers 609, guard 611 (e.g. for
guard rings), aluminum 613 and optional tissue glue 617 for
electrode 615, biocompatible polymer 601 wrapping the device and
perforation hole 619 opened through the device.
[0074] In one embodiment, device 600A may include thin silicon
substrate about less than 10 micrometers to allow more than a few
percents of light coming from the back side of the device to reach
the photo sensors as optical decay length of visible light may be a
few microns in silicon. Thin silicon substrate may be based on
fabrication processes using SOI (silicon on insulator) wafers or
thinning a silicon wafer down after the MOS process.
[0075] Turning now to FIG. 6B, device 600B may include similar
layered structures as in device 600A of FIG. 6A. In one embodiment,
device 600B may be implanted in a sub-retinal manner with light 649
coming from the front side of the device. Electrodes and photo
sensors of device 600B may face the side towards retina bipolar
cells 625.
[0076] In an alternative embodiment as shown in FIG. 6C, device
600C may include photo sensor 633 on the front side and electrode
637 on the back side of the device. Advantageously, electrodes in
device 600C will not block incoming light to photo sensors. In one
embodiment, device 600C may be implanted in an epi retina manner
with light 647 coming from the front side and electrodes facing
retina ganglion cells 645 on the back side. Device 600C may include
layered structures having silicon 629 with transistors/sensors 631,
oxide layer 627, optional tissue glue 643 for electrode 637,
biocompatible polymer 635 wrapping the device and perforation hole
641 across the front and back surfaces of the device. Electrode 637
may be coupled with processing circuitry including, for example,
transistors 631, based on conducting vias, such as TSV (through
silicon via) in aluminum 639.
[0077] Alternatively, in FIG. 6D, device 600D may include similar
layered structures as in device 600C of FIG. 6C. Device 600D may be
implanted in a sub-retinal manner with light 653 coming from the
back side of the device. Electrodes of device 600D may face the
side towards retina bipolar cells 651.
[0078] FIGS. 7A-7B are block diagrams illustrating guard rings to
confine electric flows in exemplary embodiments of the present
invention. Device 700A of FIG. 7A may include electrodes fitted
with local return paths, or "guard ring" to confine electric flow
from the electrodes. In one embodiment, device 700A may be an
flexible integrated device with layered structures including
silicon 707 having transistors 709 and photo sensor 711, oxide
layers 719, electrode 715 over aluminum 717, and biocompatible
polymer layers 701, 703 wrapping around the device over
barrier/adhesive layer 705. Device 700A may be implanted within
tissue 721 in a current driving mode. For example, current 723 from
electrode 715 may follow the lowest impedance path. Device 700A may
include guard 713 as guard ring (or local return electrode) to
provide a local return path guiding current 723 from undesired
target directions.
[0079] Similarly in FIG. 7B, device 700B may operate in a voltage
driving mode with electric field 727 from electrode 715 confined
via guard 713. Device 700B may include optional dielectric 725 for
electrode 715.
[0080] Preferably, electric fields or electrical currents can be
confined (or made smaller, narrower) locally close to originating
electrodes through guard rings. Thus, unwanted stimulation of
sensory cells other than target neurons of each electrode, such as
stimulating the bipolar cells without exciting the ganglion cells,
may be prevented. As a result, a flexible integrated device with
guard rings may not need extra return electrodes. Electro fields
from one electrode may not interfere with other electro fields from
separate electrodes using guard rings. Optionally, guard rings
providing limited return paths (e.g. 30 micron in length) may allow
electrodes to target (or select) different layers of neuron cells
(e.g. within 200-250 micron thickness of a retina).
[0081] FIG. 8 is a block diagram illustrating layered structures
for flexible devices with protruding electrodes in one embodiment
of the present invention. For example, device 800 may comprise
flexible and integrated chip with protruding electrode arrays.
Device 800 may include layered structures having barrier layer 805,
metal/dielectric layers 807, silicon with active components 809,
and polymer 811 wrapping the device with the polymer 813. Electrode
803 may be elevated with a protruding tip in close proximity with
target neuron cell 801. Preferably, when implanted, elevated
stimulus electrodes can push through some of separation layers of
tissues to be in closer proximity to the target locations of
stimulation. Thus, the required threshold current or power to
depolarize the target neurons may be reduced to enable higher
number of electrodes with finer resolution.
[0082] FIG. 9 is a block diagram illustrating layered structures in
flexible devices with multi-level electrodes in one embodiment of
the present invention. For example, device 900 may comprise
flexible and integrated chip with arrays of electrode protruding in
multi-levels. Device 900 may include layered structures having
barrier layer 905, metal/dielectric layers 907, silicon with active
components 909, and polymer 913 wrapping the device with the
polymer 911. Electrodes 917, 903 may be positioned in two different
levels to separately stimulate neuron cells 901, 915.
[0083] In one embodiment, multiple-level protruding electrodes,
such as electrodes 917, 903, may differentially stimulate different
strata in different types of neuron cells (e.g. ON type cells, OFF
type cells, or other applicable types of cells). For example,
multiple-level protruding electrodes may separately target neurons
ON-pathway and OFF-pathway as retina connections between bipolar
cells and ganglion cells separated into two different levels of
strata. The depolarizing bipolar cells may contact the On-center
ganglion cells. The dendrites of these On-center ganglion cells may
extend mainly into the lower part of the inner plexiform layer. The
hyperpolarizing bipolar cells may contact the OFF-center ganglion
cells. The dendrites of the OFF-center ganglion cells may run
predominately in the upper part of the inner plexiform layer.
[0084] FIGS. 10A-10B are schematic diagrams illustrating exemplary
signal processing circuitry in flexible devices according to one
embodiment of the present invention. Device 1000A of FIG. 10A may
include pixel unit 1005 coupled with neighboring pixel units 1001,
1003, 1007, 1009 in a two dimensional pixel unit array. Pixel unit
1005 may be indexed by (m, n) in the two dimensional pixel unit
array to receive incoming light at time t represented by I(m, n,
t). Each pixel unit may exchange information on received light with
neighboring units (or other applicable pixel units).
[0085] In one embodiment, each pixel unit may include signal
processing circuitry to receive inputs from neighboring pixel
units. For example, referring to FIG. 10A, signals I(m, n+1,t),
I(m-1, n, t), I(m, n-1, t), and I(m+1, n, t) representing light
received or sensed from neighboring pixel units 1001, 1003, 1007,
1009 may be available to pixel unit 1005. The arrangement of pixel
units may be based on rectangular, hexagonal (e.g. with each pixel
unit having six closes neighbor pixel units), or other applicable
two dimensional or multi-dimensional array.
[0086] In certain embodiments, a flexible integrated device may
include signal processing circuitry capable of simulating neuron
network processing mechanisms similar to the center/surround
antagonism receptive field of neurons. For example, a pixel unit
may generate a pixel current output (or a stimulus) proportional to
the difference of the sum of center pixel light intensity and the
averaged sum of surround light intensity on its neighbors to excite
proper RGC spiking. In general, a pixel unit may use different
weights to sum over inputs from local coupled neighboring pixel
units, such as those closest neighbors, second closest neighbors,
third closest neighbors, etc. to derive a processed signal derived
from captured light for generating a stimulus.
[0087] For example, circuitry 1000B of FIG. 1000B may include a
processing element 1015 generating a weighted output Id(m, n) 1017
from sensed signal inputs 1019 separately weighted through weigh
settings 1011, 1013 (e.g. resistor components). In one embodiment,
pixel unit 1005 of FIG. 10A may include circuitryl000B for signal
processing. Four of sensed signals I(m-1,n), I(m+1,n), I(m, n-1),
I(m, n+1) 1019 (e.g. inputs from neighboring pixel units) may be
weighted with equal weights of 1/4 of sensed signal I(m, n) via
resistor components, such as R 1013 and R/4 1011. In some
embodiments, weights may be set (e.g. dynamically configured) to
about zero (e.g. equivalent to disconnecting from corresponding
neighboring pixel units) for a majority of neighboring pixel units
except for those pixel units at metering locations to reduce effect
of background absolute light intensity in a similar manner as
multi-point metering used in digital cameras. In some embodiments,
signal subtraction may be applied in processing signals exchanged
from neighboring pixels units to generate stimuli based on relative
intensity of incoming light instead of absolute intensity.
[0088] FIG. 10C is a schematic diagram illustrating an exemplary
configuration of pixel units for processing signals according to
one embodiment of the present invention. Array 1000C may include
multiple pixel units, such as PU 1061, arranged with a geometric
relationship in a two (or more) dimensional manner. Each pixel unit
may include components of pixel unit 107 of FIG. 1A or pixel unit
109 of FIG. 1B. PU 1061 may be positioned with layers of
neighboring pixel units, such as layer 1099, layer 10101. An
immediate (or closest) layer (or group) of neighboring pixel units
of PU 1061 may include layer 1099 having PU 1063-PU 1073. Layer
10101 may include pixel units PU 1075-PU 1097. Distance between
(immediate) neighboring pixel units, such as PU 1061 and PU 1067,
may be around tens of micrometers (e.g. 30 .mu.m). Stimuli signals
generated by PU 1061 may be based on weighted sum of light signals
received (e.g. inputs) via neighboring pixel units in layer 1099
and layer 10101 or more neighboring layers. For example, each layer
of pixel units may be configured with a separate weight (such as
using the Laplacian of Gaussian Algorithm).
[0089] FIG. 10D is a block diagram illustrating a flexible device
wirelessly configured via an external device according to one
embodiment of the present invention. Flexible device 1019 may be
based on, for example, device 100A of FIG. 1A or device 100B of
FIG. 1B. In one embodiment, flexible device 1019 may be wirelessly
coupled with external processing device 1053 via wireless path (or
link) 1047. Commands/data may be transmitted over path 1047 between
flexible device 1019 and external device 1053, for example, to
configure, test or perform special (e.g. management, debugging,
etc.) operations on flexible device 1019.
[0090] According to some embodiments, flexible device 1019 may
include pixel unit array 1021, control circuitry 1029 and inductive
coil 1045. External device 1053 may include inductive coil 1049 as
primary coil when coupled (e.g. magnetically) with a secondary coil
such as inductive coil 1045. Flexible device 1019 may draw power
from implant device power source of external device 1053 via
wireless path 1047 established between coils 1045, 1049. Flexible
device 1019 may sense light input from image 1057 to generate
stimuli driving load 1059, such as neuron cells to enable visual
perception. Here for exemplifying purpose, the inductive coils are
used for both transmitting power and transmitting data (for
example, using ASK amplitude--shift keying or FSK frequency-shift
keying), although two sets of inductive coils maybe optimized
separately and used for transmitting power or transmitting
data.
[0091] External device may include implant device power source,
signal/data processor (e.g. microprocessors or other applicable
processors), storage components (e.g. volatile or non-volatile
memories) for storing parameters, for example, to configure pixel
unit array 1021. External device 1053 and implant device power
source may be powered via power source 1051, such as battery, solar
power converter or other applicable power source. Parameters values
to configure flexible device 1019 may be received from array
parameter input 1055 and/or generated/computed via data
processors.
[0092] In one embodiment, pixel unit array 1021 includes sensor
array 1023, processing circuitry 1025 and electrode array 1027,
based on, for example, pixel unit 107 or pixel unit 109 of FIGS.
1A, 1B. Sensor array 1023 may include photo diodes to detect
incoming light signals. Processing circuitry 1025 may be based on
mixed-signal analog and digital processing mechanism with
configurable parameters according to geometric or topologic
arrangements in the array of pixel units. For example, processing
circuitry 1025 may include tunable waveform shaping circuitry to
provide varied amounts of stimuli according to, for example,
characteristics of waveform (e.g. amplitude, frequency, gain,
durations, shapes etc..) or stimulus sequence generated. Processing
circuitry may include different modes of operations switchable via
control circuitry 1029. In some embodiments, when powered on,
control circuitry 1029 may automatically reconfigure pixel unit
array 1021 with a set of previously stored array parameters (e.g.
locally stored or wirelessly retrieved).
[0093] Control circuitry 1029 can include pixel interface circuitry
1031, power manager 1037 and wireless interface circuitry 1039.
Power manager 1037 can include low-drop out regulator LDO, multiple
voltage generation circuits etc. In one embodiment, power manager
1037 may draw power wirelessly via path 1047. External commands may
be received via wireless interface circuitry 1039 to access (e.g.
load, retrieve, read, sense or configure etc.) pixel unit array
1021 via pixel interface circuitry 1031. For example, wireless
interface circuitry 1039 may include transceiver 1043 to establish
wireless link and/or communications via wireless path 1047.
Transceiver 1043 may embed lightweight message protocol to enable
messages communication to wireles sly exchange data/commands. The
interface circuitry 1039 may also generate clock signals for
internal random logic operations.
[0094] Command/data handler logic 1041 may interpret received
commands and perform operations accordingly. For example,
command/data handler logic 1041 may identify a mode in a mode
switch command received via transceiver 1043 to cause pixel unit
array 1021 to change its mode of operation via pixel interface
circuitry 1031. Command/data handler logic 1041 may extract
parameter values carried via received commands or instructions. The
extracted parameter values may be loaded to targeted pixel units of
pixel unit array 1021 according to array element selection logic
1033.
[0095] In some embodiments, testing or diagnostic commands may be
received to send stimulus signals to selected pixel units for
identify load or neuron characteristics to adjust array parameters
in pixel unit array 1021. Command/data handler logic 1041 may
deliver the stimulus instructed by the test commands to the select
pixel units. Sensing circuitry 1035 may capture sensed responses
via participating electrodes (e.g. in sensing mode) in electrode
array 1027. Command/data handler logic 1041 may send out data
carrying the sensed responses of targeted loads via transceiver
1043.
[0096] FIG. 10E is a schematic diagram illustrating another example
of a signal processing circuitry in flexible devices. For example,
circuit 1000E may include components of processing circuitry 1025
of FIG. 10D. In one embodiment, circuit 1000E may include
processing elements configured or wired (e.g. prewired, hardwired,
dynamically wired) with algorithms implemented based on operations
either in voltage mode or in current mode. For example, the
algorithms may include Laplacian algorithm for weighted summing of
signals.
[0097] In one embodiment, pixel current summing circuit 10115 may
receive pixel light intensity 10111 to drive load 10119 coupled
with pixel current summing circuit 10115. Pixel light intensity
10111 sensed by a pixel can be converted into mirrored current
10129 based on the amplitude of a current via, for example, current
mirror circuit 10127. Pixel current summing circuit 10115 may
receive weighted currents 10113 from neighboring pixels based on
weighting the current amplitudes from the neighboring pixels.
Mirrored current 10129 and weighted currents 10113 may be coupled
to load 10119. In one embodiment, the difference of mirrored
current 10129 and weighted currents 10113 can be fed into load
10119 based on the current polarity. This current may flow through
counter electrode 10121 back to the internal ground. Current flows
to load 10119 and reset 10117 can be controlled by switches timed
by switch timers 10123, 10125.
[0098] FIGS. 11A-11B are block diagrams illustrating operations of
configured flexible devices in one embodiment of the present
invention. For example, flexible integrated device 1133 may be
configurable to provide portions of functionality identified from
neuron cells, such as retinal ganglion cells 1105 and/or neural
cell networks 1107, to reestablish damaged or deteriorated vision
perception. Neural cell networks 1107 may include neuron cells such
as horizontal cells, bipolar cells, amacrine cells or other retina
cells etc. Device 1133 may include processing circuitry 1101
coupled with micro electrode array 1103 capable of sending stimuli
to and/or sensing responses from neuron cells.
[0099] In one embodiment, device 1133 may be configurable when
operating in a calibration/programming mode. Device 1133 may
operate in other modes such as a normal mode to stimulate neuron
cells from incoming light to enable vision perception. In some
embodiments, during a calibration/programming mode, processing
circuitry 1101 may switch between a sensing mode and a driving mode
to identify and configure processing characteristics (e.g. via a
programmable logic array or other applicable programmable
circuitry) such that proper stimuli can be generated for desired
sensory output O(pi, qi) 1115 from incoming light I(xi, yi) 1111
(e.g. generated light) when a portion of the neuron cells are
unable to function properly (e.g. damaged, decayed, deteriorated
etc.)
[0100] For example, processing circuitry 1101 may enter a sensory
mode right after sending stimulus from incoming light I(xi, yi)
1111 to normal working or relatively healthy neuron cells to
produce sensory output O(pi, qi) 1115. In some embodiments, light
I(xi, yi) 1111 may be generated to optically select and configure a
portion (e.g. a pixel unit or a group of pixel units) of device
1133. Processing circuitry 1101 in the sensing mode may be capable
of detecting responses from the neuron cells, such as retinal
ganglion cells 1105. The responses may be voltages, waveforms or
other applicable signals or spikes over a period of time to
represent sensory output O(pi, qi) 1115. Processing circuitry 1101
may store information including relationship between incoming light
and the corresponding responses detected. The information may
represent inherent processing characteristics H(pi, qj, xi, yi)
1135 in neuron cells, for example, based on the relationship
indicated by the expression O=H*I.
[0101] Subsequently, as shown in FIG. 11B, processing circuitry
1101 may be configured to perform operations to make up for lost or
altered visual information processing capabilities of neuron cells.
For example, photoreceptive cells 1109 may be damaged or bleached
to block neural cell networks 1107 from processing sensed light
signals. As a result, visual perception may be based on processing
characteristics G'(pi, qj, x'i, y'j) 1135 of retinal ganglion cells
1105.
[0102] In one embodiment, processing circuitry 1101 may be
configured (e.g. automatically or manually) to perform operation
(or transform operation) H'(x'i, y'j, xi, yj). For example, stimuli
to retina ganglion cells 1105 may be generated in the configured
processing circuitry 1101 according to effective light input I'=H'
*I to allow perceived output O'(pi, qj) 1123 (e.g. corresponding to
a result of operations G'*I') to be close to O(pi,qj) 1115. In one
embodiment, H'(x'i, y'j, xi, yj) may be programmed based on
inherent processing characteristics H(pi, qj, xi, yj). Processing
circuitry 1101 may operate in a driving mode to configure the
processing capabilities. Device 1133 may operate in a normal mode
of operation, or in a calibration mode of operation for further
fine tuning or adjustment of the configured processing
capabilities.
[0103] In one embodiment, processing circuitry may incorporate
electrical sensing circuitry to enable measurement of retina neuron
response kinetics during a calibration mode, for example, when
device 1133 is implanted in an epi-retina manner. With the ability
to switch the device (or chip) to electrical sensing right after
electrical stimulation, the ON cells and OFF cells can be
identified through the response time, and this information can be
used to formulate the specific electrical stimulus from the nearby
electrode when local light information is sensed by photo sensors
on the device.
[0104] FIG. 12 is a block diagram illustrating a system to
configure flexible devices in one embodiment of the present
invention. System 1200 may include configurable retinal prosthesis
device 1133 with on-chip processing circuitry 1101 optically or
wireles sly coupled with external or remote control device 1201 to
provide a control or feedback path for tuning/adjusting
configurable device 1133. In one embodiment, processing circuit
1101 and electrode array 1103 may include electrical parameters or
settings which can be self configured or externally updated (e.g.
via external commands). For example, characteristics of system
1200, such as light sensitivity, stimulus intensity, or other
applicable parameters may be changed to achieve desired visual
perception via these settings. Alternatively or optionally,
configurable device 1133 may include a configuration for generating
stimuli from incoming light captured. In one embodiment, a patient
may operate remote control 1201 via user control 1207 based on
perceived visions in visual cortex 1205.
[0105] In some embodiments, external commands 1203 may be optical
commands included in optical inputs 1209 which may comprise
predetermined visual patterns. Alternatively, external commands
1203 may be wirelessly transmitted (e.g. based EM signals) to
device 1133 via wireless transceiver. Device 1133 may include
certain light sensing pixels together with special decoding circuit
on chip to detect special light pulse pattern from optical input
1203 to enter the chip into calibration mode for tuning/adjustment.
Alternatively, the external commands may wirelessly cause device
1133 to enter a calibration mode or other modes of operation.
[0106] In one embodiment, each pixel or regions of pixels of device
1133 may be separately accessed optically or wirelessly through
light projection (e.g. into the eye on the implanted region). The
pixel or regions can be electrically accessed on chip to tune
electrical stimulus parameters to achieve targeted effects of
visual sensation. In one embodiment, test patterns, e.g. via
optical input 1209, can be projected onto the implanted retina or
directly viewed by implanted patients. The targeted visual effects
may be described to the patients for conducting manual tuning on
parameters of implanted retina prosthesis chips using the external
optical input device to allow better approximation of the targeted
visual effects.
[0107] FIG. 13 is a flow diagram illustrating a method to configure
flexible devices in one embodiment described herein. Exemplary
process 1300 may be performed by a processing circuitry that may
comprise hardware (circuitry, dedicated logic, etc.), software
(such as machine code executed in a machine or processing device),
or a combination of both. For example, process 1300 may be
performed by some components of system 1200 of FIG. 12.
[0108] In one embodiment, the processing logic of process 1300 may
detect light patterns (e.g. predetermined or dynamically generated)
from received light via photo sensors at block 1301. The processing
logic of process 1300 may decode the captured light to extract the
light patterns optically encoded in the light. On detecting the
light patterns, the processing logic of process 1300 may cause a
device to enter a calibration mode for configuration. The device
may comprise an array of pixel units to receive light to enable
perception of a vision from the light. The pixel units are
configurable via electrical parameters.
[0109] At block 1303, in one embodiment, the processing logic of
process 1300 may receive light patterns to select one or more of an
array of pixel units in a flexible integrated device. The light
patterns may be associated with known effects of visual sensation.
For example, a patient implanted with the device may be aware of
which visual perception to be expected, such as the shape of the
image of light, the relative intensity of the image of light or
other visual effects. At block 1305, the processing logic of
process 1300 may generate stimuli from selected pixel units to
stimulate neuron cells to cause actual effect of visual sensation
similar to a normal person should experience with the light
patterns received. In some embodiments, the light patterns may
include selection light patterns to identify which pixel units
should be selected.
[0110] Subsequently, at block 1307, in one embodiment, the
processing logic of process 1300 may receive external commands to
update electrical parameters of a flexible integrated device. The
external commands may be optically or wirelessly received. The
processing logic of process 1300 may update the electrical
parameters to cause adjustment of actual effects of visual
sensation from the light patterns (or other applicable incoming
light) received via the selected pixel units updated with the
electrical parameters. The captured light (e.g. the light patterns)
may be associated with known visual effects. As a result of the
update, the actual effect of visual sensation may be adjusted to
match the known effects of visual sensation to proper configure the
device. In some embodiments, light patterns may be separately
generated for pixel selection and for electrical or circuitry
updates on the selected pixels.
[0111] FIG. 14 is a block diagram illustrating a system to
configure flexible devices in another embodiment of the present
invention. System 1400 may be based on configurable device 1133
including circuitry 1101 and electrode array 1103. In one
embodiment, configurable device 1133 can provide configurability
through switchable digital logics to vary its output stimulating
waveform to retinal neurons. Pixel calibration data can be stored
in external control device 1403, which may include wireless power
source, microprocessor, memory devices and external data interface.
External control device 1403 may send wireless commands 1403, for
example, to configure configurable device 1133.
[0112] In one embodiment, pixel calibration data can be
periodically updated from external control device 1403 to
configurable device 1133, for example, based on visual examination
on a user. These data may be uploaded wirelessly to registers of
implanted configurable device 1133 at its "power on" (e.g. when the
device is switched on) so the implanted configurable device 1133
doesn't require the integration of a non-volatile memory or other
memory devices associated with a processor logic (such as a
microprocessor).
[0113] FIG. 15 is a perspective diagram illustrating an exemplary
configuration of a flexible retina device coupled with a control
device. Configuration 1500 may be based on flexible chip 1501
including configurable device 1133. External control device 1403
and primary coil 1509 may be embedded in a wearable fixture, such
as a pair of eyeglass. Flexible chip 1501 coupled with secondary
coil 1505 via flex cable 1503 may be implanted in eyeball 1507. A
wireless link may be established between external control device
1403 and flexible chip 1501 via primary coil 1509 and secondary
coil 1505, for example, to transport wireless commands and/or power
from external control device 1403 to circuitry in flexible chip
1501.
[0114] FIG. 16 is a flow diagram illustrating another method to
configure flexible devices in one embodiment described herein.
Exemplary process 1600 may be performed by a processing circuitry
that may comprise hardware (circuitry, dedicated logic, etc.),
software (such as machine code executed in a machine or processing
device), or a combination of both. For example, process 1600 may be
performed by some components of system 1000D of FIG. 10D or system
1400 of FIG. 14.
[0115] In one embodiment, the processing logic of process 1600 may
detect diagnostic (or test) commands from waveforms received at an
interface of a device at block 1601. The interface may include a
wireless transceiver, such as transceiver 1043 of FIG. 10D. The
device may comprise an array of pixel units to receive light to
stimulate neuron cells to cause an effect of visual sensation from
the light. The pixel units can have configurable parameters for the
stimulation to the neuron cells. In certain embodiments, the
interface may be based on wireless signals (e.g. waveforms) which
may carry power to wirelessly power the device. The diagnostic
commands can be embedded within the wireless signals.
[0116] For example, the pixel units can deliver stimuli from an
optical input to the neuron cells. The stimuli can cause known
visual sensation via a network of neuron cells. The adjustable
components may be configured to allow the pixel units to generate
updated stimuli from the optical input to cause the known visual
sensation without requiring the presence or the working of the
network of neuron cells.
[0117] At block 1603, the processing logic of process 1600 may send
data related to electric characteristics of the neuron cells via
the wireless interface according to the diagnostic commands
received. For example, the processing logic of process 1600 can
detect mode change commands from the wireless signals at the
interface. The mode change commands may be processed, e.g. via
wireless interface circuitry 1039 of FIG. 10D, to cause the device
to enter a particular mode, such as a neuron identification mode, a
test mode, a calibration mode or other applicable mode (e.g. from
an operating more or regular usage mode). In one embodiment, the
diagnostic commands may be received in the neuron identification
mode to collect multiple samples (e.g. over sampling) of the
electrical characteristics (e.g. one sample for each sample of
sensed data). The electrical characteristics may be sensed via
electrodes (e.g. electrode array 1027 of FIG. 10D) in a sensing
mode for each sample data collected.
[0118] The processing logic of process 1600 can send multiple
samples of data carrying measurements (e.g. via sensing) of the
electrical characteristics of the neuron cells to an external
processing device, such as device 1053 of FIG. 10D. Different types
of the neuron cells or effective electric load may be determined
based on the electrical characteristics. Sophisticated data
processing operations may be performed on the data carrying sampled
electrical characteristics (e.g. in multiple samples) to derive
(e.g. removing background noises included in the sensed electrical
characteristics). At block 1605, the processing logic of process
1600 may detect configuration commands received at the interface
after sending data (e.g. in multiple samples) carrying electrical
characteristics of the neuron cells to the external processing
device.
[0119] At block 1607, the processing logic of process 1600 may
update the configurable parameters according to the configuration
commands detected. The processing logic of process 1600 can
generate the stimulation according to the updated configurable
parameters to improve the effect of visual sensation from the light
at block 1609.
[0120] In one embodiment, an implantable device, such as device
1501 of FIG. 15 or device 1019 of FIG. 10D, can interface with
retina cells for retina prosthesis. The device can comprise an
array of pixel units, such as pixel unit array 1021 of FIG. 10D,
capable of receiving light and stimulating the retina cells to
enable perception of received light. Each pixel unit can include an
electrode, an associated photo sensor and a processing circuitry.
The photo sensor can receive incoming light. The electrode can
stimulate targeted neuron cells. The processing circuitry may
generate a stimulus from the received light for the electrode to
deliver to the targeted neuron cells. The pixel units may include
adjustable components to accommodate different amounts of
stimulation to the retina cells.
[0121] A control circuitry of the device, such as control circuit
1029 of FIG. 10D, may be capable of configuring the adjustable
components for the pixel units. In one embodiment, the control
circuit can include a wireless interface circuitry, such as
wireless interface circuitry 1039 of FIG. 10D, and a pixel
interface circuitry, such as pixel interface circuitry 1031 of FIG.
10D. The wireless interface circuitry can allow external
communications to configure, calibrate, or test the pixel units or
device. The pixel interface circuitry can allow selective access to
the pixel units, for example, according to commands received from
external communication to an external processing device, such as
device 1053 of FIG. 10D.
[0122] The processing circuitry of the array of pixel units can
perform processing functions according to the adjustable components
updated by the parameter values for the configuration. For example,
photo sensors of the array of pixel units may be associated with
electrical parameters determined by the adjustable components.
Sensitivity of the photo sensors to the change of incoming light
may depend on the associated electrical parameters. In one
embodiment, the light (or incoming light) may include a background
light. The parameter values may be configured depending on the
background brightness to dynamically change the sensitivity of the
photo sensors to reduce effect of the absolute background light
intensity of the light.
[0123] In one embodiment, the pixel unit may be coupled with
neighboring pixel units in the array. An intensity signal from the
photo sensor may indicate received light. The pixel unit may
receive intensity signals from the neighboring pixel units to
perform signal processing operations on the intensity signals
directly received and/or indirectly received from the neighboring
pixel units. For example, a weighed combination of the intensity
signals may be performed to reduce the effect of absolute
background light intensity. The weight combination may depend on
weights configured according to the adjustable components.
[0124] Each pixel unit of an array of pixel units may be arranged
with one or more layers of neighboring pixel units in the array.
Each layer of neighboring pixel units may correspond to those pixel
units located within a predefined range of distances to the pixel
unit. A neighboring pixel unit may not belong to separate layers of
neighboring pixel units (i.e. non overlapping). The neighboring
pixel units from which the intensity signals are received for the
pixel unit may include multiple layers of neighboring pixel units.
In other words, multiple layers of neighboring pixel units may be
considered in deriving the stimulation signal of a pixel unit. Each
layer of pixel units may be defined according to similar inter unit
distance to this pixel unit.
[0125] In one embodiment the adjustable components of the pixel
units may be configured to adjust the amount of stimulation to the
retina cells without requiring a processor (e.g. processing logic
capable of executing instructions stored in a memory or storage
components) in the device. In one embodiment, the adjustable
components may be coupled with one or more registers to store the
parameter values for the configuration. Alternatively or
optionally, the adjustable components may include one or more
variable resistors whose resistances updated by the parameter
values as configured.
[0126] In some embodiments, configuration of the device can be
based on parameter values wirelessly received via external commands
received, for example, over a wireless communication. For example,
a wireless interface circuitry of the device can be coupled with an
induction coil to establish wireless link, such as link 1047 of
FIG. 10D. The wireless link may be established based on magnetic
induction mechanism, RF mechanism, or other applicable low power
wireless communication mechanisms. Data signals may be embedded
within the wireless link to carry external commands to the device.
The wireless link may be capable of carrying power from external
source, such as device 1053 of FIG. 10D, to drive the device.
[0127] In one embodiment, the device may include a decoding logic
to extract the external commands, such as configuration commands,
from the data signals. The control logic of the device may include
detection logic (e.g. in transceiver 1043 of FIG. 10D) to detect
arrival of the external commands wireles sly received to allow
continuous tuning of the adjustable components as the light
changes.
[0128] The external commands (e.g. configuration commands) received
can identify a portion of the array of pixel units to configure the
adjustable components with the parameter values for the identified
portion of the array of pixel units (i.e. without affecting other
portions of the array of pixel units). In certain embodiment, an
array of pixel units can be partitioned in to a plurality of two
dimensional zones. The identified portion of the array of pixel
units may correspond one of the zones to configure the parameter
values for each pixel unit of the identified zone.
[0129] In one embodiment, the pixel units may be selectively
accessed (e.g. via addresses received from external commands) to
load, retrieve or identify electrical parameters of one or more of
the pixel units. For example, request commands may be received at
the device via a wireless communication from an external device to
trigger or cause selective access of the pixel units. The request
commands may select (or address) one or more pixel units to
transmit electrical parameters of the selected pixel units to an
external processing device. Subsequently, parameter values
determined based on these electrical parameters may be received at
the device to configure the selected pixel units.
[0130] The array of pixel units may include one or more modes of
operations, such as a diagnostic mode (e.g. for detecting whether
the device has any defect), operating (or usage) mode, calibration
mode, assisted usage mode, neuron identification mode, or other
applicable modes. The array of pixel units may switch from one mode
to another mode (e.g. from a first mode to a second mode) based on
external commands received over a wireless communication.
[0131] In one embodiment, a device, such as device 1403 of FIG. 15,
to configure an array of pixel units of an implantable device can
include a driver logic to send commands wireles sly to the
implantable device, a memory to store executable instructions, a
sensor components (e.g. array of light sensors or other applicable
sensors) to detect environment status (e.g. background light
intensity) for the implantable device and a processing logic to
execute the instructions for configuring the implantable device. In
one embodiment, the implantable device may interface with retina
cells to cause visual sensation via light received via the pixel
units.
[0132] The driver logic may be coupled with a primary coil capable
of remotely coupling with the implantable device, for example, via
a secondary coil of the implantable device. A wireless link may be
established between the primary and secondary coils to carry
commands to configure the pixel units in the implantable device.
For example, the commands may include configuration settings stored
in the memory of the device for configuring the pixel units. In
some embodiments, the wireless link may carry power from the
primary coil to the secondary coil to power the implantable device
wirelessly. The configuration commands may be embedded in the
wireless link carrying the power.
[0133] In one embodiment, the processing logic may determine
parameter values for configuring the pixel units based on the
environmental status detected and the settings stored in the
memory. The processing logic may compose and send configuration
commands including the parameter settings determined to the
implantable device via the driver logic.
[0134] In the foregoing specification, the invention has been
described with reference to specific exemplary embodiments thereof.
It will be evident that various modifications may be made thereto
without departing from the broader spirit and scope of the
invention as set forth in the following claims. The specification
and drawings are, accordingly, to be regarded in an illustrative
sense rather than a restrictive sense.
* * * * *