Mar 16, 2022 06:43 PM
Stackable ‘holobricks’ can make giant 3D images
https://www.cam.ac.uk/research/news/stac...-3d-images
RELEASE: Researchers have developed a new method to display highly realistic holographic images using 'holobricks' that can be stacked together to generate large-scale holograms.
The researchers, from the University of Cambridge and Disney Research, developed a holobrick proof-of-concept, which can tile holograms together to form a large seamless 3D image. This is the first time this technology has been demonstrated and opens the door for scalable holographic 3D displays. The results are reported in the journal Light: Science & Applications.
As technology develops, people want high-quality visual experiences, from 2D high resolution TV to 3D holographic augmented or virtual reality, and large true 3D displays. These displays need to support a significant amount of data flow: for a 2D full HD display, the information data rate is about three gigabits per second (Gb/s), but a 3D display of the same resolution would require a rate of three terabits per second, which is not yet available.
Holographic displays can reconstruct high quality images for a real 3D visual perception. They are considered the ultimate display technology to connect the real and virtual worlds for immersive experiences.
"Delivering an adequate 3D experience using the current technology is a huge challenge," said Professor Daping Chu from Cambridge's Department of Engineering, who led the research. "Over the past ten years, we've been working with our industrial partners to develop holographic displays which allow the simultaneous realisation of large size and large field-of-view, which needs to be matched with a hologram with a large optical information content."
However, the information content of current holograms information is much greater than the display capabilities of current light engines, known as spatial light modulators, due to their limited space bandwidth product.
For 2D displays, it's standard practice to tile small size displays together to form one large display. The approach being explored here is similar, but for 3D displays, which has not been done before. "Joining pieces of 3D images together is not trivial, because the final image must be seen as seamless from all angles and all depths," said Chu, who is also Director of the Centre for Advanced Photonics and Electronics (CAPE). "Directly tiling 3D images in real space is just not possible."
To address this challenge, the researchers developed the holobrick unit, based on coarse integrated holographic displays for angularly tiled 3D images, a concept developed at CAPE with Disney Research about seven years ago. Each of the holobricks uses a high-information bandwidth spatial light modulator for information delivery in conjunction with coarse integrated optics, to form the angularly tiled 3D holograms with large viewing areas and fields of view.
Careful optical design makes sure the holographic fringe pattern fills the entire face of the holobrick, so that multiple holobricks can be seamlessly stacked to form a scalable spatially tiled holographic image 3D display, capable of both wide field-of-view angle and large size. The proof-of-concept developed by the researchers is made of two seamlessly tiled holobricks. Each full-colour brick is 1024×768 pixels, with a 40° field of view and 24 frames per second, to display tiled holograms for full 3D images.
"There are still many challenges ahead to make ultra-large 3D displays with wide viewing angles, such as a holographic 3D wall," said Chu. "We hope that this work can provide a promising way to tackle this issue based on the currently limited display capability of spatial light modulators."
A new brain-computer interface with a flexible backing
https://jacobsschool.ucsd.edu/news/release/3417
RELEASE: Engineering researchers have invented an advanced brain-computer interface with a flexible and moldable backing and penetrating microneedles. Adding a flexible backing to this kind of brain-computer interface allows the device to more evenly conform to the brain's complex curved surface and to more uniformly distribute the microneedles that pierce the cortex. The microneedles, which are 10 times thinner than the human hair, protrude from the flexible backing, penetrate the surface of the brain tissue without piercing surface venules, and record signals from nearby nerve cells evenly across a wide area of the cortex.
This novel brain-computer interface has thus far been tested in rodents. The details were published online on February 25 in the journal Advanced Functional Materials. This work is led by a team in the lab of electrical engineering professor Shadi Dayeh at the University of California San Diego, together with researchers at Boston University led by biomedical engineering professor Anna Devor.
This new brain-computer interface is on par with and outperforms the "Utah Array," which is the existing gold standard for brain-computer interfaces with penetrating microneedles. The Utah Array has been demonstrated to help stroke victims and people with spinal cord injury. People with implanted Utah Arrays are able to use their thoughts to control robotic limbs and other devices in order to restore some everyday activities such as moving objects.
The backing of the new brain-computer interface is flexible, conformable, and reconfigurable, while the Utah Array has a hard and inflexible backing. The flexibility and conformability of the backing of the novel microneedle-array favors closer contact between the brain and the electrodes, which allows for better and more uniform recording of the brain-activity signals. Working with rodents as model species, the researchers have demonstrated stable broadband recordings producing robust signals for the duration of the implant which lasted 196 days.
In addition, the way the soft-backed brain-computer interfaces are manufactured allows for larger sensing surfaces, which means that a significantly larger area of the brain surface can be monitored simultaneously. In the Advanced Functional Materials paper, the researchers demonstrate that a penetrating microneedle array with 1,024 microneedles successfully recorded signals triggered by precise stimuli from the brains of rats. This represents ten times more microneedles and ten times the area of brain coverage, compared to current technologies.
Thinner and transparent backings. These soft-backed brain-computer interfaces are thinner and lighter than the traditional, glass backings of these kinds of brain-computer interfaces. The researchers note in their Advanced Functional Materials paper that light, flexible backings may reduce irritation of the brain tissue that contacts the arrays of sensors.
The flexible backings are also transparent. In the new paper, the researchers demonstrate that this transparency can be leveraged to perform fundamental neuroscience research involving animal models that would not be possible otherwise. The team, for example, demonstrated simultaneous electrical recording from arrays of penetrating micro-needles as well as optogenetic photostimulation.
Two-sided lithographic manufacturing. The flexibility, larger microneedle array footprints, reconfigurability and transparency of the backings of the new brain sensors are all thanks to the double-sided lithography approach the researchers used.
Conceptually, starting from a rigid silicon wafer, the team's manufacturing process allows them to build microscopic circuits and devices on both sides of the rigid silicon wafer. On one side, a flexible, transparent film is added on top of the silicon wafer. Within this film, a bilayer of titanium and gold traces is embedded so that the traces line up with where the needles will be manufactured on the other side of the silicon wafer.
Working from the other side, after the flexible film has been added, all the silicon is etched away, except for free-standing, thin, pointed columns of silicon. These pointed columns of silicon are, in fact, the microneedles, and their bases align with the titanium-gold traces within the flexible layer that remains after the silicon has been etched away. These titanium-gold traces are patterned via standard and scalable microfabrication techniques, allowing scalable production with minimal manual labor. The manufacturing process offers the possibility of flexible array design and scalability to tens of thousands of microneedles.
Toward closed-loop systems. Looking to the future, penetrating microneedle arrays with large spatial coverage will be needed to improve brain-machine interfaces to the point that they can be used in "closed-loop systems" that can help individuals with severely limited mobility. For example, this kind of closed-loop system might offer a person using a robotic hand real-time tactical feedback on the objects the robotic hand is grasping.
Tactile sensors on the robotic hand would sense the hardness, texture, and weight of an object. This information recorded by the sensors would be translated into electrical stimulation patterns which travel through wires outside the body to the brain-computer interface with penetrating microneedles. These electrical signals would provide information directly to the person's brain about the hardness, texture, and weight of the object. In turn, the person would adjust their grasp strength based on sensed information directly from the robotic arm.
This is just one example of the kind of closed-loop system that could be possible once penetrating microneedle arrays can be made larger to conform to the brain and coordinate activity across the "command" and "feedback" centers of the brain. Previously, the Dayeh laboratory invented and demonstrated the kinds of tactile sensors that would be needed for this kind of application, as highlighted in this video.
Pathway to commercialization. The advanced dual-side lithographic microfabrication processes described in this paper are patented (US 10856764). Dayeh co-founded Precision Neurotek Inc. to translate technologies innovated in his laboratory to advance state of the art in clinical practice and to advance the fields of neuroscience and neurophysiology.
https://www.cam.ac.uk/research/news/stac...-3d-images
RELEASE: Researchers have developed a new method to display highly realistic holographic images using 'holobricks' that can be stacked together to generate large-scale holograms.
The researchers, from the University of Cambridge and Disney Research, developed a holobrick proof-of-concept, which can tile holograms together to form a large seamless 3D image. This is the first time this technology has been demonstrated and opens the door for scalable holographic 3D displays. The results are reported in the journal Light: Science & Applications.
As technology develops, people want high-quality visual experiences, from 2D high resolution TV to 3D holographic augmented or virtual reality, and large true 3D displays. These displays need to support a significant amount of data flow: for a 2D full HD display, the information data rate is about three gigabits per second (Gb/s), but a 3D display of the same resolution would require a rate of three terabits per second, which is not yet available.
Holographic displays can reconstruct high quality images for a real 3D visual perception. They are considered the ultimate display technology to connect the real and virtual worlds for immersive experiences.
"Delivering an adequate 3D experience using the current technology is a huge challenge," said Professor Daping Chu from Cambridge's Department of Engineering, who led the research. "Over the past ten years, we've been working with our industrial partners to develop holographic displays which allow the simultaneous realisation of large size and large field-of-view, which needs to be matched with a hologram with a large optical information content."
However, the information content of current holograms information is much greater than the display capabilities of current light engines, known as spatial light modulators, due to their limited space bandwidth product.
For 2D displays, it's standard practice to tile small size displays together to form one large display. The approach being explored here is similar, but for 3D displays, which has not been done before. "Joining pieces of 3D images together is not trivial, because the final image must be seen as seamless from all angles and all depths," said Chu, who is also Director of the Centre for Advanced Photonics and Electronics (CAPE). "Directly tiling 3D images in real space is just not possible."
To address this challenge, the researchers developed the holobrick unit, based on coarse integrated holographic displays for angularly tiled 3D images, a concept developed at CAPE with Disney Research about seven years ago. Each of the holobricks uses a high-information bandwidth spatial light modulator for information delivery in conjunction with coarse integrated optics, to form the angularly tiled 3D holograms with large viewing areas and fields of view.
Careful optical design makes sure the holographic fringe pattern fills the entire face of the holobrick, so that multiple holobricks can be seamlessly stacked to form a scalable spatially tiled holographic image 3D display, capable of both wide field-of-view angle and large size. The proof-of-concept developed by the researchers is made of two seamlessly tiled holobricks. Each full-colour brick is 1024×768 pixels, with a 40° field of view and 24 frames per second, to display tiled holograms for full 3D images.
"There are still many challenges ahead to make ultra-large 3D displays with wide viewing angles, such as a holographic 3D wall," said Chu. "We hope that this work can provide a promising way to tackle this issue based on the currently limited display capability of spatial light modulators."
A new brain-computer interface with a flexible backing
https://jacobsschool.ucsd.edu/news/release/3417
RELEASE: Engineering researchers have invented an advanced brain-computer interface with a flexible and moldable backing and penetrating microneedles. Adding a flexible backing to this kind of brain-computer interface allows the device to more evenly conform to the brain's complex curved surface and to more uniformly distribute the microneedles that pierce the cortex. The microneedles, which are 10 times thinner than the human hair, protrude from the flexible backing, penetrate the surface of the brain tissue without piercing surface venules, and record signals from nearby nerve cells evenly across a wide area of the cortex.
This novel brain-computer interface has thus far been tested in rodents. The details were published online on February 25 in the journal Advanced Functional Materials. This work is led by a team in the lab of electrical engineering professor Shadi Dayeh at the University of California San Diego, together with researchers at Boston University led by biomedical engineering professor Anna Devor.
This new brain-computer interface is on par with and outperforms the "Utah Array," which is the existing gold standard for brain-computer interfaces with penetrating microneedles. The Utah Array has been demonstrated to help stroke victims and people with spinal cord injury. People with implanted Utah Arrays are able to use their thoughts to control robotic limbs and other devices in order to restore some everyday activities such as moving objects.
The backing of the new brain-computer interface is flexible, conformable, and reconfigurable, while the Utah Array has a hard and inflexible backing. The flexibility and conformability of the backing of the novel microneedle-array favors closer contact between the brain and the electrodes, which allows for better and more uniform recording of the brain-activity signals. Working with rodents as model species, the researchers have demonstrated stable broadband recordings producing robust signals for the duration of the implant which lasted 196 days.
In addition, the way the soft-backed brain-computer interfaces are manufactured allows for larger sensing surfaces, which means that a significantly larger area of the brain surface can be monitored simultaneously. In the Advanced Functional Materials paper, the researchers demonstrate that a penetrating microneedle array with 1,024 microneedles successfully recorded signals triggered by precise stimuli from the brains of rats. This represents ten times more microneedles and ten times the area of brain coverage, compared to current technologies.
Thinner and transparent backings. These soft-backed brain-computer interfaces are thinner and lighter than the traditional, glass backings of these kinds of brain-computer interfaces. The researchers note in their Advanced Functional Materials paper that light, flexible backings may reduce irritation of the brain tissue that contacts the arrays of sensors.
The flexible backings are also transparent. In the new paper, the researchers demonstrate that this transparency can be leveraged to perform fundamental neuroscience research involving animal models that would not be possible otherwise. The team, for example, demonstrated simultaneous electrical recording from arrays of penetrating micro-needles as well as optogenetic photostimulation.
Two-sided lithographic manufacturing. The flexibility, larger microneedle array footprints, reconfigurability and transparency of the backings of the new brain sensors are all thanks to the double-sided lithography approach the researchers used.
Conceptually, starting from a rigid silicon wafer, the team's manufacturing process allows them to build microscopic circuits and devices on both sides of the rigid silicon wafer. On one side, a flexible, transparent film is added on top of the silicon wafer. Within this film, a bilayer of titanium and gold traces is embedded so that the traces line up with where the needles will be manufactured on the other side of the silicon wafer.
Working from the other side, after the flexible film has been added, all the silicon is etched away, except for free-standing, thin, pointed columns of silicon. These pointed columns of silicon are, in fact, the microneedles, and their bases align with the titanium-gold traces within the flexible layer that remains after the silicon has been etched away. These titanium-gold traces are patterned via standard and scalable microfabrication techniques, allowing scalable production with minimal manual labor. The manufacturing process offers the possibility of flexible array design and scalability to tens of thousands of microneedles.
Toward closed-loop systems. Looking to the future, penetrating microneedle arrays with large spatial coverage will be needed to improve brain-machine interfaces to the point that they can be used in "closed-loop systems" that can help individuals with severely limited mobility. For example, this kind of closed-loop system might offer a person using a robotic hand real-time tactical feedback on the objects the robotic hand is grasping.
Tactile sensors on the robotic hand would sense the hardness, texture, and weight of an object. This information recorded by the sensors would be translated into electrical stimulation patterns which travel through wires outside the body to the brain-computer interface with penetrating microneedles. These electrical signals would provide information directly to the person's brain about the hardness, texture, and weight of the object. In turn, the person would adjust their grasp strength based on sensed information directly from the robotic arm.
This is just one example of the kind of closed-loop system that could be possible once penetrating microneedle arrays can be made larger to conform to the brain and coordinate activity across the "command" and "feedback" centers of the brain. Previously, the Dayeh laboratory invented and demonstrated the kinds of tactile sensors that would be needed for this kind of application, as highlighted in this video.
Pathway to commercialization. The advanced dual-side lithographic microfabrication processes described in this paper are patented (US 10856764). Dayeh co-founded Precision Neurotek Inc. to translate technologies innovated in his laboratory to advance state of the art in clinical practice and to advance the fields of neuroscience and neurophysiology.