Researchers from Gwangju Institute of Science and Technology (GIST) and Institute for Basic Science (IBS) have developed a perovskite-based camera, inspired by the structures and functions of birds' eyes, specializing in object detection.
Schematic illustration showing the visual ecology of birds. Image from Science Robotics
The eyes of different organisms in the natural world have evolved and been optimized to suit their habitat and the environment in which they survive. As a result of countless years of evolutionary adaptation to the environment of living and flying at high altitudes, bird eyes also have unique structures and visual functions. In the retina of an animal's eye, there is a small pit called the fovea that refracts the light entering the eye. Unlike the shallow foveae found in human eyes, bird eyes have deep central foveae, which refract the incoming light to a large extent. The region of the highest cone density lies within the foveae, allowing the birds to clearly perceive distant objects through magnification. This specialized vision is known as foveated vision.
While human eyes can only see visible light, bird eyes have four cones that respond to ultraviolet (UV) as well as visible (red, green, blue; RGB) light. This tetrachromatic vision enables birds to acquire abundant visual information and effectively detect target objects in a dynamic environment.
Inspired by these capabilities, the research team designed a new type of camera that specializes in object detection, incorporating artificial fovea and a multispectral image sensor that responds to both UV and RGB. First, the researchers fabricated the artificial fovea by mimicking the deep central foveae in the bird's eyes and optimized the design through the optical simulation. This allows for the camera to magnify distant target objects without image distortion.
The team then used perovskite materials to fabricate the multispectral image sensor. Four types of photodetectors were fabricated using different perovskite materials that absorb different wavelengths. The multispectral image sensor was finally fabricated by vertically stacking the four photodetectors.
The first co-author Dr. PARK Jinhong states, “We also developed a new transfer process to vertically stack the photodetectors. By using the perovskite patterning method developed in our previous research, we were able to fabricate the multispectral image sensor that can detect UV and RGB without additional color filters.”
Conventional cameras that use a zoom lens to magnify objects have the disadvantage of focusing only on the target object and not its surroundings. On the other hand, the bird-eye-inspired camera provides both a magnified view of the foveal region along with the surrounding view of the peripheral region. By comparing the two fields of vision, the bird-eye-inspired camera can achieve greater motion detection capabilities than the conventional camera. In addition, the camera is more cost-effective and lightweight as it can distinguish UV and RGB light without additional color filters.
The research team verified the object recognition and motion detection capabilities of the developed camera through simulations. In terms of object recognition, the new camera demonstrated a confidence score of 0.76, which is about twice as high as the existing camera system's confidence score of 0.39. The motion detection rate also increased by 3.6 times compared to the existing camera system, indicating significantly enhanced sensitivity to motion.
"Birds’ eyes have evolved to quickly and accurately detect distant objects while in flight. Our camera can be used in areas that need to detect objects clearly, such as robots and autonomous vehicles. In particular, the camera has great potential for application to drones operating in environments similar to those in which birds live,” remarked Prof. Kim.
This innovative camera technology represents a significant advancement in object detection, offering numerous potential applications across various industries.
