Event-Driven Optical Sensor Inspired by Human Eyes

Innovation: Academia

Oregon State University

2020

Image: Soroush Karimi / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Sense Light (Visible Spectrum) From the Environment

Living systems constantly receive signals from their environment that help them survive. Light (in the visible spectrum) can come from other living systems (such as fireflies) or from non-living sources (such as the sun). Survival often depends on sensing and responding to challenges like low light conditions or light that has been altered in some way. Because basic survival is at stake, living systems must excel at meeting those challenges. A well-known phenomenon is how water bends light. A stork trying to catch a fish underwater can compensate for this bending effect so that when it strikes at the fish, it has a good chance of catching it.

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Sense Light (Non-visible Spectrum) From the Environment

Living systems interact with each other and with their environments to gain information. Sometimes that information is in the electromagnetic spectrum. Wavelengths in the electromagnetic spectrum are also called the non-visible spectrum, because humans can’t detect them with the naked eye. These include ultraviolet (UV) light, infrared (IR) light, radio waves, and other wavelengths. Detecting within these spectra requires strategies beyond those used for visible light, so many living systems that depend on these signals have specialized organs to do so. For example, beetles that feed on burned trees have sensory organs that detect infrared radiation emitted by fires, enabling them to quickly locate a burned area.

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Sense Motion

Perceiving motion is important for a living system to sense where it is in relation to a moving environment, which is critical in locating resources or wayfinding. This applies whether the environment itself is in motion (such as water movement coming from a nearby fish) or the living system is moving within a stationary environment (such as a bird flying through the air). Because motion dampens over distance and the cost of missing those motion signals is high, living systems must be quite sensitive to these signals. For example, fast-flying big brown bats have microscopic, stiff, domed hairs on their wing membranes that act as a sensor array to monitor flight speed and airflow conditions.

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Optical sensors from Oregon State University only respond to changes in light intensity and motion to more efficiently process information.

Benefits

Dynamic
Increased efficiency
Cost-reducing

Applications

Solar energy
Medical implants
Autonomous vehicles

UN Sustainable Development Goals Addressed

Goal 3: Good Health & Wellbeing
Goal 11: Sustainable Cities & Communities

The Challenge

Robotic eyes have trouble seeing as well as human eyes because they are unable to process multiple streams of information simultaneously. Robotics eyes usually process data in a sequential order, delaying the overall transmission of data. Additionally, synthetic eyes have smaller fields of vision and lower definition, leading to a lower quality of visual information.

Innovation Details

The optical sensor works similarly to the human eye in that it can process multiple streams of information at once, and it pays closest attention to objects that are moving rather than static. The sensor is made of ultrathin layers of perovskite semiconductors, which change from strong electrical insulators to strong conductors when placed in light. Due to this light sensitivity, the sensor’s network pays special attention to changes in light intensity and responds accordingly. The result is that the sensor focuses its energy on moving objects rather than expending energy on a visual field that is not changing. This allows the sensor to track motion without using complex image processing technology.

Biological Model

Human eyes have a component called the retina. This retina contains two types of photoreceptors, rods and cones. The photoreceptors convert light into signals that stimulate biological processes. However, the optic nerve only has ~1 million connections projecting to the brain. This means that a significant amount of image preprocessing and compression must take place in the retina before the image can be transmitted.

References

Journal article

A perovskite retinomorphic sensor

Applied Physics Letters

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