Mar 4 2021
Scientists have taken cues from the eyes of mantis shrimp to design a new type of optical sensor that is small enough to fit on a smartphone but can also perform polarimetric and hyperspectral imaging.
This SIMPOL image shows spectral imaging of a scene containing objects with different colors, as well as the letters NCSU, which contain different polarization states. Image Credit: Ali Altaqui.
Lots of artificial intelligence (AI) programs can make use of data-rich hyperspectral and polarimetric images, but the equipment necessary for capturing those images is currently somewhat bulky. Our work here makes smaller, more user friendly devices possible. And that would allow us to better bring those AI capabilities to bear in fields from astronomy to biomedicine.
Michael Kudenov, Study Co-Corresponding Author and Associate Professor of Electrical and Computer Engineering, North Carolina State University
With regards to this study, hyperspectral imaging denotes technologies that can disintegrate the visible wavelengths of light into narrower bands. The human eye cannot differentiate between such subtle changes in color, but computers can—this makes hyperspectral imaging useful for tasks like finding the chemical composition of objects in the image.
Polarimetry relates to the measurement of polarization in light, the data that can be utilized to identify the surface geometry of an object in the image. For instance, the study determines if the surface is smooth or rough and also finds what is the angle of the surface relative to the light source
It is well known that light is difficult to explain since it acts as both a particle and a wave. If a wave of light travels from Point A to Point B, the path present between those two points is considered as the direction of the light. If the light is considered as a particle, it moves in a straight line from Point A to Point B.
However, the light is also an electromagnetic field that oscillates similar to a wave. If the wave is imagined to wiggle up and down or side to side as it moves from Point A to Point B, polarization is considered as a measurement of the orientation of that wave in the line of the path.
Although bigger devices with the ability to capture polarimetric and hyperspectral images exist, smartphone-sized imaging technologies have met with considerable difficulties.
For instance, the design of cell phone camera technologies leads to very limited faults in the alignment of the different wavelengths of light in the final image. The outcome is not a big thing for capturing family photos but poses a problem for scientific image analysis.
The issue increases when a camera can capture more colors, as happens in the case of hyperspectral technologies.
The makers of the new light sensors were motivated by the eyes of mantis shrimp, which are remarkably good at precisely capturing delicate gradations of color. Hence, the team made an organic electronic sensor that imitates the eye of mantis shrimp.
It is known as the Stomatopod Inspired Multispectral and POLarization sensitive (SIMPOL) sensor, as stomatopod is another name for mantis shrimp.
The team designed a prototype SIMPOL sensor that could register three polarization channels and four spectral channels at the same time. In comparison, the charge-coupled devices found in smartphones have just three spectral imaging sensors—which detect blue, green and red—and just two polarization channels.
Aditionally, the SIMPOL prototype can quantify the three polarization channels and four color channels at a single point. By contrast, CCDs depend on imaging sensors spread throughout various points.
Although it is just a proof of principle, the team employed modeling simulations to find out whether the design can be employed to make detectors with the ability to sense up to 15 spatially registered spectral channels.
SIMPOL’s color channels can discern spectral features 10 times narrower than typical imaging sensors; in other words, it is 10 times more precise.
Michael Kudenov, Study Co-Corresponding Author and Associate Professor of Electrical and Computer Engineering, North Carolina State University
“Our work demonstrates that it is possible to create small, efficient sensors that can simultaneously capture hyperspectral and polarimetric images. I think this opens the door to a new breed of organic electronic sensing technologies,” stated Brendan O’Connor, co-corresponding author of the paper and an associate professor of mechanical and aerospace engineering at NC State.
The first author of the study is Ali Altaqui, a postdoctoral researcher at NC State. The study’s co-corresponding author is Brendan O’Connor.
The study was co-authored by Pratik Sen, a former PhD student at NC State; Harry Schrickx, a PhD student at NC State; Michael Escuti, a professor of electrical and computer engineering at NC State; the late Robert Kolbas, a former professor of electrical and computer engineering at NC State; Jeromy Rech and Wei You of the University of North Carolina at Chapel Hill; and Jin-Woo Lee and Bumjoon J. Kim of the Korea Advanced Institute of Science and Technology.
The study was performed with financial support from the National Science Foundation under grants 1809753 and 1639429, and from the National Research Foundation of Korea, under grant NRF-2017M3A7B8065584.
Journal Reference:
Altaqui, A., et al. (2021) Mantis shrimp-inspired organic photodetector for simultaneous hyperspectral and polarimetric imaging. Science Advances. doi.org/10.1126/sciadv.abe3196.