One of Superman's superpowers is X-ray vision, which allows him to see through solid objects. Using Superman as inspiration, researchers at the University of Texas at Dallas (UTD) and Seoul National University (SNU) have made the ability to see through packaging and walk through walls a reality using an imaging chip small enough to fit into a smartphone.
Researchers have created a tiny chip that can take images of objects through cardboard. This technology can be installed in smartphones, bringing us one step closer to superhuman X-ray vision capabilities (without X-rays).
"This technology is like superhuman X-ray vision," said Kenneth O, a professor of electrical engineering at the University of Texas and director of the Texas Center of Analog Excellence (TxACE) and one of the study's co-authors. "Of course, we're using a 200 gigahertz to 400 gigahertz signal instead of potentially harmful X-rays."
The imager microchip technology, first demonstrated in 2022, is the culmination of more than 15 years of work by O and his team of students, researchers and collaborators. The chip emits radiation in the terahertz (THz) range, which is electromagnetic radiation with a frequency range between 0.1 terahertz (100 gigahertz) and 10 terahertz, with corresponding wavelengths ranging from 3 millimeters to 0.03 millimeters. These waves are invisible to the human eye and are considered safe, with frequencies higher than radio waves and microwaves but lower than infrared.
With the 2022 model, O demonstrated that the 430GHz beam generated by the microchip can penetrate fog, dust and other obstacles that optical light cannot penetrate. They bounce off the object and reflect back to the microchip, where the pixels receive the signal and generate an image. This imager does not rely on external lenses, which are often used to improve the clarity and sharpness of the image. Instead, it uses complementary metal-oxide semiconductor (CMOS) technology, which is used to make modern consumer computer processors, memory chips and other digital devices.
CMOS has become an affordable way to generate and detect terahertz signals, especially at frequencies of 200 gigahertz and above, where it provides better resolution. So the researchers set out to improve the image quality of their 2022 model and make the technology small enough to fit into a handheld device. The new imaging chip uses a 1x3 array of 296GHz CMOS pixels and also has no lens.
"The chip we designed has no lenses or optics, so it can be installed in mobile devices," said Wooyeol Choi, the paper's corresponding author and an assistant professor in the Department of Electrical and Computer Engineering at Shanghai Jiao Tong University. "Pixels generate images by detecting signals reflected from target objects, which are shaped like 0.5 mm squares, about the size of a grain of sand."
The technology has been tested to image cardboard-covered objects (a USB dongle, a blade, an integrated circuit and a plastic gasket) from about a centimeter (0.4 inches) away. For safety and privacy reasons, the researchers intentionally scanned the imager at such a close distance to the object. Basically, the idea is to allay concerns that a thief might use the device to scan the contents of someone's bag from a distance. The researchers plan to enable the next iteration to capture images from five inches (12.7 centimeters) away.
Brian Ginsburg, director of RF/millimeter wave and high-speed research at Texas Instruments (TI) Kilby Labs, said: "Fifteen years of research, a 100 million-fold increase in pixel performance, and digital signal processing technology made this imaging demonstration possible. This disruptive technology demonstrates the potential capabilities of true terahertz imaging."
The researchers envision their smartphone microchip imager being used for everything from finding wall studs and wooden beams behind walls to identifying cracks in pipes and the contents of envelopes and packages. They also believe it could have applications in the medical field.
This research was supported by Texas Instruments' (TI) Millimeter-Wave and High-Frequency Microsystems Fundamental Technology Research Program and Samsung's Global Research Expansion Program.
This research was published in IEEE Transactions on Terahertz Science and Technology.