Researchers from The University of Texas at Dallas and Seoul National University have developed an imager chip inspired by Superman’s X-ray vision that could be used in mobile devices to make it possible to detect objects inside packages or behind walls.

Chip-enabled cellphones might be used to find studs, wooden beams or wiring behind walls, cracks in pipes, or outlines of contents in envelopes and packages. The technology also could have medical applications.

The researchers first demonstrated the imaging technology in a 2022 study. Their latest paper, published in the March print edition of IEEE Transactions on Terahertz Science and Technology, shows how researchers solved one of their biggest challenges: making the technology small enough for handheld mobile devices while improving image quality.

“This technology is like Superman’s X-ray vision. Of course, we use signals at 200 gigahertz to 400 gigahertz instead of X-rays, which can be harmful,” said Dr. Kenneth K. O, director of the Texas Analog Center of Excellence (TxACE) and the Texas Instruments Distinguished University Chair in the Erik Jonsson School of Engineering and Computer Science.

The research was supported by the Texas Instruments (TI) Foundational Technology Research Program on Millimeter Wave and High Frequency Microsystems and the Samsung Global Research Outreach Program.

“It took 15 years of research that improved pixel performance by 100 million times, combined with digital signal processing techniques, to make this imaging demonstration possible. This disruptive technology shows the potential capability of true THz imaging,” said Dr. Brian Ginsburg, director of RF/mmW and high-speed research at TI’s Kilby Labs.

With privacy issues in mind, the researchers designed the technology for use only at close range, about 1 inch from an object. For example, if a thief tried to scan the contents of someone’s bag, the thief would need to be so close that the person would be aware of what they were doing, Dr. O said. The next iteration of the imager chip should be able to capture images up to 5 inches away and make it easier to see smaller objects.

The imager emits 300-GHz signals in the millimeter-wave band of electromagnetic frequencies between microwave and infrared, which the human eye cannot see and is considered safe for humans. A similar technology, using microwaves, is used in large, stationary passenger screeners in airports.

“We designed the chip without lenses or optics so that it could fit into a mobile device. The pixels, which create images by detecting signals reflected from a target object, have the shape of a 0.5-mm square, about the size of a grain of sand,” said Dr. Wooyeol Choi, assistant professor at Seoul National University and the corresponding author of the latest paper.

The advances to miniaturize the imager chip for mobile devices are the result of nearly two decades of research by Dr. O and his team of students, researchers and collaborators through the TxACE at UT Dallas.

A study author and electrical engineering graduate student Walter Sosa Portillo BS’21 came to work in O’s lab as an undergraduate after learning about this imaging research.

“The first day I came to orientation, they talked about Dr. O’s research, and I thought it was really interesting and pretty cool to be able to see through things,” said Portillo, who is researching medical applications for the imager.

Last year, researchers from the US and Canada reported in PLOS ONE creating electrical batteries from ice. The electrical output is modest, just 0.1 milliwatt. But this may be a sign of good things to come. The scientists worked over the course of two seasons to design and produce electrochemical cells that will work to generate electricity.

Dr. Daniel Helman and Dr. Matthew Retallack met at the European Consortium for Political Research in Montreal, Canada in 2015. Helman was presenting ideas about solar panels from ice, and Retallack was the discussant of the session.

“I think there was a mutual respect and love of research,” says Helman. They went on to develop different prototypes. The model that finally won out uses acid to create a difference in pH between two layers of ice plus a few additives.

The most mobile charge carrier in ice is the proton, so it makes sense to think of protons traveling from one layer to the other because of the pH difference. The travel of charged particles is how batteries generate electricity.

In this case, table salt, kaolinite clay and monopotassium phosphate help to donate or receive charged particles, along with muriatic acid (HCl). A mesh screen and sheet aluminum were used as the electrodes.

The materials used in the experiments are all commonly available, and commonly regarded as safe. It makes one wonder what would be possible using more optimized materials. Moreover, photosensitive particles added in can probably produce dye-sensitized solar cells.

The original experiments for dye-sensitized solar cells used chlorophyll taken from spinach to change local pH in response to sunlight. While the electrical output may be small, the point is not lost that large swaths of land at high latitudes might be available.

Fields, lakes or other open land might be safely put to good use in humanity’s quest to transition away from fossil fuels. The additives in this experiment were chosen for their relative safety in the environment.

The generation of electricity from ice also sheds light on one of the more enduring questions facing science right now. Where did life come from? Current thought is that organisms originated either in small ponds near volcanic, geothermal fields, or near mid-ocean ridges. But there is a problem. RNA gets diluted without a membrane, and then cannot act as a catalyst.

An icy setting solves this problem. RNA may remain concentrated in small regions on, for example, the ice of a comet or meteorite. Thus, generation of electricity from ice could provide a proto-metabolism for the start of organismal development with self-catalyzing RNA on such icy meteorites (like the Murchison meteorite) or on an early Snowball Earth.

Both of these ideas are not so far fetched. Solar panels from ice may be useful in some settings. And an icy worlds hypothesis for the origin of life may explain why we don’t see any of the early stages here on Earth now.

Dr. Helman is currently a visiting assistant professor of Environmental Studies at Wofford College in Spartanburg, South Carolina. Dr. Retallack ran the experiments while at Carleton University in Toronto.

Provided by
Wofford College