New material may help us build Predator-style thermal vision specs
Films of IR-sensitive material only tens of nanometers thick are tough to make.
Military-grade infrared vision goggles use detectors made of mercury cadmium telluride, a semiconducting material that’s particularly sensitive to infrared radiation. Unfortunately, you need to keep detectors that use this material extremely cool—roughly at liquid nitrogen temperatures—for them to work. “Their cooling systems are very bulky and very heavy,” says Xinyuan Zhang, an MIT researcher and the lead author of a new study that looked for alternative IR-sensitive materials.
Added weight was a sacrifice the manufacturers of high-end night-vision systems were mostly willing to make because cooling-free alternatives offered much worse performance. To fix this, the MIT researchers developed a new ultra-thin material that can sense infrared radiation without any cooling and outperforms cooled detectors at the same time. And they want to use it to turn thermal vision goggles into thermal vision spectacles.
Staying cool
Cooling-free infrared detectors have been around since before World War II and mostly relied on pyroelectric materials like tourmaline that change their temperature upon absorbing infrared radiation. This temperature change, in turn, generates an electric current that can be measured to get a readout from the detector. Although these materials worked, they had their issues. Operating at room temperature caused a lot of random atomic motion in the pyroelectric material, which introduced electrical noise that made it difficult to detect faint infrared signals.
In cooled mercury cadmium telluride detectors, this atomic motion is dramatically lower. “Cooling them down to liquid nitrogen temperatures is done to suppress the internal noise,” Zhang explains. Her team figured getting this kind of low-noise performance out of pyroelectric materials was theoretically possible. The caveat was that these materials need to be absurdly thin to get the noise down. And this made manufacturing a bit tricky.
Non-stick surfaces
The process of fabricating ultra-thin films (between one and a few tens of nanometers) made of various materials is called epitaxy and is used in manufacturing chips and two-dimensional semiconductors. It relies on growing crystalline structures on a substrate material. The key challenge is getting those crystalline films off the substrate without damaging them—they tended to stick to the substrates like fried eggs to an old pan.
One way to do that is called remote epitaxy, where an intermediate layer made out of graphene or other material is introduced between the substrate and the growing crystals. Once the epitaxy process is done, the substrate and everything on it are soaked in a chemical solution that dissolves this intermediate layer, leaving the crystalline film intact. This works but is expensive, difficult to scale, and takes a lot of time. To make the process cheaper and faster, the MIT team had to grow the crystals directly on the substrate, without any intermediate layers. What they were trying to achieve was a non-stick frying pan effect but at an atomically small scale.
Weakening the bonds
The material that prevented the crystalline films from sticking to substrates wasn’t Teflon but lead. When the team was experimenting with growing different films in their previous studies, they noticed that there was a material that easily came off the substrate, yet retained an atomically smooth surface: PMN-PT, or lead magnesium niobate-lead titanate.
The lead atoms in the PMN-PT weakened the covalent bonds between the film and the substrate, preventing the electrons from jumping through the interface between the two materials. “We just had to exert a bit of stress to induce a crack at the interface between the film and the substrate and we could realize the liftoff,” Zhang told Ars. “Very simple—we could remove these films within a second.”
But PMN-PT, besides its inherent non-stickiness, had more tricks up its sleeves; it had exceptional pyroelectric properties. Once the team realized they could manufacture and peel away PMN-PT films at will, they tried something a bit more complex: a cooling-free, far-infrared radiation detector. “We were trying to achieve performance comparable with cooled detectors,” Zhang says.
The detector they constructed was made from 100 pieces of 10-nanometer-thin PMN-PT films, each about 60 square microns, that the team transferred onto a silicon chip. This produced a 100-pixel infrared sensor. Tests with ever smaller changes in temperature indicated that it outperformed state-of-the art night vision systems and was sensitive to radiation across the entire infrared spectrum. (Mercury cadmium telluride detectors respond to a much narrower band of wavelengths.)
But before the US Air Force that funded this study gets its predator-like thermal vision spectacles—or even super-thin, lightweight FIR sensors—there are a few challenges left to overcome.
Next-gen night vision?
Sensors and their cooling systems alone are not enough to build a good night-vision system. “We are still working to develop this into a functional night-vision device. We still need some optical design to focus light onto our detector, some power supply, circuitry, and we need to integrate this into our goggles,” Zhang says.
She said that, although the infrared detecting layers are very thin themselves, finding space for all the other parts will be the next problem to solve on the way toward miniaturizing night-vision devices further. “I think night-vision contact lenses will be challenging to build, but I expect our technology could potentially be used to make something that looks like normal spectacles,” Zhang suggested. Other applications she is considering are infrared sensors that could enable autonomous cars to orient themselves better in difficult weather conditions, like during a heavy fog. But there’s a lot we can potentially do with easily manufactured ultra-thin films.
Zhang thinks the atomic liftoff method developed by her team can be applied to other films, not just ones containing lead. Her team suspects that it can induce the same non-stick effect using lead in the substrate, rather than in the film. This should open a path toward using them in wearable sensors, flexible transistors, or even very small computers. “If we can generalize this method to other materials, we can use it in many other applications,” Zhang claims.
Nature, 2025. DOI: 10.1038/s41586-025-08874-7
Jacek Krywko is a freelance science and technology writer who covers space exploration, artificial intelligence research, computer science, and all sorts of engineering wizardry.
