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“This advancement reduces detection limits and paves the way for safer and more energy-efficient medical imaging and industrial monitoring,� says Omar F. Mohammed, the corresponding author on the study. “It demonstrates that cascade-engineered devices enhance the capabilities of single crystals in X-ray detection.�

Just like visible light and radio waves, X-rays are a form of electromagnetic radiation. Their high-energy state allows them to pass through most objects � including the soft tissues of our bodies. To produce an X-ray image, called a radiograph, the rays either pass through the body and appear as shadowy shapes on the image, or get stuck in denser tissues like bones, leaving behind a brighter, white area. The amount of radiation a patient is exposed to during a single scan is not dangerous, and one would have to undergo thousands of scans to start to notice compounding effects. However, these repeated exposures to high-energy rays can damage electronic equipment or pose a risk to someone like an X-ray technician. So, the fewer rays used during a scan, the better, right?

Unfortunately, fewer rays mean a lower-quality radiograph. But by increasing the sensitivity of the detector, a low-dose, high-quality X-ray could theoretically be produced. So, Omar Mohammed and colleagues at the King Abdullah University of Science and Technology engineered a device that facilitates these safer X-ray conditions.

To increase X-ray detector sensitivity, the researchers aimed to minimize the dark current � the residual background noise � generated by the device. To do so, they created detectors using specialized methylammonium lead bromide perovskite crystals, and then they connected the crystals in an electrical configuration known as a cascade.

The cascade configuration nearly halved the dark current, which improved the X-ray detection limit by five times compared with previous detectors made from the same crystals but without the cascade.  Radiographs made with the new detector revealed fine details, such as a metal needle piercing a raspberry and the interior components of a USB cable. The team states that this technology is a promising method for developing foldable, safer and sensitive commercial X-ray devices, which would serve to minimize radiation exposure during medical procedures and capture subtle details in industrial monitoring.

The authors acknowledge funding from the King Abdullah University of Science and Technology (KAUST).