Perovskite pillars printed on a graphene substrate; each pillar defines a pixel for the creation of the image. Image: L. Forró, EPFL. Since Wilhelm Röntgen discovered them in 1895, X-rays have become a staple of medical imaging. In fact, barely a month after Röntgen's famous paper was published, doctors in Connecticut took the first ever radiograph of a boy's broken wrist.
There has been a lot of progress since. Aside from radiographs, which most people experience at least once in their lives, current medical uses for X-rays include fluoroscopy and radiotherapy for cancer. There is also computer tomography (CT), which involves taking multiple X-ray scans of the body from different angles and then combining them in a computer to generate virtual cross-sectional 'slices' of a body.
Nonetheless, medical imaging often works with low-exposure conditions, and therefore requires cost-effective, high-resolution X-ray detectors that can operate at what is called a 'low photon flux'. Photon flux simply describes how many photons hit the detector at a given time and determines the number of electrons it generates in turn.
Now, scientists led by László Forró at the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have produced a novel version of just such a detector. Using 3D aerosol jet-printing, they developed a method for producing highly efficient X-ray detectors that can easily be integrated into standard microelectronics to considerably improve the performance of medical imaging devices. The scientists report their new detector in a paper in ACS Nano .
The new detector combines graphene, which is a single layer of carbon atoms in a honeycomb pattern, and perovskites, which are materials made up of organic compounds bound to a metal. Perovskites are versatile, easy to synthesize, and are at the forefront of a wide range of applications, including solar cells, LED lights, lasers and photodetectors.
Aerosol jet-printing is a fairly new process that is used to make 3D-printed electronic components like resistors, capacitors, antennas, sensors and thin-film transistors. It can even print electronics on a particular substrate, like the case of a cell phone.
Using the aerosol jet printing device at CSEM in Neuchatel, the researchers 3D-printed perovskite pillars on a graphene substrate. The idea is that the perovskite pillars act as the X-ray detector and electron discharger, while the graphene amplifies the outgoing electrical signal.
The research team used a methylammonium lead iodide (MAPbI3 ) perovskite. MAPbI3 has recently attracted a lot of attention because of its fascinating optoelectronic properties, which pair well with its low fabrication cost. "This perovskite has heavy atoms, which provide a high scattering cross-section for photons, and makes this material a perfect candidate for X-ray detection," says Endre Horváth, a chemist at EPFL.
The results were stunning. The method produced X-ray detectors with a record sensitivity that demonstrated a four-fold improvement on the best-in-class medical imaging devices.
"By using photovoltaic perovskites with graphene, the response to X-rays has increased tremendously," says Forró. "This means that if we would use these modules in X-ray imaging, the required X-ray dose for forming an image could be decreased by more than a thousand times, decreasing the health hazard of this high-energy ionizing radiation to humans."
Another advantage of the perovskite-graphene detector is that it is simple to form images using it. "It doesn't need sophisticated photomultipliers or complex electronics," says Forró. "This could be a real advantage for developing countries."
This story is adapted from material from EPFL , with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source .
Since Wilhelm Röntgen discovered them in 1895, X-rays have become a staple of medical imaging. In fact, barely a month after Röntgen's famous paper was published, doctors in Connecticut took the first ever radiograph of a boy's broken wrist.
There has been a lot of progress since. Aside from radiographs, which most people experience at least once in their lives, current medical uses for X-rays include fluoroscopy and radiotherapy for cancer. There is also computer tomography (CT), which involves taking multiple X-ray scans of the body from different angles and then combining them in a computer to generate virtual cross-sectional 'slices' of a body.
Nonetheless, medical imaging often works with low-exposure conditions, and therefore requires cost-effective, high-resolution X-ray detectors that can operate at what is called a 'low photon flux'. Photon flux simply describes how many photons hit the detector at a given time and determines the number of electrons it generates in turn.
Now, scientists led by László Forró at the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have produced a novel version of just such a detector. Using 3D aerosol jet-printing, they developed a method for producing highly efficient X-ray detectors that can easily be integrated into standard microelectronics to considerably improve the performance of medical imaging devices. The scientists report their new detector in a paper in ACS Nano .
The new detector combines graphene, which is a single layer of carbon atoms in a honeycomb pattern, and perovskites, which are materials made up of organic compounds bound to a metal. Perovskites are versatile, easy to synthesize, and are at the forefront of a wide range of applications, including solar cells, LED lights, lasers and photodetectors.
Aerosol jet-printing is a fairly new process that is used to make 3D-printed electronic components like resistors, capacitors, antennas, sensors and thin-film transistors. It can even print electronics on a particular substrate, like the case of a cell phone.
Using the aerosol jet printing device at CSEM in Neuchatel, the researchers 3D-printed perovskite pillars on a graphene substrate. The idea is that the perovskite pillars act as the X-ray detector and electron discharger, while the graphene amplifies the outgoing electrical signal.
The research team used a methylammonium lead iodide (MAPbI3 ) perovskite. MAPbI3 has recently attracted a lot of attention because of its fascinating optoelectronic properties, which pair well with its low fabrication cost. "This perovskite has heavy atoms, which provide a high scattering cross-section for photons, and makes this material a perfect candidate for X-ray detection," says Endre Horváth, a chemist at EPFL.
The results were stunning. The method produced X-ray detectors with a record sensitivity that demonstrated a four-fold improvement on the best-in-class medical imaging devices.
"By using photovoltaic perovskites with graphene, the response to X-rays has increased tremendously," says Forró. "This means that if we would use these modules in X-ray imaging, the required X-ray dose for forming an image could be decreased by more than a thousand times, decreasing the health hazard of this high-energy ionizing radiation to humans."
Another advantage of the perovskite-graphene detector is that it is simple to form images using it. "It doesn't need sophisticated photomultipliers or complex electronics," says Forró. "This could be a real advantage for developing countries."
This story is adapted from material from EPFL , with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source .