Sensors - Page 5

Researchers at the Dutch Organization for Applied Scientific Research and Eindhoven University of Technology in the Netherlands have recently used a solution-processed photodetector made of a metal halide perovskite to fabricate a thin and flexible scanner. This scanner can be used to scan both fingerprints and paper documents.

"Fabricating photodetectors with low dark currents and integrating them into high-resolution backplanes remains challenging," Albert J. J. M. van Breemen and his colleagues wrote in their paper. "Here, we show that solution-processed metal halide perovskite photodiodes on top of an amorphous indium gallium zinc oxide transistor backplane can be used to create a flexible image sensor that is ~100'μm thick and has a resolution of 508 pixels per inch."

Scientists at EPFL and their collaborators have developed a simple and low-cost perovskite-based device that detects neutrons. The perovskite materials used in the study are based on lead and bromine. Both contain single crystals of a compound called methylammonium lead tri-bromide.

The team first placed these crystals in the path of a neutron source. The neutrons, hitting the crystals, penetrate the nucleus of the atoms within the crystal, exciting them into a higher energy state. When they relax and decay, gamma rays are created. These gamma photons charge the perovskite, delivering a tiny current that can be estimated.

The U.S. Defense Advanced Research Projects Agency (DARPA) is currently seeking research proposals for the development of x-ray technology capable of what the agency calls "extreme photo imaging."

As part of its Extreme Photon Imaging Capability - Hard X-Ray (EPIC-HXR) project, DARPA said it is looking to develop uncooled hard x-ray imagers based on advanced nanocrystalline materials with high spatial and energy resolution, including quantum dot and perovskite materials.

Researchers at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have reported a breakthrough in energy-efficient phototransistors - devices that could someday help computers process visual information similarly to the human brain and be used as sensors in applications like self-driving vehicles.

The structures rely on metal-halide perovskites. Jeffrey Blackburn, a senior scientist at NREL and co-author of a new paper outlining the research, said: 'In general, these perovskite semiconductors are a really unique functional system with potential benefits for a number of different technologies'. 'NREL became interested in this material system for photovoltaics, but they have many properties that could be applied to whole different areas of science.'

A University of North Texas researcher and his team have reported a breakthrough in using additive manufacturing to further research into flexible solar panels.

Anupama Kaul, Professor of Engineering from the Departments of Materials Science and Engineering and Electrical Engineering, has successfully used additive manufacturing to print inks of 2D perovskites.

Various dangerous chemicals are currently used for agriculture and industry, including fumigants like methyl iodide, which is used to control insects and fungi. The wrong amounts or incorrect use of these fumigants can be harmful to people and degrade the ozone layer. As it’s invisible and doesn’t smell, it’s hard to tell whether there are dangerous amounts of methyl iodide present, and until now the best way to test for it was in a laboratory using expensive, complicated equipment, which isn’t practical in many real-world settings. Some cheaper, lightweight detection methods have been tried, but they didn’t have enough sensitivity and took too long to deliver results.

Now, a research team led by the ARC Centre of Excellence in Exciton Science, along with Australia’s national science agency CSIRO and the Department of Defense, has found a perovskite-based way to detect methyl iodide, with the accuracy, flexibility and speed necessary for practical use. This new sensing mechanism is also versatile enough for use in detecting a wide range of fumigants and chemical warfare agents.

A team of scientists,  led by László Forró from the School of Basic Sciences at the Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland, has developed a new X-Ray Photodetector based on perovskites and graphene.

Using 3D aerosol jet-printing technology, the team designed a new technique for creating highly efficient x-ray photodetectors that can be easily added to standard microelectronic circuits, creating more powerful medical imaging devices that can deliver better scan qualities.

A research group, led by Prof. HAN Keli from the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences, recently revealed the luminescence enhancement mechanism of a series of new lead-free quadruple halide perovskite nanocrystals, and prepared high-performance photodetectors.

The researchers reported a series of quadruple perovskite colloidal nanocrystals with ordered vacancies. By alloying Cs₄MnBi₂Cl₁₂ nanocrystals, the fluorescence quantum yield could be increased by nearly 100 times.

Researchers at Ecole Polytechnique Fédérale de Lausanne (EPFL), assisted by teams at Croatia's University of Split, have developed a perovskite that can detect gamma rays.

The 'oriented crystal'crystal growth' (OC2G) method of large MAPbBr3 crystals . a) Growing of large crystals by the suspended seed crystal; b,c) The consecutive steps of fusing together individual single crystals into a large crystal. Image by EPFL

"This photovoltaic perovskite crystal, grown in this kilogram size, is a game changer," says EPFL's Professors Lászlo Forró. "You can slice it into wafers, like silicon, for optoelectronic applications, and, in this paper, we demonstrate its utility in gamma-ray detection."

Researchers at Oregon State University have reported recent advances with a new type of perovskite-based optical sensor that more closely mimics the human eye's ability to perceive changes in its visual field. The sensor could be highly beneficial for fields like image recognition, robotics and artificial intelligence.

The team explained that previous attempts to build a human-eye type of device, called a retinomorphic sensor, have relied on software or complex hardware. However, the new sensor's operation is part of its fundamental design, using ultrathin layers of perovskite semiconductors that change from strong electrical insulators to strong conductors when placed in light.