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This image shows detail of the Megaframe’s CMOS 32 × 32 single-photon avalanche detector array.
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European researchers have created a novel ultra-fast high-resolution video camera, reports ICT Results (Brussels), an organisation covering EU-funded information and communication technologies research. According to the researchers, the device is the world’s first 1024-pixel, photon-resolution, million-frame-per-second CMOS camera. The development could enable dozens of medical applications, including one scenario that can record ‘thought’ processes travelling along neurons.
The camera can detect a single photon at a rate of one million frames per second, enabling it can record molecular processes with unprecedented clarity. “We need this sort of detail because biomedical scientists are studying processes at the intracellular and molecular levels,” says Edoardo Charbon, coordinator of the EU-funded Megaframe project. Conceived in the summer of 2004, the Megaframe project was formed to respond to the growing interest of the scientific and engineering community in low-cost techniques for single-photon counting. The Megaframe researchers expect the project to lead to new insight into molecular reactions. To accomplish this feat, the scientists are using a variety of emissive materials, enabling them to visualise what is happening in microscopic biomedical processes.
One technique the researchers are employing is fluorescence lifetime imaging microscopy (FLIM), in which a fluorescent material is introduced to the area of interest. Fluorescence has a particular spectrum of emission and rate of decay. One fluorophore in particular, Oregon Green Bapta (OGB-1), decays at a rate proportionate to the presence of calcium, which is an indicator of neuron activity. “So it is possible, for example, to go inside neurons and look at their ion channels. These are the channels that allow neurons to communicate with other neurons,” explains Charbon. “And you can basically see the amount of calcium that is present. You can probe optically how neurons communicate with other neurons just by looking at the concentrations of calcium in real time.”
The scientists can use the OGB-1 to indicate the presence and concentration of calcium, and the process can be recorded in ultra-fine detail thanks to single-photon detectors, such as the ones present in the Megaframe camera.“Biomedical scientists could, in principle, use this microscopic information about calcium to learn about macroscopic conditions such as Parkinson’s, Alzheimer’s or epilepsy,” Charbon says.
But that’s just the beginning. According to the researchers, the Megaframe project could benefit any medical science that relies on visible light emissive scanning technologies such as FLIM. In addition, it could also be used where visible light is not present. Other applications currently under exploration by Megaframe scientists include intracellular DNA sequencing and proteomics, two techniques for drug discovery, as well as basic scientific research for gene sequencing and protein-folding.
“For example, the camera could be used to detect and display the impact of certain drugs, or certain combinations of drugs, in animal or human models,” Charbon says, adding that Megaframe researchers are currently looking at oligonucleotides, which are “very short sequences of DNA mounted directly onto the detectors for labelled and label-free monitoring of the hybridisation process.”
Other areas where Megaframe’s work could boost research include cell membrane scanning to discover which kind of bacteria is present there. The research also could be extended to look at issues such as water purity and waterborne bacteria.
Another promising technique is the combination of fluorescence imaging with magnetic resonance imaging (MRI). “In MRI, you need very strong magnetic fields in the cavity where you are performing the imaging-up to 10 Tesla. But conventional fluorescence technology won’t work in these conditions,” says Charbon.
But Megaframe’s choice of photo detector—the Single-Photon Avalanche Diode (SPAD)—has been tested successfully in fields up to 9.4 Tesla, he explains. “Thus, it can be envisaged to have a system where fluorescence-enhanced imaging and functional MRI may be used simultaneously,” Charbon explains. “This could be very useful in a number of biomedical applications, where one wants to monitor the correlation between the presence of certain molecules in organs, such as the brain, and their function.”
http://cordis.europa.eu/ictresults
