Nano loudspeakers could lead to cooler, quieter, more compact MRIs

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Physicists from the Joint Quantum Institute (JQI), a collaborative venture of the National Institute of Standards and Technology (NIST) and the University of Maryland, have developed a theory that uses a nanomechanical membrane like a nano-sized loudspeaker to detect weak electrical signals and cool electrical circuits used in MRI.

The membrane would be coupled to an electrical circuit and an electrical signal, even a faint one, will cause the membrane to quiver based on the strength of the signal.

"We can then bounce photons from a laser off that membrane and read the signal by measuring the modulation of the reflected light as it is shifted by the motion of the membrane. This leads to a change in the wavelength of the light," explained Jake M. Taylor, PhD, physicist at JQI.

Present technology for measuring the wavelength of light is highly sensitive, which makes it ideal for detecting the nanoscopic motions of the loudspeaker caused by extremely faint electrical signals. The ability to detect these electrical signals may someday make MRI procedures much easier.

"MRI machines are so big because they are stuffed with really powerful superconducting magnets, but if we can reduce the strength of the signals we need for a reading, we can reduce the strength, and the size, of the magnets," said Taylor. "This may mean that one could get an MRI while sitting quietly in a room and forgo the tube."

According to their calculations, the researchers said a side effect of the process would be the loss of a considerable amount of heat from the system, from room temperature to -270 C. This cooling would in turn reduce noise in the system and provide for better signal detection.