Over the years, motion pictures have developed remarkably, offering us more realistic video clips than the choppy and hazy ones in the past. This change is accredited to the development of image technology over the time, starting with the 19th-century Lumiere brothers’ modest 16 frames per second (FPS) video and progressing to immersive gaming settings with 150 FPS. But the actual question is whether we can use this technology to photograph and comprehend the very microscopic processes that go on within the human body, such as the firing of neurons in the brain, besides using it for entertainment.
Recently, the Photonics and Quantum Enabled Sensing Technology Lab, located at the Indian Institute of Technology, Bombay, has taken a novel step by utilising the capabilities of a specialised high FPS camera to obtain time-changing or “dynamic” images of extremely weak magnetic fields that are typical of those found in neurons.
They claim to research the internal anatomy of the human brain using neuroimaging methods like magnetic resonance imaging (MRI), magneto encephalography (MEG), and functional magnetic resonance imaging (FMRI). With the aid of these methods, researchers can examine particular brain activities by measuring electromagnetic signals that give an overview of combined cell activity. Additionally, because these signals were weak, the technologies used to detect those required large, extremely potent magnets.
In order to create extremely sensitive, atomic-size magnetometers that can map magnetic fields at such low physical scales, the researchers take advantage of the special characteristics of NV centres.
The magnetic fields in neurons fluctuate at a rate that is too fast for the current NV-based magnetometers to measure. Any change occurring faster than that can only be recorded as a snapshot since high-resolution photographs from the current generation of NV magnetometers must be taken between a few minutes and many hours. This research team of Prof. Saha are the first researchers to present an innovative and experimentally effective approach that decreases acquisition times from several minutes per frame to an order of 100 FPS by incorporating a specialised, easily accessible “lock-in” camera into a magnetic field microscope configuration. It has never happened before in history that sub-second magnetic field microscopy has been demonstrated globally using this method.
A very thin microscopic wire (also known as a “microwire”) and a microscopic coil of wire (also known as a “micro coil”) were used as the two types of magnetic field sources in the experiment’s setup. By modulating NV centre spins with microwave frequencies that fluctuate over a millisecond time period, they produce fluctuation in the magnetic field. Low-light photoluminescence is produced as a result of the interaction in the NV defect centre within the diamond crystal layer, which captures this quickly shifting magnetic field.
Therefore, NV-based microscopes have the potential to be an effective substitute technology for assessing mammalian brain activity. The core of the future new subject of “Quantum sensing” is such a method of improving the precision of sensing electromagnetic fields at the tiny level, using quantum characteristics of atomic constituents.