Tricorders & Sensors

Tricorder Tech: Quantum Sensing In Your Pocket

By Keith Cowing

April 26, 2023

Filed under quantum sensing, smartphone, tricorder

Tricorder Tech: Quantum Sensing In Your Pocket — An illustration of the spatially-resolved ODMR (optically detected magnetic resonance) system for magnetic field imaging. CREDIT Exciton Science

Editor’s note: If you have seen a Tricorder on Star Trek then you know it pretty much answers a wide range of questions. It tells you about the planet you are on, what life forms may or may not be there, and if need, be how your body is doing as you walk around on a strange new world. That’s a lot of computation and senor capability in a small package. But if you are on an Astrobiology Away Team you might just want to have things like this. According to one of the researchers: “You could imagine using this technology being added to smartphones to help with remote medical diagnostics, or identifying defects in materials.”

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Smartphones could one day become portable quantum sensors thanks to a new chip-scale approach that uses organic light-emitting diodes (OLEDs) to image magnetic fields.

Researchers from the ARC Centre of Excellence in Exciton Science at UNSW Sydney have demonstrated that OLEDs, a type of semiconductor material commonly found in flat-screen televisions, smartphone screens and other digital displays, can be used to map magnetic fields using magnetic resonance.

Sensing of magnetic fields has important applications in scientific research, industry and medicine.

Published in the prestigious journal Nature Communications, this technique is able to function at microchip scale and – unlike other common approaches – does not require input from a laser.

The majority of existing quantum sensing and magnetic field imaging equipment is relatively large and expensive, requiring either optical pumping (from a high-powered laser) or very low cryogenic temperatures. This limits the device integration potential and commercial scalability of such approaches.

By contrast, the OLED sensing device prototyped in this work would ultimately be small, flexible and mass-producible.

The techniques involved in achieving this are electrically detected magnetic resonance (EDMR) and optically detected magnetic resonance (ODMR). This is achieved using a camera and microwave electronics to optically detect magnetic resonance, the same physics which enables Magnetic Resonance Imaging (MRI).

Using OLEDs for EDMR and ODMR depends on correctly harnessing the spin behaviour of electrons when they are in proximity to magnetic fields.

OLEDs, which are highly sensitive to magnetic fields, are already found in mass-produced electronics like televisions and smartphones, making them an attractive prospect for commercial development in new technologies.

a Sketch of the set-up for spatially resolved ODMR. The inset shows the image of EL intensity captured by the sCMOS camera. The B field arrow represents the magnetic field gradient across the OLED along x-direction in the horizontal 𝑥−𝑦 plane. b Scheme of pixel binning where 𝑛 × 𝑛 adjacent camera pixels are merged into one combined pixel called “super-pixel” via pixel binning process. The optical signal (EL intensity) of each super-pixel is the average of the signals of all the 𝑛 × 𝑛 individual camera pixels. c Double Gaussian fits of ODMR spectrums of two super-pixels with binning size 𝑛 = 3. Super-pixel 1 and super-pixel 2 corresponds to the super-pixel at position of (−63.4 µm, 0.0 µm) and (52.4 µm, 0.0 µm) in d, respectively. The solid circle dots label out the resonant peak position in the fit curves. d 2D spatial map of the resonance frequency (𝑓ODMR ) of the ODMR spectrums of 166 × 166 super-pixels with binning size 𝑛 = 3. The entire region contains 500 × 500 camera pixels, and the super-pixel size is about 0.91(5) × 0.91(5) µm (𝑛 = 3). Weak EL signal is also observed outside the defined area of the OLED due to the high hole conductivity of the PEDOT:PSS thin film. This provides the ODMR spectrums across the entire region. e The most left figure (𝑛 = 3) shows a zoom-in view of a sub-region (10 × 10 super-pixels) of the 2D map in d, which is marked by the yellow dash square in d. The 𝑥−𝑦 coordinates in e are consistent with that in d. The rest four figures in e show the spatial map of the magnetic field in the same sub-region but with different binning sizes. – Nature Communications

Professor Dane McCamey of UNSW, who is also an Exciton Science Chief Investigator, said: “Our device is designed to be compatible with commercially available OLED technologies, providing the unique ability to map magnetic ﬁeld over a large area or even a curved surface.

“You could imagine using this technology being added to smartphones to help with remote medical diagnostics, or identifying defects in materials.”

First author Dr Rugang Geng of UNSW and Exciton Science added: “While our study demonstrates a clear technology pathway, more work will be required to increase the sensitivity and readout times.”

Professor McCamey said that a patent has been filed (Australian Patent Application 2022901738) with a view toward potential commercialisation of the technology.

Sub-micron spin-based magnetic field imaging with an organic light emitting diode, Nature Communications (open access)

Astrobiology

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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