Just from the abstract it seems like this could be defeated by spy camera manufacturers by placing a Faraday cage around the camera components. It looks like they acknowledge that under Limitations:
> The latest smartphones employ low-power DDR techniques [49][50] and integrate Faraday cages internally to mitigate electromagnetic radiation (EMR) leakage [51]. The combination of the two measures significantly increase difficulty to detect smart- phone cameras’ memory EMRs using the current ESauron prototype.
Spray-on inks are targeting package-level EMI shielding.. Jetted inks are also being proposed for in-package EMI isolation between individual dies in a multi-die package especially for high-frequency devices. Some suppliers propose micron-sized, prioritising cost and maturity. Flat flakes offer higher conductivity if aligned well. Others develop nano or even particle-free inks, offering the thinnest solution.. Most offer a hybrid solution, siting somewhere between full nano to full micro and full spherical to full flake.. Some.. mechanisms to fine-tune layer thickness post-deposition to locally boost performance in EMI hotspots.
> The latest smartphones employ low-power DDR techniques [49][50] and integrate Faraday cages internally to mitigate electromagnetic radiation (EMR) leakage [51]. The combination of the two measures significantly increase difficulty to detect smart- phone cameras’ memory EMRs using the current ESauron prototype.