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Investigation and Monitoring of Time-varying Environments on Macro and Nano Scales

Periodic Reporting for period 2 - In Motion (Investigation and Monitoring of Time-varying Environments on Macro and Nano Scales)

Reporting period: 2020-04-01 to 2021-09-30

Detection of motion has been always a problem of high importance in many fundamental and applied disciplines. The project investigates interactions of electromagnetic waves with moving objects in the presence of cluttered and moving environment and leverage the generated new knowledge towards a set of transformative applications. Fundamental property of Maxwell’s equations scalability with respect to operation frequencies suggest considering a wide range of practically important phenomena simultaneously and exploit advantages of tools, developed across different disciplines. An extreme diversity of scenarios, dealing with objects from centimetre down to nanometre scales, share similar underlining physics. Classical diffraction of waves limits resolution in imaging and sensing applications, while a presence of multiple and moving scatterers introduce additional complexity. Wavelength-comparable moving objects of centimeter and micron sizes (separately) are monitored with GHz and optical waves, correspondingly.
In order to monitor nano-scale objects, classical diffraction limit should be surpassed. This problem, being highly important from both fundamental nano-science and applicative bio-related perspectives, requires developing novel approaches. Hereinafter, two main highly important objectives will be discussed, underlining the diversity of the research and capability of multidisciplinary tools to solve them.
- Detecting a motion without a line of sight (radio physics)
Radar systems are already integrated within safety systems, deployed in modern vehicles. It is quite clear that those elements will remain as essential parts within monitoring and controlling mechanisms, powering self-driving cars. In contrary to visible spectral range, which is used for camera monitoring, radar systems utilize centimeter and millimeter waves for active detection. Automotive Radars provide solutions to scenarios, where camera technologies fail. Multipath interference and demand of having a direct line of sight to a target can significantly degrade performances of short-range radars, operating in a cluttered environment (urban, for example). A hypothetical scenario is a pedestrian or a cyclist, crossing a road behind a parked vehicle. In this case, a driver has less than a second to react. Hence, developing an alarming system, capable to assist a driver, is a matter of life.
During the first part of the project we have developed a new of a kind system, capable to detect objects without a line of sight. The summary appears in Nature Communications 10 (1), 1423 (2019) and a patent was licensed.
- Detecting biological activity at nanoscale (optics)
The fast-changing and evolving landscape of biomedical challenges motivates continued development of new functional platforms. Implantable devices made from biocompatible materials, capable of responding to optical signals, and tailoring propagation of light waves can be employed in health monitoring applications and therapeutics. Incorporation of such elements into living tissue can boost light–tissue interactions and shift conventional approaches toward precision medicine by opening new opportunities in sensing, photothermal therapy, photoacoustic tomography, and bioimaging. One of the grand challenges on those pathways is the miniaturization of biocompatible photonic structures along with providing multifunctionality, such as monitoring of vital biological processes, light-responsive drug release, or local heating of a nanoscale area with the simultaneous measurement of its temperature.
During the first part of the project we have developed a new material platform for theranostic applications and tools for mechanical manipulation of our functional drug delivery capsules on micro and nanoscales. Those capabilities paves a way to precise control over biological processes on a cell level, which are essential for developing new biomedical devices.
The summary appears in Advanced Materials, 2008484 (2021) and Micromachines, 11(90) (2020).
During the first half of the project more than 20 journal manuscripts have been published. The results are organized, following work packages of the initial program.

- Detection of motion with centimeter waves (radar science)

Several novel radar systems have been developed and applied towards detection and monitoring of scenarios, which are hardly addressable with existing systems. Scenario 1 – detection of moving objects without having a line of sight in application to road safety. He have developed a concept of a partially coherent radar signal, capable to provide superior range resolution with a low bandwidth, outperforming existing systems by two orders of magnitude. Scenario 2 - another strategy to provide a road safety is to increase a radar visibility. In this endeavor we have developed several beacons, which increased radar returns by orders of magnitude. Being physically small, our miniature super scatteres have radar cross sections, similar to big vehicles. It means, that a small object in a pocket can significantly increase a pedestrian visibility, assisting a driver to avoid an accident.

- Controlling a motion of micsocale objects

In order to study biological processes on a cell level, mechanical control over a motion is essential. While immobilizing a cell on a substrate can provide a partial solution, maintaining a natural fluid environment is important in numerous studies. In order to achieve mechanical control over a cell’s motion, we use focused laser beams - optical tweezers. This approach is extremely important in biological science and a Nobel Prize was awarded to A. Ashkin at 2018 for this discovery. Our research comes to address the problem of phototoxicity and phtodamage, which can emerge if a cell is directly illuminated with a laser beam, as it is typically done. In particular, with the aid of additive manufacturing, we have developed new generation of optomechanical swimmers, which can clamp a cell and manipulate it almost on demand. Those swimmers, in fact, act as a surgeon hands on a microscale, capable to provide a mechanical control over a patient (a cell).

- Investigation of nanoscale motion

Control and monitoring of nanoscale events are extremely challenging, since those processes cannot be investigated by means of classical optical microscopy owing to diffraction limits. High resolution tools, e.g. scanning electron microscopy, do exist, but are extremely invasive and harmful for biological activities. In order to investigate the motion of nano-scale colloids with an outlook to biological processes, we have developed two noninvasive approaches – (i) quantum sensing and (ii) nanostructured substrates. The key idea of the first approach is to utilize quantum correlation of light, on which mechanical motion is imprinted. Careful analysis of light statistics allows extracting an information on velocities and turbulent nature of a fluid around a nanoparticle. The second approach is to design nanostructured surfaces, which allow tailoring optomechnical motion of nano-scale particles. In a sharp contrast to classical optical tweezers, subject to the diffraction limit, our approach allows controlling nanoscale particles and even assemble several nano-objects together, paving a way for controllable nanoscale interactions, driven by light.
The majority of the results are published in high impact journals, demanding a novelty beyond the existing state of the art.

During the implementation of the project we have developed a new direction, related to wireless technologies and, in fact, established a new direction in the field.

- Long-range ceramic RFID

Radio frequency identification (RFID) is a widely used technique for noncontact data readout via a wireless communication channel. RFID elements are widely employed in warehouses logistics, billing systems, as biometric identifiers and in many other applications. Mature technology allows introducing RFID tags almost everywhere and tailors their electromagnetic design per application. While communication protocols in RFID communications are subject to international regulations, hardware realizations keep advancing, targeting different specifications in their niches. A scenario, which we would like to consider hereinafter, is inspired by the Internet of Small Things. In this paradigm, each low-cost item is marked by a passive RFID tag, which can be interrogated by a reader from a distance. Having severe cost limitations, this approach requires using small footprint passive tags, which should also be accessible from a reasonable several-meters distance and without any preliminary knowledge on object’s orientation in space. Those specifications, being considered simultaneously, seemingly contradict each other, challenging commonly used design approaches.
During the last year we have developed and experimentally demonstrated a new approach, where high-index ceramic resonator serves the function of RFID tag antenna. Being capable to accommodate several resonances within a small cavity volume, ceramic elements were designed to provide 10-20 meters detection range of the passive RFID channel, paving a way to new Internet of Small Things applications.
Nanobotanics - flowers generating nanoparticles
Bioimaging of cells with nanoscale drug delivery capsules inside
Partially Coherent Radar
Optomechanically driven micromachine for cell manipulation
Golden Vaterite - novel meta-particle for theranostic applications