Flexible InteligenT NEar-field Sensing Skins

Project Information

FITNESS

Grant agreement ID: 101098996

DOI

10.3030/101098996

EC signature date 19 January 2023

Start date 1 April 2023

End date 31 March 2027

Funded under

• The European Innovation Council (EIC)

Total cost

€ 3 603 992,00

EU contribution

€ 3 603 992,00

Coordinated by

UNIVERSITE CATHOLIQUE DE LOUVAIN
Belgium

Periodic Reporting for period 1 - FITNESS (Flexible InteligenT NEar-field Sensing Skins)

Reporting period: 2023-04-01 to 2024-03-31

Summary of the context and overall objectives of the project

The vision of FITNESS project consists of redefining the sense of ‘touch’ of devices, leading to a transformation in safe and efficient human-device interaction. This is enabled by measuring disturbances in the ‘near field’ of advanced electromagnetic metasurfaces (MTSs) which can also be used for ‘far field’ communications. The obtained ultra-low power smart thin skins can help humans transcend physical limits. The thin surface can be curved and stretched and will be made of new low-loss polymers developed within FITNESS, which will be functionally textured. The strength of the detection signal will be inversely proportional to the distance between the sensing surface and the object to be detected, while also providing good 3D localization of the object.

The same technology can also be used for long-distance communication and detection (from a few meters on). These radically new surfaces will outperform the current bulky, costly and non-conformal sensing technologies provided by radar, infrared sensors and cameras. Due attention will be paid to integration of electronic components and to heat dissipation.

The enabling technology essentially corresponds to MTSs. Those surfaces look like a printed-circuit board; they have a ground plane, a thin dielectric layer (yellow in Fig. 1) and, printed on top of it, a large number of subwavelength metallic patches (orange dashed), which can be modelled as a surface reactance. A pin-feed excites an electromagnetic surface wave (SW) and the launched SW becomes a leaky wave (LW) when a modulation appears in the shape and orientation of the electrically small patches.

The final product envisioned is a thin surface covering for instance a robot (see Fig. 1) with a number of transmitting and receiving pins. The correlation between signals received at receiving pins informs about the presence and location of an object in the very-near field, through perturbation of surface waves, but it should also be able to detect objects in the far field. The latter capability will be made possible by a modulation of the MTS, allowing leaky-wave radiation.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Sensing and communication capabilities of the MTS ( Fig. 1) over both near-field and far-field ranges is an essential advantage of the proposed technology. Indeed, currently two different technologies would be necessary for near-field sensing (i.e. capacitive sensing or air-flux based detection) and for far field sensing and communication (radar and antenna arrays).

The project is organized around the following Work Packages:
1) Management
2) Sparse MTSs (reducing the number of electronic components)
3) Curved MTSs, to conform to the shape of a robot or a human
4) Integration with electronic components
5) Flexible Radio Frequency materials, based on polymers
6) Dissemination

The first deliverables concerned a number of tools for management and dissemination. An Interface Control Document (ICD) organizes the cooperation between WPs. That has been followed immediately by an exploitation plan, where the different existing solutions for near-field sensing devoted to robotics have been described and where exploitation is outlined. More recently, 3 more deliverables have been provided, regarding sparse MTSs, integration with RF correlator modules and initial design of low-loss RF polymers. Based on the exploitation plan, it has been decided to shift up the frequency from 10 GHz to 24 GHz.

The present report describes the results achieved in all WPs. In a nutshell, WP1 is management and follow-up of the project, WP2 describes the feeding of the MTS and a technique to make it sparse, which should facilitate its integration with the electronics (cf. WP4). WP3 provides modeling and results for propagation along curved MTS (extension of WP2). WP4 describes a MTS-electronics co-design methodology, based on equivalent-circuits, a first correlation experiment with a MTS (designed under WP2) validated through a direction-finding experiment, as well as analysis of thermal aspects (incl. measurements). WP5 paves the way toward the use of flexible substrates, with progress toward low-loss polymers and characterization techniques of materials, indispensable for the high-frequency MTSs foreseen in WP2. WP6 deals with communication, dissemination and exploitation of FITNESS results.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Close cooperation between WPs allowed progress toward the goals described above. In WP2 new MTS unit-cells for polymer substrates and feeders have been developed; they allow wider bandwidth and will hence be more robust against folding the MTS (WP5). WP2 also analyzed sparse arrays with a new solution, for which a patent has been filed; work is now in progress regarding 2D implementation. In parallel, WP3 anticipated the work toward curved MTSs and analysis tools have been developed regarding propagation of waves on curved grounded substrates, including a homogenized MTS impedance sheet. It has been shown that the MTS sheet allowed the use of a much thinner substrate. A more compact and physical representation of the fields has been obtained through the use of the Watson transform. In WP4, a first integration between a new MTS and receiver electronics has been carried out. With this goal, an equivalent-circuit representation of the two-port MTS has been established. An elementary correlation experiment has been carried out and has been successfully validated through a direction-finding operation. Heat dissipation has been observed through close cooperation with an external partner (Microsanj). WP5 used specifications provided from WP2 and WP4 and started printing MTS test patterns (anchor-like) on a polypropylene substrate with unexpectedly good adherence results; stretching and pattern deformation issues still need to be solved. Materials provided by our Chemistry partner have been tested by other partners; a shift from block-copolymers toward hybrid copolymers is now going on with the goal of achieving both lows loss and high flexibility. To conclude, good mutual exchange of specifications took place between partners and good initial results pave the way toward integrated demonstrators of the FITNESS technology. The preliminary results of the project have already been showcased by our industrial partner at several conferences.

Figure describing the different layers of the envisioned MTS