If current production and waste management trends continue, it is projected that roughly 12 billion metric tons of plastic waste will be in landfills or in the natural environment by 2050. Plastics represent a significant environmental problem: They are for the most part not biodegradable, cause problems for terrestrial and aquatic life, and enter the food chain in the form of microplastics. A shift towards a circular economy has been proposed to meet these challenges, in which production, circulation and consumption do not leave behind negative footprints and do not deplete natural resources. An essential component in the transition to a circular economy involves turning waste into value, thereby giving incentives to reduce, reuse and recycle. Simplified and low-cost methods of sorting materials are currently making a great impact on the environment: It is estimated that the reverse vending machines of the company TOMRA alone capture 35 billion beverage containers every year, and thereby reduce greenhouse gas emissions by an equivalent of 2 million cars driving 10’000km annually.
Photonic sensors are ideally suited for material sorting due to the spectroscopy technique, which allows for discrimination between different polymer types by illuminating with near infrared electromagnetic fields and measuring absorption. An important development goal is to make such spectroscopy simple, affordable and energy efficient.

The ElastoMETA project aims to design and fabricate functional nanostructured surfaces, known as metasurfaces, to meet these goals. These surfaces contain simple subwavelength nano-structures that can shape light which is transmitted through them. Despite their simplicity, they offer a new paradigm for advanced field manipulation due to unprecedented control of phase, polarization, amplitude and dispersion of the electromagnetic fields. The versatility of this approach is evident by the short time during which numerous realizations have been made: e.g. micro-lenses, filters, couplers, emitters and even holograms. With further development, metasurfaces are expected to have several advantages over existing optical sensor technologies for recycling applications (e.g. diffractive optics), in terms of (i) increased efficiency, (ii) relative ease of fabrication, and (iii) enhanced functionality.

The ElastoMETA project aims to develop designs and cost-effective nanostructuring processes for (a) tuneable, filtering and efficient lens designs, and (b) directional infrared emitters, for plastic detection. These developments are central to improving the efficiency and functionality of a spectroscopic microsensor for a circular economy. To this end ElastoMETA combines:

Romanian expertise in:

UV-nanoimprint : National R&D Institute of Materials Physics (INCDFM)

Electron beam lithography : National R&D Institute in Microtechnology (IMT)

Theoretical photonics : University of Bucharest (UB)

with Norwegian expertise

at SINTEF Microsystems and Nanotechnology (SINTEF MiNaLab) in developing micro-optical sensor devices for industrial plastic and gas detection.

This new long-term strategic partnership aims to bring developments at the forefront of photonics and nanotechnology towards commercial sensor applications for a competitive Romanian and Norwegian industry within the circular economy.

ElastoMETA demands close collaboration of the Romanian and Norwegian partners on interdisciplinary and interrelated work, related to i) design and simulation of functional structures acting as tunable, filtering lenses and directional sources, 2) process development using electron beam lithography for design verification, 3) UV nanoimprint lithography for cost effective nanostructuring of large area lenses, 4) embedding structures in elastomeric substrates to allow for mechanical tuneability 5) optical characterization and testing of the manufactured structures and 6) dissemination and evaluation of the project.