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D3.2 Report about the printed the geotracking flexible tag - EXECUTIVE SUMMARY

Deliverable 3.2 reports results related to T3.2- Smart geotracking flexible tag from WP3. The objective of this task is to build the full demonstrator of the geotracking tag and demonstrate its functionality at lab scale. the geotracking tag comprises a flexible foil based on nanocellulose with a combination of printed antennas, including Ultra High Frequency and Ultra Wide Band antennas, and a small rigid multipoint control unit part (MCU). Both the flexible foil and the rigid MCU are fully integrated through an overmoulding process using a flexible thermoplastic material such as Thermoplastic Polyurethane (TPU). Unlike conventional tags based on Printed Circuit Board (PCB) with a protective casing, the proposed tag overcomes limitations related to the shape and surface material of the objects to be tracked. It is designed to be attached to objects such as tools, vehicles, and parts in assembly lines that can have curved surfaces.

The key innovation of the tag lies in its fabrication using In-Mould Electronics (IME) which combines the functional printing of electronics and the hybridization of electronic components with traditional plastic transformation processes, such as injection moulding. In the case discussed in this study, IME processing is applied over printed antennas on nanocullose substrate developed by Fedrigoni/Arjowiggins with a directly hybridized rigid control module. Both elements are then protected by an over-moulded flexible layer of TPU.

The antennas are printed by screen printing with the customized Ag nanoparticle-based ink developed by Genesink (GNK), and the assembly of the MCU is optimized by Pick&Place equipment. The control circuit has been designed by Uwinloc/Apitrak (UWL) using all electrical specifications. A pre-series of 40 units has been prepared for validation activities. UWL has tested the quality of the printed antennas in the first stage, followed by a design of secure communication protocols in the second stage. The data transfer from the tag to the beacon is secured by the data characteristics, including a low transmitted signal's power and information transmitted at a very low level.

The functionality of the injected tags has been confirmed with a laboratory setup, positioning them less than 1 meter away from an energy source and a beacon. Furthermore, the stability of the injected tags (non-functional) upon exposure to 90% RH and 50 ºC for 300 h has been assessed in a climate chamber.

While the module is functioning as expected, the energy harvesting performance is not yet equivalent to that of the standard PCB-based TAG. Further statistical analysis must be performed to verify if this is consistent over multiple modules (and hence points out a flaw in the antenna design, that can then be corrected) or if it is due to a variation in the production process (requiring a tighter quality control).

By analysing the all the test, we were able to identify critical points for improvement and guidelines to help ensure successful manufacturing of in-mould tags in future projects.

1. Encapsulation of components: Encapsulation is essential to provide adequate protection of fragile components like quartz crystals, which are particularly vulnerable to damage during the injection process.
2. Injection parameters: injection parameters should be optimized to minimize injection pressure, which can damage the control unit assembly components, particularly the quartz crystal.

3. MCU design: MCU design should be optimized to ensure proper alignment and contact of the MCU pads with the printed antennas, preferably using SMD pads instead of side vias channels.
4. MCU components selection: fragile components like the quartz crystal should be avoided whenever possible to reduce the risk of failure during injection process.

By following these guidelines, manufacturers can improve the yield of in-mould tag production, resulting in more functional and reliable products.
We have effectively established the feasibility of producing functional in-mould tags. Nonetheless, additional research is needed to assess the compatibility of crucial components like quartz crystals with the injection moulding process. If incompatibility issues arise, it will be necessary to explore alternative circuit designs and components to ensure successful production of in-mould tags.