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D3.3 Report about the biometric photosensor - EXECUTIVE SUMMARY

Deliverable 3.3 presents the results of task T3.3 – Biometric photosensor from WP3, focusing on the objective of building a complete demonstrator of the fingerprint sensor and demonstrate its functionality at the laboratory scale. The deliverable focuses on the materials and plastic processing, encapsulation strategies, and performance analysis.

Regarding the manufacturing parts, the fingerprint sensor comprises a fully printed photodetector frontplane that utilizes MADRAS' advanced materials as electrodes and transport layers and the cutting-edge PM6 donor polymer and DTY6 non-fullerene acceptor molecule as photoactive materials. The frontplane composed by PM6:DTY6/PEDOT:PSS:WO3/Ag NW stack is printed on top of a TFT backplane based on IGZO. The hole transport layer (HTL) and transparent conductive electrode (TCE) are developed inks provided by MADRAS partners, specifically University of Pardubice (UPA) and Genesink (GNK).

The frontplane is printed on top of a TFT backplane. This setup allows the reader to scan and identify users' fingerprints using an optical imaging component. Furthermore, the signal captured by the photosensors is digitally treated to extract additional biometric data such as heart rate.

To ensure protection against moisture and mechanical stress, we have applied thin film encapsulation and hardcoat layers. These layers have undergone climate chamber stress testing of 300 hours at both 50ºC and 90ºC. Additionally, by employing a screen-printed thin film hardcoat layer, we have achieved mechanical protection without compromising imaging resolution.
We have successfully laminated the PI foil, which serves as the substrate for device manufacturing, transitioning it from a glass substrate to a plastic one. Subsequently, chip bonding was carried out. However, our attempts to thermoform the fingerprint sensor into the desired pyramid shape were not entirely satisfactory. Unfortunately, due to the absence of functional fingerprint sensors on foil, a comprehensive analysis of the impact of imperfections on fingerprint functionality could not be fully assessed. Nonetheless, we have successfully demonstrated the feasibility of thermoforming thin film electronics on thin PI substrates, although it is important to consider the limitations imposed by potential mould designs.

While we extensively investigated the plastic processing steps, we were unable to thermoform and inject mould the actual fingerprint sensors on foil and integrate them into a 3D part for the scooter. Consequently, the validation of the fingerprint reader has been conducted using a functional fingerprint sensor on glass.

Subsequently, the deliverable addresses the integration of the fingerprint reader with an electronic unit, a readout software, and an authentication software. The sensor's capability to accurately scan and identify users' fingerprints has been demonstrated. Additionally, an initial penetration test has been conducted to assess the system's resilience against potential security gaps. The results show that 75% of the security requirements are covered. A list of actions has been proposed to increase this percentage in the second assessment that will be reported in D4.3.