During the first period of InComEss project, the attention was centered on the screening of materials and the definition of KPIs. The boundaries/conditions for each use-case and specific sensor were also addressed.
During the first and second period, research efforts were focused on the development and characterization of novel smart materials: high-performance polymer based lead-free piezoelectric materials and new thermoelectric materials based on carbon/thermoplastic composites free of rare-earth. Different piezoelectric and thermoelectric generators (PEG, TEG) were fabricated and characterised at lab-scale and supported by theoretical simulations. Regarding the energy storage developments, carbon and conductive polymer and carbon-based electrode supercapacitors were investigated and developed by Screen-printing. Carbon-based supercapacitors were also developed and scaled up by Roll-to-Roll process.
From the power management side, successful power conditioning circuits (PCC) were specifically developed to match each type of generator, connection to supercapacitor and wireless sensor nodes (WSN). A miniaturised Fibre Optic Sensors (FOS) interrogator with reduced energy consumption, Wireless MEMS nodes were developed and optimized together with an IoT platform.
During the last period the attention was centered on the demonstration phase. It has been seen that:
• The InComEss PEG and TEG prototypes developed in the project have demonstrated their ability to generate electricity upon mechanical vibrations and temperature differences, but their power output was not sufficient to PCC/electronics neither the sensors selected for each use-case. The performances of the InComEss prototypes are still far away from the commercial solutions (based on lead and rare-earth). Because of this, commercial solutions were investigated in parallel.
• In the Aeronautic demo, the tests performed have validated the functioning of powered WSN by PEG. This was achieved by harvesting the available mechanical vibrations of the wing slat (with a lead-based PEG) which was able to power the PCC, the interrogator and FOS and transmit data to an IoT platform. Each 2 minutes the IoT platform received temperature data (read by the FOS) of a slat composite laminate skin.
• The Automotive use-case also demonstrated the reliability of powering WSN by TEG. It was possible to harvest the thermal waste on the vehicle’s exhaust system (by using an inorganic TEG) to power fuel level WSN and data monitoring through an IoT platform. The influence of vehicle working condition/ driving modes on the exhaust gas mass flow and temperature difference on the TEG were studied observing the data of fuel level sensor each 1.5-2 minutes.
• The building demo has demonstrated the potential to include FOS in a façade envelope for Structural Health Monitoring. However, the demonstration of the piezoelectric generators (lead-based) failed during the tests of impact, rain, and wind observing the generated output power was not enough for feeding the conditioner circuit and electronics. Further research is needed regarding the frequency vibrations to excite the piezoelectric generator.
Moreover, it is important to highlight that besides that further improvements of developed energy generator/prototypes' efficiency are needed, it is key also to investigate other sensors/WSN and other communication protocols with much lower energy consumption for implementing new lead-free piezoelectrics and rare-earth free thermoelectrics with the aim of feeding sensors and data monitoring.
