A new avenue for microenergy sources in autonomous sensors?
Modern vehicles connected to the IoT typically require large numbers of sensors, and these sensors need a reliable supply of power. We spoke to Professor Ausrine Bartasyte, Associate Professor Samuel Margueron and Doctor Giacomo Clementi about European ITN ENHANCE project’s work in developing piezoelectric energy harvesters that could reduce the environmental impact of the automotive and information sector. The autonomous cars, trucks and other
Lead-free Piezoelectric materials
vehicles of the future, which are expected to the market after 2025, will require a large number of sensors, for example in speaker systems, parking aids or temperature/pressure sensors. Sensors will also be required for systems in the infrastructure and environment to enable the vehicle to communicate with surrounding objects. All these sensors and systems require energy sources. The different systems inside a car are typically connected by large amounts of wiring, greatly adding to the overall weight and complexity of the vehicle. “There may be more than 2 kilometres of wiring inside a car,” says Giacomo Clementi, a researcher at the FEMTOST Institute in Besancon, France. After completing his PhD as an early stage researcher (ESR) in the ENHANCE project, an initiative bringing together academic and industrial partners from across Europe, Clementi is now working to develop hybrid energy harvesters which will address these issues and help reduce the environmental impact of the automotive sector. “Our idea in the project is to reduce the wiring cost and the complexity of cars. At the same time, reductions in the weight of the car will also lead to reduced CO2 emissions,” he explains. The ENHANCE project itself is an Innovative Training Network (ITN), which provides training to ESRs across a range of disciplines, including chemistry, physics and electronics. This reflects the complexity of the project’s work in developing a complete energy harvesting
Clementi’s primary focus is on vibrational energy harvesting, so converting mechanical energy from the environment into electrical energy, which can then be stored or used to power small wireless sensors inside a vehicle. Piezoelectric materials, which have an internal electric charge, hold great potential in this respect. “When piezoelectric materials are essentially shocked or deformed by mechanical stress, due to their intrinsic atomic structure, they can convert this deformation into an electrical charge. That charge can then be stored in a battery, or used immediately to power a sensor,” outlines Clementi. Researchers are seeking to replace commonly used lead-based piezoelectric ceramics, prohibited under EU regulations since 2016, with environmentally-friendly piezoelectric materials offering competitive performance, in particular a piezoelectric material called lithium niobate (LiNbO3). “I am studying the microfabrication of this material and its application in vibrational energy harvesting,” says Clementi. “This finds applications not only in transportation, but also in areas like smart buildings, factory automation, internet of things (IoT) and structural health monitoring.” In the frame of ENHANCE project, it was demonstrated that LiNbO3 implemented in vibrational energy harvesters offers
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Micro-energy harvesting team at Institute FEMTOST: Merieme Ouhabaz, Giacomo Clementi, Mario Constanza, Samuel Margueron, Ausrine Bartasyte and Bernard Dulmet (from left to right).
system. “We are taking a multi-disciplinary approach, starting from the material and finishing with the electronics. We’re not focusing on just one part, we’re looking at the complete system,” says Professor Ausrine Bartasyte, Deputy Director of the FEMTO-ST Institute and the coordinator of the project. The ESRs are also receiving training in ‘soft’ skills, such as how to write presentations or apply for research funding, which will help prepare them for their future careers, whether in academia or industry. “We organised schools, workshops and conferences covering topics from chemistry and physics, to electronics to micro and nano-technology, as well as soft skills,” outlines Professor Bartasyte.
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