PILLAR 1 - ENERGY RECOVERY AND STORAGE
Laboratories : UMET, L2EP, Gemtex, IEMN
Lead researchers : Sophie Barrau, Frédéric Giraud, François Rault, Aurélie Cayla, Kamal Lmimouni
Other participants : Jean-François Brun, Corinne Binet, L. Burgnies, Cédric Cochrane
Technical support : Jean-Francois Tahon, Adeline Marin, Ahmed Addad, D. Guerin, F. Dassonville, E. Gonthier
The global demand for energy continues to rise, and to avoid excessive proliferation, part of the solution lies in combating energy waste. There are abundant opportunities for untapped energy sources: mechanical, thermal, electromagnetic, solar, and more.
We can enhance the energy efficiency of systems through controlled management that requires interconnected sensors. For example, converting all lost energy (regardless of its nature) into electricity could power the sensors. Energy recovery and conversion are versatile concepts that apply to a wide range of needs, from powering thousands of households to small-scale devices consuming only a few milliwatts (mW) or less, such as miniaturized radio receivers, RFID chips, hearing aids, various sensors, and more.
While energy recovery from large sources is widely practiced today, one of the current challenges is achieving energy autonomy for portable and self-powered devices (without wires and without maintenance intervention). This includes wireless sensors that can be powered with less than 10 μW of power, thus requiring the use of micro-harvesting.
Mechanical energy sources are ubiquitous, offering innovative energy conversion opportunities!
Piezoelectricity enables the collection of mechanical energy generated by vibrations and movements of the human body. Thermoelectricity, on the other hand, explores the conversion of heat into electricity. Finally, electromagnetic waves, naturally emitted or generated by controlled transmitters, can be transformed into electrical energy. These complementary energy sources have promising applications, particularly in smart textiles, paving the way for self-powered and advanced integrated devices.
The different energy sources
Mechanical Energy - Piezoelectricity
For example, the available power for a volume of 1 cm3 is approximately 100 μW for vibrations and between 1 and 10 mW for human body movements (arms, legs, heels). Piezoelectricity is a conventional conversion technique used to collect this mechanical energy. The principle involves the emergence of a potential difference between two faces of a piezoelectric material subjected to deformation.
Thermal Energy - Thermoelectricity
In the case of converting heat into electricity, thermoelectricity shows promise. Based on the Seebeck effect, it manifests as a potential difference at the junction of two materials subjected to a temperature gradient. The generated electrical power depends on the materials used, the magnitude of the gradient, and the temperature range at which it occurs. Currently, the focus is on temperatures ranging from ambient to 100°C. It is a temperature range in which known thermoelectric materials are not very efficient, but can typically generate 10 µW with a temperature gradient of around 50°C for a device surface area of a few cm2.
Electromagnetic Waves
Electromagnetic waves are naturally and periodically emitted, for example, by the sun. They can also be generated through the utilization of various controlled transmitters (cell phones, Wi-Fi access points, etc.).
Micrometer waves from solar radiation can be converted into electrical energy through different types of solar cells (inorganic, organic, etc.). These cells exhibit varying performance levels depending on their stability, conversion efficiency, and manufacturing processes, which directly impact their final cost.
The conversion of electromagnetic energy from radio-frequency (RF) waves into electrical energy is accomplished through rectifying antennas (or rectennas). The available electrical power to power targeted devices depends on several factors, including the source (Bluetooth, Wi-Fi, etc.), the environment, and more.
Networking rectifying antennas allows for an increase in the amount of collected energy. Similarly, the concept of metasurfaces achieved by structuring a metallic surface incorporating rectifying electronics (diodes) is being considered to enhance the collection of electromagnetic energy. The power levels available in Wi-Fi technology appear suitable for low-power wireless sensors: 20 µW under typical conditions and up to 100 µW under extreme conditions. However, ambient electromagnetic energy varies based on the number of connections.
As a result, electromagnetic sources complement other energy sources, and comprehensive management of different energies is necessary.
Applications
In terms of applications, smart textiles are excellent candidates for utilizing various energy conversion methods (piezoelectricity, thermoelectricity, electromagnetic waves).
Smart textiles have been the subject of interesting research for years, aiming to develop portable and self-powered devices. Until now, energy converters were simply added to the textile, with the textile primarily serving as a support. In the future, the level of integration of these elements will be improved so that the textile structure itself participates in the energy conversion from multiple sources. Although textiles, particularly due to their specific usage requirements, may introduce certain constraints, they offer great potential in terms of multi-scale approaches (nano, micro, macro) and structures (2D, 3D).
The recovered mechanical, thermal, and electromagnetic energy from films or textiles is then converted and managed by a microcontroller to power
Electromagnetic waves are generated by a rectenna antenna, thermal energy by a thermoelectric effect and mechanical energy by a piezoelectric effect. These three sources are collected on films or textiles before passing through a microcontroller, which converts them to power various devices in the form of sensors that can be integrated into the textile. The illustration shows the various stages in this process: first recovery, then electrical conversion, followed by storage, application via a microcontroller and, finally, the integration into sensors.
In this context, self-powering sensors through a single- or multi-source approach is a challenge in terms of autonomy. Teams from the four Lille laboratories, UMET, IEMN, GEMTEX, and L2EP, have collaborated to develop autonomous sensors (integrated or not in textiles) powered by the recovery of mechanical energy (piezoelectric effect), thermal energy (thermoelectric effect), or electromagnetic waves (RF). The expertise of these four laboratories is complementary and covers a wide spectrum, ranging from materials and structures to energy recovery systems and device power supply.
Among the flagship projects associated with this first pillar, it is worth mentionning:
- The ANR PRC NanoPiC (2016-2021) "Study of Multi-scale Piezoelectric Behavior of Micro- and Nano-Structured Innovative Composites" (coordinated by S. Barrau - UMET), aiming to manufacture micro- and nano-structured ceramic-polymer piezoelectric composites and characterize their piezoelectric behavior at macroscopic and nanoscopic scales;
- The PIAVE AUTONOTEX project (2015-2021) "Energy Autonomy of Connected Textiles," which aims to develop and industrialize personal protective clothing and reactive and connected medical sheets. GEMTEX focuses on the development of conductive compounds, the spinning of filaments with piezoelectric properties, and the prototyping of energy harvesting textiles (utilizing the piezoelectric effect);
- The ANR CONTEXT project (2017-2022) "Connected Textiles for Communications around the Human Body," aiming to develop smart textiles integrating radiofrequency (RF) technologies and components for wireless communications between objects located in networks around the human body (WBAN). Near-field communication (NFC) technology at 13.56 MHz is employed for energy transfer between a smartphone and distant sensors. Antennas, transmission lines, and organic components are being developed by GEMTEX and IEMN;
- The Interreg BIOHARV project (2016-2021) "Biosourced Piezoelectric Textiles for Electricity Generation," which aims to develop 100% polymer mechanical energy recovery devices using multi-component piezoelectric textiles;
- The Interreg LUMINOPTEX program (2017-2021) "New Smart Textiles for Autonomous Ambient Lighting" aims to integrate organic light-emitting diodes (OLEDs) into textiles, which will be autonomously powered by harvesting available energy within buildings in the form of radio frequencies (WiFi) and storing this energy electrochemically in batteries or supercapacitors. GEMTEX and IEMN have studied integrated textile antennas and flexible substrate metasurfaces for WiFi wave energy harvesting.
Objectives
The first objective revolves around the design of piezoelectric, thermoelectric, or electromagnetic wave harvesting materials and structures. It draws upon the research work and expertise of UMET, IEMN, and GEMTEX:
- UMET's expertise lies in piezoelectric and thermoelectric polymers and composites [Defebvin et al. (2017); Barrau et al. (2018); Brun et al. (2020)];
- IEMN specializes in the fabrication of electromagnetic wave harvesters [Ferchichi et al. (2018); Khaldi et al. (2017)];
- GEMTEX focuses on the fabrication of energy-harvesting textiles [Chapron et al. (2021); Talbourdet et al. (2018)].
The second objective is dedicated to the development of a mono- or multi-source power supply system for an autonomous sensor. In this case, the expertise of L2EP [Ghenna et al. (2017); Giraud et al. (2019)] in energy management and system design will be leveraged.
Scientific challenges
The first scientific challenge regards maximizing the energy recovery efficiency. To fully exploit the energy potential, the shape and dimensions of the structures (films or textiles) and the type of materials (rigid, flexible) need to be optimized.
The second scientific challenge involves the electrical conversion within the system. The energy from any electrical source (variable frequency, variable voltage, etc.) must be shaped to adapt to the load (storage element, battery, etc.). Additionally, optimal conditions for extracting this energy must be ensured, regardless of the operating point of the source, which may require, for example, implementing a closed loop (internal system optimization).
Task description
Task 1 – Identification of Different Scenarios Involving the Trio "Resource/Structure/Materials"
The recovery of energy from a resource (mechanical, thermal, electromagnetic) involves the use of suitable structures and materials. All partners will be involved in this task, in which two or three scenarios will be identified to establish a specific "structure + materials" specification for a defined resource. The characteristics of materials (polymers, ceramics, thin films, composites) as well as structures (geometry, rigid or flexible electrodes) will be addressed. Different scenarios for integration into textiles or transferring structures onto textiles will also be considered.
Task 2 – Structure Optimization
Subtask 2a: Piezoelectric and Thermoelectric Structures
The structure suitable for a defined resource in Task 1, related to mechanical or thermal energy harvesting, will be manufactured at UMET. For example, in the case of mechanical energy recovery through vibrations, beam fabrication will be considered. The optimization of the structure can be achieved through a geometry-driven modeling approach. Thermoelectric structures should exhibit specific flat and flexible architectures, such as those obtained through inkjet printing or electrospinning processes.
These activities will be carried out within the scope of a Ph.D. program (2022/2025), in collaboration with a full-time engineer recruited for the entire project duration (2022/2027).
Subtask 2b: Electromagnetic Energy Harvester
For electromagnetic energy recovery, the optimization of antenna and metasurface geometries, as well as rectifying electronics, will be addressed at IEMN using 3D simulation tools (HFSS, CST Studio Suite) and RF circuit simulations (ADS). To optimize the structures effectively, the electronic components developed at IEMN will be characterized in advance using the CHOP platform (Optical and Photonic Microwave Frequency Characterization) to introduce their characteristics into the simulation software. In this task, system miniaturization will also be pursued for better overall integration. Electromagnetic energy recovery structures based on antennas or metasurfaces will be manufactured on flexible substrates (such as Kapton) or rigid substrates (such as FR4) using conventional Printed Circuit Board (PCB) technologies. The manufactured structures will be systematically characterized in the anechoic chamber (an experiment room with walls that absorb sound or electromagnetic waves, reproducing free-field conditions without causing echoes that could disrupt measurements) of the IEMN's Electromagnetic Compatibility (EMC) platform in terms of frequency responses and collected power.
Regarding the power collection aspect, the experimental study will focus on determining the optimal load resistance for maximizing power recovery. "Soft technologies" or low-temperature and low-cost approaches (surface functionalization, solution deposition, inkjet printing, nano printing, evaporation, etc.) will be preferred over conventional optical and electronic lithography methodologies, which will be reserved for miniaturization issues.
These works will be carried out as part of a postdoctoral program (2022/2026).
Subtask 2c: Textiles
The structures can be transferred onto textiles or integrated into textiles through embroidery, weaving, or knitting. Two platforms of GEMTEX, focusing on multifunctional materials and smart textiles, will be used to develop autonomous smart textile systems.
Part of these activities will be conducted within the framework of a Ph.D. program (2022/2025), and another part will be part of a postdoctoral program (2022/2026).
Task 3 – Materials Fabrication and Properties
The piezoelectric or thermoelectric materials will be synthesized at UMET, taking into account the specificities and specifications defined in Task 1. The physicochemical characterization of the materials relies on the advanced characterization platform of the CHEVREUL federation and involves structural and morphological studies. The physical characterization (electrical, mechanical, thermal) and the piezoelectric (piezoelectric coefficient) and thermoelectric performances of the materials are based on the specific and complementary equipment of the laboratory.
These works will be carried out within the scope of a Ph.D. program (2022/2025), in collaboration with a full-time engineer recruited for the entire project duration (2022/2027).
Based on the scenarios considered in Task 1, the rectifying elements and adaptation circuits for electromagnetic energy harvesters will be designed using organic materials (polymers, copolymers, small molecules with low molecular weight...) or inorganic materials that can be perfectly shaped for transfer or integration into textile surfaces. The organic materials constituting the active layer will be studied and optimized in terms of the relationships between morphology, structure, and transport properties. This will allow achieving high charge transport mobilities necessary to overcome the barriers for their application in very high-frequency systems.
These activities will be carried out as part of a postdoctoral program (2022/2026).
Task 4 – Design and Validation of Energy Harvesting Systems
Based on a usage scenario and in line with the nature of the energy source, an optimal energy management method is proposed. For this purpose, a systemic modeling approach, which takes into account all energy exchanges within the system, will be implemented by L2EP. Simulations will be conducted to validate the most effective strategies. These strategies will then be implemented using specific converters tailored to the power levels involved.
These works will be carried out by a full-time engineer recruited for the entire project duration (2022/2027).
Task 5 – Adjustment of Specifications and Proof of Concept (POC)
Based on the systems manufactured in Task 4, an adjustment of the "structures + materials" specifications associated with a specific energy source (defined in Task 1) will be carried out to optimize the system.
Upon completion of this task, the development of a Proof of Concept (POC) will be conducted. The POC will consist of a multi-source system that combines both a mechanical energy source and a thermal energy source to power an autonomous sensor.
These works will be carried out by a full-time engineer recruited for the entire project duration (2022/2027).
Impacts
The recovery of wasted energy to generate electricity is a societal challenge that requires the emergence of new green energy production systems, as developed within the framework of this pillar 1. Furthermore, this project aligns with the goal of relocating manufacturing to France or Europe to better control environmental effects.
COMASYS strengthens local interactions among various partners and enables mastery of the different stages of system design. The project will open new opportunities for innovation in diverse industries covering materials, components, and textiles. It can enhance connections with the Hauts-de-France region, which currently supports several projects through co-funding of theses, as well as interactions with competitiveness clusters such as EuraMaterials or centers of excellence such as Plastium.
Courses on piezoelectric and thermoelectric materials are currently taught in the Master 2 program in Polymer Engineering and Materials for the Environment (IPME), specializing in Polymer Systems Engineering (ISP). Within the "Smart Textiles" domain of the major in Technical Textile Engineering at ENSAIT, courses related to the addressed theme are offered to third-year students in the engineering program. One such course is titled "Textile & Energy." As part of the integration between the Master's and Doctoral programs and the establishment of graduate programs, cross-training workshops involving students from various departments of the University of Lille will be offered, along with interdisciplinary internships at the partner laboratories, as part of the Master's program.
References
Barrau, S.; Ferri, A.; Da Costa, A.; Defebvin, J.; Leroy, S.; Desfeux, R.; Lefebvre, J.-M.; Nanoscale Investigations of α- and γ-Crystal Phases in PVDF-Based Nanocomposites, ACS Applied Materials & Interfaces 10;15, 13092-13099 (2018), [doi: 10.1021/acsami.8b02172]
Brun, J.-F.; Binet, C.; Tahon, J.-F.; Addad, A.; Tranchard, P.; Barrau, S.; Thermoelectric properties of bulk multi-walled carbon nanotube - poly(vinylidene fluoride) nanocomposites: Study of the structure/property relationships, Synthetic Metals 116525 (2020), [doi: 10.1016/j.synthmet.2020.116525]
Chapron, D.; Rault, F.; Talbourdet, A.; Lemort, G.; Cochrane, C.; Bourson, P.; Devaux, E.; Campagne, C.; In-situ Raman monitoring of the poly(vinylidene fluoride) crystalline structure during a melt-spinning process. J. Raman Spectrosc. 2021, [doi: 10.1002/jrs.6081].
Defebvin, J.; Barrau, S.; Lyskawa, J.; Woisel, P.; Lefebvre, J.-M.; Influence of nitrodopamine-functionalized barium titanate content on the piezoelectric response of poly(vinylidene fluoride) based polymer-ceramic composites, Composites Science and Technology 147, 16-21 (2017), [doi: 10.1016/j.compscitech.2017.05.001]
Ferchichi, K.; Pecqueur, S.; Guerin, D.; Bourguiga, R.; Lmimouni, K.; Organic rectifier diode with very low turn on voltage for RF energy harvesting in Smart Textiles Applications; Organic and Hybrid Sensors and Bioelectronics XI 10738, 1073813 (2018).
Ghenna, S.; Giraud, F.; Giraud-Audine, C.; Amberg M.; Vector control of piezoelectric transducers and ultrasonic actuators; IEEE Transactions on Industrial Electronics 65 (6), 4880-4888 (2017) [doi: 10.1109/TIE.2017.2784350]
Giraud, F.; Giraud-Audine, C.; Piezoelectric Actuators: Vector Control Method: Basic, Modeling and Mechatronic Design of Ultrasonic Devices, Ed. Butterworth-Heinemann (2019)
Khaldi, W.; Hafsi, B.; Ferchichi, K.; Boubaker, A.; Nasri, A.; Lmimouni, K.; Kalboussi, A.; Traps density and temperature effects on the performance of rectifying diode based on penacene"; Organic Electronics. Volume 44, May 2017, Pages 106-109
Talbourdet, A.; Rault, F.; Lemort, G.; Cochrane, C.; Devaux, E.; Campagne, C.; 3D Interlock design 100% PVDF piezoelectric to improve energy harvesting. Smart Mater. Struct. 2018, 27, doi:10.1088/1361-665X/aab865.
