work packages

The Innovative Training Network entitled “Piezoelectric Energy Harvesters for Self-Powered Automotive Sensors”: From Lead-Free Materials to Smart Systems, ENHANCE project, is structured around seven technical Work Packages (WPs), which directly meet the project’s goals, and address the ethical, training, and dissemination issues of the project.

Objectives : To manage project’s goals, to promote network based activities and to ensure the achievement of the deliverables. More specifically:

• Create an attractive training environment that can encourage creativity, mobility, responsibility and autonomy of the early state researchers, in line with cutting edge knowledge, technology and innovation.
• Create a multidisciplinary network based on research excellence in which the joint research activity will be more efficient than the uncoordinated efforts of individual partners in the specific field
• Ensure a democratic administration and financial management, ensuring the achievement of the deliverables on-time.

Objectives : Create an economical and technological roadmap, select the prototype applications while at the same time supply guidelines on how to operate. The objective will also be to provide specifications of target applications, constraints of industrial fabrication/integration process, performance requirements for materials/devices, and specifications for the test conditions. Finally, will have to evaluate ENHANCE’s technologies, products and their industrial scalability. More specifically :

• Target two autonomous sensor applications in the car where vibrations, light or high; select off-shelf micro-sensor systems adapted for defined applications and definition of their specifications, power usage profile, sampling frequency, acceptable dimensions of harvester system, etc. (PSA, ST). Create a system-level application modeling and simulation (SystemC/SystemC-AMS, embedded software) (ST).
• Collect data from end-user (PSA) energy sources available and their specifications (frequency ranges, amplitudes, temperature and its gradients, shocks, light intensity, etc.) and working conditions (corrosive environment, pressure) at the sensor location; Supply EH performance requirements and pre-design the performance requirements of separate system components and materials and the performance of the selected technologies (INSA, CTEC and Imperial).
• Learn constraints and requirements of industrial processes of precursor and material synthesis from EpiValence and AIXTRON (UFC, UCO, INSTM), MEMS and NEMS, physical and circuital modelling and simulation from ST (UFC, GINP, INSTM, Imperial), industrial assembling of harvester systems from CTEC (Imperial and INSA).
• Collect data from partners about the performance of available piezoelectric materials and the existing architectures and performances of harvesters; learn about existing patents and on-going research (all beneficiaries); Summarize and provide the data to all partners (CTEC).
• Evaluation of cost/market and viability to industrial manufacturing/applications of proposed technologies/materials/devices/interfaces (industrial partners);
• Exploitation of the results and contribution to the knowledge transfer to the industry and initiation of new collaborations and industrial links.

Objectives : To synthesise metalorganic precursors with improved characteristics to be employed in advanced CVD coating techniques and electrospinning. To apply molecular engineering to enable the growth of substrate supported VAN, SSNM and control of their dimensions. Moreover, grow of Pb-free piezoelectric films or nanostructures on Si or metal foil substrates with FoM of 20 GJ/m3 at RT and of 10 GJ/m3 up to 600 °C (FoM of standard PZT films in silicon technology (10-14 GJ/m3)) and mechanical quality ( > 300); (v) Achieve photocurrent density of 20 mA/cm2 in films/nanostructures on Si or metal foils with FoM> 10 GJ/m3; (vi) Optimize films/ nanostructures with pyroelectric and piezoelectric FoMs of > 10 GJ/m3 and 25 J/m3K2 in large temperature range (RT - 600°C). More specifically :

• Fabrication of heterostructures based on 1-2 μm thick LiNbO3 crystal/electrode/metal or Si substrate by WoW technology (frecInIsys, Mh9) and supply of state- of art PZT films on Si and metal substrates (EPFL, Mh9).
• Synthesis of Li, K, Na & Nb metal-organic complexes: single and bimetallic sources, alkoxides, alkenolates and allied compounds (INSTM) enabling better incorporation of alkaline elements in the films or nanostructures of LN (UFC) and KNN (UCO) and facilitating 3D growth by solution or gas-phase methods with controlled stoichiometry through a careful tailoring of the metal coordination sphere based on beta-diketonate or alkoxide ligands;
• Physico-chemical and mechanistic studies of the complexes through NMR, FT-IR and mass spectrometry, while the thermal properties will be studied through dynamic and isothermal thermogravimetric analysis and differential scanning calorimetry (INSTM); 4. Optimization of CVD deposition conditions for films/nanostructures on Si or metal foil substrates by using new & commercial precursors through simulations of chemical process, gas flows and heat transfer (AIXTRON) and experimental tuning of parameters (UCO, UFC and INSTM). Elucidation of experimental parameters enabling growth of substrate supported nanostructures to control their growth orientation and dimensions of 1D VAN (UCO, UFC, INSTM).
• Optimization of high piezoelectric and pyroelectric FoMs and/or high photocurrent density of LN:Fe (UFC), doped BiFeO3 (INSTM) and 0.94KNN-0.06LN (UCO) films/nanostructures by engineering their properties by tuning the texture/ nonstoichiometry/ oxygen deficiency/ composition&doping/defects/ size effect/ domain structure and selection/integration of adapted electrodes materials to the functional heterostructures. 6. Fabrication of one-dimensional nanofibers and their interwoven to obtain SSNM of KNN and its derivatives. Elaboration of chemical and processing parameters and tandem approaches (Electrospinning + CVD) to control texture/stoichiometry and optimization of physical properties by tuning solid solution composition and different types of doping of KNN phase (UCO);
• Characterization of composition/structure/morphology of thin films/SSNM/VAN and contribution to understanding the relationship between processing- composition-structure-morphology-physical properties-device performances (UFC, INSTM & UCO).

Objectives : To complete the characterization of piezoelectric, elastic, dielectric, pyroelectric and photovoltaic properties, to estimate Py- and Pi-FoM of developed thin films and nanostructures as electro-active materials for EHs. To micro-fabricate basic transducers and designed hybrid transducers from reference and advanced materials; demonstrate piezoelectric transduction of 500 Hz vibrations with efficiency of 300-500 μW/cm2/g2. More specifically:

• Finite element simulation (FEM, e.g. COMSOL) (ST) will be used for the optimization of (i) the efficiency of “contour mode d31” or “d33” piezoelectric transduction (to find out in- and out-of-plane rigidities) by tailoring the shape and the type (cantilever, suspended structures, etc.), electro-active layer thickness, combination of multilayers, modes of transduction, placement of mass, and configuration of the electrodes to optimize elastic properties and strain distribution and to maximize charge collection by sub-centimetre Pi-transducers of vibrations with frequency of 500 Hz; (ii) VINGs working in non-resonant mode; (iii) electrode material/thickness to obtain low work function of electrodes for PV devices and increase quality factor for piezoelectric transducers (EPFL, FrecInIsys, GINP).
• Verification of feasibility of the designed piezoelectric and hybrid transducers; Simulation of micro-fabrication process of transducers (ST).
• Micro-fabrication of optimized piezoelectric and designed hybrid transducers from grown film heterostructures (UFC) and nanostructures (GINP) and corresponding reference materials. UFC and GINP have long years of experience in fabrication of micro- and nano-devices based on films and nanostructures.
• Characterization of piezoelectric coefficients, polarization remanence, dielectric and elastic properties of developed piezoelectric materials (EPFL). The piezoelectric coefficients of nanostructures will be measured by means of AFM (GINP). Pyroelectric coefficients will be measured by applying heating-cooling cycles (EPFL). In order to estimate the photovoltaic properties, the photocurrent generated by illumination in simple sandwich heterostructure (INSTM). FoM of developed films and nanostructures will be calculated. Finite element simulation (FEM, e.g. COMSOL) (ST)will be used as a countercheck for experimental measurements (EPFL, frecInIsys, GINP) and predictive scaling predictive scaling of length and diameter of nanostructures, placement of electrodes on nanostructures (GINP).

Objectives : To engineer an EHs transducer able to harvest constructively thermal and vibrational energies or vibrational and solar energies, simultaneously; create a Py-Pi EH able to work efficiently in RT-600 °C temperature range; engineer a high-performance Pi- transducer system with wide-band of operating vibrational frequencies (100-500 Hz) and multi-degrees of freedom. Achieve vibrational energy harvesting by electromagnetic and piezoelectric transduction mechanisms, simultaneously; create compact transducers with volume < 1 cm3; (v) Generated power by designed EHs in order of 0.7-1 mW/cm2/g2 at ambient conditions and > 0.5 mW/cm2/g2 up to 600°C from frequency profiles (100 Hz- 500 Hz) present in cars. More specifically:

• The hybrid harvester design will be designed on the basis of real working conditions of harvesters (supplied by WP1). Initially, the proof of concept designs of hybrid harvesters will be done by using reference materials (VAN ZnO, WoW LN, or PZT films). The second step will be implementation to the developed lead-free films or nanostructures developed in WP2.
• Design & mechanical modelling using automatics and control tools of: (i) optimised multi-frequency and multi-degrees of freedom (able to harvest vibrations with different motion vector and of different origins) PiViEH systems permitting to maximise charge extraction and to increase the electrical damping at the mechanical resonant frequency; (ii) mechanical structure of hybrid thermal-vibrational EHs enabling addition of pyroelectric, thermal expansion and piezoelectric effects and able to harvest efficiently up to 600°C (UFC).
• Holistic optimisation & development by optimising mechanical geometry and winding structure for wide-band PiEHs based on mechanical oscillator structures for motion energy harvester enabling also electromagnetic energy transduction (EM-PiEH), or exploitation of photovoltaic effect (PV-PiEH).
• Characterization of efficiency of hybrid energy harvesting by Py-Pi, PV-Pi and EM-Pi transducers at simulated working conditions, representing real ranges of amplitudes and frequencies available in the cars.

Objectives : To power modules with compact size/minimal number of external components and ultralow-power operations; achieve an increase in real output power by smart electronic interfaces and to attain stabilized output voltage of 1-3 V; build electronic interfaces enabling hybrid energy harvesting; integrate harvesters and their electronics, test the harvesters. More specifically :

• Development, modelling and design of power electronics interface (circuit topology, regulation & management circuits) which allows: (i) co-design of the mixed electromechanical systems (Imperial, INSA); (ii) tuning the resonant frequency of mechanical system and impedance matching according to the multiple source vibration frequencies (Imperial, INSA); (iii) harvesting of energy in an efficient way from several sources (vibrational-solar (Imperial) and thermal-vibrational (INSA ) sources) and conversion effects (piezoelectric-electromagnetic (Imperial)); (iv) optimal operation of the extraction interfaces and maximizing of output- power (INSA).
• Development of: (i) electronics interfaces with low power consumption; (ii) rectifying interfaces with low voltage levels for micro-scale harvesters; (iii) low capacitance compatible electrical interfaces required for EHs based on dielectric materials; (iv) electrical components able to step up DC voltage to a suitable level with minimal loses; (v) dedicated interface for arrays of transducers.
• Modelling of the complete non-linear energy harvester systems (including advanced transducers, smart electronics interface and packaging adapted to sensor/harvester working conditions) from inputs of partners (Imperial, UFC, INSA) will be realized by CTEC.
• Development of a custom test bench enabling to test the harvesters (developed by partners) in the conditions close to the real working conditions (supplied by WP1) will be done by CTEC. Characterisation of the efficiencies of ViEHs, Th-Vi EHs and Lt-Vi EHs on laboratory test bench (CTEC); Packaging of demonstrators (CTEC) and characterization on test vehicles (PSA).
• Simulation of the performance of prototype sensor systems including the specifications of developed ENHANCE power modules (ST)

Objective : To set out the ethics requirements the project must comply with, following the ethical standards and guidelines of Horizon2020, regardless of the country in which the research is carried out.