ENERGY HARVESTING UNDER EXCITATION OF UNIMORPH BEAM FOR SENSOR APPLICATIONS Almuatasim Alomari, Ashok K. Batra, and Mohan Aggarwal Materials Science Group, Department of Physics, Chemistry & Mathematics, Alabama A&M University, Normal, AL DESIGN & TESTING OF A PIEZOELECTRIC ENERGY HARVESTER DESIGN & TESTING PIEZOELECTRIC ENERGY HARVESTER USING COMSOL ABSTRACT Piezoelectric cantilever beams with polyvinylidene fluoride (PVDF) have been widely used as unimorph and bimorph to harvest vibration energy from ambient environment. The harvesting of ambient vibration energy for use in low energy electronic devices, such as, wireless sensor networks (WSN’s) has attracted significant interest. PVDF and its copolymers have high flexible energy harvesting devices and robust mechanical stability compared to inorganic materials. In this research, we report enhanced performances of poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) thick film based energy generators experimentally and theoretically. Experimental method was carried out using cheap cost effective solution-casting technique. The theoretical model was simulated and modeled based on Lumped parameter method (LPM) and finite element method (FEM), respectively. CONCEPT: PIEZO–MICRO-ELECTRIC GENERATOR A 2 dimensional (2D) of unimorph cantilever beam (UCB) with Iron beam are used for the simulation in COMSOL. The model is designed in COMSOL as shown below. The model consists of UCB with different lengths attached at the front of aluminum beam. The lengths of shim layer and piezomaterial are made equal. Using solid mechanics module, one end of the model is fixed and the other end is made to move freely with tip mass. Meshing a geometry is done using size parameters for free tetrahedral, with a fine mesh near the clamped end. The first mode shape of unimorph cantilever beam is shown at resonance frequency of 35 Hz as shown in figure below. Capacitor Resistance LED Switch Diode P(VDF-TrFE) First Mode shape of Unimorph Cantilever Beam with Tip Mass Meshed Unimorph Cantilever Beam with Tip Mass PREPERATION PRINCIPLE OF A PIEZO-ELECTRIC FILM P(VDF) powder Methyl-Ethyl-Ketone (MEK) + 60oC for 24 hours P(VDF-TrFE) solvent Solvent Annealing 110oC for 2-3 hours Silver coating (Electrolyte) V Film poling 60oC with 10kV/cm for 2-3 hours SMART MATERIALS PARAMETERS & CONSTITUENTS INVESTIGATED Material Properties of Unimorph Cantilever beam Unimorph cantilever beam P(VDF-TrFE) layer Cantilever beam Length (mm) 20 55 Width (mm) 16 Thickness (mm) 0.15 0.2 Young’s Modulus (Gpa) 5 117 Density (kg/m3) 1800 7800 Dielectric constant 12 Piezo strain constant ( 10-12 C/m) -23 Capacitance (nF) 2.7 Electromechanical coefficient Ɵ (N/V) 4.5×10-5 Output Voltage and Electric Output Power Versus Frequency Mechanical Input Power Versus Frequency OBJECTIVES Fabrication of P(VDF-TrFE)thick films under optimum conditions. Characterization of the Films for electrical and piezoelectric properties. Investigate experimentally and theoretically the output electrical parameters of piezoelectric samples fabricated in our laboratory and determine the efficiency of energy harvester. Modeling the piezoelectric energy harvester devices using COMSOL Multiphysics and determine the output electrical performance parameters ENERGY HARVESTING SIMULATION OF PIEZOELECTRIC Output Voltage Versus Load Resistance Mechanical Input Power and Electric Output Power Versus Load Resistance PC Picoscope Exitation Source Vibration Shaker Amplifier Brüel & Kjaer 2718 Controller Function Generator GF8046 ELENCO Accelerometer Brüel & Kjaer 4810 Measured Acceleration Experienced by EH Voltage Output from EH Channel 1 Channel 2 Sinusoidal Signal to Shaker Laser Microtrack II mti Instruments P(VDF-TrFE) Film THEOREITICAL & CIRCUIT TECHNIQUE OF PIZOELECTRIC ENERGY HARVESTER (PEH) Piezoelectric Element RL c k m P(VDF-TrFE) Film Tip Mass x y z Output Voltage and Electric Output Power Versus Acceleration Mechanical input Power Versus Acceleration Piezoelectric Cantilever Beam for Energy Harvesting Lumped Parameter Model RESULTS OF PIEZOELECTRIC ENERGY HARVESTER CANTILEVERS WITH CONFIGURATIONS PIEZOELECTRIC ENERGY HARVESTING FORMULI Experimental, Simulation, and Modeling Functional Parameters of Piezoelectric Energy Harvester Acceleration Functional Response versus Output Voltage, Output Electrical Power, and Applied Mechanical Power of Piezoelectric Energy Harvester Using COMSOL Multiphysics UCB Experimental Simulation Error (%) COMSOL Resonance Frequency (Hz) 35 35.1 0.28 35.05 0.14 Output Voltage (mV) 50.5 60.9 20.5 62.1 22.7 Electric Power (nW) 12.7 18.5 45.6 9.5 25.7 Acceleration (g) Output voltage (mV) Electric Power (nW) Mechanical Power (mW) 0.1 31 0.2 0.01 62 1.1 0.04 0.3 93 2.2 0.09 0.4 124 3.8 0.16 0.5 155 6 0.26 0.6 186 8.7 0.37 0.7 217 11.7 0.52 0.8 248 15.4 0.66 0.9 279 19.4 0.83 1 310 24 1.01 EXPERIMENTAL & THEORETICAL RESULTS USING MATLAB Design by Sheral Carter, AAMU Physics Department 2016 INVESTIGATIONS OUTCOME The preliminary results obtained can be summarized as follows: Piezoelectric poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) is a valuable material, which can be used for energy conversion in different environment and applications. Fabricated thick films with piezoelectric materials based on modified poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) type material system with high piezoelectric coefficients. Characterized the fabricated modified piezoelectric elements for the dielectric and piezoelectric properties. Simulation and modelling piezoelectric energy harvester with MATLAB program and COMSOL Multiphysics software showed good agreement between experimental and theoretical results. Output Voltage Versus Frequency Output Power Versus Frequency REFERENCES Cho, Y., Park, J. B., Kim, B. S., Lee, J., Hong, W. K., Park, I. K., ... & Kim, J. M. (2015). Enhanced energy harvesting based on surface morphology engineering of P (VDF-TrFE) film. Nano Energy, 16, 524-532. Tseng, H. J., Tian, W. C., & Wu, W. J. (2013). P (VDF-TrFE) polymer-based thin films deposited on stainless steel substrates treated using water dissociation for flexible tactile sensor development. Sensors, 13(11), 14777-14796. Tang, L., & Yang, Y. (2012). A multiple-degree-of-freedom piezoelectric energy harvesting model. Journal of Intelligent Material Systems and Structures, 23(14), 1631-1647. Emam, M. (2008). Finite element analysis of composite piezoelectric beam using comsol. Erturk, A., & Inman, D. J. (2011). Piezoelectric energy harvesting. John Wiley & Sons. c: Damping Coefficient k: Spring Constant ξT: Total Damping Ratio Ep: Young’s Modulus of Piezoelectric Material Es: Young’s Modulus of Substrate Material lm: Length of Tip Mass, l: Length of the Beam, w: Width of the Beam tp: Thickness of Piezoelectric Material, ts: Thickness of Substrate Material mp: Tip Mass, me: Effective Mass, m: Beam Mass ρp: Density of Piezoelectric Material, ρs: Density of Substrate Material ACKNOWLEDGMENTS The authors gratefully acknowledge support for this work through NSF grant # EPSCoR R-II-3 (EPS-1158862). The authors thank Mr. Garland Sharp for fabrication of the sample holders. Output Power Versus Load Resistance Output Voltage Versus Load Resistance