Q-factor Amplification: An Analysis of Damping Mechanisms for Resonant Kinetic Energy Harvesters

Transcript

Every year, toxic batteries from infrastructure end up in our landfills, leaching chemicals into the soil and driving climate change through the release of harmful gases. My project offers a solution to this environmental crisis by optimizing kinetic energy harvesters, which capture ambient vibrations and convert them into electricity. To solve the common issue of energy inefficiency, I put metallic resonators through rigorous trials including thermal management and surface-level optimization to amplify their Q-factor. By chilling the metals and refining their surface topography, I was able to successfully limit the damping mechanisms that usually cause energy leakage. My results demonstrate that these optimized conditions significantly increase Q-factor, providing a blueprint for high-efficiency energy harvesters and a more sustainable, green future for our Earth.

Problem

Modern infrastructure relies heavily on toxic chemical batteries to power essential sensors. Unfortunately, a staggering volume of these disposable batteries end up in landfills. According to CORDIS (an EU-funded database), "About 78 million batteries powering the [Internet of Things] devices will be [discarded] globally every day by 2025 if nothing is done..." Although this statistic is a year old, it is still alarming and relevant as it highlights that these batteries (which act as drivers of climate change by releasing hazardous pollutants and greenhouse gases) are being thrown out in massive quantities in our ecosystems. Therefore, they pose a significant environmental risk unless changes are made.

Solution

Kinetic energy harvesters offer a sustainable solution to this crisis. These devices capture ambient vibrations and convert them into electricity, making them key for eliminating toxic battery dependency. They are renewable, maintenance-free, and capable of operating for decades. However, despite their potential, energy harvesters often struggle with efficiency, largely due to energy loss caused by damping.

Optimizations of these harvesters can significantly increase efficiency (Q-factor), reduce damping, and advance the future of green technology.

The Setup

My setup consisted of a cantilever beam configuration, using either an aluminum or steel rod secured within a C-clamped vise. To ensure consistency, I applied specific, uniform clamping pressure for every trial. To minimize metal-on-metal damping, I wrapped the secured portion of the rod in paper (1 inch), leaving 11 inches of the resonator exposed to vibrate. To isolate external interference, a mat was placed around the base of the resonator to dampen floor-borne vibrations. Data was captured using the Phyphox app (developed by RWTH Aachen University) on my device positioned two inches from the rod. I maintained a constant Fast Fourier Transform (FFT) sample size of 8,192 to ensure high-resolution frequency across all trials.

Methodology

To generate a consistent excitation force, I built a novel PVC conduit striker designed specifically for this situation. This striker acted as a guide for the ball to roll down and strike the metallic resonator with the exact same impact force for every trial, ensuring that any changes in the Q-factor were due to the material conditions rather than the strike itself. To quantify the results, I analyzed the captured vibrations using the following decay formula:

Q=  π × f × τ

In this equation, f represents the resonant frequency and τ (tau) represents the decay time constant. I conducted four trials to observe their effects on Q-factor: chilling (via dry ice), thermal heating, topographical optimization (smoothing the surface), and a final trial where I subjected the resonators to both changes in surface topography and chilling (dry ice). For each optimization technique, I performed 5 trials to eliminate outliers and receive averages for Q-factor. After evaluating the data, I identified the baseline volts of my kinetic energy harvester and then used those amplification techniques to see if the volts would increase due to a higher Q-factor.

Calibrated Control

To validate the accuracy of my measurement system, I tested a standard tuning fork with a known frequency of 440 Hz. My device recorded a frequency of 439.45 Hz; this small error margin of 0.125% confirms that the system is highly accurate. I then calculated the tuning fork's Q-factor, which averaged 22,669. This value was validated by cross-referencing it with the study "High quality factor tuning fork resonators with various resonance frequencies," which confirmed a high Q-factor is possible for a high-quality tuning fork.

Baseline Trials

The resonators used in this study were 12 inches long and 0.5 inches in diameter. I conducted baseline experiments to establish the original Q-factor of the rods before any optimizations. The aluminum Q-factor averaged 906, while the steel Q-factor averaged 1,021. These baseline averages served as the control for trials.

Dry Ice Trials

The first amplifying method involved submerging the rods in dry ice at -78.5 °C. The rods were insulated for 12 hours to ensure they were sufficiently chilled. This trial aimed to observe how Q-factor fluctuates at sub-ambient temperatures and whether kinetic energy harvesters would be more efficient in colder climates.

Aluminum: Showed a 49.9% increase in energy containment, with a Q-factor 1,358.

Steel: Showed a similar 23.8% increase, with an amplified Q-factor of 1,264.

This difference in percentage is likely due to aluminum's high thermal conductivity allowing deeper cooling, reducing internal friction significantly.

Heat Trials

To test the opposite end of the spectrum, I heated the rods to 350°C to determine if adding thermal energy would have the inverse effect of dry ice by increasing internal damping. The results were significant.

Aluminum: Experienced a 43.16% decrease, dropping to an average Q of 515.

Steel: Experienced a massive 35.06% decrease, dropping to a Q of 663.

Surface Topography Trials

To investigate the impact of surface roughness, I applied a multi-stage sanding process to both rods using 60, 120, and 220 grit sandpaper. Between each stage, the rods were thoroughly cleaned to remove metallic debris, ensuring a uniform matte-polished finish.

Aluminum: Responded with a 39.96% increase, reaching a Q of 1,268.

Steel: Showed a much smaller 22.04% increase, resulting in a Q of 1,246. This suggests that aluminum's lower density makes it more susceptible to surface-level acoustic scattering than steel.

Surface Topography & Dry Ice Trials

Due to the surface topography and dry ice trials displaying the highest percentage improvements across the amplification trials, I subjected the rods to both of the optimizations at the same time. This was to see how Q-factor can be further amplified by combining these methods.

Aluminum: Q-factor increased to 1,469 with an percent improvement of 62.14%.

Steel: a percent improvement of 44.07% with an increased Q of 1,471.

The dry ice trials and surface topography trials demonstrate that Q-factor can be amplified. These optimization techniques can improve the energy efficiency of kinetic energy harvesters.

Thermal Management Trials

The experimental results indicate that cooling (dry ice) significantly improved the average Q-factor for both aluminum and steel resonators. This improvement is attributed to the reduction of thermal noise (random atomic vibrational interference) and thermoelastic damping (energy lost as heat), which minimizes internal molecular friction and allows acoustic waves to survive with minimal energy loss. These findings have major implications for infrastructure in climates like Northern Manitoba as they suggest that kinetic energy harvesting is significantly more efficient during winter months and colder areas. In contrast, heating the resonators to 350°C consistently decreased the Q-factor; the elevated thermal energy accelerated damping, dissipating the vibrations as wasted heat.

Surface Topography Optimization

The investigation into surface topography was a multi-stage sanding process. Refinement of the surface significantly increased the Q-factor of the aluminum resonator while the steel resonator showed a more moderate improvement. These results confirm that a smoother surface reduces acoustic scattering.

Summary

The combination of these methods produced the highest percentage improvement in Q-factor. This was further demonstrated by using the amplification trials on a finished kinetic energy harvester build, increasing the voltage produced.

My research demonstrates that optimizing the properties of a resonator, specifically through surface refinement and thermal management, significantly amplifies the Q-factor. In the context of kinetic energy harvesting, a higher Q-factor directly correlates to better energy efficiency and power output. By replacing toxic chemical batteries with high-Q mechanical resonators, infrastructure sensors can be transitioned to sustainable technology, contributing to a greener future.

Moving forward, I want to apply these optimization methods to specialized kinetic energy harvesters for site-specific infrastructure. While my current harvester serves as a proof-of-concept, the next phase of my research will focus on engineering devices for high-impact environments, such as traffic heavy highways and bridges. By customizing the resonator's material and surface topography to a specific location, I can further amplify Q-factor and maximize power output. This is to further prove that efficient harvesters can reliably replace batteries in the most demanding industrial settings.

I would like to thank my parents and grandparents for inspiring and motivating me to always try my best! Their faith has taught me- if I can dream it, I can be it!

My siblings, you have truly helped shaped the person I am. Thank you for always being there for me.

Thank you Uncle Steve for allowing me to borrow the multimeter. Thank you Linde Canada, Chris and Davin for the Dry Ice and support. Thank you Julie Buckingham for sharing my story and helping to inspire young women in science!

Thank you to Bison Regional Science Fair- Dr. Anju Bajaj and Baljot Rai, for nurturing my pursuit in science. I am truly honored to have your support and encouragement.

To Sanford Collegiate, Red River Valley School Division and all my teachers- you have cheered me on throughout this adventure. Thank you so much, you are all so awesome!

ABC News. (n.d.). 'Urgent' need to establish lithium-ion recycling facilities as toxic waste soars. https://www.abc.net.au/news/2024-10-29/lithium-ion-battery-waste-recycling-facility-strategy-australia/104463106

British Engineering Services. (n.d.). A Guide to Young's Modulus and Material Stiffness. https://besgroup.com/blogs/a-guide-to-youngs-modulus-and-material-stiffness/

Cabin Radio. (n.d.). Batteries starting fires at Yellowknife’s landfill, city says. https://cabinradio.ca/102550/news/yellowknife/batteries-starting-fires-at-yellowknifes-landfill-city-says/

CERN. (n.d.). Materials in cryogenics. https://indico.cern.ch/event/90787/sessions/113900/attachments/1093424/1559936/Materials_in_Cryogenics.pdf

Copper.org. (n.d.). Cryogenic Properties. https://copper.org/applications/marine/cuni/properties/cryogenic/

Cowboy State Daily. (n.d.). Lithium-Ion Battery Fires At Rock Springs Dump Could Signal Bigger Disasters. https://cowboystatedaily.com/2025/08/05/lithium-ion-battery-fires-at-rock-springs-dump-could-signal-bigger-disasters/

Electrochem. (n.d.). https://s24.q4cdn.com/142631039/files/doc_downloads/2023/08/LITHIUM-THIONYL-CHLORIDE-CELLS-AND-BATTERIES_US-OSHA_EN_FINAL_062323.pdf

envisioning. (n.d.). Kinetic Energy Harvesting. https://www.envisioning.com/research/horizons/kinetic-energy-harvesting

European Commission. (n.d.). Up to 78 million batteries will be discarded daily by 2025, researchers warn. https://cordis.europa.eu/article/id/430457-up-to-78-million-batteries-will-be-discarded-daily-by-2025-researchers-warn#:~:text=About%2078%20million%20batteries%20powering,rising%20number%20of%20IoT%20devices.

Fly-Wing. (n.d.). What Are Bridge Rectifiers and How Do They Work? https://www.flywing-tech.com/blog/bridge-rectifiers-everywhere-what-you-need-to-know-about-diode-bridges/

iLearn Engineering. (n.d.). What are mechanical resonance and damping in engineering? https://www.ilearnengineering.com/civil/what-are-mechanical-resonance-and-damping-in-engineering

Institute for Energy Research. (n.d.). Environmental Impacts of Lithium-Ion Batteries. https://www.instituteforenergyresearch.org/renewable/environmental-impacts-of-lithium-ion-batteries/#:~:text=The%20disposal%20of%20the%20batteries%20is%20also%20a%20climate%20threat,combusting%2C%20and%20releasing%20toxic%20fumes

Intechopen. (n.d.). Kinetic Energy Harvesting. /www.intechopen.com/chapters/45931

Kinergizer. (n.d.). https://kinergizer.com/#:~:text=Fitting%20lifetime%20of%20your%20device,that%20they%20need%20to%20power.

LibreTexts. (n.d.). Lattice Structures in Crystalline Solids. https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Inorganic_Chemistry_(LibreTexts)/07%3A_The_Crystalline_Solid_State/7.02%3A_Formulas_and_Structures_of_Solids/7.2.02%3A_Lattice_Structures_in_Crystalline_Solids#:~:text=sections%20that%20follow.-,U

McGill Physics. (n.d.). Decay of a resonance. https://www.physics.mcgill.ca/~grant/224/14-224.pdf

MDPI. (n.d.). Vibration-Based Energy Harvesters: New Ways to Scavenge Energy. https://www.mdpi.com/1996-1073/16/13/5019

Nanomotion. (n.d.). The Piezoelectric Effect. https://www.nanomotion.com/nanomotion-technology/the-piezoelectric-effect/

NationBuilder. (n.d.). Battery Crisis. https://assets.nationbuilder.com/boomerangalliance/pages/4332/attachments/original/1708306417/Battery_Recycling_Crisis_Fact_sheet_2024.pdf?1708306417

Physics O & A Level. (n.d.). What is Resonance? 7 Fascinating Insights That Simplify Learning. https://physicsoandalevel.com/what-is-resonance/

Royal Society of Chemistry. (n.d.). The drive to recycle lithium-ion batteries. https://www.chemistryworld.com/features/the-drive-to-recycle-lithium-ion-batteries/4012222.article

Saft. (n.d.). Batteries solutions for structural health monitoring: OSMOS case study. https://saft.com/en/case-studies/batteries-solutions-structural-health-monitoring-osmos-case-study-0#:~:text=Saft%27s%20lithium%20battery%20technology%20proved,to%20improve%20your%20browsing%20experience

Science Direct. (n.d.). Energy Dissipation. https://www.sciencedirect.com/topics/engineering/energy-dissipation

Science Direct. (n.d.). High-Performance Piezoelectric Energy Harvesters and Their Applications. https://www.sciencedirect.com/science/article/pii/S2542435118301260

Science Direct. (n.d.). Internal Friction in Metals. https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-0502820553900148/first-page-pdf

Science Direct. (n.d.). Piezoelectric Effect. https://www.sciencedirect.com/topics/engineering/piezoelectric-effect

Science Direct. (n.d.). Q Factor. https://www.sciencedirect.com/topics/physics-and-astronomy/q-factor

Science Direct. (n.d.). Young's Modulus. https://www.sciencedirect.com/topics/materials-science/youngs-modulus

Semantic Scholar. (n.d.). Kinetic Energy Harvesting. https://www.semanticscholar.org/paper/Kinetic-Energy-Harvesting-Zhu-Beeby/f090c4f9546c417947402c8f1ba53df6807302fc

Shutterstock. (n.d.). Battery Landfill royalty-free stock footage. https://www.shutterstock.com/video/search/battery-landfill?dd_referrer=https%3A%2F%2Fwww.google.com%2F

Stanford University. (n.d.). Quality Factor (Q). https://ccrma.stanford.edu/~jos/fp/Quality_Factor_Q.html

Tadiran Batteries. (n.d.). Guidelines for Disposal of Lithium Cells and Batteries. https://s24.q4cdn.com/142631039/files/doc_downloads/2023/08/LITHIUM-THIONYL-CHLORIDE-CELLS-AND-BATTERIES_US-OSHA_EN_FINAL_062323.pdf

Taylor & Francis an informa business. (n.d.). Thermoelastic damping. https://taylorandfrancis.com/knowledge/Engineering_and_technology/Mechanical_engineering/Thermoelastic_damping/

Tourism Winnipeg. (n.d.). Top 50 things to do to celebrate Winnipeg's 150th. https://www.tourismwinnipeg.com/things-to-do/only-in-the-peg/read,post/1563/top-50-things-to-do-to-celebrate-winnipeg-s-150th

Treehugger. (n.d.). How Should I Dispose of All My Old Batteries? https://www.treehugger.com/how-should-i-dispose-of-all-my-old-batteries-4861460

UPS. (n.d.). 40% of Nasty Landfill Chemicals from Batteries. https://blog.upsbatterycenter.com/40-of-nasty-landfill-chemicals-from-batteries/