Energy Scavenging from Vibrations – Summary Lecture

Problem Review

Energy Harvesting Wind Water Solar Temperature Vibration

Energy Scavenging through Vibration

Piezoelectric Piezoelectricity is the ability of certain materials to produce a voltage when subjected to mechanical stress. Piezoelectric materials also show the opposite effect, where application of an electrical field creates mechanical stress (size modification) in the crystal.

Piezoelectric Frequency Response

Components Provided

Methods for Solving the Problem

Finding Solutions

Rotary-to-Reciprocating Motion An Example Asymmetric Cam

Rotary-to-Reciprocating Motion Another Example Asymmetric Cam

An Asymmetric Cam is not Necessary for Rotary-to-Reciprocating Motion

Charging Circuit A super capacitor (0.47F 5.5v) is used to store electric charge. A Zener diode (BZX85-C5V6) is used to protect the super capacitor. Rectifying diodes Super capacitor Zener diode

Charging Circuit - Example

Engineering Principles and Concepts

Gear Ratio A B driving driven

Gear Train drivingidlerdriven A B C A B C D Simple gear trainCompound gear train

Gear Train - Example

Alternating Current vs. Direct Current In alternating current (AC) the movement (or flow) of electric charge periodically reverses direction. In direct current (DC) the movement of electric charge doesn’t change direction.

Diode + v - i v i Diodes allow the electric current to flow in only one direction.

4 Diode Bridge

The Meaning of Frequency Frequency means the number of times something occurs within a given time period. Frequency for waves is usually measured per second. The unit for frequency is Hertz (Hz), which means per second.

Spectrum Decomposition

Design Trade-offs Two types of testing stations that generate vibrations for the piezo buzzer are designed, with/without a gearbox. The gearbox provides the flexibility to tune the vibration frequency to match the resonant frequency of the piezo buzzer. The more complex the design is, the longer the time and higher the costs it takes to implement it, but the more chance that it should provide better results.

Lesson Learned More Complex is not Always Better Simple Design

Experimental Results Simple Design Charging the Battery Time response Spectrum

Experimental Results Complex Design Charging the Battery Time response Time (minutes) Battery (Volts)

Engineering Design Process Identify the need or problem Research the need or problem Develop possible solutions Select the best solutions Construct a prototype Test and evaluate the prototype Modify to improve the design if needed

Reflective Problem Solving Strategies define the problem Implement the design reflect analyze the problem identify design variables propose solutions Test, evaluate, and improve the design

Societal Impact Energy harvesting or the process of acquiring energy from the surrounding environment has been a continuous human endeavor throughout history.

Piezoelectric materials, such as the lead zirconate titanate (PZT), are great candidates for energy harvesting using vibrations from the surrounding environment. Societal Impact

Wireless corrosion monitoring systems Application Areas vibrating structurevehicle frequency Accel. PSD mechanical energy Self-powered Wireless Corrosion Sensor low power wireless transceiver corrosion sensorenergy harvester Biomechanical Energy Harvester

References 1.M. Raju, “Energy Harvesting, ULP meets energy harvesting: A game-changing combination for design engineers,” Texas Instrument White Paper, Nov R.J.M. Vullers, V. Leonov, T. Sterken, A. Schmitz, “Energy Scavengers For Wireless Intelligent Microsystems,” Special Report in Microsystems & Nanosystems, OnBoard Technology, June Imec, “Design for analog and RF technologies and systems,” 4.Imec, “Micropower generation and storage,” 5.F. Whetten, “Energy Harvesting Sensor Systems – A Proposed Application for f, ” DOC: IEEE / f 6.C. Cossio, “Harvest energy using a piezoelectric buzzer,” EDN, pg.94-96, March 20, 2008