Download Strip Placement - Villanova University

Michael Erwin
Ross Martin (Team Leader)
Tao Nguyen
Clifton Weng
Ursula Zangrilli
Dr. Chun and Prof. Dougherty
Overview
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Introduction
Objectives
Ideas and Results
Economics
Case Studies
Final Thoughts
Intro and Objectives
Tao Nguyen
Introduction
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Almost Everyone Uses Portable Electronics
Palm Pilot (200 mW), MP3 Players (110 mW),
Laptops (10 W)
All run out of power in a matter of hours
Power Estimates
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Breathing – 0.42 W
Blood pressure – 0.37 W
Exhalation – 0.40 W
Footsteps – 5 W
Challenges
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How do we generate power?
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How can we harness it?
State of the Art
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Hand crank/Shake Flashlights
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Kinetic watches
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Swatch Automatic/Autoquartz
Seiko Kinetic
Seiko Thermic watches
Objectives
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Design a device to generate electrical power from
the human body
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Various devices that convert human mechanical to
electrical energy
A circuit to harness this energy
Use this power to charge the batteries of portable
electronics
Harness enough electrical power to charge a cell
phone battery
The Design Idea
Ross Martin
The Idea
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Shoe based generator
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Incorporates piezoelectric strips
Strips generate electricity through polarization
induced by stretching of the fibers
Screen printed silver electrodes provide electrical
contacts
The Idea
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Each strip produces:
40 volts peak-to-peak per pulse
 6-9 uAmps per pulse
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Final output is an AC voltage
The Idea
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AC->DC Conversion
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Pass AC wave through transformer rectifier
Capacitor filter smoothes the wave even
further
Voltage regulation
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Maintain a steady output voltage between 3.7
and 4.1V
As high a current output as possible
The Idea
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Circuit tucked under heel in sealed
package
Wire feeds power to battery being charged
Standard charging plug for phone
Phone held in modified holder on ankle
Research Results
Results
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Initial design was as shown above
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Converter to 555 timing chip to battery
Results
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Eliminated due to
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No need for timing with low current
3 pole transformer introduces unnecessary
complexity
Large number of components lower output
Results
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Second design: Dedicated charging chip
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Use of LM3658 to control charging
Pros: introduces layers of battery safety
 Cons: 4.5v-6v input voltage range, 50mA
minimum current
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Put to the side, pending higher current and
better voltage control
Results
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Re-evaluation of design strategy
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Focus on sustainable voltage levels
Plans for intelligent charging continued as a
second goal for post experiment work
Results
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Third design: Converter with capacitor
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2 versions: half and full wave
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Half wave yielded moderate voltages of up to 6V
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Required unrealistic strip movements
Acceptable, but not ideal
Results
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Full wave produces voltages in excess of 15V
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Uses diode bridge rather than paired set
Easily obtainable via normal movements
Full rectification gives twice as many pulses within
acceptable voltage range
Results
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Voltage output of Diode Bridge
Results
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Addition of capacitors reduce ripple between pulses
Results
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Results of design
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Working converter circuit
Ample voltage for charging
Insufficient current
Economics
Tess Zangrilli
Costs for Prototype
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Piezoelectric strips(3):$25 per strip
Circuit components:about $1
Phone Plug: $1
Inserts: $5
Total=$82
Costs to Mass Produce
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Startup
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Customizations
Per unit costs:
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$5-10 per strip
Circuit components: <$1
Phone Plug: <$1
Insert: <$1
Independent Case Studies
Cliff Weng
Case Study #1: Inductor
circuit
Piezo strips
Slug Velocity: 1.3 m/s
Number of turns: 100,000
Total Length: 8 cm
Coil Diameter: 2 cm
Current Produced: 0.015 amps
Inductor
Case Study #2: Windmill
Piezo strips
circuit
Bellows Dimensions:
2.5 cm x 1.3 cm x 5 cm
Bellows Nozzle Diameter:
0.5 cm
Air Velocity:
19 m/s
Turbine Speed:
4 RPMs
Turbine
Final Thoughts
Mike Erwin
Were our Goals Achieved?
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Design a device to generate electrical
power from the human body
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Succeeded
Use this power to charge the batteries of
portable electronics
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Not possible using available supplies
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Proved to be possible. - Nokia
Harness enough electrical power to charge
a cell phone battery
Lessons Learned
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Test Testing Equipment
Simple is Better
More Specific is Better
Allow plenty of time for Complications
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Items in the Mail
Mixed Group Complications
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Main Focus EE
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Piezo strips
ME Case Studies
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other possibilities could have allowed MEs to contribute more
Future Group Possibilities
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Improve current design
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Using Specially Designed Strips
Implement Case Studies
Move Beyond the Phone
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With improved design(s), possible to charge other
electronics
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I-Pod
Palm Pilot
Laptop
Special thanks go to
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Dr Chun and Prof Dougherty
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Advanced Cerametrics
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New Balance Shoes
Questions?