Michael Erwin Ross Martin (Team Leader) Tao Nguyen Clifton Weng Ursula Zangrilli Dr. Chun and Prof. Dougherty

Overview Introduction Introduction Objectives Objectives Ideas and Results Ideas and Results Economics Economics Case Studies Case Studies Final Thoughts Final Thoughts

Intro and Objectives Tao Nguyen

Introduction Almost Everyone Uses Portable Electronics Almost Everyone Uses Portable Electronics Palm Pilot (200 mW), MP3 Players (110 mW), Laptops (10 W) Palm Pilot (200 mW), MP3 Players (110 mW), Laptops (10 W) All run out of power in a matter of hours All run out of power in a matter of hours

Power Estimates Breathing – 0.42 W Breathing – 0.42 W Blood pressure – 0.37 W Blood pressure – 0.37 W Exhalation – 0.40 W Exhalation – 0.40 W Footsteps – 5 W Footsteps – 5 W

Challenges How do we generate power? How do we generate power? How can we harness it? How can we harness it?

State of the Art Hand crank/Shake Flashlights Hand crank/Shake Flashlights Kinetic watches Kinetic watches Swatch Automatic/Autoquartz Swatch Automatic/Autoquartz Seiko Kinetic Seiko Kinetic Seiko Thermic watches Seiko Thermic watches

Objectives Design a device to generate electrical power from the human body Design a device to generate electrical power from the human body Various devices that convert human mechanical to electrical energy Various devices that convert human mechanical to electrical energy A circuit to harness this energy A circuit to harness this energy Use this power to charge the batteries of portable electronics Use this power to charge the batteries of portable electronics Harness enough electrical power to charge a cell phone battery Harness enough electrical power to charge a cell phone battery

The Design Idea Ross Martin

The Idea Shoe based generator Shoe based generator Incorporates piezoelectric strips Incorporates piezoelectric strips Strips generate electricity through polarization induced by stretching of the fibers Strips generate electricity through polarization induced by stretching of the fibers Screen printed silver electrodes provide electrical contacts Screen printed silver electrodes provide electrical contacts

The Idea Each strip produces: Each strip produces: 40 volts peak-to-peak per pulse 40 volts peak-to-peak per pulse 6-9 uAmps per pulse 6-9 uAmps per pulse Final output is an AC voltage Final output is an AC voltage

The Idea AC->DC Conversion AC->DC Conversion Pass AC wave through transformer rectifier Pass AC wave through transformer rectifier Capacitor filter smoothes the wave even further Capacitor filter smoothes the wave even further Voltage regulation Voltage regulation Maintain a steady output voltage between 3.7 and 4.1V Maintain a steady output voltage between 3.7 and 4.1V As high a current output as possible As high a current output as possible

The Idea Circuit tucked under heel in sealed package Circuit tucked under heel in sealed package Wire feeds power to battery being charged Wire feeds power to battery being charged Standard charging plug for phone Standard charging plug for phone Phone held in modified holder on ankle Phone held in modified holder on ankle

Research Results

Results Initial design was as shown above Initial design was as shown above Converter to 555 timing chip to battery Converter to 555 timing chip to battery

Results Eliminated due to Eliminated due to No need for timing with low current No need for timing with low current 3 pole transformer introduces unnecessary complexity 3 pole transformer introduces unnecessary complexity Large number of components lower output Large number of components lower output

Results Second design: Dedicated charging chip Second design: Dedicated charging chip Use of LM3658 to control charging Use of LM3658 to control charging Pros: introduces layers of battery safety Pros: introduces layers of battery safety Cons: 4.5v-6v input voltage range, 50mA minimum current Cons: 4.5v-6v input voltage range, 50mA minimum current Put to the side, pending higher current and better voltage control Put to the side, pending higher current and better voltage control

Results Re-evaluation of design strategy Re-evaluation of design strategy Focus on sustainable voltage levels Focus on sustainable voltage levels Plans for intelligent charging continued as a second goal for post experiment work Plans for intelligent charging continued as a second goal for post experiment work

Results Third design: Converter with capacitor Third design: Converter with capacitor 2 versions: half and full wave 2 versions: half and full wave Half wave yielded moderate voltages of up to 6V Half wave yielded moderate voltages of up to 6V Required unrealistic strip movements Required unrealistic strip movements Acceptable, but not ideal Acceptable, but not ideal

Results Full wave produces voltages in excess of 15V Full wave produces voltages in excess of 15V Uses diode bridge rather than paired set Uses diode bridge rather than paired set Easily obtainable via normal movements Easily obtainable via normal movements Full rectification gives twice as many pulses within acceptable voltage range Full rectification gives twice as many pulses within acceptable voltage range

Results Voltage output of Diode Bridge Voltage output of Diode Bridge

Results Addition of capacitors reduce ripple between pulses Addition of capacitors reduce ripple between pulses

Results Results of design Results of design Working converter circuit Working converter circuit Ample voltage for charging Ample voltage for charging Insufficient current Insufficient current

Economics Tess Zangrilli

Costs for Prototype Piezoelectric strips(3):$25 per strip Piezoelectric strips(3):$25 per strip Circuit components:about $1 Circuit components:about $1 Phone Plug: $1 Phone Plug: $1 Inserts: $5 Inserts: $5 Total=$82 Total=$82

Costs to Mass Produce Startup Startup Customizations Customizations Per unit costs: Per unit costs: $5-10 per strip $5-10 per strip Circuit components: <$1 Circuit components: <$1 Phone Plug: <$1 Phone Plug: <$1 Insert: <$1 Insert: <$1

Independent Case Studies Cliff Weng

Case Study #1: Inductor Slug Velocity: 1.3 m/s Number of turns: 100,000 Total Length: 8 cm Coil Diameter: 2 cm Current Produced: amps Inductor Piezo strips circuit

Case Study #2: Windmill 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 Piezo strips circuit

Final Thoughts Mike Erwin

Were our Goals Achieved? Design a device to generate electrical power from the human body Design a device to generate electrical power from the human body Succeeded Succeeded Use this power to charge the batteries of portable electronics Use this power to charge the batteries of portable electronics Not possible using available supplies Not possible using available supplies Harness enough electrical power to charge a cell phone battery Harness enough electrical power to charge a cell phone battery Proved to be possible. - Nokia Proved to be possible. - Nokia

Lessons Learned Test Testing Equipment Test Testing Equipment Simple is Better Simple is Better More Specific is Better More Specific is Better Allow plenty of time for Complications Allow plenty of time for Complications Items in the Mail Items in the Mail Mixed Group Complications Mixed Group Complications Main Focus EE Main Focus EE Piezo strips Piezo strips ME Case Studies ME Case Studies other possibilities could have allowed MEs to contribute more other possibilities could have allowed MEs to contribute more

Future Group Possibilities Improve current design Improve current design Using Specially Designed Strips Using Specially Designed Strips Implement Case Studies Implement Case Studies Move Beyond the Phone Move Beyond the Phone With improved design(s), possible to charge other electronics With improved design(s), possible to charge other electronics I-Pod I-Pod Palm Pilot Palm Pilot Laptop Laptop

Special thanks go to Dr Chun and Prof Dougherty Dr Chun and Prof Dougherty Advanced Cerametrics Advanced Cerametrics New Balance Shoes New Balance Shoes

Questions?