RECOGNIZING OPPORTUNITY RECOGNIZING OPPORTUNITY

CLUELESS TODDLER

UNSUSPECTING VICTIM

SOURCE OF ENERGY

THE

VERDICT:

HARVEST

HIM

THE POWER OF WALKINGTHE POWER OF WALKING

(1.5W) x (2 steps/sec x 0.6 steps/sec)=

5 W

● Flexible PVDF deflects 0.6 times/sec

● Highly durable

● Easy to cut into appropriate shape

PIEZOELECTRIC SOLE INSERTS PIEZOELECTRIC HEEL INSERTS

● Semi-flexible PZT

● Takes advantage of greatest force

● Heel strike with 130% apparent mass

(12.5%) x (67W)=

8.4 W

8.4 mJ

1.3 mW

8.4 mW

THE SODANO APPROACHTHE SODANO APPROACH

PSI-5H4E (PZT)CAR COMPRESSOR (ACCELEROMETER)

THE PROS:

● At resonant frequency, 40mAh NiMH 1.2V button cell charged in 1 hour

● With a random signal, 40mAh NiMH 1.2V button cell charged in 1.5 hour

● (144C x 1.2v)/3600s = 50mW

● Presents the piezoelectric setup

THE CONS:

● Accelerometer has a completely random frequency (1-1000 Hz)

● 185 PSI-5H4E sheets = $7 316.75

● Extreme brittleness: 0.267mm thick

PIEZOCERAMICS: PZTPIEZOCERAMICS: PZT

● “The direct piezoelectric effect” (Pierre & Jacques Curie in 1880):

Generating of an electric current by applying mechanical stress

● During WWII, the greatest class of piezoelectric elements shifted to man-made FERROELECTRICS:

1. Barium Titanate (BaTiO3B)

2. PZT (Lead Zirconate Titanate)

● PZT is most economical and efficient alternative

TOKYO STATION: MARUNOUCHI TOKYO STATION: MARUNOUCHI NORTH TICKET GATENORTH TICKET GATE

3609 J IN 10 HOURS

● OCTOBER 16 4:00 AM – 2:00 PM

● 785,801 daily commuters on average for the year 2007

KEY ASSUMPTIONS:

● We assume all 785,801 commuters undergo only a one-way commute to work, school, etc.

● Neglect any return-trips that occur 4AM and 2PM that would otherwise increase the number of ‘commuters’

● The same number of commuters walk through the platforms only once between 4AM and 2PM

● Distribute themselves evenly

LOCATING THE TICKET GATESLOCATING THE TICKET GATES

1

6

2 3 45

7

810

1211

9

● 785,555/12 GATES =

65 000 COMMUTERS AT MARUNOUCHI NORTH

1) 65 000/6 PLATFORMS =

10,000 COMMUTERS

2) (3609/6) J / 10,000 COMMUTERS =

60 mJ PER COMMUTER

The piezoelectric floor at Marunouchi North Gate

FINANCINGFINANCING● 480 disc-shaped piezoelectric elements with a diameter of 30 mm

● 480 units x $30/unit = $14 400

● Only units that commuters apply mechanical stress on are productive

“The piezoelectric elements covering the floor are commercially

available ceramic piezoelectric elements”

● Three pairs of footprints

● Two lanes: one proceeding down to Level D and the other proceeding up to Level B

x (3 x 6) x $30/unit =

$6 480

12 x (3 x 6) x $30/unit =

$6 480

SHIELDING AND OUTPUTSHIELDING AND OUTPUT● Rubber matting surrounding the piezoelectric elements in the same plane

● Rubber matting below the circular piezoceramics and shielding them from above

● 1.4 million visitors/year = 3,850 visitors daily

● 3,850 x 2 x 55 mJ = 462 Joules daily

● 462 J x 7 days = 3 234 Joules weekly

PART A: Exhibit Output

PART B: Battery Capacity

● 800mA x 3600 s x 1.2 V = 3456 Joules

A NiMh“green battery”: 800mAh / 1.2V / AAA

WHAT IS IT GOING TO POWER?WHAT IS IT GOING TO POWER?

● Illustrate practicality of piezoelectricity on a small scale

● Power the Robot in the maze in the ‘Roving Mars’ Exhibit

● 2 AA Alkaline batteries as its current power supply

● Batteries replaced once every 2 – 2.5 weeks

● 1 AAA Green battery is recharged once every week; hence, a use-recharge cycle with period of two weeks

THE BOMBSHELLTHE BOMBSHELL

●“After the 3rd week of the experimental period, production of electricity decreased due to a degradation in durability”

● The gargantuan number of commuters at Marunouchi North Ticket Gate eventually oversaw the breakdown of the piezoelectric platformsWHAT IS THE RATE OF DEGRADATION?

10 000 commuters/day x 21 days = 210 000 commuters1.4 million/0.21 million ≈ 7 replacements per annum

7 x $6 480 = $45 360 per annum

THE PIEZO-POWER GATETHE PIEZO-POWER GATE

AB

C

D

E

G

A

B

C

D

E

F

Exhibit Info

Voltmeter

Power Bar

Ammeter

Piezoelectric Platform

F

Piezo-Power Gate Sign

G Electrical Output Info

SUMMARYSUMMARY

-work in progress-work in progress

-debating points to include-debating points to include