Joe Paradiso, Nate Shenck
To develop a rugged piezoelectric shoe insert and complementary conditioning
electronics for unobtrusive, parasitic harvesting of the compression energy
normally lost while walking....
Energy is readily available at two locations in a shoe.
Curvature and relaxation at the ball of the foot, and Heel strike displacement at the heel cup
ML demonstrations of Energy Scavenging in the Shoes:
Media Lab PVDF flexible film stave
THUNDER(tm) PZT unimorph with power conditioning electronics, 12-bit encoder and RFID transmitter
The implants are unobtrusive and do not affect the gait of the bearer. They generated 20-80 mW of peak power (1-2 mW average) during brisk walk and were demonstrated in a low-power, wireless application:
Work continues... ML working with TTT consortium member, Draper Laboratory:
Bimorph Insole from below
A bimorph PZT design, connected in parallel, doubles the source power and cuts source impedance.
Power measurements at 1.1 Hz
Power conditioning: Must regulate very high-voltage, low-frequency, micro-power, capacitive source... "Direct Discharge" is lossy
Hybrid "Forward-Converter" topology
This work in progress; thesis will be completed in early May '99.