Direct-Current Nanogenerator Driven by Ultrasonic Waves
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Direct-Current Nanogenerator Driven by Ultrasonic Waves Bryan Schubert EE C235 April 9, 2008 X. Wang, J. Song and Z. L. Wang, Science 316, 102 (2007).
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Direct-Current Nanogenerator Driven by Ultrasonic Waves. Bryan Schubert EE C235 April 9, 2008. X. Wang, J. Song and Z. L. Wang, Science 316 , 102 (2007). Application. Energy scavenging Remote powering of implanted devices Force/pressure sensors. - PowerPoint PPT Presentation
Transcript of Direct-Current Nanogenerator Driven by Ultrasonic Waves
Direct-Current Nanogenerator Driven by Ultrasonic Waves
Bryan Schubert
EE C235
April 9, 2008
X. Wang, J. Song and Z. L. Wang, Science 316, 102 (2007).
Application
• Energy scavenging
• Remote powering of implanted devices
• Force/pressure sensors
X. Wang, J. Song and Z. L. Wang, Science 316, 102 (2007).
Principle of operation
• Piezoelectric effect:– d is piezoelectric coefficient
Z. L. Wang and J. Song, Science 312, 242 (2006).
dE zz /
Principle of operation
• Pt-ZnO Schottky barrier
Z. L. Wang and J. Song, Science 312, 242 (2006).
AFM scan of nanowire array
Principle of operation
• Nanowire contact scenarios:I. & II. Nanowire is bent until
compressed side contacts electrode.
III. Resonating nanowire.
IV. Compressed nanowire.
X. Wang, J. Song and Z. L. Wang, Science 316, 102 (2007).
Fabrication
X. Wang, J. Song and Z. L. Wang, Science 316, 102 (2007).
*J. Frühauf and S. Krönert, Microsyst. Technol. 11, 1287 (2005).
• ZnO Nanowires– Grown on Al2O3, using Au particles as catalyst for Vapor-Liquid-Solid process.
• 10/μm2 density• 1 μm long• 40 nm diameter
• Pt-coated Si zigzag electrode– Wet-etching*
• 1 μm peak-to-peak• 200 nm Pt layer
• Total device• 2 x 106 μm2 area
Performance
• Equivalent circuit
– Vs, nanowire source
– Ri, active NW contact resistance w/ electrode
– Rw, inactive NW resistance – 30 kΩ
– Rc, measurement device contact resistance w/ electrode – 30 Ω
– IA ≈ Vs/(Rc+Ri)
– V ≈ -VsRw/(Ri+Rw)
• Output for 41 kHz wave
– 0.15 nA increase in IA
– V = -0.7 mV output
– R = 3.56 kΩ
– Estimated 250 to 1000 NW engaged
X. Wang, J. Song and Z. L. Wang, Science 316, 102 (2007).
Performance
• Alternative designs– CNTs are not piezoelectric– Flat electrode does not allow contact of compressed edge.
X. Wang, J. Song and Z. L. Wang, Science 316, 102 (2007).
Performance
X. Wang, J. Song and Z. L. Wang, Science 316, 102 (2007).
* Z. L. Wang and J. Song, Science 312, 242 (2006)
• Durability– Can produce dc output
for over 1 hour
• Power– 1 to 4 fW per fiber– 1 pW total output– 0.00125 to 0.005% of
fibers contribute
• Efficiency*– Mechanical-to-
electrical, 17 to 30%
Improvements
• Control nanowire dimensions to optimize power per nanowire (1 fW to 10 fW per fiber).
• Control spacing and patterning to optimize nanowire co-operation (10 μW/cm2 => 0.2 μW for this device).
