Carbon Nanotube Flow Sensors
Shankar Ghosh,1
A. K. Sood,1*
N. Kumar2
We report that the flow of a liquid on single-walled carbon
nanotube bundles induces a voltage in the sample along the direction of
the flow. The voltage that was produced fit a logarithmic velocity dependence over nearly six decades of velocity. The magnitude of the
voltage depended sensitively on the ionic conductivity and on the polar
nature of the liquid. Our measurements suggest that the dominant
mechanism responsible for this highly nonlinear response involves a
direct forcing of the free charge carriers in the nanotubes by the
fluctuating Coulombic field of the liquid flowing past the nanotubes.
We propose an explanation based on pulsating asymmetric ratchets. Our
work highlights the device potential for nanotubes as sensitive flow
sensors and for energy conversion.
1 Department of Physics, Indian Institute of
Science, Bangalore 560 012, India.
2 Raman Research
Institute, C.V. Raman Avenue, Bangalore 560 080, India.
*
To whom correspondence should be addressed. E-mail:
asood{at}physics.iisc.ernet.in
