Development of a Multiwalled Carbon Nanotube Voltage Sensor Using Copper Oxide Nanofluids

Carbon Nanotubes (CNTs) are allotropes of carbon having superior mechanical, electronic, physical, and optical properties. When a fluid is passed through the nanotubes, the fluid exerts a mechanical force on the walls of the CNT due to which a strain is induced on the surface of the CNTs creating a net charge at the center of the strained hexagon. This induced polarity produces a voltage across the nanotubes. In this project, nanofluids (cuprous oxide in ethylene glycol) in addition to conventional fluids were passed through multiwalled CNTs (MWCNTs), and a voltage was observed (upto 4.1 mV in the case of nanofluids) after the capillary rise of the flowing fluid in the nanotube sensor. This was in agreement with previously conducted studies on the piezoelectric effect due to the flow of conventional fluids on single-walled CNTs (SWCNTs). The voltage generated across the MWCNTs for the different fluid systems was compared and characterization was done with respect to the fluid system. An attempt was made to present the voltage generated as a function of the fluid and flow properties. The article aims to highlight the possible use of MWCNTs in sensor-based technology and energy conversion devices.