This paper presents a highly sensitive flow-rate sensor with carbon nanotubes (CNTs)\nas sensing elements. The sensor uses micro-size centimeters long double-walled CNT (DWCNT)\nstrands as hot-wires to sense fluid velocity. In the theoretical analysis, the sensitivity of the sensor\nis demonstrated to be positively related to the ratio of its surface. We assemble the flow sensor by\nsuspending the DWCNT strand directly on two tungsten prongs and dripping a small amount of\nsilver glue onto each contact between the DWCNT and the prongs. The DWCNT exhibits a positive\nTCR of 1980 ppm/K. The self-heating effect on the DWCNT was observed while constant current\nwas applied between the two prongs. This sensor can evidently respond to flow rate, and requires\nonly several milliwatts to operate. We have, thus far, demonstrated that the CNT-based flow sensor\nhas better sensitivity than the Pt-coated DWCNT sensor.
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