Aligned carbon nanotube based ultrasonic microtransducers for durability monitoring incivil engineering

Abstract

Structural health monitoring of porous materials such as concrete is becoming a majorcomponent in our resource-limited economy, as it conditions durable exploitation ofexisting facilities. Durability in porous materials depends on nanoscale features which needto be monitored in situ with nanometric resolution. To address this problem, we putforward an approach based on the development of a new nanosensor, namely a capacitivemicrometric ultrasonic transducer whose vibrating membrane is made of alignedsingle-walled carbon nanotubes (SWNT). Such sensors are meant to be embedded in largenumbers within a porous material in order to provide information on its durability bymonitoring in situ neighboring individual micropores. In the present paper, we report onthe feasibility of the key building block of the proposed sensor: we have fabricatedwell-aligned, ultra-thin, dense SWNT membranes that show above-nanometer amplitudesof vibration over a large range of frequencies spanning from 100 kHz to 5 MHz.