Carbon nanotubes based ultrasonic microtransducers for durability monitoring

Structural health monitoring of porous materials such as concrete is becoming a major stake in our resource-limited economy, as it conditions durable exploitation of existing facilities. Durability in porous materials depends on nanoscale features which need to be monitored in-situ with nanometric resolution. To address this problem, we put forward an approach based on the development of a new nanosensor, namely a capacitive micrometric ultrasonic transducer whose vibrating membrane is made of aligned single-walled carbon nanotubes (SWNT). Such sensors are meant to be embedded in large number within a porous material in order to provide with information on its durability by monitoring in-situ neighboring individual micropores. In the present paper, we report on the feasibility of the key building block of the proposed sensor: we have fabricated well-aligned, ultra-thin, dense SWNT membranes that show above-nanometer amplitudes of vibration in a large range of frequencies spanning from 100 kHz to 5 MHz. PACS: 07.07.Df, 68.37.-d, 85.35.Kt, 85.85.+j