Evaluation of sensitivity of stiffness-sensitive electret microphones.

This paper presents an evaluation of the sensitivity of a new thin-film stiffness sensing technology that utilizes commercial electret microphones. The analysis allows comparison of commercial microphones for stiffness sensing applications. A mathematical method to estimate the stiffness sensitivity of a commercial microphone from its acoustic sensitivity is developed. Experimental results are presented on the use of the developed method in a sensor that estimates carbon dioxide concentration by utilizing a carbon nanotube thin film on an electret microphone.