Novel micromachined silicon acoustic delay line systems for real-time photoacoustic tomography applications
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In current photoacoustic tomography (PAT) systems, ultrasound transducer arrays and multi-channel data acquisition (DAQ) electronics are used to receive the PA signals. To achieve real-time PA imaging, massive 1D or even 2D transducer arrays and large number of DAQ channels are necessary. As a result, the ultrasound receiver becomes very complex, bulky and also costly. In this paper, we report the development of novel micromachined silicon acoustic delay line systems, which are expected to provide a new approach to address the above issue. First, fundamental building block structures of the acoustic delay line systems were designed and fabricated. Their acoustic properties were characterized with ultrasound and photoacoustic measurements. Second, two different acoustic delay line systems (parallel and serial) were designed and fabricated using advanced micromachining processes to ensure compact size, high accuracy, and good repeatability. The transmission of multiple acoustic signals in the acoustic delay line systems were studied with ultrasound experiment. Experimental results show that the silicon acoustic delay line systems can guide multiple channels of acoustic signals with low loss and distortion. With the addition of a set of suitable time delays, the time-delay acoustic signals arrived at a single-element transducer at different times and were unambiguously received and processed by the following DAQ electronics. Therefore, the micromachined silicon acoustic delay line systems could be used to combine multiple signal channels into a single one (without the involvement of electronic multiplexing), thereby reducing the complexity and cost of the ultrasound receiver for real-time PAT application. 2013 Copyright SPIE.