Ultrasonic micro-arrays for imaging the human auditory system

Ultrasound is a safe, cheap, and reliable method of obtaining real-time images of biological tissue. The resolution of an ultrasound system is primarily determined by the operating frequency of the transducer. High-frequency ultrasound imaging systems have much greater resolution than conventional low-frequency systems and can typically resolve tissue structures between 20 and 100 microns in size at the cost of a limited penetration depth (< 1 cm). In spite of the limited penetration depth, this technology has great potential as an imaging technique for visualizing small sub-surface tissue structures. While high-frequency ultrasound has been successfully applied to intravascular imaging, ophthalmic imaging, and pre-clinical small animal imaging, it has not yet realized its full potential as a routine diagnostic tool. The primary reason for this is that as the transducer operating frequency increases, the dimensions of the ultrasound transducer decreases proportionally, making them extremely difficult to fabricate. If these fabrication issues can be overcome, however, a great improvement in image quality can be obtained over the relatively unsophisticated high-frequency systems that are currently used. This could potentially lead to the routine clinical use of this technology and create many new clinical and commercial opportunities. This research program describes the development of a high-resolution array-based ultrasound imaging system, specifically for investigating tissue structures of the ear and auditory system. High-frequency ultrasound has the ability to revolutionize diagnostics in this field by providing in-vivo and real-time visualization of the micro anatomy in the middle and inner ear. The transducer arrays that will be developed will be small enough to be situated at the tip of an endoscopic probe which can be inserted into the ear canal and up against the round window membrane of the cochlea. The micro-arrays will be designed in order to maximize the image volume within the cochlea and use a novel analog electronic system to focus the ultrasound beam.