Experimental Demonstration of Linear Frequency Modulated Excitation in MAET with Magnetic Field Measurements

Magneto-acousto-electrical tomography (MAET) is an imaging technique that enables electrical conductivity mapping by combining ultrasound-generated acoustic waves with magnetic field interactions. It detects Lorentz force-induced electrical signals generated as acoustic waves propagate through a conductive body within a static magnetic field. This study presents the first experimental demonstration of linear frequency modulated (LFM) excitation and matched filtering-based pulse compression in MAET with magnetic field measurements. The experiments are conducted under a high static magnetic field of 1.5 T. A linear phased array (LPA) transducer is used to generate acoustic waves, driven by a 50 V peak amplitude ultrasound driver. Low-Q receiver coils are employed to detect signals from a phantom containing a graphite disc embedded in an agar-water medium. A two-stage cascaded amplifier with a total gain of 82.6 dB is employed. Experimental results show that LFM excitation improves the signal-to-noise ratio (SNR) by approximately 12.7 dB compared with conventional single-cycle excitation. The measured full width at half maximum is 2.7 mm, and the peak sidelobe level is -16.8 dB, confirming the feasibility of using LFM-based pulse compression in MAET to enhance SNR while preserving spatial resolution.