Multifrequency electrical impedance tomography system based on undersampling combined with a fast digital demodulation algorithm.

Multifrequency electrical impedance tomography (MFEIT) has shown great application prospects in the field of biomedical imaging. To realize high-precision multifrequency electrical impedance information acquisition, a high-precision MFEIT system with undersampling combined with a fast digital demodulation algorithm is proposed. The system is integrated with 16 electrodes, and semi-parallel acquisition is used. In addition, a novel multifrequency digital demodulation algorithm is applied to enhance the accuracy of multifrequency excitation signal demodulation and achieve rapid demodulation. This improvement is achieved by analyzing the process of the multifrequency digital demodulation algorithm and combining undersampling with a fast digital demodulation technique. To evaluate the proposed method, a systematic comparative experiment is conducted. The experimental results demonstrate that the demodulation error using the undersampling method is less than 0.7% within the frequency range of 5-500 kHz. In addition, the system achieves a maximum signal-to-noise ratio of 62.92 dB, an average blur radius of 0.953, and an average position error percentage of 9.3%. The results indicate that the MFEIT system constructed based on the above research has good performance and a high signal-to-noise ratio.