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A wideband electrical impedance tomography sys-tem based on bioimpedance spectrum (BIS) analysis was pro-posed to image biological objects. The system integrated 16 electrodes to realize driving and measurement over 1 kHz -1.1 MHz. A modified Howland current source and voltage mea-surement channels were designed to obtain complex impedance. Peripheral component interconnect (PCI) interface based serial data acquisition module transferred the measurement data to a host PC. The system has the least SNR of 40 dB in each channel and good consistency. The system utilized a two-step strategy, based on short time Fourier transform and Hilbert transform, the wideband chirp excitation signal was employed to analyze the BIS firstly, from which the sensitive bandwidth, i.e. the frequency range in which the amplitude (and phase angle) of the object changes rapidly, is obtained. Then, the discrete frequency points among the sensitive bandwidth were selected to compose a multi-sinusoidal signal for impedance tomography with time difference and frequency difference methods. An impedance model was tested to evaluate the performance of BIS analysis. Experiments on phantoms consisting of carrot cylinder and nylon rod were designed to verify the working strategy of the system. The results indicated that the developed system can distinguish the objects and reconstruct medium distribution with high image contrast and frequency resolution. Compared with the traditional multi-frequency electrical impedance tomography, the proposed method and system show advantages in imaging the local electrical properties with high frequency resolution and obtaining the frequency difference images in the sensitive bioimpedance spectrum bandwidth.
|Journal||IEEE Transactions on Instrumentation and Measurement|
|Early online date||18 Feb 2019|
|Publication status||E-pub ahead of print - 18 Feb 2019|
- Voltage measurement
- Image Reconstruction
- Bioimpedance spectrum (BIS)
- electrical impedance tomography (EIT)
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- 1 Finished
1/04/16 → 31/03/18