An electrical impedance tomography (EIT) system based on frequency division multiplexing (FDM) is proposed for real-time lung physiological imaging. The FDM technique allows the integration of 13 dedicated voltage sensing channels by combining data on-chip and sharing of ADC to alleviate area penalty caused by multi-channel. The EIT SoC is of the following features: 1) early I/Q demodulation to relax the bandwidth requirement of analog front end and minimize the impact of motion artifacts and DC electrode offset; 2) eliminates the need of adaptive gain control (AGC) with constant inverted “V-shape” gain configuration to compensate amplitude variations across all channels; 3) FDM to combine 13 pairs of I/Q signals into two data streams for quantization using only two Modulators (DSMs); 4) batch data recovery by Blackman window corrected FFT without any digital filtering involved; and 5) lowest power consumption and smallest area occupation per channel reported to date. The EIT SoC occupies an area of 11.28-mm2 in 130nm CMOS technology with a total power consumption of 1.53-mW under 1-V power supply. As a result, it generates lung EIT images at up to 5 frames per second (fps).

This paper aims to present a proof-of-concept for a novel piezoelectric motor using a single-phase driving signal. The stator is constructed by bonding a Terfenol-D plate and a piezoelectric ceramic (PZT) plate onto the outer surface of a metal base. The PZT plate based on d 31 effect is used to simultaneously excite two in-plane bending modes of the stator. Similarly, the Terfenol-D plate can also be used to excite the two bending modes. By superposition of the two bending modes, elliptical motions of the stator surface points are generated. The working modes and vibration characteristics of the motor are analyzed by finite element analysis software. The resonance frequencies of the two bending modes are tuned to be close by additional mass. The dimensions of the stator are optimized to maximize the output displacement. To confirm the feasibility of the proposed design, a prototype motor is fabricated and tested. The size of the prototype motor is about 11.2×10.7×28.0 mm ³ . The tested resonance frequencies of the two bending modes are 16.0820 kHz and 16.3476 kHz respectively. The maximum no-load speed is 85 rpm. The applied driving voltage is 100 V _o-p (peak voltage) at a frequency of 16.34 kHz.

Objective. Electrical impedance tomography (EIT) generates cross-sectional images through non-invasive impedance measurements from surface electrodes. While impedance above 200 kHz can reveal intracellular properties, most existing EIT images are published at frequencies below 200 kHz. When frequencies exceed 200 kHz, the accuracy of impedance measurements declines due to the distributed circuit parameters such as parasitic capacitance, on-resistance of switch and the series inductance, with a more significant impact on larger impedance. To overcome this limitation, this paper proposes an approach to enhance the precision of impedance measurement through self-identification of distributed parameter. Approach. Firstly, the distributed circuit parameters are identified via correction measurements of precision resistances in the frequency range from 5 kHz to 1 MHz; then, the circuit is accurately modeled; finally, transfer impedance measurements during imaging process are corrected using the established circuit model. Main results. The distributed circuit parameter self-identification method was verified through a goodness-of-fit test, confirming the consistency between the model’s predicted values and the actual values of the component. The test results indicate that at 1 MHz, the relative residuals follow a right-skewed distribution with an average value of 0.08%, which demonstrates high model accuracy. At 1 MHz, the relative error after correction for the 499 Ω precision resistor measurement is reduced by 12.01%, and for the 56 pF precision capacitor in parallel with 249 Ω, the relative error after correction is 0.46%. Significance. The proposed method can extend the frequency range of EIT and other impedance technologies from below 200 kHz to up to 1 MHz, while ensuring good measurement accuracy.