A 3.8-mW 1.9-m $\Omega$ / $\surd$ Hz Electrical Impedance Tomography IC With High Input Impedance and Loading Effect Calibration for 3-D Early Breast Cancer Detect System

This article introduces an advanced 3-D electrical impedance tomography (EIT) imaging system for improving stability in the face of contact impedance variations. The 6-mm ² chip is manufactured through a TSMC 180-nm CMOS process and incorporates two key features: 1) a high-input-impedance instrumentation amplifier (IA) with auxiliary source followers to ensure robust voltage sensing and 2) a trans-conductance (TC) current driver with a trans-impedance (TI) monitoring circuit, enabling precise measurement of the injected current while eliminating the loading effect. The proposed IC has a low power dissipation of only 3.8-mW, excluding the injection current, and offers an impressive impedance resolution of 1.9-m $\Omega$ / $\surd$ Hz. The input impedance of IA has been significantly enhanced, reaching 2.9 G $\Omega$ at 100 Hz and 230 k $\Omega$ at 1 MHz, indicating high performance over a wide range of frequencies. To prove its effectiveness, this article successfully reconstructed 3-D images of a human phantom using a mobile device. Additionally, the entire system was designed with a 3-D rotatable imaging application that can determine the location of cancer by directly rotating the breast model.