Multiplexerless Current Excitation Stage for EIT Bioimpedance Measurements

J. A. Gutierrez-Gnecchia, A. Tellez-Anguianoa, G. M. Chavez-Camposa,

D. Infante Sáncheza, D. Lorias Espinozab

a Instituto Tecnologico de Morelia, Departamento de Ingenieria Electronica, Avenida Tecnologio 1500, Morelia, Mich., C.P.

58000, Mexico

b CINVESTAV/IPN, Departamento de Ingenieria Electrica, Seccion Biotecnologia, Av. Instituto Politécnico Nacional 2508, C. P.

07360, México, D. F., Mexico.

Abstract

Physiological measurements occupy a large part of the Electrical Impedance Tomography (EIT) application spectrum; measurements ranging from monitoring lung and cardiac functions to cancer diagnosis have been continuously reported for the past three decades. In particular for cancer diagnosis it has been reported that impedance measurements in the range of 20MHz to 100 MHz can be used to differentiate healthy tissue from malignant tissue. However, EIT results are often restricted to the α and lower β dispersion frequency ranges. The authors revisit the use of transconductance amplifiers to build a multiplexerless current excitation stage for obtaining images in the β dispersion range. Ex-vivo (swine tissue) bioimpedance test results are in agreement with previously reported work using commercial impedance analysis equipment. In-vivo (human thigh) EIT tests show that is possible to identify different tissues from reconstructed EIT images.

Keywords: Bioimpedance measurements; Electrical Impedance Tomography; Analogue Design; Instrucmentation; breast cancer diagnosis