Analog Front-End for the Integrated Circuit AD5933 Used in Electrical Bioimpedance Measurements

Abstract

In the recent decades the bioimpedance has been used in many areas of medicine. The technological advance of electronics has enabled the increase of bioimpedance applica- tions. Measuring biological tissues is a hard work, which leads to the need of continuous research based on better methods and equipments for diagnosis. Many electronics manufacturers have helped the biomedical area through the development of new electronic components and equipment. The objective of this work is to adapt the impedance meter AD5933 for bioim- pedance measurements. Two Analog Front-End (AFE) circuits were built with different Voltage Controlled Current Source (VCCS) topologies, which are a load-in-the-loop and a mir- rored modified Howland current sources. Circuits were im- plemented and both two and four electrode measurements in the frequency range of 5 to 100 kHz were performed. Results showed that both front-end circuits are suitable to be used with the AD5933 at lower frequencies. Also, it might be a low-cost alternative for electrical bioimpedance applications.