Design and Evaluation of an Electrical Bioimpedance Device Based on DIBS for Myography during Isotonic Exercises

Abstract

Electrical Bioimpedance Spectroscopy (EIS) is a technique used to assess passive electrical properties of biological materials. EIS detects physiological and pathological conditions in animal tissues. Recently, the introduction of broadband excitation signals has reduced the measuring time for application techniques such as Electrical Bioimpedance Myography. Therefore, this work is aimed at proposing a prototype by using discrete interval binary sequences (DIBS), which is based on a system that holds a current source, impedance acquisition system, microcontroller and graphical user interface. Measurements between 5 Ω to 5 kΩ had impedance acquisition and phase angle errors of aproximately 2% and were lower than 3 degrees, respectively. Based on a proposed circuit, bioimpedance of the chest muscle (Pectoralis Major) was measured during isotonic exercise (push-up). As a result, our analyses have detected tiredness and fatigue. We have explored and proposed new parameters which assess such conditions, as both the maximum magnitude and tiredness coefficient. These parameters decrease exponentially with consecutive push-ups and were convergent in the majority of the sixteen days of measurement.

Bioimpedance Sensors: A Tutorial

“…12(e)), pseudo-random binary sequences (Fig. 12(f)) such as maximum length binary sequence (MLBS) and discrete interval binary sequence (DIBS) and Walsh functions have been proposed as multifrequency excitation signals [185], [195]. MLBS can be very easy to generate, but the amplitude of each frequency component decreases with increasing frequency and thus also the SNR, while also containing frequency components that may not be of interest.…”

“…Measurement of the current through sense resistors at the output of the current source is an approach to ensure the injected current amplitude is known and that the appropriate reference signal is used for impedance (phase) calculations. Differential current sources are preferred when possible, to minimize the common-mode voltage across the load and thus improve the instrumentation's overall common-mode rejection ratio (CMRR) [6], [195]. Decoupling capacitors (C X = 1-10 µF, see Fig.…”

“…The differential dc voltage across the current source terminal should be zero. Load-in-theloop [199] and differential Howland current sources [6], [180], [195], [200] are the most common approaches when using discrete components, while for integrated realizations, operational transconductance amplifiers (OTA) with feedback through current sense resistors to regulate the injected current are often used [177], [201], [202]. In the load-in-the-loop configuration, the tissue (Z L ) is connected to the amplifier output through a small resistor R safe and the virtual ground of the inverting terminal, as shown in Fig.…”

“…The following relationships must be satisfied: R 4 = R x + R 3 and R 3 = R 5 . The output current is then set by [195]…”

Design of Howland current sources using differential evolution optimization

“…Electrical Bioimpedance Spectroscopy (EBS) has been widely used over the last 50 years for biomedical applications [ 1 ], such as cancer diagnoses [ 2 ], monitoring of physiological activity (lung fluids [ 3 ], muscle contractions [ 4 ] and cardiac output [ 5 ]) and real-time tomography [ 6 ]. EBS uses the correlation between material constitution/geometry and electrical impedance to characterize the tissue [ 7 ].…”