About this Research Topic
Bioimpedance analysis has been successfully used for cancer diagnosis and biomaterial characterizations due to its safety, low cost, effectiveness, portability and applicability. The technique measures the impedance spectra of the material under study and then obtains its biological properties by using a fitting model. The correct extraction of properties depends on the model but also on the quality of measured data which, in turn, depends on the bioinstrumentation used for capturing and processing the signals. The more accurate the instrumentation for measuring the impedance spectra of any material, the better its characterization. However, stray capacitance and electronic noises affect the data and, consequently, weaken the use of this technique for medical applications. Higher input impedance amplifiers, noise feedback control, wider frequency range current source and stray capacitance attenuators, are some examples of innovative solutions to improve the bioinstrumentation performance.
Measuring electrical bioimpedance in a wide frequency range from 10 Hz to 10 MHz is very difficult in terms of electronics. Most recent commercial electrical components, such as instrumentation amplifiers, buffers and operational amplifiers do not have the ideal characteristics for working in a BIA device, particularly at higher frequencies (>1 MHz). In order to overcome the limitations of integrated circuits (IC), prominent solutions have been using current conveyors circuits developed with bipolar/CMOS/Bi-CMOS architectures. Other recent advances are related to the improvements of the voltage controlled current source for driving the biological loads, such as the modified Howland current source (HCS). Special HCS circuits with error feedback control can be designed for driving high loads in a wider frequency range. Some BIA systems use multiple electrodes, which then requires the use of multiplexers which, in turns, add more stray capacitance in the measuring system. Multiple current sources, error feedback control and buffer isolation might be of interest for the purpose of improving the BIA accuracy.
The scope of this research topic is to bring new trends and innovative instrumentation techniques, resulting in an accurate bioimpedance spectroscopy system working in a wide frequency range. The specific themes of interest for BIA applications include but are not limited to:
- Current conveyors
- Howland source topology
- Negative impedance converters
- Multisource drive systems
- Novel analog switching
- Novel instrumentation amplifiers
- Feedback control circuits
Measuring electrical bioimpedance in a wide frequency range from 10 Hz to 10 MHz is very difficult in terms of electronics. Most recent commercial electrical components, such as instrumentation amplifiers, buffers and operational amplifiers do not have the ideal characteristics for working in a BIA device, particularly at higher frequencies (>1 MHz). In order to overcome the limitations of integrated circuits (IC), prominent solutions have been using current conveyors circuits developed with bipolar/CMOS/Bi-CMOS architectures. Other recent advances are related to the improvements of the voltage controlled current source for driving the biological loads, such as the modified Howland current source (HCS). Special HCS circuits with error feedback control can be designed for driving high loads in a wider frequency range. Some BIA systems use multiple electrodes, which then requires the use of multiplexers which, in turns, add more stray capacitance in the measuring system. Multiple current sources, error feedback control and buffer isolation might be of interest for the purpose of improving the BIA accuracy.
The scope of this research topic is to bring new trends and innovative instrumentation techniques, resulting in an accurate bioimpedance spectroscopy system working in a wide frequency range. The specific themes of interest for BIA applications include but are not limited to:
- Current conveyors
- Howland source topology
- Negative impedance converters
- Multisource drive systems
- Novel analog switching
- Novel instrumentation amplifiers
- Feedback control circuits
Keywords: Impedance Spectroscopy, Electrical Bioimpedance, Bioinstrumentation, Biomedical instrumentation, Biomedical Sensors, Electrode Geometry, Analog Signal Processing, Current Source Instrumentation Amplifier
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