Bio-impedance Circuit Feedback Loop for Leakage Current Compensation
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Solution Overview
Problem
Smaller dry electrodes in portable medical devices lead to worse electrode impedance, compromising the quality and accuracy of physiological signal measurements, particularly in bio-impedance calculations, due to significant leakage currents caused by parasitic capacitance.
Innovation Solution
A bio-information acquisition system circuit is designed with a terminal, output circuit, feedback circuit, and calibration circuit to reduce leakage currents by using a shield line to minimize parasitic capacitance and a feedback loop to neutralize leakage currents, and a phase compensator to stabilize the feedback loop, ensuring accurate impedance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If smaller dry electrodes are used in portable medical devices, then device portability and user comfort are improved, but electrode impedance increases and signal quality deteriorates
Solution Approach 1:
The patent implements a feedback circuit that receives the output signal, generates a current signal, and feeds it back to the terminal. This feedback mechanism actively compensates for the high impedance effects of small dry electrodes, maintaining signal quality while enabling portable device design.
Solution Approach 2:
The patent changes the electrical parameters of the measurement system by introducing a feedback current signal that dynamically adjusts to counteract the high electrode impedance. This parameter modification allows small electrodes to function effectively in portable devices without sacrificing measurement accuracy.
2Volume of moving object
If smaller dry electrodes are used, then device size is reduced, but leakage currents increase due to parasitic capacitance
Solution Approach 1:
The feedback circuit generates a compensatory current signal that counteracts the leakage currents caused by parasitic capacitance in small electrodes. This active compensation enables miniaturized devices to maintain accurate bio-impedance measurements despite increased leakage effects.
Solution Approach 2:
The patent converts the harmful leakage currents into a manageable parameter by measuring their effect through the feedback circuit and compensating for them. The feedback mechanism transforms the adverse leakage effect into a correctable signal deviation, enabling accurate measurements in compact devices.
3Measurement precision
If feedback circuit is added to compensate leakage currents, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the feedback circuit functions with the existing output circuit, allowing the same circuitry to perform both signal generation and leakage compensation. This integration reduces overall device complexity while maintaining measurement accuracy.
Solution Approach 2:
The feedback circuit is designed to perform multiple functions: generating the current signal, compensating for leakage currents, and maintaining measurement accuracy. This multi-functionality reduces the need for separate dedicated circuits, thereby limiting the increase in device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The circuit effectively reduces leakage currents and stabilizes the feedback loop, enhancing the accuracy of bio-impedance measurements and maintaining signal quality, thereby improving the reliability of physiological information obtained from portable medical devices.
Implementation Method 1
the feedback circuit is configured to receive the output signal to generate a current signal to the terminal
Implementation Method 2
significant leakage currents caused by parasitic capacitance
Implementation Method 3
a phase compensator to stabilize the feedback loop
Data Source
AI summary
The present invention provides a circuit applied to a bio-information acquisition system, wherein the circuit includes a terminal, an output circuit, a feedback circuit and a calibration circuit. In the operations of the circuit, the terminal is arranged to receive an input signal, the output circuit is configured to generate an output signal according to the input signal, the feedback circuit is configured to receive the output signal to generate a current signal to the terminal, and the calibration circuit is configured to generate a control signal to control the feedback circuit to determine a level of the current signal according to the output signal.