Active EEG Electrode Circuit Without Onboard Power Supply
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Solution Overview
Problem
Existing EEG electrode systems face challenges with signal degradation due to long connection cables picking up background noise and impedance issues, and existing solutions are often complex, expensive, or unsuitable for implantation due to the need for a power source within the electrode.
Innovation Solution
An active electrode design featuring a housing with a measurement sensor and electronic circuit including a transistor with specific terminal connections, connected to a remote electronic unit for amplification, eliminating the need for a power source within the electrode and minimizing signal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a preamplifier is integrated into the electrode housing to amplify the signal immediately, then signal amplification is improved, but the electrode requires a power supply within the housing making it unsuitable for implantation
Solution Approach 1:
The invention divides the amplification system into two segments: a passive electrode housing containing only the sensor and a remote active unit containing the power supply and main amplification circuitry. This segmentation allows the electrode to be implantable while still providing signal amplification through the remote unit that connects via cable.
Solution Approach 2:
The cable connecting the electrode to the remote unit acts as an intermediary, transmitting the weak signal from the passive electrode to the active remote unit for amplification. This intermediary approach allows power supply functions to be separated from the implantable electrode while maintaining signal integrity.
2Power
If long connecting cables are used to connect electrodes to a remote amplification unit, then signal amplification is enabled, but the cables act as antennas capturing background noise and cause signal degradation
Solution Approach 1:
The system performs preliminary amplification at the remote unit before signal transmission through the cable, and uses shielding and filtering in advance to protect against noise. The passive electrode captures the signal without adding noise, and the remote unit prepares the signal for transmission with minimal interference.
Solution Approach 2:
The invention converts the potential harm of long cables by using them in a controlled configuration where they connect to a shielded remote unit with proper grounding and filtering. The cable length that would normally be a disadvantage is accepted as necessary for remote placement, but its harmful effects are neutralized through proper shielding and the passive nature of the electrode housing.
3Measurement precision
If electronics including an analog-to-digital converter are integrated into the electrode housing, then signal processing is improved, but the solution becomes complex to implement
Solution Approach 1:
The invention segments the electronic functions into the remote unit (containing ADC and processing electronics) and the electrode housing (containing only passive sensing elements). This segmentation simplifies the implantable electrode while concentrating complex electronics in a remote unit that is easier to service and power.
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 solution provides effective signal amplification near the detection zone while avoiding signal degradation and allowing for implantation without electrical risks, by using a transistor with current biasing and a remote electronic unit for power, thus enhancing EEG signal quality and safety.
Implementation Method 1
Said housing housing an electronic circuit comprising a transistor which has a first terminal, a second terminal connected to said sensor and forming an input, a third terminal
Data Source
Figure 1~2B
Figure 3
AI summary
The invention relates to an active electrode (1) for measuring electrical activity, implantable or non-implantable, characterized in that it comprises: - A housing (10); - A measuring sensor (11) adapted to said first housing and intended to capture an electrical input signal (IN); - Said housing (10) housing an electronic circuit comprising a transistor (T1) which has a first terminal, a second terminal connected to said sensor and a third terminal; - An electrical connection device (12) comprising a first connection point (X1) connected to said first terminal of the transistor (T1), a second connection point (X2) connected to the third terminal of the transistor (T1) and a third connection point (X3) connected to the second terminal of the transistor (T1).