Flexible EMG Sensor with Integrated Amplification and Filtering
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Solution Overview
Problem
Conventional EMG sensors used in prosthetic devices are rigid, large in size, and lack flexibility, leading to potential separation from the skin and flawed readings due to changes in the residual limb's contour and shape. Additionally, these sensors are prone to electromagnetic interference (EMI) and require amplification of microvolt signals.
Innovation Solution
A flexible EMG sensor with electrodes adapted for external skin attachment, featuring a dual-amplification system and multiple filters to reject high-frequency noise, ensuring stable signal amplification and noise reduction. The sensor is housed in a flexible PCB module, allowing for adjustable fit and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional rigid EMG sensors are used, then structural stability is maintained, but flexibility and adaptability to limb shape changes are lost
Solution Approach 1:
The patent employs a flexible PCB (printed circuit board) structure instead of rigid housing to contain the EMG sensor components. This flexible PCB can conform to changes in residual limb contour and shape while maintaining the electrical and functional integrity of the sensor, thereby resolving the contradiction between structural stability and adaptability to limb shape changes.
2Ease of operation
If rigid housing is used for EMG sensor, then manufacturing precision is maintained, but ease of operation and flexible adjustment are reduced
Solution Approach 1:
The flexible PCB housing allows the sensor to be easily adjusted and conform to the user's residual limb shape while maintaining manufacturing precision through controlled fabrication processes. The flexibility enables better user comfort and adaptability without sacrificing the precision required for accurate EMG signal acquisition.
3Measurement precision
If electrodes are embedded into cavity for contact sensing, then measurement precision is improved, but adaptability to changing limb contours is lost
Solution Approach 1:
The flexible PCB structure allows the electrodes to maintain continuous contact with the skin surface despite changes in limb contour and shape. This flexibility ensures that the electrodes remain properly positioned for accurate EMG measurement while adapting to the user's residual limb morphology, thereby maintaining both measurement precision and adaptability.
4Measurement precision
If signal amplification is added to handle microvolt signals, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent integrates the signal amplification circuitry directly into the flexible PCB housing with the electrodes and other sensor components. By merging the amplification function with the existing sensor structure, the design achieves precise microvolt signal detection without proportionally increasing overall device complexity. The amplifiers are incorporated as part of the integrated flexible circuit board design.
5Measurement precision
If filters are added to reject high-frequency noise, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The filtering circuitry is integrated into the flexible PCB structure alongside the amplifiers and electrodes. The filters are designed to work in conjunction with the amplification stages, combining multiple functions (amplification and filtering) into a single integrated circuit board. This approach improves noise-rejected signal accuracy while minimizing the increase in device complexity through functional integration.
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 flexible EMG sensor provides stable and accurate signal detection, resistant to changes in limb shape and prone to electromagnetic interference, while maintaining a compact size and flexible adjustment, enhancing the reliability of prosthetic devices.
Implementation Method 1
Electromyography is a method of measuring the functional state of skeletal muscles based on detection of electric potentials appearing therein
Implementation Method 2
a first amplifier (108) connected to the electrodes (102), and configured to generate a first amplified signal based on a differential signal associated with the electrodes (102)
Implementation Method 3
a second amplifier (112) connected to the first amplifier (108), and configured to generate a second amplified signal based on the first amplified signal
Implementation Method 4
a first filter (114) connected to the second amplifier (112), and configured to reject high-frequency noise from the second amplified signal to generate an output signal
Data Source
AI summary
In view of the foregoing, an aspect herein provides an Electromyography (EMG) sensor (100) further includes electrodes (102) adapted to be attached to an external surface of skin of a limb, and configured to sense signals from the external surface of the skin, a first amplifier (108) connected to the electrodes (102), and configured to generate a first amplified signal based on a differential signal, existing in microvolts, associated with the electrodes (102), a second amplifier (112) connected to the first amplifier (108), and configured to generate a second amplified signal based on the first amplified signal, and a first filter (114) connected to the second amplifier (112), configured to reject high-frequency noise from the second amplified signal to generate an output signal and prevents interference by the electromagnetic interference from nearby electrical noise, false high-frequency signals and in-circuit internal electronic noise. An Electromyography (EMG) system (200) includes the EMG sensor (100) installed in an electronic device, a control circuitry (116) connected to the EMG sensor (100) and configured to control an operation of the electronic device based on the output signal.