Capacitive ECG Sensor with Active Shielding for X-Ray Transparency
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Solution Overview
Problem
Capacitive sensors for bioelectrical signal measurement in clinical environments face challenges such as cleanability, disinfectability, mechanical robustness, and compatibility with medical imaging, while existing solutions like textile-based sensors are not x-ray transparent and interfere with medical data acquisition.
Innovation Solution
A signal measurement circuit with a flat, layered design featuring a sensor electrode and active shielding layer, connected via insulating layers, which are electrically conductive and made from carbon-enriched plastic, ensuring watertightness, cleanability, and x-ray transparency, with a thin, flexible structure for molding onto a patient's body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If textile-based sensors are used for capacitive ECG measurement, then flexibility and patient comfort are improved, but cleanability and disinfectability deteriorate due to fabric structure
Solution Approach 1:
The patent replaces textile-based sensors with a sensor element comprising thin film layers (sensor electrode layer, insulating layers, shielding layer) that can be molded onto the patient's body. This film-based construction provides flexibility and comfort like textiles while enabling proper cleaning and disinfection procedures in clinical environments.
2Ease of operation
If textile-based sensors are used for capacitive ECG measurement, then flexibility and patient comfort are improved, but x-ray transparency deteriorates causing interference with medical data acquisition
Solution Approach 1:
The patent uses thin film construction with materials that are x-ray transparent, allowing medical imaging to proceed without interference while maintaining the flexibility needed for patient comfort and proper positioning on the body.
3Reliability
If metallic surfaces are used for ECG measurement, then electrical conductivity is improved, but x-ray transparency deteriorates
Solution Approach 1:
The patent employs composite material structures where conductive layers (sensor electrode layer, shielding layer) are combined with insulating layers in a multi-layer film configuration. This composite approach maintains necessary electrical conductivity while using materials that are x-ray transparent, avoiding the use of metallic surfaces that would block x-rays.
4Measurement precision
If the coupling area between sensor and patient is increased to improve signal quality, then capacitance is improved, but device complexity and positioning difficulty increase
Solution Approach 1:
The patent uses a flexible thin film sensor element that can be easily molded onto the patient's body to achieve optimal coupling area and signal quality without complex positioning procedures. The flexibility of the film construction simplifies adaptation to different body surfaces.
5Strength
If the sensor structure is made robust for mechanical stress resistance, then mechanical robustness is improved, but flexibility and moldability deteriorate
Solution Approach 1:
The patent employs thin film construction that inherently provides both flexibility for molding onto the patient's body and sufficient mechanical robustness to withstand handling and use in clinical environments. The multi-layer film structure achieves this balance through material selection and layer configuration.
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 a robust, easily cleanable, and x-ray transparent capacitive ECG sensor that maintains high signal quality and patient comfort, while being resistant to mechanical stress and interference, ensuring effective bioelectrical signal measurement without obstructing medical imaging.
Implementation Method 1
In order to achieve a good signal quality of the heartbeat signal, the amplitude of the measured signal must preferably be high. This can be achieved by a high capacitance between the patient and the sensor.
Implementation Method 2
Between the sensor electrode layer and the active shielding layer runs a first insulating layer, likewise embodied to be flat, which prevents a short circuit from occurring between the sensor electrode layer and the active shielding layer.
Data Source
AI summary
A signal measurement circuit comprises: a sensor electrode layer connected via a sensor cable to a measurement amplifier circuit; an active shielding layer, which runs along a side of the sensor electrode layer that faces away from the patient; and a first insulating layer that runs between the sensor electrode layer and the active shielding layer. The sensor electrode layer and the active shielding layer are embodied to be electrically conductive.