Inductive Coupled Electrochemical Impedance Sensor for In Vivo Monitoring
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Solution Overview
Problem
Conventional methods for measuring electrical conductivity and impedance in vivo environments face challenges due to cytotoxicity, immune response, mechanical strain, and the need for power-efficient solutions, as they often rely on active circuitry and non-biocompatible materials, which can lead to sensor drift and failure.
Innovation Solution
A sensor system utilizing inductively coupled coils with a primary and secondary circuit, where the secondary circuit includes a thin film coil and metal contact electrodes, allowing for non-contact, wireless measurement of electrochemical impedance by applying an alternating current to the primary coil, thereby avoiding the use of microcontrollers and discrete electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active circuitry such as microcontrollers, ASICs, or discrete components is used for conductivity measurements, then measurement capability is achieved, but cytotoxicity and immune response increase
Solution Approach 1:
The patent extracts and removes active electronic components (microcontrollers, ASICs, discrete components) from the implantable sensor system. Instead, it uses a passive inductive coupling mechanism where a primary coil in an external device wirelessly transmits electrical signals to a secondary coil in the implant, which then measures impedance through electrochemical reactions at inert electrodes. This extraction of active circuitry eliminates the source of cytotoxicity and immune response while maintaining measurement capability.
Solution Approach 2:
The patent introduces an intermediary wireless inductive coupling mechanism between the external measurement device and the implantable sensor. The primary coil in the external device and the secondary coil in the implant act as intermediaries, allowing electrical signals to be transmitted without direct physical contact or wired connections. This intermediary mechanism enables measurement capability while avoiding the need for active electronic components that cause biological harm.
2Object-affected harmful factors
If electronics are encapsulated with biocompatible polymers to mitigate cytotoxicity, then biocompatibility improves, but water vapor and ion permeation create undesired current paths altering bias voltages
Solution Approach 1:
The patent extracts the active electronic components that would require encapsulation from the implantable system. By using passive inductive coupling and inert electrodes, the system eliminates the need for complex polymer encapsulation layers, thereby removing the pathway for water vapor and ion permeation that would otherwise create undesired current paths and alter bias voltages.
Solution Approach 2:
The patent changes the operational parameters of the measurement system by using high-frequency AC signals instead of DC bias voltages. This parameter change allows the system to operate without vulnerable bias voltage references that would be affected by polymer permeation, thereby maintaining reliability while using biocompatible materials.
3Duration of action of moving object
If the implant is subjected to chronic and repeated mechanical strain from blood flow and movements, then in vivo monitoring capability is maintained, but sensitive components are damaged or signal measurement errors are introduced
Solution Approach 1:
The patent extracts sensitive electronic components from the implantable system, leaving only robust inert electrodes and a simple coil structure. This extraction eliminates the vulnerable components that would be damaged by mechanical strain, while the remaining structure can withstand chronic mechanical stress from blood flow and bodily movements.
Solution Approach 2:
The patent employs thin film construction for the implantable sensor, making it mechanically compliant with surrounding tissues. This flexible thin film structure can accommodate chronic and repeated mechanical strain without damaging sensitive components or introducing signal measurement errors, thereby maintaining continuous monitoring capability.
4Object-affected harmful factors
If soft flexible materials are used to mechanically match tissue properties and minimize damage, then tissue compatibility improves, but power requirements for electronics increase heating concerns
Solution Approach 1:
The patent extracts all active electronic components from the implantable system, eliminating the source of power consumption and heating. The passive inductive coupling mechanism requires no power supply in the implant, and the inert electrodes perform measurements through electrochemical reactions that generate negligible heat, thereby resolving the heating concern while maintaining tissue compatibility.
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
Enables continuous, chronic monitoring of physiological signals in wet, ionic environments with minimal harm to the host, reducing power requirements and avoiding errors in signal measurement, while being applicable to a broad spectrum of applications due to its thin film construction and simplicity.
Implementation Method 1
The primary electrically conducting coil is inductively coupled to the secondary electrically conducting coil
Implementation Method 2
an alternating current source energizes (e.g., applies an alternating current to) the primary electrically conducting coil during impedance measurements
Data Source
AI summary
A sensor for measuring electrochemical impedance includes a primary circuit that includes a primary electrically conducting coil and a secondary circuit that includes a secondary electrically conducting coil. The primary electrically conducting coil is inductively coupled to the secondary circuit. During operation, the secondary electrically conductive couple has contact electrodes that contact a medium for which the impedance is to be measured. An alternating current source energizes the primary electrically conducting coil during impedance measurements.