Passive Transponder Loops for Orientation-Independent Pressure Sensing
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Solution Overview
Problem
Existing transponder coils used in medical devices, such as those for measuring blood flow in blood vessels, suffer from a pronounced figure-eight directional characteristic, leading to unreliable coupling with readout coils due to orientation dependence, making signal transmission inconsistent and difficult to control.
Innovation Solution
A passive transponder system with two conductor loop structures, each coupled to a capacitive pressure sensor, forming non-overlapping resonant circuits with winding axes at a non-zero angle, ensuring distinct resonant frequencies and interwoven design for stable coupling regardless of orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single transponder coil is used, then the device structure is simple, but the coupling with readout coil is unreliable due to orientation dependence
Solution Approach 1:
The transponder is divided into multiple conductor loop structures (at least two) with different winding axes. Each loop structure operates at a distinct resonant frequency, allowing the system to segment the coupling function across multiple independent elements rather than relying on a single orientation-dependent coil.
Solution Approach 2:
The invention changes the resonant frequency parameter of each conductor loop structure to be distinct from the others. This frequency differentiation allows the readout device to selectively excite and read from specific loop structures, overcoming the orientation dependency that plagues single-coil designs.
2Reliability
If multiple conductor loop structures with different resonant frequencies are used, then coupling reliability is improved, but the device complexity increases
Solution Approach 1:
Multiple conductor loop structures are merged into a single integrated transponder unit. The loops are combined such that they share common components (capacitive pressure sensors, housing, power supply) while maintaining electrically independent resonant circuits, thus achieving reliable multi-frequency operation without linearly increasing overall device complexity.
Solution Approach 2:
The conductor loop structures serve multiple functions simultaneously: they act as inductive sensors for pressure measurement, as transponder elements for wireless communication, and as resonant circuits for frequency-selective operation. This multi-functionality reduces the need for separate dedicated components for each function.
3Adaptability or versatility
If conductor loop structures are interwoven, then directional characteristic is improved to match circular blood vessel shape, but manufacturing precision requirements increase
Solution Approach 1:
The conductor loops are arranged in three-dimensional space with winding axes oriented at different angles (e.g., perpendicular to each other). This spatial arrangement in multiple dimensions allows the transponder to achieve omnidirectional coupling characteristics that match the circular geometry of blood vessels, rather than being limited to planar configurations.
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 reliable and controllable coupling with readout coils, providing consistent signal readout and minimizing mutual interference, thus improving the directional characteristic to match the circular shape of blood vessels, allowing for accurate pressure wave measurements.
Implementation Method 1
devices are used that utilize inductively coupled communication between a transponder or a passive resonant circuit and a reader. The transponder or passive resonant circuit is supplied with power via inductive coupling.
Implementation Method 2
Each conductor loop structure is coupled to one of the capacitive pressure sensors to form a resonant circuit. The resonant frequencies of the resonant circuits are selected such that they do not overlap.
Data Source
Figure 1
Figure 2
Figure 3~4B
AI summary
The invention relates to a passive transponder system comprising a first or second conductor loop structure and a first and a second capacitive pressure sensor, wherein each conductor loop structure is coupled to one of said capacitive pressure sensors to form a resonant circuit, and the first conductor loop structure is positioned at a non-vanishing angle in relation to the second conductor loop structure. The resonant frequencies of the resonant circuits are selected such that they do not overlap to result in beating. The invention also relates to a pressure wave measuring device comprising such a passive transponder system, and a read-out unit.