Implantable Antenna Impedance Modulation for IMD Communication
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Solution Overview
Problem
Implantable medical devices (IMDs) face challenges in wireless communication and complexity due to the need for separate modulators and increased power consumption, which can limit their size, complexity, and communication range.
Innovation Solution
An antenna structure for IMDs is designed with an inner and outer conductive loop that is magnetically coupled, where the output of a capacitive sensor modulates a carrier signal by changing impedance, eliminating the need for a separate modulator and allowing sensor measurements to be transmitted wirelessly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate modulator is used to modulate sensor measurements onto carrier signals, then communication functionality is achieved, but device complexity and size increase
Solution Approach 1:
The patent combines the modulator functionality directly into the antenna structure by using a capacitive sensor that is electrically coupled to the antenna. The sensor's capacitance variations directly modulate the carrier signal transmitted by the antenna, eliminating the need for a separate modulator component. This merging of functions reduces device complexity while maintaining communication functionality.
Solution Approach 2:
The antenna is designed to serve multiple functions: it acts as both the radiating element for wireless communication and the modulator for encoding sensor data. The capacitive sensor integrated with the antenna provides both sensing capability and signal modulation, making the antenna a multi-functional component that reduces overall device complexity.
2Reliability
If a separate modulator is used for wireless communication, then signal modulation is achieved, but power consumption increases
Solution Approach 1:
By merging the modulator function into the antenna-sensor system, the patent eliminates the power consumption associated with a separate modulator circuit. The capacitive sensor's natural capacitance variations directly modulate the carrier signal without requiring additional active modulation circuits, thereby reducing overall power consumption while achieving signal modulation.
3Loss of information
If sensor measurements are stored within the IMD, then data availability is maintained, but device size and memory requirements increase
Solution Approach 1:
The patent extracts the data storage function from the implantable medical device and relocates it to an external device. The IMD continuously transmits sensor measurements via the antenna without storing them internally, thereby eliminating the need for onboard memory while ensuring data availability through continuous transmission to the external device for storage and retrieval.
4Reliability
If traditional wireless communication components are used, then communication capability is achieved, but communication range is limited
Solution Approach 1:
The antenna's multi-functional design, serving as both radiating element and modulator, optimizes the communication system's efficiency. This integration allows for better impedance matching and signal coupling between the sensor and antenna, improving transmission efficiency and extending communication range compared to traditional separate-component designs.
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
This solution reduces the complexity and size of IMDs, conserves power, and extends communication range, enabling efficient wireless data transmission of sensor measurements without the need for additional components or storage within the device.
Implementation Method 1
An antenna structure for an implantable medical device may include an inner portion that is magnetically coupled to an outer portion. In one embodiment, the inner and outer portions comprise conductive loops.
Implementation Method 2
the capacitance of the capacitive sensor varies as a function of the sensed parameter, which in turn results in a change in impedance of the antenna. This variation in impedance resulting from the sensed parameter modulates a carrier signal for transmission to another device.
Data Source
AI summary
An antenna structure, for use in an implantable medical device, may include an inner portion that is magnetically coupled to an outer portion. In one example, the inner and outer portions include conductive loops. In accordance with the techniques of this disclosure, a capacitive sensor is electrically coupled to one of the conductive loops of the antenna of the implantable medical device. As the capacitance of the capacitive sensor changes as a function of the sensed parameter, an impedance of the antenna varies with the output of the capacitive sensor. This variation in impedance of the antenna modulates a carrier signal with the measured parameter. In other words, the measured parameter is modulated onto the carrier signal as a change in amplitude caused by variation in impedance of antenna during radiation/transmission.