Pulse Delay Modulation for Inductive Links
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Solution Overview
Problem
Existing inductive links for implantable medical devices face challenges in achieving high data rates and efficient power transmission due to electromagnetic field absorption and cross-coupling between power and data coils, which limits bandwidth and increases complexity and power consumption.
Innovation Solution
The use of pulse delay modulation (PDM) for wireless data and power transmission across inductive links, where a power carrier signal and data waveform are transmitted simultaneously, and the interference signal is used to determine zero crossings and recover the data packet, reducing the need for separate data carriers and frequency-stabilization circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high frequency carrier is used for data transmission to achieve high data rate, then data rate is improved, but power loss in tissue increases due to electromagnetic field absorption
Solution Approach 1:
The patent segments the transmission function into two separate carriers: a low-frequency power carrier (below 20 MHz) for efficient power transfer and a high-frequency data carrier (>50 MHz) for high-rate data transmission. This segmentation allows each carrier to operate at its optimal frequency without compromising the other, resolving the contradiction between data rate and power loss.
Solution Approach 2:
The patent merges power transmission and data transmission into a single inductive link by using two separate carriers simultaneously. The power carrier and data carrier share the same physical medium (inductive link) but operate at different frequencies, enabling both functions to coexist without requiring separate transmission channels.
2Use of energy by moving object
If a separate power carrier is used to achieve high power transfer efficiency, then power transfer efficiency is improved, but device complexity increases due to dual-carrier requirements
Solution Approach 1:
The inductive link is designed to serve multiple functions simultaneously: it acts as both a power transmission channel and a data transmission channel. The same pair of coils performs both power transfer and data communication, eliminating the need for completely separate power and data links while maintaining high efficiency for both functions.
3Productivity
If power carrier frequency is increased to achieve high data rate, then data rate is improved, but temperature elevation occurs due to excessive power loss
Solution Approach 1:
The transmission spectrum is segmented into two frequency regions: a low-frequency band for power carrier to minimize tissue heating, and a high-frequency band for data carrier to maximize data rate. This frequency segmentation prevents temperature elevation while maintaining high productivity.
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 approach enables efficient and robust simultaneous data and power transmission with increased data rates, reduced power consumption, and improved resistance to power carrier interference, suitable for high-performance implantable medical devices.
Implementation Method 1
inductive links for implantable medical devices... transmitting coils... receiving coils
Implementation Method 2
receiving coils of an inductive link... receive... an interference signal
Data Source
AI summary
Certain implementations may include systems, methods, and apparatus for wirelessly transmitting data and power across inductive links using pulse delay modulation (PDM). According to an example implementation, a method is provided that includes generating a power carrier signal; generating a data waveform from a series of binary bits, the data waveform including a series of pulses in synchronization with the power carrier signal; transmitting, from one or more transmitting (Tx) coils of an inductive link, the power carrier signal and the data waveform; receiving, by one or more receiving (Rx) coils of the inductive link, an interference signal, the interference signal based at least in part on a superposition of the transmitted power carrier signal and the transmitted data waveform; determining zero crossings of the received interference signal; determining delays associated with the zero crossings; and determining the data packet based at least in part on the delays.