Mid-field Wireless Power Transfer for Implantable Sensors
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Solution Overview
Problem
Current implanted electrostimulation systems face issues such as large device size, inefficient wireless power transfer, and limited data transmission capabilities due to the use of inductive coupling and backscattered techniques, leading to complications like pocket infections, lead dislodgment, and shallow energy penetration.
Innovation Solution
A wireless power receiving device utilizing sub-wavelength structures to manipulate evanescent fields outside tissue, generating a spatially focusing and adaptive steering field inside tissue for efficient energy transfer, combined with AC-DC conversion chains and DC-DC conversion circuits to improve power conversion efficiency and enable high-data-rate transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If inductive coupling is used for wireless power transfer, then power can be delivered to implantable devices, but the energy penetration depth is limited and rectification efficiency is low (as low as 5%)
Solution Approach 1:
The patent changes the operating regime from strongly coupled inductive coupling to weakly coupled mid-field wireless power transfer. This parameter change enables propagating waves to penetrate deeper into tissue while achieving high rectification efficiency (up to 50% or more) through optimized antenna design and impedance matching circuits.
2Device complexity
If backscattered technique is used for data transmission, then implementation is simple, but data rate is limited and transmission performance decays at deep tissue locations
Solution Approach 1:
The implantable device uses a single wireless interface that serves dual functions: receiving power and transmitting data simultaneously. The same antenna and communication circuitry used for mid-field power transfer also handle data transmission, eliminating the need for separate backscattered communication hardware and enabling high data rates at deep tissue locations.
3Reliability
If conventional implanted electrostimulation systems are used, then electrical pulses can be delivered to targeted nerve or muscle region, but device size is large requiring leads and pocket implantation which causes infections and lead dislodgment
Solution Approach 1:
The patent extracts and removes the power source and communication circuitry from the implantable device, placing them in an external mid-field power transfer system. This leaves only a small implantable antenna and load, eliminating the need for leads, pockets, and associated hardware that cause infections and dislodgments, while maintaining reliable electrical pulse delivery to targeted tissues.
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 efficient wireless power transfer to small implanted devices at deeper locations with improved rectification efficiency up to 50% and high-data-rate transmission, reducing the need for leads and allowing for more sophisticated physiological monitoring and stimulation.
Implementation Method 1
a coupler configured to induce an alternating current or voltage in the presence of electromagnetic fields or oscillating sound pressure waves
Implementation Method 2
A wireless power receiving device utilizing sub-wavelength structures to manipulate evanescent fields outside tissue, generating a spatially focusing and adaptive steering field inside tissue for efficient energy transfer
Data Source
AI summary
Implantable devices and/or sensors can be wirelessly powered by controlling and propagating electromagnetic waves in a patient's tissue. Such implantable devices/sensors can be implanted at target locations in a patient, to stimulate areas such as the heart, brain, spinal cord, or muscle tissue, and/or to sense biological, physiological, chemical attributes of the blood, tissue, and other patient parameters. In some embodiments, the implantable devices can include power management schemes that have one or more AC-DC conversion chains arranged and configured to rectify the induced alternating current or voltage into one or more energy domains. Methods of use are also described.