Midfield Power Transfer for Deep Tissue Implants
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Solution Overview
Problem
Current implantable electrical stimulation systems face challenges due to large battery sizes, limited miniaturization, and inefficient wireless power transfer methods, leading to issues like pocket infections, lead dislodgment, and limited device lifetime, as well as difficulties in powering small devices at deeper tissue depths.
Innovation Solution
The development of midfield power transfer technology using patterned metal plates with subwavelength structures that manipulate evanescent fields to generate spatially confined and adaptive energy transport within tissue, allowing for wireless power transmission to small implantable devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If near-field coupling methods are used for wireless power transfer, then power can be transferred to implantable devices, but the power harvesting structure becomes large (centimeter scale) and the external coils become bulky and inflexible
Solution Approach 1:
The patent changes the fundamental parameter of electromagnetic field coupling from near-field to far-field resonance coupling. This enables the power harvesting structure to be miniaturized to sub-centimeter dimensions while maintaining wireless power transfer capability, directly resolving the contradiction between power transfer reliability and device size
Solution Approach 2:
The patent employs a universal resonant frequency approach where both the external transmitter and implanted receiver operate at the same resonant frequency. This multi-functional resonance coupling mechanism enables efficient power transfer with dramatically reduced hardware size, making the system both reliable and miniaturized
2Reliability
If near-field coupling is used, then wireless power transfer is possible, but the intrinsic exponential decay of the near field limits miniaturization beyond superficial depths (greater than 1 cm)
Solution Approach 1:
The patent fundamentally changes the coupling parameter from near-field to far-field resonance, which eliminates the exponential decay limitation. This enables effective power transfer to implants located at depths greater than 1 cm, directly resolving the contradiction between power transfer reliability and tissue penetration depth
Solution Approach 2:
The patent employs dynamically adjustable resonant frequencies that can be tuned to optimize power transfer at different tissue depths. This dynamic resonance coupling allows the system to maintain reliable power transfer whether the implant is at superficial or deep locations within the body
3Length of stationary object
If far-field radiative methods are used, then power transfer to deep tissue is possible, but the radiative nature severely limits the energy transfer efficiency
Solution Approach 1:
The patent employs dynamic resonant coupling where both transmitter and receiver are tuned to the same resonant frequency. This resonant synchronization dramatically enhances energy transfer efficiency compared to conventional far-field radiative methods, resolving the contradiction between deep tissue penetration and energy efficiency
Solution Approach 2:
The patent changes the operating parameter from broad-spectrum far-field radiation to narrow-band resonant coupling. This parameter change concentrates energy transfer at specific resonant frequencies, minimizing energy loss while maintaining the ability to reach deep tissue locations
4Reliability
If traditional implantable systems with batteries are used, then devices can be implanted, but the battery size prevents miniaturization and requires periodic surgical replacement
Solution Approach 1:
The patent extracts the battery from the implanted device entirely, replacing it with a wireless power receiving system. This extraction eliminates the need for periodic surgical replacement while maintaining continuous device functionality, directly resolving the contradiction between device reliability and operational duration
Solution Approach 2:
The patent implements a self-powered implantable device that receives wireless power through the body from an external transmitter. The device serves itself by continuously harvesting power without external intervention or battery replacement, resolving the contradiction between maintaining functionality and extending operational lifetime indefinitely
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 deep tissue power transfer, reducing device size and increasing lifespan, while minimizing tissue heating and infection risks, with power transfer efficiencies two to three orders of magnitude higher than traditional near-field systems.
Implementation Method 1
These midfield sources may manipulate evanescent fields outside a material (e.g., tissue) to excite and control propagating fields inside the material and thereby generate spatially confined and adaptive energy transport in the material
Implementation Method 2
the source is capable of generating an electromagnetic field with a spatial frequency spectrum of the field adjacent to the source having non-negligible components that lie in the range of k0≤√{square root over (kx2+ky2muscle)}
Data Source
AI summary
Described herein are devices, systems, and methods for wireless power transfer utilizing a midfield source and implant. In one variation, a midfield source may be realized by a patterned metal plate composed of one of more subwavelength structures. These midfield sources may manipulate evanescent fields outside a material (e.g., tissue) to excite and control propagating fields inside the material (e.g., tissue) and thereby generate spatially confined and adaptive energy transport in the material (e.g., tissue). The energy may be received by an implanted device, which may be configured for one or more functions such as stimulation, sensing, or drug delivery.