Ceramic Insert Craniometry Tray for RF Charging
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Solution Overview
Problem
Implantable medical devices, particularly neurostimulators placed in the skull, face challenges with remote charging and communication due to metallic housings causing eddy currents, which degrade charging efficiency and prevent proper remote communication.
Innovation Solution
Replacing a portion of the metallic tray with a ceramic insert that has an upstanding sidewall, aligned behind the molded header supporting the charging and communication antennas, to reduce eddy currents and enhance coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metallic housing is used for the implantable medical device, then the housing can be hermetically sealed to protect internal electronic components, but the metal prevents remote charging signals from reaching the power source and blocks electromagnetic coupling for communication
Solution Approach 1:
The metallic housing is segmented by introducing a non-metallic window portion that divides the housing structure into metal and non-metal sections. This allows the housing to maintain hermetic sealing through the metal portions while creating a pathway for RF energy transmission through the non-metallic window, resolving the contradiction between sealing integrity and charging efficiency.
Solution Approach 2:
The housing employs composite construction by combining metallic materials (for hermetic sealing) with non-metallic materials (for RF transmission) in a single structure. The non-metallic window portion integrates with the metallic housing to create a composite assembly that simultaneously achieves both protective sealing and electromagnetic transparency for remote charging.
2Strength
If a metallic housing is used for the implantable medical device, then structural strength is provided, but the metal causes eddy currents during charging that degrade charging efficiency and prevent proper remote communication
Solution Approach 1:
The housing applies local quality by making only the critical window portion non-metallic while keeping the rest of the housing metallic. This localized modification eliminates eddy currents specifically at the RF transmission area where they would cause energy loss, while preserving the structural strength of the overall metallic housing structure.
3Ease of operation
If the communication and charging antennas are placed in a molded polymeric header connected to the metallic housing, then the antennas are positioned outside the metal housing, but the metallic material of the tray behind the polymeric header still causes eddy currents that severely degrade charging efficiency
Solution Approach 1:
The non-metallic window portion is extracted from the metallic housing structure and positioned specifically behind the polymeric header and antennas. This extraction creates a dedicated RF-transparent zone that removes the source of eddy currents from the charging path, allowing antennas positioned in the polymeric header to operate efficiently without interference from metallic materials.
4Device complexity
If a ceramic window is used in the device housing with antennas contained inside behind the ceramic window, then the antennas can be positioned inside the housing, but eddy currents can still develop during charging because the ceramic window is completely framed by the metal housing
Solution Approach 1:
The non-metallic window portion extends in a new dimensional configuration by protruding from the housing surface or creating a three-dimensional RF-transparent pathway. This dimensional extension ensures that the non-metallic material sufficiently interrupts the metallic framing around the window, preventing eddy current formation while maintaining antenna integration within the housing.
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
The ceramic insert significantly improves the efficiency of remote charging and communication by minimizing eddy currents, allowing for effective transmission of RF or inductive energy and maintaining the functionality of bendable screw tabs for secure implantation.
Implementation Method 1
the metallic material of the tray behind the polymeric header supporting the charging and communication antennas can cause eddy currents during charging and remote communication that can severely degrade charging efficiency
Implementation Method 2
an active implantable medical device (AMID) that is configured for placement in the skull and is adapted for remote charging
Implementation Method 3
a communication antenna for remote two-way communication
Data Source
AI summary
A medical tray that is useful for containing an implantable medical device is a body cavity is described. The medical tray is particularly useful in a craniometry and comprises a ceramic insert joined to a metallic main tray. The main tray comprises a base plate extending to an upstanding main sidewall. An inlet extends inwardly through the main sidewall and into the base plate with the inlet having an inlet peripheral edge. The ceramic insert comprises a planar plate portion extending to an upstanding insert sidewall. The insert has an insert peripheral edge having an insert shape that is conformal with an inlet shape of the inlet peripheral edge. A metallization is supported on the insert peripheral edge and a braze joins the metallization supported on the insert peripheral edge to the inlet peripheral edge.