LCP Housing for Implantable Medical Devices
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Solution Overview
Problem
Implantable medical devices (IMDs) face challenges with hermetic sealing, size constraints, and unwanted shielding due to metallic casings, which complicate manufacturing, increase costs, and limit their placement within the body for effective recharging and communication.
Innovation Solution
The use of a liquid crystal polymer (LCP) housing for IMDs, which allows for simpler manufacturing, reduced size, and improved power transfer, eliminating the need for metal casings, enabling deeper and more flexible placement within the body while maintaining hermeticity and reducing charging time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metallic case is used for hermetic sealing, then hermeticity is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the material parameter from metal to liquid crystal polymer (LCP), which fundamentally alters the manufacturing process. LCP allows injection molding and ultrasonic welding, eliminating complex hermetic sealing steps required for metal cases while maintaining hermeticity through the polymer's inherent barrier properties and weldable joints.
Solution Approach 2:
The patent replaces mechanical hermetic sealing methods (such as laser welding or brazing metal components) with injection molding and ultrasonic welding of LCP. This substitution simplifies the manufacturing system by using conventional plastic processing equipment instead of specialized metal sealing equipment, reducing manufacturing complexity while achieving equivalent hermetic protection.
2Object-affected harmful factors
If a metallic case is used for shielding, then electromagnetic shielding is provided, but power transfer efficiency decreases
Solution Approach 1:
The patent extracts the shielding function from the structural housing by using LCP material that inherently provides electromagnetic isolation through its dielectric properties. The LCP housing itself serves both structural and shielding purposes, eliminating the need for separate metal shielding layers while maintaining power transfer efficiency for wireless charging and communication.
Solution Approach 2:
The patent employs LCP as a composite material that combines mechanical structural properties with electromagnetic shielding capabilities. The liquid crystal polymer's molecular structure provides both the physical integrity needed for housing and the dielectric properties needed for electromagnetic isolation, achieving dual functionality without metal components.
3Strength
If a metallic case is used for structural support, then mechanical strength is provided, but device size increases
Solution Approach 1:
The patent changes the material parameters of the housing from metal to LCP, which has a different strength-to-weight ratio and allows for thinner wall designs. The LCP material maintains sufficient mechanical strength for implantable applications while enabling a more compact device form factor, reducing overall device volume compared to traditional metal-cased IMDs.
4Reliability
If conventional thermoplastic welding is used for sealing, then hermetic sealing is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs ultrasonic welding of LCP components, which is a self-aligning process where the ultrasonic vibration automatically distributes the weld heat and pressure along the bonding interface. This self-service mechanism compensates for minor dimensional variations in the molded parts, achieving hermetic seals without requiring extremely tight manufacturing tolerances on the housing components.
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
LCP housings enable smaller, more cost-effective IMDs with improved power transfer and flexibility in placement, allowing for efficient recharging and communication, reducing the size of external chargers and receive coils, and enabling faster charging with less interference.
Implementation Method 1
LCP is extremely inert in biological environments and has barrier properties an order of magnitude greater than epoxy plastic materials and is virtually impermeable to moisture, oxygen, and other gases and liquids
Implementation Method 2
LCP combines the low cost and light weight of a polymer with suitable dielectric properties and protective capabilities. High frequency performance is possible because of the dielectric constant and loss properties of LCP are much lower than those of conventional materials
Implementation Method 3
LCP packaging may also be laser welded at the bond line using infrared (IR) laser to create the seal. The LCP material is transparent to IR, so the beam passes through the LCP material with minimal absorption. An IR-absorbant material may be added to the LCP at the bond line, localizing heating to the immediate seal area
Implementation Method 4
LCP is also readily processed by injection molding and thermoforming using conventional equipment at fast speeds with excellent replication of mold details
Data Source
AI summary
An implantable medical device having a liquid crystal polymer (LCP) housing. Circuitry is positioned within the housing to perform a predefined function, such as generate a stimulation waveform, or pump a fluid, or turn on a motor, for example. The circuitry may include a power source, and the power source may be a rechargeable power source.