Implantable Microphone With Incompressible Liquid Pressure Compensation
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Solution Overview
Problem
Existing implantable microphones for hearing prosthesis systems are sensitive to pressure changes due to their hermetic sealing, which affects acoustic sensitivity and can lead to microphone failure, as they require a good acoustic impedance match with surrounding tissue but are prone to deformation from external pressure variations.
Innovation Solution
An implantable microphone design featuring a cylindrical or double cone-shaped housing filled with incompressible liquid, with housing membranes and an acoustic-electric transducer to convert acoustic signals into electrical signals, providing a stable acoustic impedance match and minimizing pressure-induced deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hermetic seal is used to protect the implantable microphone from the surrounding tissue environment, then reliability is improved, but the microphone becomes sensitive to pressure changes causing deformation and performance degradation
Solution Approach 1:
The patent introduces a compliant membrane as an intermediary element between the hermetic seal and the acoustic environment. This membrane allows pressure equalization while maintaining the hermetic seal, thus protecting the microphone from pressure-induced deformation while preserving the protective sealing function.
Solution Approach 2:
The patent changes the physical state of the internal environment by introducing a compressible gas or fluid medium that can accommodate pressure changes. This allows the hermetic seal to maintain its protective function while the internal medium absorbs pressure variations, preventing membrane deformation and microphone performance degradation.
2Measurement precision
If thin metal membranes are used to achieve good acoustic impedance match, then acoustic sensitivity is improved, but the membranes become more susceptible to pressure-induced deformation
Solution Approach 1:
The patent applies counteracting forces to balance the pressure differential across the thin metal membrane. By introducing a compliant opposing membrane or using a compressible internal medium, the system creates counterpressure that offsets external pressure changes, allowing the thin membrane to maintain its acoustic sensitivity without suffering from pressure-induced deformation.
Solution Approach 2:
The patent creates a composite structure combining thin metal membranes with compliant materials or gas-filled chambers. This composite design allows the thin metal membrane to maintain its excellent acoustic impedance match while the compliant components absorb pressure stresses, preventing deformation and performance degradation.
3Reliability
If pressure inside the hermetic housing is increased to shift the pressure range, then resistance to pressure changes is improved, but the complexity of pressure management increases
Solution Approach 1:
The patent employs passive pressure equalization mechanisms that automatically respond to pressure changes without requiring active control systems. The compliant membranes and compressible internal media self-regulate pressure differential through their physical properties, eliminating the need for complex active pressure management systems while maintaining reliability across varying pressure conditions.
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 use of an incompressible liquid within the microphone housing reduces sensitivity to pressure changes, maintaining acoustic sensitivity and preventing microphone failure, while ensuring a good acoustic impedance match with surrounding tissue.
Implementation Method 1
A cylindrical microphone housing has opposing circular cylinder ends and an interior volume containing an incompressible housing liquid
Implementation Method 2
An acoustic-electric transducer is coupled to the housing membrane for converting movement of the housing membrane into a corresponding electrical microphone signal
Data Source
AI summary
An implantable microphone is described for use in hearing prosthesis systems. A cylindrical microphone housing has opposing circular cylinder ends and an interior volume containing an incompressible housing liquid. At least one housing membrane is on one of the cylinder ends and is in contact with the housing liquid and moveable in response to an acoustic signal outside the housing. An acoustic-electric transducer is coupled to the housing membrane for converting movement of the housing membrane into a corresponding electrical microphone signal.