How Silicon Microphones Use Layers to Shrink Sound Sensors
A design for a tiny, silicon-based microphone that stacks a sound-sensing chip and an electronic processor chip together with an intermediate layer to save space.
Original patent title: “USRE42346E1 - Solid state silicon-based condenser microphone”
A design for a tiny, silicon-based microphone that stacks a sound-sensing chip and an electronic processor chip together with an intermediate layer to save space. Granted to Epcos Pte Ltd in 2011 with 18 claims and 4 forward citations.
Key facts
Coverage
What does this patent actually cover?
This patent describes a way to build a microphone using silicon, the same material used for computer chips. It uses a tiny, flexible diaphragm that moves when sound waves hit it, creating a change in electrical charge between it and a fixed backplate. To make this small enough for devices like phones, the patent stacks the sensor chip on one side of an intermediate layer and an electronic processing chip (ASIC) on the other. A hole through this middle layer allows sound to reach the diaphragm, while electrical paths on the layer connect the two chips together.
The gap
What does this patent NOT cover?
- Does not cover microphones that use traditional mechanical membranes instead of silicon-based diaphragms
- Does not cover microphones where the electronic circuit is placed side-by-side with the sensor rather than stacked
- Does not cover non-capacitive sensing methods like piezoelectric or optical microphones
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The innovation lies in using an intermediate layer as both a mechanical spacer and an electrical bridge, allowing the sensor and the ASIC to be flip-chip mounted back-to-back in a vertical stack.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
MEMS microphones in smartphones
Laptop integrated microphones
Voice-activated smart home speakers
Hearing aid microphone components
Why it matters
The bigger picture
This technology is the foundation of the MEMS (Micro-Electro-Mechanical Systems) microphone industry. By enabling the integration of sensors and electronics into a single, compact package, it allowed microphones to shrink from the size of a coin to a tiny speck, making them essential for modern smartphones, tablets, and voice-controlled smart speakers.
Filed
July 11, 2002
Granted
May 10, 2011
Market context
Who's building on this
Companies in this space
Major semiconductor manufacturers like Knowles, Infineon, and STMicroelectronics dominate this space, building on the fundamental concepts of silicon-based MEMS integration described here.
Market impact
This design helped trigger the transition from bulky electret microphones to high-performance, mass-produced MEMS microphones. It enabled the miniaturization of audio input hardware, which is now a standard requirement for virtually every mobile electronic device produced today.
Claim 1 — Plain English
What this patent covers
This patent describes a way to build a microphone using silicon, the same material used for computer chips. It uses a tiny, flexible diaphragm that moves when sound waves hit it, creating a change in electrical charge between it and a fixed backplate. To make this small enough for devices like phones, the patent stacks the sensor chip on one side of an intermediate layer and an electronic processing chip (ASIC) on the other. A hole through this middle layer allows sound to reach the diaphragm, while electrical paths on the layer connect the two chips together.
The clever bit
The innovation lies in using an intermediate layer as both a mechanical spacer and an electrical bridge, allowing the sensor and the ASIC to be flip-chip mounted back-to-back in a vertical stack.
What it does not cover
- Does not cover microphones that use traditional mechanical membranes instead of silicon-based diaphragms
- Does not cover microphones where the electronic circuit is placed side-by-side with the sensor rather than stacked
- Does not cover non-capacitive sensing methods like piezoelectric or optical microphones
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Early stage
Citation count
14/40
Early citations
Claim breadth
12/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
5/20
Granted 10–20 years ago
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$10K – $33K
Midpoint $20K · expired or expiring · industry ×1.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
18 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Hvims, H. L., Gravad, M. A., Heschel, M., Bouwstra, S., Rombach, P., Hansen, O., & Müllenborn, M. (2011). How Silicon Microphones Use Layers to Shrink Sound Sensors (U.S. Patent No. RE42,346). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/RE42346/cyclone-vacuum-cleaner
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Silicon Microphones Use Layers to Shrink Sound Sensors cover?
A design for a tiny, silicon-based microphone that stacks a sound-sensing chip and an electronic processor chip together with an intermediate layer to save space.
Who owns patent US RE42346?
Epcos Pte Ltd owns this patent, granted in 2011.
When does this patent expire?
This patent is expected to expire on May 10, 2031, when the invention enters the public domain.
What is patent US RE42346 cited by?
This patent has been cited by 4 later patents that build on its ideas.
What problem does this patent solve?
This technology is the foundation of the MEMS (Micro-Electro-Mechanical Systems) microphone industry. By enabling the integration of sensors and electronics into a single, compact package, it allowed microphones to shrink from the size of a coin to a tiny speck, making them essential for modern smartphones, tablets, and voice-controlled smart speakers.
What does this patent NOT cover?
Does not cover microphones that use traditional mechanical membranes instead of silicon-based diaphragms
Patent monitoring