# How a Tiny Sensor Uses an Extra Weight to Detect Motion > This patent describes a miniature sensor that detects movement or force by measuring changes in electrical signals between tiny plates, featuring a clever extra weight to make it more sensitive. - **Patent:** US 20110120221 - **Original title:** Mems sensor, method of manufacturing thereof, and electronic apparatus - **Owner:** Seiko Epson - **Status:** Active - **Times cited:** 40 - **Field:** consumer_electronics, semiconductors, telecommunications, automotive, robotics ## What it does This patent details a tiny sensor, known as a MEMS sensor, designed to detect physical changes like movement or acceleration. It includes a stationary "fixed portion" and a "movable weight portion" connected by a flexible "elastically deformable portion," acting like a miniature spring (Claim 1). The movable part has "movable electrode portions" that sit opposite "fixed electrode portions." When the sensor moves, the movable weight shifts, changing the gap between these electrodes, which then alters an electrical signal. The core innovation is an "additional weight portion" attached to the movable part, which helps improve the sensor's performance. For instance, this sensor could be built into a smartwatch to accurately track your steps by sensing subtle wrist movements. The patent also describes a manufacturing method that involves etching a material from both its top and bottom surfaces to create this complex structure (Claim 11). ## What it does NOT cover - Does not cover MEMS sensors that lack an "additional weight portion" connected to the movable weight portion. - Does not cover sensors where the fixed and movable electrodes are not arranged to face each other in a capacitive sensing setup. - Does not cover manufacturing processes that do not involve etching the substrate from both sides to form the additional weight portion. - Does not cover sensors that use different detection principles, such as piezoelectric or thermal, instead of capacitive sensing. - Does not cover sensors where the movable element is not coupled to the fixed portion via an elastically deformable component. ## The clever bit The clever bit is adding an "additional weight portion" to the movable part of the sensor. This seemingly simple addition allows engineers to fine-tune the sensor's mass and how it responds to forces, making it more sensitive or stable without drastically changing the overall sensor design. ## Real-world examples 1. Accelerometers in smartphones 2. Gyroscopes in drones 3. Inertial measurement units (IMUs) in robotics 4. Motion sensors in fitness trackers 5. Automotive airbag deployment sensors ## Why it matters MEMS sensors are fundamental components in countless modern electronic devices, enabling features like screen rotation, activity tracking, and impact detection. Seiko Epson, the assignee, is a major player in precision components. This patent contributes to the ongoing refinement of these tiny sensors, aiming to make them more accurate, reliable, and sensitive, which directly impacts the performance of consumer electronics and industrial applications. ## Frequently asked questions ### What does How a Tiny Sensor Uses an Extra Weight to Detect Motion cover? This patent describes a miniature sensor that detects movement or force by measuring changes in electrical signals between tiny plates, featuring a clever extra weight to make it more sensitive. ### Who owns patent US 20110120221? This patent is owned by Seiko Epson. ### When does this patent expire? This patent is expected to expire on November 17, 2030, when the invention enters the public domain. ### What is patent US 20110120221 cited by? This patent has been cited by 40 later patents that build on its ideas. ### What problem does this patent solve? MEMS sensors are fundamental components in countless modern electronic devices, enabling features like screen rotation, activity tracking, and impact detection. Seiko Epson, the assignee, is a major player in precision components. This patent contributes to the ongoing refinement of these tiny sensors, aiming to make them more accurate, reliable, and sensitive, which directly impacts the performance of consumer electronics and industrial applications. ### What does this patent NOT cover? Does not cover MEMS sensors that lack an "additional weight portion" connected to the movable weight portion. **Full plain-English explainer:** https://patentbrief.org/patent/us/20110120221/mems-sensor-method-of-manufacturing-thereof-and-electronic-apparatus **Original patent:** https://patents.google.com/patent/US20110120221 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [Combining Sealed and Exposed Sensors on One Microchip](https://patentbrief.org/patent/us/8387464/laterally-integrated-mems-sensor-device-with-multi-stimulus-sensing) — This patent describes a microchip design that integrates multiple tiny sensors on the same side, where one sensor is exposed to the outside world through a backside hole while others remain protected by a sealed cap. - [How GPS Receivers See Weak Signals by Combining Data](https://patentbrief.org/patent/us/6816710/reusable-launch-vehicle-falcon-9-booster-landing) — A method for improving GPS sensitivity by mathematically combining multiple, weak signal samples to extract navigation data that would otherwise be lost in noise. - [How a Modern Camera Sensor Captures Light and Converts It to Data](https://patentbrief.org/patent/us/5471515/cmos-active-pixel-image-sensor) — This patent describes a camera sensor technology that combines light-capturing elements with a special circuit to read out the image data quickly and efficiently, all on a single chip. - [Attaching Flexible Circuits with Light Sensors to a Chip](https://patentbrief.org/patent/us/9055681/method-for-attaching-a-flexible-structure-to-a-device-and-a-device-having-a-flex) — This patent describes a method and device for attaching a bendable circuit, which includes light-sensing or light-emitting components, onto a main chip, allowing light to pass through a hole in the chip to reach the flexible part. - [How to Stack Computer Chips on a Wafer for Smaller Devices](https://patentbrief.org/patent/us/7824959/wafer-level-stack-structure-for-system-in-package-and-method-thereof) — This patent describes a method for stacking two full wafers of computer chips, where the chips on each wafer are roughly the same overall size but have different active areas, to create a compact system-in-package.