Integrated MEMS Force Sensor With On-Die Digital Readout

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current MEMS force sensors are large, produce analog outputs that require noisy electrical conversion to digital signals, and electromechanical switches lack durability and versatility for multiple actuation levels.

Innovation Solution

Integration of sensing elements and digital circuitry on a MEMS force sensor die, using piezoresistive strain gauges and CMOS processing to convert analog signals to digital codes, with etched flexures and gaps for protection and overload prevention, and a MEMS mechanical switch with integrated CMOS circuitry for amplification and calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If wire bond pads and stacked silicon/glass die are used in current MEMS force dies, then the sensing diaphragm can be constructed, but the device size becomes relatively large

Engineering Contradiction:

Improvedevice sizeVSAvoidmanufacturing complexity

Core Design Contradiction:

Volume of moving objectVSEase of manufacture

Solution Approach 1:

The patent combines the sensing diaphragm, readout circuitry, and signal processing components into a single integrated device structure, eliminating the need for separate wire bond pads and stacked die configurations. This integration directly reduces device size while maintaining manufacturing feasibility through unified fabrication processes.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If analog output is produced by current MEMS force dies, then the sensing element can provide continuous signal, but the signal requires noisy electrical environment for conversion to digital signal

Engineering Contradiction:

Improvesignal integrityVSAvoidelectrical noise

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the analog electrical signal transmission system with a digital signal processing system integrated directly on the device. This substitution eliminates the noisy electrical environment required for analog-to-digital conversion by performing digitization within the device itself, thereby improving signal integrity and reducing susceptibility to electrical noise.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If conductive dome structures are used in electromechanical switches, then the electrical circuit can be completed, but the switches lack durability due to material wear

Engineering Contradiction:

Improveswitch durabilityVSAvoidswitch lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent replaces the mechanical conductive dome switch structure with a capacitive sensing mechanism that detects contact through electrical field changes rather than physical conduction. This substitution eliminates the wear inherent in mechanical contact systems, significantly improving durability and extending the operational lifespan of the switch.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Adaptability or versatility

If conductive material is used in electromechanical switches, then the electrical circuit can be completed, but the switches are incapable of multiple levels of actuation

Engineering Contradiction:

Improveactuation levelsVSAvoidswitch configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a capacitive sensor system that can detect and differentiate multiple actuation levels through a single sensing element. By measuring variations in capacitance corresponding to different levels of mechanical deflection or contact pressure, the system achieves multi-level actuation capability without requiring multiple separate switch configurations, thereby improving versatility while maintaining simplicity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution results in a compact, low-cost, digital force sensor capable of multiple actuation levels and dynamic force measurement, with improved durability and signal integrity.

Implementation Method 1

a sensing element arranged on the bottom surface of the sensor die, wherein the sensing element is configured to convert a strain on the bottom surface of the sensor die to an analog electrical signal that is proportional to the strain

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Data Source

PatentEP4701393A2Integrated digital force sensors and related methods of manufacture

Publication Date: 2026.02.25 NEXTINPUT INC

Figure 1~2
Figure 3~4
Figure 5~6

AI summary

Described herein is a ruggedized wafer level microelectromechanical ("MEMS") force sensor including a base and a cap. The MEMS force sensor includes a flexible membrane and a sensing element. The sensing element is electrically connected to integrated complementary metal-oxide-semiconductor ("CMOS") circuitry provided on the same substrate as the sensing element. The CMOS circuitry can be configured to amplify, digitize, calibrate, store, and/or communicate force values through electrical terminals to external circuitry.