MEMS Force Sensor Flexible Diaphragm Reducing Electrical Contacts
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Solution Overview
Problem
Current MEMS three-axis force sensors face challenges in miniaturization due to fragile beam-based elastic structures and the complexity of electrical contacting, which affects their reliability and size reduction.
Innovation Solution
A multi-axis force sensor design featuring a flexible element with a mass element on its surface and symmetrically arranged piezoresistors, reducing the number of electrical contacts through various biasing configurations, and incorporating a multilayer structure with a dielectric and semiconductor layer for improved reliability and size reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beam-based elastic structure designs are used in MEMS three-axis force sensors, then the sensors can measure forces in multiple directions, but the structures easily break and require many electrical contacts which complicates miniaturization
Solution Approach 1:
The patent replaces traditional beam-based elastic structures with a flexible membrane structure. The membrane is a continuous thin film that can deform elastically in multiple directions without the structural weaknesses of beams. This flexible membrane approach maintains the multi-axis force measurement capability while eliminating the fragility and contact complexity issues of beam-based designs.
2Adaptability or versatility
If beam-based elastic structure designs are used in MEMS three-axis force sensors, then the sensors can measure forces in multiple directions, but the designs require many electrical contacts which makes miniaturization a challenge
Solution Approach 1:
The patent merges multiple electrical contact functions into a single centralized contact point on the flexible membrane. Instead of requiring separate contacts for each piezoresistor and biasing configuration, the design integrates these functions through a unified contact architecture, dramatically reducing the number of electrical contacts needed and simplifying the overall device structure for miniaturization.
Solution Approach 2:
The flexible membrane structure serves multiple functions simultaneously: it acts as the elastic element for force sensing, the substrate for piezoresistor placement, and the electrical connection medium. This multi-functionality eliminates the need for separate structural and electrical components, reducing complexity and enabling miniaturization.
3Device complexity
If the number of electrical contacts is reduced through biasing configurations, then miniaturization is enabled, but the structural integrity must be maintained
Solution Approach 1:
The flexible membrane provides continuous structural support across the entire sensor area, distributing mechanical loads evenly and preventing stress concentration that could lead to failure. This continuous film structure maintains structural integrity while allowing the reduction of electrical contacts to a minimum number.
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 design enhances the reliability and miniaturization of MEMS three-axis force sensors by reducing the number of electrical contacts and improving the structural integrity, enabling effective measurement of forces in multiple directions while maintaining sensitivity.
Implementation Method 1
A piezo-resistive force sensor is a type of sensor that converts an input mechanical force into an electrical output signal that can be measured. It comprises piezoresistors attached to an elastic diaphragm that bends with applied mechanical force. When mechanical pressure is applied to the sensor, the diaphragm flexes inducing stress in the piezoresistors. Consequently, their electrical resistance values change.
Data Source
AI summary
A device is provided that includes a flexible element including a center, a top surface, a bottom surface, one or more edges, a central area surrounding the center, and a peripheral area adjacent to the one or more edges; and a mass element located on the top surface of the flexible element in the central area such that the flexible element bends in a direction when a force acts on the mass element, wherein the flexible element defines a horizontal xy-plane and a vertical z-direction which is perpendicular to the horizontal xy-plane; and wherein the flexible element has a multilayer structure comprising a dielectric layer forming the bottom surface of the flexible element and a semiconductor layer on top of the dielectric layer.