MEMS Thermal Gradient Sensing via Bond Wire Voltage

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Solution Overview

Problem

Microelectromechanical systems (MEMS) sensors in compact electronic devices face issues with thermal gradients caused by external heat sources, leading to unpredictable temperature effects and corrupted measurements due to non-uniform thermal energy distribution, which affects the accuracy of motion and orientation sensing.

Innovation Solution

A MEMS sensor design with vertically-stacked semiconductor layers and external bond wires that measure voltage differences across these layers to calculate thermal gradients, allowing for real-time modification of operational parameters and compensation for thermal effects, using thermocouple principles with bond wires of different materials to determine temperature differences and gradients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If MEMS sensors are used in compact electronic devices, then device integration and compactness are improved, but measurement accuracy deteriorates due to thermal gradients from external heat sources

Engineering Contradiction:

Improvedevice compactnessVSAvoidsensing accuracy

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The patent segments the temperature measurement function by placing multiple temperature sensors at different locations within the MEMS device package. This allows independent measurement of thermal gradients at various points, enabling the system to detect and compensate for non-uniform temperature distribution while maintaining compact form factor.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements a feedback mechanism where measured temperature data from multiple sensors is used to calculate thermal gradients, which then feed into a compensation algorithm that adjusts the sensor output readings. This closed-loop feedback system continuously corrects for thermal effects, maintaining measurement accuracy despite compact packaging constraints.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If multiple temperature sensors are added to measure thermal gradients, then measurement accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvethermal gradient measurement accuracyVSAvoidsensor system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the temperature sensors multi-functional by using them both for direct temperature measurement and for calculating thermal gradients through differential measurement. The same sensor array serves dual purposes: monitoring absolute temperature and detecting temperature differences across the package, reducing the need for additional dedicated gradient sensors.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the temperature sensing function with the existing MEMS sensor package structure. Temperature sensors are integrated into the package substrate or housing, merging the thermal measurement capability with the mechanical support structure, thereby avoiding additional discrete components and reducing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If temperature compensation is implemented, then measurement reliability is improved, but processing complexity increases

Engineering Contradiction:

Improvemeasurement reliabilityVSAvoidsignal processing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs preliminary action by pre-calculating and storing compensation characteristics during manufacturing or system initialization. Thermal gradient compensation parameters and correction algorithms are prepared in advance based on characterized thermal behavior, allowing the runtime processing to use pre-computed correction factors rather than performing complex real-time thermal modeling.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter representation by transforming raw temperature readings into compensated sensor outputs through mathematical transformation. The compensation process adjusts measurement parameters (scale factors, offset values) based on measured thermal gradients, converting the problem from complex physical modeling to parameter adjustment, which is computationally simpler and more reliable.

Inventive Principle:

Principle #35Parameter changes

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

This solution enables accurate measurement and compensation for thermal gradients, improving the reliability of MEMS sensors by correcting for temperature-induced errors and ensuring precise operation in varying environmental conditions.

Implementation Method 1

Methodology Applied

Scientific EffectSeebeck effect: Seebeck Effect

Data Source

PatentUS11312621B2Sensing thermal gradients within a microelectromechanical device

Publication Date: 2022.04.26 INVENSENSE INC

AI summary

The performance of a microelectromechanical systems (MEMS) device may be subject to unwanted thermal gradients or nonuniform temperatures. The thermal gradients may be approximated based on voltage measurements taken through bond wires coupled to bond points located on the MEMS device. Thermal gradient measurement may be improved depending on the arrangement of bond wires and/or the material of the bond wires. Sense circuitry that is coupled to the MEMS device may determine corrective actions, such as updating the operation of the MEMS device, that compensate for the adverse effects from the thermal gradients.