Single-Crystal Silicon Strain Sensor for Battery Swelling Detection

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Solution Overview

Problem

Secondary batteries face challenges in measuring deformation and swelling, which can lead to increased risk of explosion, and existing strain sensors lack sensitivity and accuracy in detecting these phenomena.

Innovation Solution

A strain sensor using a thin-film single-crystal silicon-based strain gauge is developed, attached to the exterior of a secondary battery case, with a backing part, wiring, and encapsulation to detect deformation and swelling accurately.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a strain sensor is attached to measure deformation and swelling of secondary batteries, then the ability to detect safety risks is improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvebattery safety monitoringVSAvoidsensor structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The strain sensor is divided into distinct functional layers: a flexible substrate for mounting, a single-crystal silicon strain gauge layer for sensing, and an encapsulation layer for protection. This segmentation allows each layer to be optimized independently while simplifying the overall manufacturing process through modular assembly.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sensor employs a composite structure combining the flexibility of polymer substrates with the high sensitivity of single-crystal silicon strain gauges, and protects them with an encapsulation layer. This composite approach achieves both safety monitoring capability and manufacturing feasibility.

Inventive Principle:

Principle #40Composite materials

2Measurement precision

If existing strain sensors are used to detect battery deformation, then the manufacturing process is simpler, but the measurement precision and sensitivity are insufficient

Engineering Contradiction:

Improvedeformation detection accuracyVSAvoidsensor fabrication difficulty

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces conventional mechanical strain gauge structures with a thin-film single-crystal silicon-based strain gauge fabricated using semiconductor processing techniques. This substitution achieves superior measurement precision through atomic-level crystal structure control while enabling batch manufacturing through standardized photolithography and etching processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The strain gauge sensitivity is optimized by controlling the thickness of the single-crystal silicon layer (100-300 nm) and adjusting the etching depth to expose the crystalline structure. These parameter changes maximize the piezoresistive effect for high-precision deformation detection.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If a thin-film single-crystal silicon strain gauge is used to improve sensitivity, then the measurement accuracy is improved, but the manufacturing process complexity increases

Engineering Contradiction:

Improvestrain detection sensitivityVSAvoidfabrication process steps

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The single-crystal silicon strain gauge layer is pre-fabricated on a silicon wafer with controlled crystal orientation before being transferred to the flexible substrate. This preliminary fabrication allows precise control of gauge factors through crystal orientation selection, while the transfer process simplifies final assembly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A flexible substrate serves as an intermediary carrier that receives the pre-fabricated single-crystal silicon strain gauge layer through transfer printing. This intermediary approach decouples the complex thin-film fabrication from the final sensor assembly, reducing overall manufacturing complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 strain sensor effectively measures deformation and swelling of secondary batteries with high sensitivity and accuracy, reducing the risk of explosion and improving battery safety.

Implementation Method 1

a strain gauge installed on the backing part and formed of single-crystal silicon

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Implementation Method 2

a backing part attached to an exterior of a case of a secondary battery

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4530591A1Strain sensor, manufacturing method of strain sensor, and secondary battery equipped with strain sensor

Publication Date: 2025.04.02 SAMSUNG SDI CO LTD

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AI summary

Disclosed is a secondary battery including a case configured to surround an exterior of an electrode assembly, and a strain sensor attached to an exterior of the case to detect deformation of the case. The strain sensor may include a backing part attached to the exterior of the case; a strain gauge installed on the backing part and formed of single-crystal silicon; a wiring part stacked on the backing part, along with the strain gauge, and electrically connected to the strain gauge; and an encapsulation part fixed to the backing part while surrounding the strain gauge and the wiring part excluding a portion of the wiring part.