Micromechanical Sensor Module with Passive Wake-Up Transducer

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Solution Overview

Problem

Inertial sensors face challenges in achieving high measurement accuracy while minimizing energy consumption, particularly in detecting sporadically occurring accelerations and maintaining continuous monitoring without excessive power consumption, which is crucial for self-sufficient and mobile devices.

Innovation Solution

An integrated micromechanics-based sensor module that incorporates a passive secondary transducer as a wake-up generator within the movable structure or electronic circuit, allowing the primary transducer to switch from a rest state to a measurement state efficiently, reducing overall power consumption by using mechanical energy conversion without auxiliary power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the primary transducer and electronic circuit are kept active for continuous monitoring, then measurement accuracy and detection capability are improved, but power consumption increases significantly

Engineering Contradiction:
Improvedetection capabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically switches between active and low-power states based on detection needs. The secondary transducer remains active in low-power mode and only activates the primary transducer and full electronic circuit when an event is detected, enabling adaptive power management that balances detection capability with energy conservation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses periodic sampling with long pauses to reduce query data rates and save energy. The secondary transducer performs intermittent monitoring rather than continuous measurement, allowing the primary transducer to remain inactive for extended periods while still detecting sporadic events when they occur.

Inventive Principle:
Principle #19Periodic action

2Use of energy by moving object

If the sensor is switched off completely to save energy, then power consumption is reduced, but the sensor cannot detect sporadically occurring accelerations

Engineering Contradiction:
Improvepower consumptionVSAvoiddetection capability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The secondary transducer serves as an intermediary that bridges the gap between complete shutdown and full activation. It operates in a low-power state capable of detecting events and triggers the primary transducer only when necessary, enabling the system to detect sporadic accelerations while maintaining low power consumption during idle periods.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The secondary transducer autonomously monitors for events without requiring power from the main system. It self-activates the primary transducer when an event is detected, eliminating the need for continuous power supply while ensuring detection capability is maintained for sporadic accelerations.

Inventive Principle:
Principle #25Self-service

3Use of energy by moving object

If cyclic measurement with long pauses is used to reduce power consumption, then energy usage is reduced, but short signals such as shock signals cannot be detected

Engineering Contradiction:
Improvepower consumptionVSAvoiddetection accuracy
Core Design Contradiction:
Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The system replaces the mechanical/capacitive sensing mechanism of the primary transducer with a piezoelectric secondary transducer for the wake-up function. The piezoelectric effect provides inherent high-pass filtering that naturally responds to rapid changes and short signals while ignoring steady-state conditions, enabling detection of shock signals even during low-power cycles.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system changes the operational parameters of the sensing mechanism by using different transducer types with different frequency responses. The secondary transducer operates at a frequency range optimized for detecting short, impulsive signals, while the primary transducer handles continuous measurement, allowing accurate detection of shock signals during cyclic measurement modes.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If a passive secondary transducer is integrated into the movable structure, then space and manufacturing costs are reduced, but the structural complexity of the movable structure increases

Engineering Contradiction:
Improvemanufacturing costVSAvoidstructural complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The secondary transducer is merged with the movable structure or integrated into the electronic circuit's movable structure. This consolidation eliminates the need for separate components and mounting structures, reducing overall device complexity while maintaining manufacturing advantages through integrated production processes.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The movable structure serves multiple functions: it supports the primary transducer for high-accuracy measurement and simultaneously provides the structural framework for the secondary transducer. This multi-functionality reduces the need for additional dedicated structures, simplifying the overall design while enabling cost-effective manufacturing.

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

This approach enables continuous, accurate detection of accelerations with significantly reduced energy usage, achieving low power consumption in idle modes and extending battery life, while maintaining high measurement accuracy and reliability.

Implementation Method 1

a passive secondary transducer for converting a mechanical signal of the movable structure into an electrical signal... For example, a piezoelectric signal converter can be used as a secondary converter, which generates a voltage signal as a result of a mechanical signal

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP2646837B8Sensor module with waking device
Publication Date: 2015.08.19 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

The invention relates to a sensor module on a micromechanical basis having at least one moveable structure, at least one active primary transducer for converting a mechanical signal of the moveable structure into an electrical signal, and an electronic circuit for capturing, using measurement technology, movements of the moveable structure, wherein the sensor module has, in addition to the active primary transducer, at least one passive secondary transducer for converting a mechanical signal of the moveable structure into an electrical signal, wherein the primary transducer and the secondary transducer are coupled to the electronic circuit, and wherein the secondary transducer is provided as a wake-up generator for the primary transducer and/or the electronic circuit from a rest state into a measurement state. It is therefore the object of the present invention to propose an integrated sensor module on a micromechanical basis having a high measurement accuracy, which has, in continuous use, a low energy consumption and which also detects with a high level of accuracy sporadically occurring accelerations of the moveable structure in the sensor module using measurement technology. The object is achieved by a sensor module of the generic type defined in the beginning, in which the secondary transducer is integrated in the moved structure and/or a further moveable structure is integrated in the electronic circuit.