MEMS Acoustic Sensor Integrated Temperature Detection
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Solution Overview
Problem
Conventional acoustic sensors lack integrated temperature detection functionality, leading to inaccurate environmental temperature measurements due to self-heating and thermal conduction issues from underlying printed circuit boards.
Innovation Solution
A micro-electro-mechanical system (MEMS) acoustic sensor with a piezoelectric diaphragm and an integrated temperature sensor member, where the temperature sensor is formed from materials like molybdenum or doped polysilicon, and is configured as a resistor within the cantilever structure, allowing direct exposure to environmental temperatures and using a Wheatstone Bridge circuit for resistance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a temperature sensor is integrated into the acoustic sensor package, then temperature detection functionality is provided, but self-heating effects and thermal conduction from underlying printed circuit boards cause inaccurate measurements
Solution Approach 1:
The temperature sensor is segmented from the main acoustic sensor structure and placed in a separate, isolated package. This physical separation allows the temperature sensor to be thermally isolated from the acoustic sensor's heat sources and the printed circuit board, enabling accurate temperature measurements while maintaining the acoustic sensor's functionality.
Solution Approach 2:
A thermal isolation structure acts as an intermediary between the temperature sensor and the acoustic sensor package. This intermediary structure minimizes thermal conduction paths, allowing the temperature sensor to accurately detect environmental temperature without being influenced by self-heating effects or thermal conduction from the underlying printed circuit board.
2Measurement precision
If the temperature sensor is exposed to the environment for accurate measurement, then measurement precision improves, but the sensor becomes more susceptible to environmental factors
Solution Approach 1:
The temperature sensor is positioned in a specific location within the package that provides local thermal exposure to the environment while maintaining overall protection. The sensor is exposed to environmental temperature through a dedicated aperture or opening, while the rest of the sensor structure remains protected from harmful environmental factors such as moisture and dust.
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
Enables accurate and direct detection of environmental temperatures by minimizing self-heating effects and providing reliable temperature measurements through the integration of temperature sensing within the acoustic sensor package.
Implementation Method 1
piezoelectric MEMS microphones, which converts sound pressure into an electrical voltage
Implementation Method 2
a temperature sensor member configured to detect temperature... include a resistor that cooperates with temperature circuitry to detect its resistance. Preferably, this resistance is configured to vary, in a known manner, as a function of the temperature of the resistor
Data Source
AI summary
An acoustic sensor has a MEMS die with MEMS structure. Among other things, the MEMS structure includes a diaphragm configured to mechanically respond to incident acoustic signals, and a temperature sensor member configured to detect temperature.