MEMS Environmental Sensor Transfer Cavity for Low-Power Detection
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Solution Overview
Problem
Existing environmental sensors, such as pressure sensors, displacement sensors, and vibration sensors, face challenges in achieving high signal-to-noise ratio and low power consumption simultaneously, and their integration is complex due to differences in chip design, material, and encapsulation structure.
Innovation Solution
A MEMS environmental sensor design utilizing a transfer cavity with differing port sizes and a magnetic sensing element to convert displacement into electrical resistance changes, enabling integration and miniaturization while maintaining high sensitivity and low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple types of environmental sensors are integrated using conventional methods, then sensor functionality is achieved, but device complexity increases due to differences in chip design, material, and encapsulation structure
Solution Approach 1:
The patent employs a universal MEMS fabrication process that can produce multiple types of environmental sensors (pressure, temperature, humidity, acceleration) using the same substrate, cavity structure, and encapsulation method. The magnetic sensing element and transfer cavity design serve multiple sensor types, eliminating the need for separate fabrication processes for each sensor type.
Solution Approach 2:
The sensor system is divided into functional modules: the transfer cavity structure, the magnetic sensing element, the elastic membranes, and the encapsulation layers. Each module can be independently optimized and fabricated, then integrated through standardized MEMS processes, reducing overall integration complexity.
2Reliability
If conventional sensor designs are used, then basic sensing functionality is achieved, but signal-to-noise ratio decreases and power consumption increases
Solution Approach 1:
The patent introduces a magnetic field as an intermediary between the physical quantity being measured and the electrical signal. The magnetic sensing element converts mechanical displacement into magnetic field changes, which are then converted into electrical resistance changes. This intermediate conversion stage improves signal-to-noise ratio while enabling low-power operation compared to direct piezoresistive or capacitive sensing.
Solution Approach 2:
The patent replaces conventional mechanical piezoresistive sensing elements with magnetic sensing elements that utilize magnetic field interactions. This substitution eliminates the need for high-power excitation currents required by traditional piezoresistive sensors, thereby reducing power consumption while improving signal-to-noise ratio through magnetic field coupling.
3Volume of moving object
If sensor chip size is reduced for miniaturization, then device size decreases, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The patent employs a nested cavity structure where the load-bearing cavity is positioned within the transfer cavity, and the magnetic sensing element is nested within the load-bearing cavity. This nested arrangement allows multiple functional elements to be compactly integrated while maintaining adequate spacing for precise fabrication. The overlapping projection design ensures proper alignment without requiring excessive lateral precision.
Solution Approach 2:
The patent applies different structural qualities to different regions of the sensor chip. The transfer cavity uses a specific aspect ratio and port size configuration optimized for force transmission, while the load-bearing cavity uses dimensions optimized for magnetic sensing. The elastic membranes have locally optimized thickness and material properties to achieve the required mechanical performance at miniaturized scales.
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 sensor achieves high signal-to-noise ratio and low power consumption, facilitating the integration and miniaturization of multiple environmental parameter sensors on a single chip.
Implementation Method 1
on the basis of the Pascal's principle, a difference in dimensions of an input port and an output port of a transfer cavity is used to transform a small displacement in a region of large volume into a large displacement in a region of small volume
Implementation Method 2
a multi-component highly sensitive material is adapted as a magnetic sensing element to convert a change in displacement, through an intermediate variable, such as a change in magnetic field, into a change in electrical resistance
Implementation Method 3
the non-magnetic metal material is uniformly dispersed in a particulate form inside the transfer medium or disposed in a film form on the surface of one side of the elastic pressure membrane facing the transfer cavity and/or on the surface of one side of the elastic pressure membrane facing the load bearing cavity, the excitation coil is provided inside the load bearing cavity, and the MEMS environmental sensor is configured to provide a radio frequency alternating current in the excitation coil for driving the non-magnetic metal material to produce an induced eddy current, thereby producing an induced magnetic field
Data Source
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AI summary
The disclosed invention is a MEMS environmental sensor and preparation method thereof. A transfer cavity is produced in the middle of a transfer substrate of a MEMS environmental sensor, and a transfer medium is located inside the transfer cavity. The surface area of an input port is larger than the surface area of an output port. An elastic transfer membrane is provided on the surface of the input port, and an elastic pressure membrane is provided on the surface of the output port. A load bearing cavity is provided in a load bearing substrate, a magnetic sensing element is positioned inside the load bearing cavity, and the load bearing cavity partially overlaps with the output port. The surface area of the input port of the transfer cavity is larger than the surface area of the output port, and on the basis of Pascal's principle, differences in the volume of the transmission cavity are used to transform a small displacement in a region of large volume into a large displacement in a region of small volume. In addition, because the output port and the end of the output port at least partially overlap, and a magnetic sensing element is arranged in the load bearing cavity, a change in displacement is produced, producing a change in a magnetic field, that is converted into a change in electrical resistance, which provides high-sensitivity and low-power detection.