Elastomeric Encapsulated MEMS Pressure Sensor for High-Force Measurement
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Solution Overview
Problem
Current semiconductor pressure sensors are not suitable for high-pressure applications due to limitations in precision, reliability, and cost, and existing packaging solutions, such as those using steel or ceramic, are cumbersome and costly, especially when oil is required for force distribution, which adds complexity and expense.
Innovation Solution
A packaged pressure sensor design featuring a container with a polydimethylsiloxane (PDMS) filling layer and a cap that transfers pressure to a MEMS sensor chip, allowing for high-directional force measurement and uniform force application, eliminating the need for oil and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If semiconductor pressure sensors are used for high-pressure applications, then measurement capability is improved, but packaging complexity and cost increase due to requirement for oil-filled containers
Solution Approach 1:
The patent extracts and eliminates the oil filling medium from the packaging system. The MEMS sensor chip is directly packaged in a ceramic or metal container without requiring oil-filled cavities, thereby simplifying the packaging structure while maintaining high-pressure measurement capability up to 100 bar or more.
Solution Approach 2:
The patent changes the packaging parameters by using solid-state construction (ceramic or metal containers) instead of fluid-filled (oil) packaging. This parameter change eliminates the need for fluid-tight sealing and complex mounting arrangements while enabling direct measurement of high pressures through the membrane structure.
2Manufacturing precision
If oil-filled packaging is used for semiconductor pressure sensors, then force distribution uniformity is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the oil filling medium from the packaging system. The force distribution uniformity is achieved through the rigid container structure and direct membrane coupling instead of fluid transmission, thereby eliminating the costs associated with oil filling, sealing, and fluid-tight manufacturing.
Solution Approach 2:
The patent employs cost-effective ceramic or metal container structures that can be mass-produced using standard manufacturing techniques. These solid-state packaging structures replace expensive oil-filled assemblies, reducing material costs and simplifying manufacturing processes while maintaining measurement precision.
3Area of stationary object
If traditional packaging with large base area is used, then force application surface is improved, but sensor size increases
Solution Approach 1:
The patent transitions from a planar force application approach (large base area) to a three-dimensional force transmission approach through the container walls and membrane structure. This allows the sensing element to be small while still accommodating large or distributed force applications through the container's lateral surfaces and top surface.
Solution Approach 2:
The patent uses a thin membrane suspended over a cavity in the container to sense pressure. This membrane provides an extensive surface area for force application while maintaining a compact overall sensor size. The membrane can be configured to match various force application surfaces without increasing the sensor's volumetric dimensions.
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 solution enables precise measurement of forces up to 100 kN with improved directionality and uniformity, reducing costs and complexity while maintaining high precision, making it suitable for various applications including automotive and electronic devices.
Implementation Method 1
Formed within the membrane are piezoresistive elements connected together to form a Wheatstone bridge. When subjected to a pressure, the membrane undergoes deformation, causing a variation of resistance of the piezoresistive elements
Implementation Method 2
capacitive sensors are available, where the membrane provides a first plate of a capacitor, whereas a second plate is provided by a fixed reference. During use, deflection of the membrane generates a variation of the capacitance of the capacitor
Implementation Method 3
A pressure sensor according to an embodiment comprises a container (2) made of elastomeric material
Data Source
AI summary
A packaged pressure sensor, comprising: a MEMS pressure-sensor chip; and an encapsulating layer of elastomeric material, in particular PDMS, which extends over the MEMS pressure-sensor chip and forms a means for transferring a force, applied on a surface thereof, towards the MEMS pressure-sensor chip.