Dual Range ASIC for MEMS Pressure Sensor
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Solution Overview
Problem
Existing pressure sensors are either fragile and inaccurate at high pressure ranges or insensitive and inaccurate at low pressure ranges, making them unsuitable for measuring across extensive pressure ranges with high precision.
Innovation Solution
A dual range ASIC (Application Specific Integrated Circuit) is integrated into a MEMS-based sensor, which uses calibration coefficients stored in EEPROM to switch between different correction factors and slopes for accurate measurement across a wide pressure range, allowing for high precision and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thin silicon diaphragm is used for high sensitivity pressure sensing, then low range pressure measurement accuracy is improved, but the sensor becomes delicate and prone to destruction when subjected to overload pressure
Solution Approach 1:
The sensor is divided into two separate sensing elements: a thin diaphragm for low-pressure measurement and a thick diaphragm for high-pressure measurement. Each diaphragm is optimized for its specific pressure range, allowing the system to achieve both high sensitivity at low pressures and durability at high pressures without compromising either aspect.
2Stress or pressure
If a thick diaphragm is used for high range pressure sensing, then high pressure measurement capability is improved, but the sensor becomes insensitive and inaccurate within low pressure ranges
Solution Approach 1:
The sensor system incorporates two distinct diaphragms with different thicknesses - a thin diaphragm for low-pressure sensing and a thick diaphragm for high-pressure sensing. This segmentation allows each diaphragm to be optimized for its intended pressure range, ensuring accurate measurements across the entire dual range without the insensitivity problem of single-thickness designs.
3Strength
If strain gauges and diaphragm capsules are made sufficiently strong for extensive pressure range, then high pressure measurement capability is improved, but sensitivity for low pressure ranges deteriorates
Solution Approach 1:
Instead of using a single strong diaphragm that compromises low-pressure sensitivity, the invention segments the sensing function into two separate diaphragms with different mechanical properties. The thin diaphragm provides high sensitivity for low-pressure measurements, while the thick diaphragm provides the strength needed for high-pressure measurements, resolving the contradiction between strength and sensitivity.
4Adaptability or versatility
If multiple piezoresistive elements are fabricated for different pressure ranges, then dual range capability is improved, but manufacturing complexity and reliability deteriorate
Solution Approach 1:
The invention segments the pressure sensing function spatially by using two separate diaphragms rather than integrating multiple piezoresistive elements into a single complex structure. This approach achieves dual range capability while maintaining simpler manufacturing processes and higher reliability, as each diaphragm can be fabricated using standard single-purpose techniques rather than complex multi-element integration.
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 dual range ASIC enables precise measurement of pressure, temperature, speed, and direction over extensive ranges with improved resolution and cost-effectiveness, suitable for applications like automotive engine lubrication systems.
Implementation Method 1
The stress can be measured by piezoresistive elements formed in a diaphragm
Data Source
AI summary
A sensor incorporates a dual range ASIC (Application Specific Integrated Circuit) for accurately sensing and measuring sensor input over extensive range along with an improved resolution. The sensor can incorporate an ASIC utilizing signals from a MEMS-based piezoresistive Wheatstone bridge. Signals can also come from capacitive pressure measurement sources. The signals can be converted to digital bit counts where calibration coefficients can be implemented to achieve high precision. The calibration coefficients corresponding to bit counts can be compared with transition points that are recorded into ASIC for effectively distinguishing different sensor ranges. The transition points can be stored in an EEPROM fabricated to suit ASIC applications.