MEMS Capacitor Particle Sensor with Adjustable Gap
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Solution Overview
Problem
Existing particle detection methods are bulky, expensive, and lack portability, making them inadequate for efficient air quality monitoring and localized pollution source identification.
Innovation Solution
A microelectromechanical systems (MEMS) capacitor-based apparatus with a gas conveyor and readout circuitry to measure capacitance changes caused by particles flowing through a gap between the capacitor plates, allowing for adjustable gap width and parallel gap configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filter-based monitoring is used to detect particle concentrations, then measurement capability is provided, but the device becomes bulky and expensive
Solution Approach 1:
The patent replaces mechanical filter-based particle detection with a capacitive sensing system. The MEMS capacitor detects particles through electrical field interactions rather than physical filtration, eliminating the need for bulky filter assemblies and enabling miniaturized sensor designs while maintaining particle concentration measurement capability
Solution Approach 2:
The patent changes the detection parameter from physical particle capture (filter mass loading) to electrical capacitance changes. By measuring capacitance variations caused by particles in the electric field, the system achieves particle detection without mechanical filters, reducing device complexity and cost
2Measurement precision
If a bank of filters with differing selectivity is used to obtain particle size distribution, then size distribution measurement is achieved, but device complexity and cost increase
Solution Approach 1:
The patent makes a single MEMS capacitor perform multiple detection functions by adjusting the gap width parameter. By varying the gap between capacitor plates, the same sensor can detect different particle sizes, eliminating the need for multiple specialized filters and simplifying the device architecture while maintaining size distribution measurement capability
Solution Approach 2:
The patent introduces dynamic adjustability of the capacitor gap width to enable the sensor to adapt its detection range. The gap can be adjusted between measurements to target different particle size ranges, allowing one sensor to replace multiple fixed-selectivity filters through dynamic reconfiguration
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 MEMS capacitor-based system enables efficient, portable, and cost-effective detection of particle concentrations and size distributions in gases, facilitating improved air quality monitoring and pollution source localization.
Implementation Method 1
readout circuitry configured to measure a capacitance of the MEMS capacitor
Implementation Method 2
detect a change in the capacitance of the MEMS capacitor caused by a particle flowing through the gap with the gas
Implementation Method 3
the gas conveyor comprises at least one of a mechanism to create a pressure difference over the gap
Implementation Method 4
a thermophoretic device configured to create a temperature gradient over the gap
Implementation Method 5
the width of the gap is adjustable by applying a voltage over the plates, such that an electrostatic force is caused to move at least one of the plates
Data Source
AI summary
According to an example aspect of the present invention, there is provided an apparatus comprising a microelectromechanical, MEMS, capacitor comprising two plates and a gap between the plates, a gas conveyor configured to cause gas to flow through the gap, and readout circuitry configured to measure a capacitance of the MEMS capacitor.