Gas Sensor With Adaptable MEMS Filter for Low Power
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Solution Overview
Problem
Existing gas sensors require high power consumption and long warm-up times, making them inefficient for low-duty-cycle operations and battery-powered applications.
Innovation Solution
A gas sensor system utilizing a single light source and detector, with an adaptable micro-electromechanical systems (MEMS) filter that rapidly switches between measurement and reference states, allowing for low power consumption and fast start-up times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a gas sensor operates continuously to maintain measurement readiness, then the response time is short, but the energy consumption increases to 0.1-1 W
Solution Approach 1:
The patent implements periodic measurement cycles where the sensor alternates between active measurement mode and low-power sleep mode. The control unit activates the light source and performs measurements at predetermined intervals, keeping the sensor in sleep mode between measurements to minimize energy consumption while maintaining the ability to detect gas concentrations periodically.
Solution Approach 2:
The sensor performs a cold start initialization sequence that includes heating the light source to operational temperature and calibrating the system before entering normal periodic operation. This preliminary action ensures the sensor is ready for immediate measurement when activated from sleep mode, reducing the effective response time despite periodic operation.
2Use of energy by moving object
If a gas sensor is cold started to enable battery operation, then the energy consumption decreases, but the start-up time increases
Solution Approach 1:
The control unit executes a cold start routine that pre-heats the light source to its operational temperature range and performs initial calibration measurements before the sensor enters periodic operation. This preliminary preparation ensures that when the sensor is activated from sleep mode, it can begin measurements quickly without requiring a full warm-up period each time.
Solution Approach 2:
The patent dynamically adjusts the heating power and duration of the light source based on the operational state. During cold start, higher power is applied to reach operational temperature faster. During periodic operation, the light source is maintained at operational temperature with minimal power input, and during sleep mode, power is reduced to maintain just enough temperature to enable quick reactivation.
3Measurement precision
If a doubly compensated sensor configuration is used to improve measurement accuracy, then the measurement precision increases, but the device complexity increases with multiple light sources and detectors
Solution Approach 1:
The patent combines the functions of multiple light sources and detectors into a single integrated sensor unit. The control unit manages both measurement and reference channels using one light source and one detector, switching between measurement and reference modes by controlling the light source wavelength or the detector measurement timing, thereby achieving doubly compensated accuracy with reduced hardware complexity.
Solution Approach 2:
The single light source is designed to emit both measurement wavelengths and reference wavelengths, and the single detector is capable of detecting both measurement and reference signals. The control unit orchestrates the timing and wavelength selection to perform both measurement and reference functions sequentially, making each component multi-functional and eliminating the need for separate dedicated components.
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 reliable and accurate gas concentration measurements with low power consumption and rapid start-up, suitable for remote, battery-powered wireless sensor applications.
Implementation Method 1
sensors for measuring the concentration of a gas by measuring the absorption of infra-red light thereby
Implementation Method 2
an adaptable filter disposed between the light source and the detector and having a measurement state in which it passes at least one wavelength band which is absorbed by the gas and a reference state in which said wavelength band is attenuated relative to the measurement state
Data Source
AI summary
A gas sensor for measuring concentration of a predetermined gas includes a light source (2) arranged to emit pulses of light, a measurement volume (10), a detector (4) arranged to receive light that has passed through the measurement volume (10), and an adaptable filter (6) disposed between the light source (2) and the detector (4). The gas sensor has a measurement state in which it passes at least one wavelength band which is absorbed by the gas and a reference state in which said wavelength band is attenuated relative to the measurement state. A controller is connected to each of the light source, the detector and the adaptable filter to change the adaptable filter between one of said measurement state and said reference state to the other at least once during a gas sensor operation period.