Combustible Gas Sensor Triggering for Low-Power Accurate Detection
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Solution Overview
Problem
Catalytic combustible gas sensors consume significant power due to high-temperature operation, which is particularly problematic for portable and wireless applications, and are susceptible to errors from ambient conditions such as temperature and humidity changes.
Innovation Solution
A sensor system incorporating a primary combustible gas sensor and a low-thermal-mass trigger sensor, where the trigger sensor activates the primary sensor only when a threshold response is detected, allowing for pulsed operation and reduced power consumption, and includes both sensing and compensating elements in a Wheatstone bridge configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor operates continuously at high temperature to ensure accurate gas detection, then measurement precision is improved, but power consumption increases significantly
Solution Approach 1:
The sensor system implements periodic heating cycles where the heating element is activated only during measurement phases rather than continuous operation. The control system heats the sensing element to operating temperature, performs measurements, then reduces or shuts off heating when measurements are not needed, thereby maintaining detection accuracy while dramatically reducing overall power consumption.
Solution Approach 2:
The sensor system dynamically adjusts the heating element's power consumption based on operational requirements. The control system modulates heating power during different operational states (measurement vs. standby), and can adjust heating intensity based on detected gas concentrations, optimizing the balance between measurement precision and power consumption.
2Difficulty of detecting and measuring
If the sensor uses high-temperature catalytic oxidation to detect combustible gases, then detection capability is improved, but the sensor becomes susceptible to errors from ambient temperature and humidity changes
Solution Approach 1:
The sensor system introduces a reference element that serves as an intermediary for compensating ambient condition effects. This reference element experiences the same environmental conditions (temperature, humidity) as the sensing element but does not react to combustible gases. By comparing the differential response between the sensing element and reference element, the system isolates and eliminates errors caused by ambient conditions while preserving combustible gas detection capability.
Solution Approach 2:
The control system continuously monitors the output signals from both the sensing element and reference element, and uses this feedback to compensate for ambient condition variations. When the reference element detects changes due to temperature or humidity, the control system adjusts the measurement interpretation accordingly, maintaining accurate combustible gas detection despite environmental fluctuations.
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
Reduces power requirements and enhances accuracy by using low-thermal-mass MEMS elements in a pulsed mode, providing rapid response times and accurate gas concentration readings while minimizing power usage.
Implementation Method 1
the sensor must sufficiently heat the sensing element through resistive heating
Implementation Method 2
catalytic oxidation of combustible gases
Implementation Method 3
catalyze combustion of an analyte
Implementation Method 4
electrical detection of the heat of reaction of a combustible gas on the oxidation catalysts, usually through a resistance change
Data Source
AI summary
A system includes a primary combustible gas sensor and a trigger combustible gas sensor including a first trigger element of low-thermal-mass which includes a first trigger heating element in operative connection with electronic circuitry. The trigger combustible gas sensor also includes a second trigger element of low thermal mass including a second trigger heating element. The second trigger element is also in operative connection with the electronic circuitry. The electronic circuitry further has a first trigger mode of operating in which the first trigger element is heated to a temperature at or above a temperature at which the first trigger element causes combustion of the at least one combustible gas analyte and wherein the second trigger element is operated as a trigger compensating element. The electronic circuitry is configured to operate the trigger combustible gas sensor to detect a value of a response at or above a threshold value. The primary combustible gas sensor is activated from a low-power state upon the threshold value being detected by the trigger combustible gas sensor.