Pulsed Combustible Gas Sensor with Constant Resistance Setpoint
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional combustible gas sensors face challenges in minimizing power consumption while maintaining accurate detection, especially in portable or wireless devices, due to the high-temperature operation of catalytic sensing elements, which are affected by ambient temperature, humidity, and pressure changes.
Innovation Solution
The method involves operating a sensing element with a heating element in a pulsed manner, using a dynamic or pulse mode with a constant resistance setpoint, and varying energy input to achieve a constant resistance setpoint, allowing for efficient detection of combustible gases with reduced power consumption by activating the sensing element only when a threshold response is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensing element is operated continuously at high temperature for accurate detection, then the measurement precision is improved, but the power consumption increases
Solution Approach 1:
The sensing element is operated in a pulsed manner rather than continuously. The system applies heating cycles to the sensing element, activating it only during measurement periods and allowing it to cool down between measurements. This periodic operation maintains the ability to detect combustible gases accurately while significantly reducing overall power consumption compared to continuous high-temperature operation.
2Measurement precision
If the sensing element is heated to high temperature for catalytic combustion, then the detection sensitivity is improved, but the response time increases due to heating delays
Solution Approach 1:
The system performs preliminary heating of the sensing element before actual gas detection is needed. By pre-heating the sensing element to its operational temperature and then maintaining it through periodic pulsing, the system ensures that when detection is required, the sensing element is already at the necessary temperature, thereby reducing the overall response time while maintaining detection sensitivity.
3Device complexity
If the sensing element operates in ambient conditions, then the device complexity is reduced, but the measurement precision deteriorates due to environmental interference
Solution Approach 1:
The system creates a localized controlled environment around the sensing element by using a pulsed heating approach. During the heating pulses, the sensing element reaches temperatures where catalytic combustion occurs, creating a local thermal zone that is less susceptible to ambient temperature variations. This localized thermal control maintains detection accuracy while keeping the overall device structure simple and exposed to ambient conditions.
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
This approach significantly reduces power consumption while maintaining accurate gas detection, enabling faster response times and increased signal magnitude, allowing for efficient operation in portable devices with minimal impact from ambient conditions.
Implementation Method 1
The oxidation catalysts typically operate in a temperature above 100° C. (and, more typically, above 300° C.) to catalyze combustion of an analyte. Therefore, the sensor must sufficiently heat the sensing element through resistive heating.
Implementation Method 2
Catalytic or combustible (flammable) gas sensors have been in use for many years to, for example, prevent accidents caused by the explosion of combustible or flammable gases. In general, combustible gas sensors operate by catalytic oxidation of combustible gases.
Implementation Method 3
The operation of a catalytic combustible gas sensor proceeds through electrical detection of the heat of reaction of a combustible gas on the oxidation catalysts, usually through a resistance change. The heating element may be a helical coil of fine wire or a planar meander formed into a hotplate or other similar physical form.
Data Source
AI summary
A gas sensor device includes a sensing element including a heating element and electronic circuitry in connection with the heating element. The sensing element forms a resistive element in a circuit of the electronic circuitry. The electronic circuity operates the sensing element in a trigger mode via a pulsed energy input to the heating element at a first duty cycle and in a primary mode via a pulsed energy input to the heating element at a second duty cycle, which is greater than the first duty cycle. The electronic circuitry is further configured to measure a response of the sensing element over time during each pulse of a plurality of pulses of the pulsed energy input. The primary mode is entered upon measurement of a value of a response at or above a threshold value in the trigger mode of operation.