Thermal-Conductivity Gas Sensor Using Thermistor Thermal Runaway
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Solution Overview
Problem
Conventional gas sensors face issues of low detection sensitivity and accuracy due to increased heat capacity and decreased responsiveness in porous gas molecule adsorption materials, and fluctuations in output levels caused by water vapor adsorption.
Innovation Solution
A gas detection device incorporating a thermal-conductivity-type gas sensor with a thermistor connected to a power supply circuit, applying excess power to induce a thermal runaway state for enhanced sensitivity and accuracy, combining with a porous gas molecule adsorption material for selective gas detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a porous gas molecule adsorption material is used to detect specific gas concentration, then gas detection sensitivity is improved, but heat capacity increases and responsiveness decreases
Solution Approach 1:
The gas sensor is divided into two independent detection units: one with porous gas molecule adsorption material for specific gas detection, and another without for general gas detection. This segmentation allows each unit to be optimized for its specific function, with the non-adsorption unit providing fast responsiveness and the adsorption unit providing high sensitivity, thereby resolving the contradiction between sensitivity and responsiveness.
Solution Approach 2:
The gas sensor is designed with multi-functionality by incorporating both porous adsorption material and non-adsorption material in a single device. The adsorption material provides specific gas detection capability, while the non-adsorption material provides general gas detection and fast response. This universal design allows the sensor to perform multiple functions simultaneously, resolving the contradiction between specialized sensitivity and general responsiveness.
2Measurement precision
If porous gas molecule adsorption material is used for gas detection, then detection sensitivity is improved, but water vapor adsorption causes output fluctuation and detection accuracy deteriorates
Solution Approach 1:
The sensor is segmented into two independent detection channels: one using porous adsorption material for specific gas detection, and another using non-adsorption material for reference measurement. The non-adsorption channel does not interact with water vapor, providing a stable reference that compensates for fluctuations caused by water vapor adsorption in the adsorption channel, thereby maintaining detection accuracy.
Solution Approach 2:
The non-adsorption material acts as an intermediary reference element that experiences the same environmental conditions (including water vapor presence) but does not adsorb water vapor itself. This intermediary provides a stable baseline that mediates the comparison with the adsorption material, allowing compensation for water vapor interference and maintaining accurate gas detection.
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 device achieves high sensitivity and improved gas detection accuracy by leveraging both thermal-conductivity-type and porous gas molecule adsorption material characteristics, enabling precise detection of various gases in diverse environments.
Implementation Method 1
A thermal-conductivity-type gas sensor utilizes the property that a thermal conductivity of an atmosphere differs depending on types and concentrations of gases therein
Implementation Method 2
a power supply circuit for applying a constant voltage to the connection circuit and supplying an excess power to the thermistor to put the thermistor in a thermal runaway state
Implementation Method 3
in the porous gas molecule adsorption material, gas molecules are desorbed from and adsorbed by the gas molecule adsorption material by heating and cooling
Implementation Method 4
a gas sensor that detects a concentration of a specific gas using a porous gas molecule adsorption material that is thermally coupled to a thermosensitive resistance element and desorbs specific gas molecules by heating
Data Source
AI summary
Provided are a gas detection device, a gas detection method, and a device including the gas detection device that are capable of enhancing responsiveness, gas detection sensitivity, and gas detection accuracy. A gas detection device (10) with a thermal-conductivity-type gas sensor (1) includes a connection circuit including a thermistor (2) having at least a pair of electrode parts (22a) and a resistor (11) connected to the thermistor (2); a power supply circuit (Ep) for applying a constant voltage to the connection circuit and putting the thermistor (2) in a thermal runaway state by supplying excess power to the thermistor (2); and a voltage detection unit for detecting a voltage between the electrodes of the thermistor (2) in the connection circuit.