Sub-ambient Vapor Sensor Cooling for Enhanced Sensitivity
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Solution Overview
Problem
Conventional capacitance sensors lack sensitivity in detecting analyte vapors, particularly volatile organic compounds (VOCs), compared to more expensive techniques.
Innovation Solution
Cooling capacitance-type vapor sensors to sub-ambient temperatures enhances their sensitivity, allowing them to detect analyte vapors at concentrations as low as one part per million by utilizing a sensor element with conductive electrodes and dielectric microporous material, along with a cooling member and operating circuit to monitor capacitance-related properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitance sensors are used without cooling, then the device complexity remains low and manufacturing cost is low, but the measurement precision and sensitivity to analyte vapors are insufficient
Solution Approach 1:
The patent applies parameter changes by cooling the sensor element to sub-ambient temperatures (e.g., -40°C to 0°C) to enhance the sensitivity and measurement precision of the capacitance sensor. This temperature parameter modification allows the sensor to detect analyte vapors at concentrations as low as one part per million, resolving the contradiction between maintaining low device complexity and achieving high measurement precision.
Solution Approach 2:
The patent implements preliminary action by pre-cooling the sensor element to a stable sub-ambient temperature before vapor detection. The cooling member (thermoelectric cooler) is activated in advance to establish the optimal temperature condition, ensuring that when analyte vapors are introduced, the sensor is already in the enhanced sensitivity state required for high-precision measurement.
2Measurement precision
If cooling is applied to enhance sensitivity, then the measurement precision improves, but the use of energy increases due to the cooling member operation
Solution Approach 1:
The patent applies periodic action by operating the thermoelectric cooler in controlled intervals rather than continuously. The cooler is activated to reach the target sub-ambient temperature, then allowed to maintain temperature passively for measurement periods, reducing overall energy consumption while preserving the enhanced sensitivity during active measurement phases.
Solution Approach 2:
The patent optimizes the temperature parameter to achieve the minimum necessary cooling (sub-ambient range of -40°C to 0°C) required to enhance sensitivity. By carefully selecting and maintaining this specific temperature range rather than extreme cold temperatures, the system achieves high measurement precision while minimizing the energy required for cooling operation.
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 sensitivity of the vapor sensors is improved by more than seven times, enabling the detection of analyte vapors at low concentrations, as demonstrated by increased capacitance measurements at sub-ambient temperatures compared to ambient conditions.
Implementation Method 1
cooling the sensor element to a sub-ambient temperature lower than the ambient temperature
Implementation Method 2
exposing the microporous material to the analyte vapor
Implementation Method 3
the sensor element has a capacitance-related property, and wherein the operating circuit is capable of monitoring the capacitance-related property of the sensor element
Data Source
AI summary
A vapor sensor comprises a sensor element (110), a cooling member (140), and an operating circuit (160). The sensor element comprises: a first conductive electrode; a second conductive electrode; and a dielectric microporous material at least partially disposed between and contacting the first and second conductive electrodes. The cooling member is in contact with, and configured to cool, the sensor element. The operating circuit is in electrical communication with the first and second conductive electrodes, and is capable of creating a voltage difference between the first and second conductive electrodes such that the sensor element has a capacitance-related property, and monitoring a capacitance-related property of the sensor element. A method of using the vapor sensor to detect an analyte vapor is also disclosed.