Semiconductor Ammonia Sensing with Humidity-Based Calibration
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Solution Overview
Problem
Existing semiconductor gas detection elements struggle to accurately measure ammonia gas concentration due to the influence of humidity, leading to inaccuracies in concentration calculations.
Innovation Solution
A method and apparatus using a semiconductor ammonia gas concentration measurement apparatus that includes a sensor element with a metal oxide semiconductor, a heater, and a humidity sensor, employing calibration formulas created at different humidity levels to account for and reduce the impact of humidity on ammonia gas detection, allowing for accurate concentration calculations based on detection humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a semiconductor gas detection element is used to detect ammonia gas concentration, then gas detection capability is provided, but measurement precision deteriorates due to humidity influence
Solution Approach 1:
The patent segments the measurement process by creating separate calibration formulas for different humidity levels (e.g., 30%, 60%, 90% RH). Each calibration formula is specifically tailored to its humidity condition, allowing the system to select the appropriate formula based on current humidity, thereby eliminating cross-interference between humidity and concentration measurements.
Solution Approach 2:
The patent changes the calibration parameter by storing multiple calibration formulas corresponding to different humidity levels. Instead of using a single universal calibration formula, the system adapts the calibration parameters (slope and intercept values) based on the detected humidity level, thus compensating for humidity-induced measurement errors.
2Measurement precision
If a single calibration formula is used for ammonia gas detection, then device complexity is reduced, but measurement precision deteriorates under varying humidity conditions
Solution Approach 1:
The patent performs preliminary calibration actions by pre-establishing multiple calibration formulas under different controlled humidity conditions before actual use. These calibration formulas are stored in advance in the system memory, so when deployment occurs, the system only needs to detect current humidity and select the corresponding pre-prepared formula, avoiding complex real-time calibration procedures.
Solution Approach 2:
The system automatically detects the current humidity level and autonomously selects the appropriate calibration formula from stored options without requiring manual intervention. The microcontroller unit (MCU) performs this selection and switching automatically, making the complex multi-calibration system easy to operate as if it were a simple single-calibration system.
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 method and apparatus enable precise measurement of ammonia gas concentration by minimizing the influence of humidity, thereby improving measurement accuracy.
Implementation Method 1
when gas in a detection target is brought into contact with the gas-sensing part, the metal oxide semiconductor reacts with the gas to cause electron exchange
Implementation Method 2
a heater that heats the sensor element
Data Source
AI summary
An ammonia gas concentration measurement method uses a semiconductor ammonia gas concentration measurement apparatus having a sensor element that detects a change in resistance value occurring by contact of a metal oxide semiconductor with ammonia gas. The method includes a calibration formula creation step of measuring concentrations of ammonia gas in a plurality of known concentrations with the sensor element for each of a plurality of detection targets having different humidity levels and creating a calibration formula showing a relationship between the concentration of ammonia gas and an output value of the sensor element for each of the humidity levels of the detection targets, and a calculation step of calculating the concentration of ammonia gas based on the output value of the sensor element at the time of detection of ammonia gas, the detection humidity, and at least one calibration formula selected from a plurality of the calibration formulae.