Breath Alcohol Sensor Volume Compensation via Pressure Integration
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Solution Overview
Problem
Existing methods for measuring breath alcohol concentration face challenges in achieving high accuracy while maintaining compactness and low production costs, as they often require complex mechanical components and are affected by variations in breath flow rate and temperature.
Innovation Solution
The method calculates the volume of the breath sample by integrating pressure over time, compensates the fuel cell output signal using calibration data to account for volume and flow rate variations, and applies temperature compensation, eliminating the need for mechanical sampling systems and allowing for a more compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared spectroscopy sensors are used to measure breath alcohol concentration, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent replaces expensive infrared spectroscopy sensors with disposable or replaceable fuel cell sensor cartridges. These fuel cell sensors are significantly cheaper to manufacture and can be replaced when depleted, providing a cost-effective alternative while maintaining adequate measurement accuracy for breath alcohol concentration testing.
Solution Approach 2:
The patent replaces complex mechanical sampling systems (motors, solenoid valves, piston-cylinder devices, diaphragm mechanisms) with an electronic pressure sensor-based flow measurement system. This substitution eliminates moving parts, reduces mechanical complexity, and lowers manufacturing costs while maintaining the ability to measure breath alcohol concentration accurately.
2Measurement precision
If mechanical sampling systems are used to ensure predetermined breath volume, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces mechanical sampling systems with an electronic system that uses a pressure sensor to measure breath flow rate and integrates this data over time to calculate total breath volume. This electronic approach eliminates motors, solenoid valves, piston-cylinder devices, and diaphragm mechanisms, significantly reducing device complexity while maintaining measurement precision through software-based volume verification.
Solution Approach 2:
The system automatically measures breath flow rate via the pressure sensor, calculates cumulative breath volume through integration, and verifies that the minimum required volume has been achieved without user intervention. The microcontroller handles the entire process of flow measurement, volume calculation, and verification autonomously, eliminating the need for user-operated mechanical sampling components.
3Measurement precision
If mechanical sampling systems are used to control breath sample volume, then measurement precision is improved, but device size increases
Solution Approach 1:
The patent replaces bulky mechanical sampling systems with compact electronic components, primarily a pressure sensor and microcontroller. The pressure sensor can be implemented as a small membrane structure, and the microcontroller handles all calculations for flow rate measurement and volume integration. This electronic approach dramatically reduces device size while maintaining the ability to ensure accurate breath sample volumes through software control.
4Measurement precision
If advanced control circuitry is used to manage breath sampling, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces advanced control circuitry with a simplified electronic system where a pressure sensor provides raw flow data that is processed by a microcontroller. The microcontroller performs flow rate calculation, volume integration, and verification through software algorithms rather than complex hardware circuitry. This approach reduces control system complexity while maintaining measurement precision through computational methods.
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 ensures accurate breath alcohol concentration measurements regardless of breath sample volume or flow rate, reduces device size and cost, and maintains accuracy across varying temperatures.
Implementation Method 1
measuring the pressure of the flow of the expired breath sample
Implementation Method 2
a fuel cell sensor which converts fuel in the shape of alcohol (ethanol) to electric current in an electrochemical reaction
Data Source
AI summary
A method and apparatus for measuring user breath alcohol concentration. A flow of an expired breath sample is passed through a fuel cell sensor giving an output signal proportional to the amount of alcohol present in the sample. By measuring pressure, the volume of the sample may be calculated by integrating pressure over expiration time of the sample, whereas breath alcohol concentration is calculated based on the fuel cell output signal. Both sample volume and breath alcohol concentration values are continually updated by integrating measured instantaneous pressure and fuel cell output signal over time, irrespective of breath sample volume. When the user stops blowing, volume compensation is performed to obtain a compensated fuel cell output signal using a stored calibration volume. Hence, an improved method for accurately measuring breath alcohol concentration of a user is achieved, capable of handling varied expired volumes of breath, obviating the need for sampling mechanism.