Ethanol Vapor Sensor with Infrared Absorption Cell
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Solution Overview
Problem
Current ethanol sensors for detecting drunk driving have limited lifetimes, insufficient sensitivity for passive detection of ethanol vapor in vehicle cabins, and are impractical for on-board use due to size and sensitivity requirements, necessitating the development of a chemical vapor sensor that can actively and passively measure ethanol with high sensitivity and specificity.
Innovation Solution
A chemical vapor sensor system utilizing a vapor concentrator to amplify ethanol concentration for infrared detection, enabling sub-ppm ethanol detection in vehicle cabin air, combined with an active breathalyzer mode for undiluted breath samples, and a microcontroller for safety system responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrochemical sensors are used to measure ethanol concentration in air, then ethanol detection capability is provided, but sensor lifetime is limited to about three years
Solution Approach 1:
The patent replaces electrochemical sensors with infrared (IR) absorption sensors to detect ethanol. The IR sensor uses optical detection instead of electrochemical reactions, eliminating the limited lifetime issue of electrochemical sensors while maintaining high detection sensitivity through spectral absorption measurements at specific wavelengths.
Solution Approach 2:
The patent changes the detection parameter from electrochemical signal to infrared absorption signal. By measuring the absorption of infrared radiation at ethanol-specific wavelengths (around 9.4 micrometers), the system achieves both long-term reliability and high measurement precision without the degradation problems of electrochemical sensors.
2Measurement precision
If metal oxide film sensors are used for breath alcohol detection, then detection capability is provided, but sensitivity is insufficient for passive detection of diluted ethanol vapor in vehicle cabins
Solution Approach 1:
The patent replaces metal oxide film sensors with infrared absorption sensors that detect ethanol through optical absorption. This substitution enables passive detection of diluted ethanol vapor in vehicle cabins because IR sensors can detect trace concentrations without requiring concentrated breath samples or active driver participation.
Solution Approach 2:
The patent introduces an infrared absorption cell as an intermediary component that enhances the interaction between infrared radiation and ethanol molecules. This allows passive detection of diluted ethanol vapor by providing a controlled path length for IR absorption, thereby achieving the required sensitivity for vehicle cabin monitoring.
3Measurement precision
If infrared sensors with long path length are used for passive ethanol detection, then detection sensitivity is improved, but device size becomes impractical for on-board vehicle use
Solution Approach 1:
The patent implements a nested configuration where the infrared source, absorption cell, and detector are integrated in a compact arrangement. The absorption cell is positioned within the sensor housing, and the optical path is folded or concentrated to achieve effective path length while minimizing overall device volume for on-board vehicle installation.
Solution Approach 2:
The patent optimizes the infrared absorption cell geometry to achieve long effective path length in a compact volume. By using multi-pass optical configurations or increasing the optical path through folding mirrors, the system achieves high detection sensitivity without requiring a physically large sensor volume.
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 system provides a practical, sensitive, and specific means to detect ethanol levels in vehicle cabins, preventing vehicle startup if intoxication is detected, while minimizing driver inconvenience and improving safety by requiring safety measures such as seatbelt use and restricted vehicle performance.
Implementation Method 1
A practical sized on-board sensor is provided having a passive measurement mode and an active breathalyzer measurement mode
Implementation Method 2
A chemical vapor sensor system utilizing a vapor concentrator to amplify ethanol concentration for infrared detection
Implementation Method 3
enabling sub-ppm ethanol detection in vehicle cabin air
Data Source
AI summary
A method to avert an unlawfully intoxicated driver from operating a vehicle is provided. The method utilizes a passive ethanol vapor sensor to measure ethanol vapor concentration in air from a vehicle cabin and imposes a safety response when the passive ethanol vapor sensor detects that a sample of vehicle cabin air indicates that a vehicle occupant exceeds the legal blood alcohol concentration (BAC) for a motor vehicle driver. The ethanol vapor sensor may have a passive measurement mode and an active breathalyzer mode. Ethanol vapor in a vehicle cabin may be passively measured and if a predetermined ethanol level is measured, a countermeasure is invoked to improve safety. An active breathalyzer may be used as a countermeasure. The active breathalyzer can be imposed for a number of vehicle trips or for a predetermined time period.