Wearable Device Ambient Skin Gas Sampling for False Positive Reduction
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Solution Overview
Problem
Wearable devices for transdermal alcohol detection often suffer from interference from airborne substances, leading to delayed detection of intoxication events, which limits their effectiveness in preventing violent behavior.
Innovation Solution
A wearable device with a sensing arrangement that collects gas samples from both the ambient environment and the skin region, using flow-control devices and a controller to differentiate between ambient and skin-derived substances, allowing for timely detection of ingested substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the device monitors air proximal to the subject's skin to detect intoxicating substances, then detection capability is provided, but false positives occur due to airborne interferants
Solution Approach 1:
The device divides the air sampling process into two distinct segments: ambient air sampling and skin-proximal air sampling. By separating these sampling sources and comparing the results, the device can distinguish between atmospheric interferants and actual transdermal alcohol, thereby improving measurement precision while reducing false positives.
2Reliability
If algorithmic means are used to differentiate intoxication events based on ethanol passage time, then false positives are reduced, but detection delay increases
Solution Approach 1:
The device performs preliminary ambient air sampling before skin-proximal sampling to establish a baseline of atmospheric alcohol levels. This preliminary action allows the device to immediately differentiate between ambient and transdermal sources without requiring time-based algorithms, thus reducing detection delay while maintaining reliability.
3Device complexity
If the device uses a single sensing arrangement, then device complexity is minimized, but the ability to differentiate between ambient and skin-derived substances is reduced
Solution Approach 1:
The sensing arrangement is designed to perform multiple functions: it can sample ambient air, sample skin-proximal air, and compare the results to differentiate between atmospheric and transdermal substances. This multi-functionality approach maintains relatively simple device architecture while achieving precise substance differentiation.
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 effectively differentiates between ambient and skin-derived substances, reducing false positives and enabling timely detection of intoxication, thereby improving the device's usefulness in preventing violent behavior.
Implementation Method 1
each one of the first flow-control device and the second flow-control device is operable between a first state and a second state based on a pressure difference between an inner side and an outer side of the flow-control device
Implementation Method 2
Transdermal alcohol detection can be used as a means of monitoring the alcohol intake of a subject
Data Source
AI summary
There is presented a wearable device (200) and corresponding system and method for sensing a substance ingested by a subject, for instance an intoxicating substance. The wearable device has a sensing arrangement extending between a first port (205a) and a second port (205b). The sensing arrangement includes two chambers, a pump and two flow-control devices. The first chamber is adapted to collect gas from a skin region of the subject. The second chamber has a sensor to sense the substance. The first flow-control device is provided at the first port (205a) and the second flow-control device is provided at the second port (205b). A controller is provided to control the pump and the sensor. The controller is operable in a first phase to sense a first gas sample from ambient environment, and a second phase to sense a second gas sample from a skin region of the subject.