PPy/PMMA/PEG Composite Breath Sensor for Acetone Detection
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Solution Overview
Problem
Current breath VOC sensors face challenges in achieving high sensitivity and selectivity due to low concentrations of biomarkers in exhaled breath and interference from water vapor, leading to poor performance in detecting acetone for non-invasive diabetes monitoring.
Innovation Solution
A PPy/PMMA/PEG composite material is developed, with two PPy/PMMA surfaces that respond differently to gases, allowing for separate measurement of resistances to enhance selectivity in detecting acetone in human breath.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional breath VOC sensors are used, then they can detect volatile organic compounds, but they exhibit high sensitivity to water vapor which interferes with target VOC detection
Solution Approach 1:
The sensing layer is divided into multiple distinct layers (first sensing layer and second sensing layer) with different material compositions. Each layer responds differently to water vapor and target VOCs, allowing the system to differentiate between water vapor interference and actual analyte signals through differential measurement
Solution Approach 2:
Different regions of the sensor (different sensing layers) are given different material properties - one layer is more sensitive to water vapor while another is more sensitive to target VOCs. This local differentiation enables selective detection by comparing responses from regions with different sensitivities
2Measurement precision
If sensor sensitivity is increased to detect low concentration VOC biomarkers, then detection capability improves, but selectivity against water vapor interference becomes more difficult to maintain
Solution Approach 1:
The sensor uses multiple sensing layers with progressively optimized compositions. The first layer provides baseline detection, while subsequent layers are engineered to enhance sensitivity to specific VOCs while maintaining water vapor rejection through differential response measurement
Solution Approach 2:
The sensing layers utilize composite materials combining conductive polymers (PPy) with different polymer matrices (PMMA, PVDF-HFP, etc.). These composite materials provide both high sensitivity to low-concentration VOCs and differential response to water vapor, enabling simultaneous achievement of sensitivity and selectivity
3Ease of operation
If conducting polymers are used to detect acetone at room temperature, then detection is achieved, but the sensors suffer from high sensitivity to moisture and performance degradation over time
Solution Approach 1:
The sensor structure segments the conducting polymer into multiple thin layers separated by different polymer matrices. This segmentation reduces the overall impact of moisture on any single conducting polymer layer while maintaining room temperature operation capability
Solution Approach 2:
Different polymer matrices (PMMA, PVDF-HFP, etc.) are introduced as intermediary layers between the conducting polymer and the environment. These intermediary layers modulate the interaction between moisture and the conducting polymer, reducing moisture sensitivity while preserving acetone detection capability and improving long-term stability
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 PPy/PMMA/PEG composite sensor demonstrates improved selectivity and stability, effectively detecting acetone at low concentrations with reduced interference from water vapor, providing a non-invasive method for monitoring blood glucose levels.
Implementation Method 1
Pristine CNTs do not efficiently adsorb VOCs, but functionalization improves their performance for sensor applications. Functionalization of CNTs with carboxylic groups and defect sites on CNTs created through acid sonication have shown improved adsorption of organic compounds
Implementation Method 2
PVDF-HFP is also known to swell when exposed to acetone. In CNT polymer composites, the swelling or contraction of polymers changes the separation between the conducting CNT material, which alters the resistance
Implementation Method 3
In the sensor of the present disclosure, the changes in the resistances on the two surfaces and across the two layers are measured separately
Data Source
AI summary
A biomedical sensor and sensor system for analysis of breath are disclosed. The biomedical sensor can include two layers arranged to swell or contract in a plane perpendicular to an axial direction while being restricted from swelling in the axial direction. The biomedical sensor includes resistance connections to allow measurement of the resistance of each layer and a combined resistance of both layers. The sensor system can include one, two, or three or more sensors, each having a pair of electrodes separated by a gap and one or more layers of composite material located within the gap. the sensor system includes resistance circuits configured to measure changes in resistance between the electrodes. A polypyrrole/polymethyl methacrylate/polyethylene glycol composite material and method of making the same are disclosed.