Colorimetric Sweat Patch for Low-Volume Glucose Screening
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Solution Overview
Problem
Conventional glucose monitoring methods from sweat suffer from low sensitivity and specificity due to low glucose concentrations and limited sweat volume, necessitating improved non-invasive and cost-effective solutions for diabetes diagnosis.
Innovation Solution
A non-invasive transdermal sweat patch sensor with an adhesive layer, glucose sensing complex, and colorimetric indicator that changes color based on glucose concentration, allowing for qualitative detection of hyperglycemia using enzyme complexes like glucose oxidase and hydrophobic/hydrophilic regions to manage sweat flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional colorimetric patches are used to measure glucose from sweat, then non-invasive glucose monitoring is achieved, but the measurement precision is poor due to low glucose concentrations and low sweat volumes
Solution Approach 1:
The sensor is divided into distinct functional zones: a hydrophilic region for sweat absorption and a hydrophobic region for reagent containment. This segmentation allows the sweat to be directed and concentrated in specific areas, improving the effectiveness of the colorimetric reaction despite limited sweat volume.
Solution Approach 2:
Different regions of the sensor substrate have different properties: the hydrophilic region attracts and concentrates sweat, while the hydrophobic region prevents unwanted fluid spread and maintains reagent integrity. This local differentiation of material properties enables precise control over fluid behavior and enhances measurement accuracy.
2Reliability
If transdermal sweat patch sensors are used for non-invasive glucose monitoring, then individual compliance is enhanced and disease transmission risk is reduced, but the sensitivity and specificity remain insufficient for reliable diabetes diagnosis
Solution Approach 1:
The sensor employs colorimetric indicators that change color in response to glucose concentration. This visual color change provides an intuitive, easy-to-interpret result that maintains operational simplicity while significantly improving diagnostic reliability through enhanced sensitivity and specificity.
Solution Approach 2:
Enzyme complexes serve as intermediaries between the glucose in sweat and the colorimetric indicator. These enzymes specifically catalyze reactions with glucose, providing high selectivity and sensitivity that enhances diagnostic reliability while maintaining the simplicity of the non-invasive patch application.
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
Enhances individual compliance and reduces disease transmission risk by providing a low-cost, easy-to-use system for detecting glucose levels in sweat, suitable for non-medical personnel, with enhanced sensitivity and specificity for early diabetes diagnosis.
Implementation Method 1
The glucose sensing complex comprises an enzyme complex that reacts with glucose, for example glucose oxidase, glucose dehydrogenase or a hexokinase/glucose-6-phosphate complex
Implementation Method 2
a colorimetric indicator (e.g. a chromogen) in operable contact with the glucose sensing complex that changes color following reaction of glucose with the enzyme complex
Implementation Method 3
an adhesive layer adapted to bond to skin of an individual, wherein the adhesive layer comprises an opening adapted to allow sweat to migrate from the skin of the individual to a glucose sensing complex
Implementation Method 4
a substrate layer disposed over the adhesive layer and comprising a glucose sensing complex, wherein substrate layer accumulates sweat that migrates from the skin of the individual into the sensor
Implementation Method 5
hydrophobic/hydrophilic regions to manage sweat flow
Implementation Method 6
hydrophobic/hydrophilic regions to manage sweat flow
Data Source
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AI summary
Described here are patches and methods for measuring glucose in sweat (and tears and the like). In general, the patches comprise an adhesive layer adapted to bond to skin of an individual, a substrate layer disposed over the adhesive layer and comprising a glucose sensing complex including a chromogen that changes color in the presence of certain concentrations of glucose, and a cover. In typical embodiments, the substrate layer has elements formed to direct and accumulate sweat that migrates from the skin of the individual to the glucose sensing complex. Methods of using the invention can comprise cleaning the skin surface, collecting sweat in a patch comprising this microfluidic constellation of elements, and observing concentrations of glucose collected in the sweat, for example either visually, or by using a smartphone or other computer processing device.