Sweat Sensor With Adaptive Inlets for Low-Volume Measurement
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Solution Overview
Problem
Existing sweat sensors face challenges in accurately measuring sweat rate and biomarker concentrations due to variations in sweat production rates and gland density, leading to inaccurate correlations with blood levels, especially in sedentary individuals, and often require complex microfluidics that are ineffective for small sweat volumes.
Innovation Solution
A sweat sensor with adjustable inlet sizes and adaptive control mechanisms to match inlet openings to the current sweat rate and gland density, using processors to select appropriate inlet sizes based on measured parameters such as fluid flow, osmolality, and galvanic skin response, ensuring accurate biomarker analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed-size inlet is used in sweat sensors, then the device structure is simple, but the measurement accuracy deteriorates due to inability to adapt to varying sweat rates and gland density
Solution Approach 1:
The patent implements a dynamic inlet size adjustment mechanism where the sensor can change the opening size of inlets based on detected sweat rate and gland density. The system includes multiple inlets with different sizes and a control mechanism that dynamically selects and adjusts the appropriate inlet size during operation, transforming a static structure into an adaptive dynamic system that optimizes measurement accuracy for varying physiological conditions.
Solution Approach 2:
The patent changes the physical parameter of inlet size to adapt to different measurement conditions. By providing multiple inlets with different opening sizes and selecting the appropriate size based on sweat rate and gland density, the system modifies the geometric parameter of the inlet to optimize fluid flow characteristics and measurement accuracy for each specific condition.
2Reliability
If complex microfluidics are used to control sweat flow, then fluid management improves, but the device complexity increases and effectiveness for small sweat volumes decreases
Solution Approach 1:
The patent divides the fluid collection system into multiple independent inlets, each with a specific size optimized for certain sweat rate ranges. Instead of using a single complex microfluidic channel, the system segments the intake into multiple simpler inlet structures, reducing overall system complexity while improving reliability for different sweat production conditions.
Solution Approach 2:
The patent uses multiple copies of inlet structures with different sizes rather than a single complex microfluidic system. Each inlet is a simplified structure that can be independently activated, replacing the need for complex flow control mechanisms while maintaining effective fluid management for varying sweat volumes.
3Quantity of substance
If large inlet openings are used to collect sufficient sweat, then sweat volume collection improves, but measurement accuracy deteriorates due to accumulation effects and inability to handle small sweat volumes
Solution Approach 1:
The patent applies different inlet sizes (different local qualities) to match specific measurement conditions. For low sweat rates, smaller inlets are used to prevent accumulation effects and maintain accurate concentration measurements. For high sweat rates, larger inlets can be activated to collect sufficient volume. This local optimization of inlet size ensures both adequate volume collection and measurement precision for each condition.
Solution Approach 2:
The system dynamically adjusts which inlet size is active based on real-time detection of sweat rate and gland density. This dynamic switching between different inlet sizes allows the system to optimize both volume collection and measurement accuracy adaptively, rather than being constrained by a fixed inlet size that cannot satisfy both requirements simultaneously.
Data Source
AI summary
The present invention relates to devices and methods for uptaking and analyzing sweat from a skin of a user. In particular, it is proposed to provide a variability in the size of the sweat sensor inlets (102, 103, 104), which can be used for improving the determination of sweat parameters like for example determining the number of active sweat glands The variability in the size of the inlets (102, 103, 104) with which the sweat sensor (100) uptakes the sweat from the user's skin (111) can be achieved by having either plurality of inlets wherein at least some of them have different opening sizes and to use the differently sized inlets based in different situations. Alternatively, one or more inlets may have openings with variable cross-sectional area, like e.g. an adjustable diameter of their opening, and also a combination of these two alternatives is of course possible. A processor of the sweat sensor may use the information from either all or only the most appropriate sized inlets to determine a sweat parameter. In another alternative, the processor may adapt the inlet to the adjustable inlet opening to the most appropriate size to then determine a sweat parameter of interest.