Wearable Sweat Sensor Using Hydrogel Electrodes
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Solution Overview
Problem
Existing sweat sensing devices face challenges in incorporating ion-selective electrodes (ISEs) and reference electrodes into wearable configurations that are robust, resistant to drift, delamination, and abrasion, while maintaining sensitivity and specificity for monitoring sweat electrolyte concentrations and trends under demanding conditions.
Innovation Solution
The use of suspension-based, hydrogel-based, and thixotropic compound-based ion-selective electrodes and reference electrodes in a wearable sweat sensing device, which includes a cassette design with microfluidic channels and ion exchange ports, allowing for accurate measurement of sweat electrolyte concentrations, trends, and ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ion-selective electrodes and reference electrodes are moved from laboratory to wearable sweat sensor configurations, then the device becomes portable and wearable, but the sensors become prone to drift, delamination, and abrasion
Solution Approach 1:
The patent applies flexible substrate technology to support the ion-selective electrodes and reference electrodes, allowing the sensors to conform to skin surfaces while maintaining electrical properties. This flexible substrate approach prevents delamination by creating a bonded interface between the electrode layers and the supporting structure, while also protecting against abrasion through the use of durable flexible materials.
Solution Approach 2:
The patent employs composite material structures combining conductive materials, protective coatings, and adhesive layers to create robust electrode assemblies. These composite structures provide both the electrical functionality needed for sweat electrolyte detection and the mechanical durability required to resist drift, delamination, and abrasion in wearable applications.
2Volume of moving object
If ion-selective electrodes are reduced in size for wearable devices, then the device becomes compact and wearable, but the sensors experience increased drift and reduced stability
Solution Approach 1:
The patent uses flexible thin film substrates to support miniaturized electrodes, maintaining structural integrity despite reduced size. The thin film structure provides mechanical support that prevents drift while keeping the overall sensor volume small enough for wearable applications.
Solution Approach 2:
The patent implements nested electrode structures where multiple electrode layers are stacked or integrated within a compact volume. This nesting approach allows multiple sensing functions to coexist in a small footprint while maintaining the stability and performance characteristics of larger electrodes through proper layer integration and support structures.
3Ease of operation
If electrodes are deposited on flexible substrates for wearable use, then the device becomes wearable and comfortable, but the electrodes may delaminate from the substrate
Solution Approach 1:
The patent employs flexible substrate technology with optimized electrode deposition processes that create strong adhesive bonding between the electrode materials and the substrate. The flexible substrate is designed with appropriate mechanical properties and surface characteristics that prevent delamination while maintaining wearability and comfort.
Solution Approach 2:
The patent uses composite material structures incorporating adhesive layers, conductive materials, and protective coatings in a multi-layer configuration. These composite structures provide both the flexibility needed for wearable applications and the bonding strength required to prevent delamination through proper material selection and layer integration.
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
This configuration provides reliable and accurate monitoring of sweat electrolyte loss and trends, improving safety and performance in extreme conditions by preventing drift and delamination, and extending the operational lifespan of the sensors.
Implementation Method 1
use of suspension-based, i.e., hydrogel-based and thixotropic compound-based, ion-selective electrodes
Implementation Method 2
use of suspension-based, i.e., hydrogel-based and thixotropic compound-based, ion-selective electrodes
Implementation Method 3
ion-selective electrodes and reference electrodes in a wearable sweat sensing device, which includes a cassette design with microfluidic channels and ion exchange ports
Data Source
AI summary
Embodiments of the disclosed invention provide devices and methods to incorporate suspension-based, i.e., hydrogel-based and thixotropic compound-based, ion-selective electrodes and reference electrodes into a wearable sweat sensing device. Embodiments of this device are configured to monitor sweat electrolyte concentrations, trends, and ratios under demanding use conditions. The accompanying method includes use of the disclosed device to track fluid and electrolyte gain and loss in order to produce an electrolyte estimate, such as a sweat electrolyte concentration, a sweat electrolyte concentration trend, a sweat rate, or a concentration ratio between a plurality of electrolytes.