Vertical-Flow Sweat Sensor Using Porous Electrode Stacking
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Solution Overview
Problem
Existing chemical and biomarker sensing technologies face challenges in integrating finely patterned interdigitated electrodes with low-cost printed electronics and standard circuit board technology, and they often struggle with low analyte diffusion and transport, especially at low concentrations, due to complex fabrication and small fluid volumes.
Innovation Solution
The use of porous substrates and electrodes with easy-to-fabricate spacer materials allows for close electrode spacing and efficient analyte transport, enabling high-performance sensing with reduced diffusive path length and minimal fluid volume, suitable for integration in wearable and microfluidic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interdigitated electrodes are closely spaced to maximize sensing performance, then measurement precision is improved, but device complexity increases due to fabrication challenges
Solution Approach 1:
The patent transitions from horizontal electrode spacing to vertical stacking, allowing electrodes to be closely spaced in the vertical dimension while maintaining larger horizontal pitch compatible with standard PCB fabrication. Multiple electrode pairs are stacked vertically with spacers, achieving high sensing performance without complex horizontal patterning.
Solution Approach 2:
The patent uses thin substrate layers and flexible spacer structures to enable vertical stacking of electrodes. The thin-film approach allows multiple electrode pairs to be integrated in the vertical direction while maintaining compatibility with standard manufacturing processes.
2Ease of manufacture
If horizontal flow configuration is used with porous substrates, then ease of manufacture is improved, but analyte transport to probes is reduced
Solution Approach 1:
The patent changes analyte transport from horizontal flow to vertical flow through the stacked electrode structure. Analytes are delivered vertically through the porous substrate and spacer regions directly to the electrode surfaces, reducing diffusion path length and improving transport efficiency while maintaining manufacturing simplicity.
3Productivity
If vertical stacking with spacers is implemented, then analyte transport efficiency is improved, but device complexity increases
Solution Approach 1:
The patent introduces spacers as intermediary elements that simultaneously perform multiple functions: maintaining vertical electrode spacing, providing analyte transport pathways, and enabling structural integration. The spacers simplify the overall design by combining support and flow functions in a single component.
4Volume of moving object
If small fluid volumes are used, then device miniaturization is improved, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent achieves miniaturization by stacking electrodes vertically rather than expanding horizontally. This vertical integration reduces the overall device footprint and fluid volume requirements while maintaining large electrode surface areas through multiple stacked pairs, preserving signal-to-noise ratio despite reduced fluid volumes.
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 approach enhances signal-to-noise ratios, stabilizes sensors quickly, and facilitates easy integration with low-cost manufacturing, achieving effective detection of analytes at low concentrations with reduced fluid requirements and simplified device design.
Implementation Method 1
the low amount of diffusion or transport of analytes in flow 105 down to the probes 190
Implementation Method 2
by advective flow in a fluid or gas
Implementation Method 3
Many of these techniques measure impedance or charge transfer
Implementation Method 4
measure impedance or charge transfer
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
An electronic sweat sensor (300) includes a plurality of porous substrates (310, 312), each porous substrate (310, 312) having an electrically conductive surface (320, 322). The porous substrates (310, 312) have a generally planar surface. The generally planar surface may be adapted to be positioned on skin (12) generally coplanar with the skin. The electronic sweat sensor (300) further includes a porous spacer (315) layer defining a gap between at least two of the porous substrates (310, 312). When an analyte flow (305), which may be from skin (12), is moving perpendicular to the planar surface and through at least one of the porous substrates (310, 312), at least one of the conductive surfaces (320, 322) provides an electrical response to the presence of the analyte flow (305).