Flexible Transdermal Platform for Continuous Interstitial Fluid Sampling
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Solution Overview
Problem
Existing transdermal sampling methods are invasive and non-continuous due to the need for large holes in the skin, causing irritation and limited durability, and require inflexible silicon substrates that are prone to lateral motion issues.
Innovation Solution
A flexible transdermal platform with electro-conducting enzyme anchor layers and resistive elements that disrupt the stratum corneum with controlled voltage pulses to allow continuous sampling of interstitial fluid without damaging living cells, using a compliant substrate for stable contact with the skin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large holes are made in the stratum corneum to sample interstitial fluid, then fluid sampling is achieved, but local irritation and inflammation occur limiting duration to a few hours or days
Solution Approach 1:
The patent uses a flexible polymer substrate with thin film structure that conforms to the skin surface, creating minimal mechanical disruption compared to rigid devices with large holes. The flexible nature allows close surface contact without causing significant irritation or inflammation.
Solution Approach 2:
The patent changes the physical parameters of the sampling interface by using a flexible polymer material with specific mechanical properties that differ from traditional rigid substrates. This allows the device to adapt to skin movement and maintain contact without causing irritation, enabling continuous sampling for extended periods.
2Manufacturing precision
If inflexible silicon substrates are used for transdermal sampling, then manufacturing precision is achieved, but lateral motion between detector and holes occurs rendering device inoperative
Solution Approach 1:
The patent replaces inflexible silicon substrates with a flexible polymer substrate that can conform to the skin surface and move with it. This eliminates lateral motion between the detector and sampling holes while maintaining manufacturing precision through appropriate fabrication techniques for flexible substrates.
Solution Approach 2:
The patent transitions from a static, rigid substrate to a dynamic flexible substrate that can adapt its shape and position on the skin surface. This allows the device to maintain stable contact and proper alignment of sampling holes with detectors even during skin movement.
3Reliability
If heat or laser ablation is used to create holes through stratum corneum, then fluid access is achieved, but tissue damage and inflammation result
Solution Approach 1:
The patent extracts the harmful thermal and mechanical effects from the sampling process by avoiding heat or laser ablation entirely. Instead, it uses a flexible substrate that creates minimal disruption to the stratum corneum, allowing fluid access without tissue damage or inflammation.
Solution Approach 2:
The patent converts the traditional approach of using aggressive methods (heat, laser, needles) to access fluid into a gentle flexible contact method. The flexibility itself becomes the beneficial feature that allows fluid sampling without the harmful effects of traditional ablation techniques.
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
Enables minimally invasive, continuous real-time sampling and analysis of interstitial fluid, maintaining equilibrium with underlying tissues for extended periods without irritation, and allows for the detection of bio-molecules and controlled delivery of chemicals.
Implementation Method 1
The heat and voltage drop between the sample electrodes does not remove the dead cells of the stratum corneum but severs connections between them
Implementation Method 2
creating capillary openings that serve to wick the interstitial fluid from the viable epidermis up to sample electrodes
Implementation Method 3
the electro-conducting layer is electrochemically activated with an anchored enzyme that modifies a target bio-molecule
Implementation Method 4
the enzyme may be, but is not limited to, glucose oxidase
Data Source
AI summary
A system and method for transdermal sampling wherein at least one pair of sample electrodes is adapted to provide voltage pulses capable of creating capillary openings in a subject's stratum corneum. Methods for using a transdermal sampling system by creating capillary openings in a subject's stratum corneum via the application of a series of voltage pulses to the stratum corneum and contacting at least a portion of at least one of the sample electrodes with interstitial fluid from the capillary openings are also presented.