Microneedle Affinity Sensor Diffusion Lag Reduction
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Solution Overview
Problem
Affinity-based biosensors face challenges in ex-vivo sensing of invasive biofluids like interstitial fluid due to lag times and loss of fluidic contact, which are not addressed by existing enzymatic sensor technologies, especially when detecting analytes at low concentrations.
Innovation Solution
A continuous ex-vivo affinity-based sensing system with a plurality of probes specific to the analyte, utilizing a diffusion pathway and microneedles to maintain fluidic communication with the dermis, reducing diffusion lag times and ensuring accurate analyte concentration measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If affinity-based sensors are used for ex-vivo sensing of invasive biofluids, then detection precision for low concentration analytes is improved, but diffusion lag time increases
Solution Approach 1:
The device segments the diffusion pathway into multiple parallel channels through the microneedle array, allowing analyte transport to occur simultaneously through multiple pathways. This segmentation reduces the effective diffusion distance and lag time while maintaining the sensitivity of affinity-based sensors for low concentration analytes.
Solution Approach 2:
The microneedles are pre-configured with affinity-based sensor elements before insertion into the skin. This preliminary preparation ensures that as soon as the microneedles penetrate the epidermis and access interstitial fluid, the sensors are immediately positioned to detect analytes, minimizing the time required for analyte diffusion and sensor equilibration.
2Ease of operation
If microneedle array is used to access interstitial fluid, then ease of operation is improved, but reliability of fluidic contact is worsened
Solution Approach 1:
The device uses an array of multiple microneedles rather than a single needle, segmenting the fluidic access function. This segmentation provides redundancy where if one or more microneedles fail to maintain fluidic contact due to skin movement or improper insertion, other microneedles in the array can still provide reliable access to interstitial fluid.
Solution Approach 2:
The microneedles are designed with specific geometric parameters including optimized length, diameter, and spacing to balance penetration capability with fluidic contact reliability. The parameters are tuned to ensure adequate penetration through the epidermis while maintaining stable contact with the dermal layer where interstitial fluid is accessed.
3Adaptability or versatility
If affinity-based sensors are used instead of enzymatic sensors, then adaptability to different analytes is improved, but device complexity increases
Solution Approach 1:
The device employs a universal platform architecture where the microneedle array and fluidic pathway structure remain constant, while only the affinity sensor elements need to be changed to detect different analytes. This universal design reduces overall device complexity compared to designing entirely different systems for each analyte type.
Solution Approach 2:
The invention uses replicated sensor elements across multiple microneedles in the array. Each microneedle contains identical or similar affinity sensor copies that can detect the same analyte, providing redundancy and simplifying the design by using repeated modular units rather than complex unique structures.
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
The system effectively reduces diffusion lag times and maintains fluidic contact with the dermis, enabling accurate and continuous monitoring of analytes in invasive biofluids, even with low concentrations, by using affinity-based sensors in conjunction with microneedles and a diffusion pathway.
Implementation Method 1
the analyte is coupled from interstitial fluid to the sensor by diffusion to the sensor
Data Source
AI summary
Described are sensing devices and methods that continuously sense at least one analyte in an invasive biofluid are described. The devices include at least one affinity-based sensor with a plurality of probes. The probes include a binding that is specific to the at least one analyte. The device further includes at least one diffusion pathway between the affinity-based sensor and the source of the invasive biofluid.