Polymer Microneedle Array with Vias for Interstitial Fluid Detection
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Solution Overview
Problem
Current biosensors for detecting physiological fluids, such as sweat or interstitial fluid, face challenges including the need for substantial physical activity to generate adequate samples, pain, inconvenience, and unsuitability for mass-fabrication, particularly due to complex fabrication methods and designs that are not easily scalable.
Innovation Solution
A sensor device featuring a polymer substrate with microneedles and vias that form apertures, coated with electrically conductive material layers, allowing for easier fabrication and mechanical stability, enabling in vivo detection of interstitial fluids and other applications like food or drug testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If hollow microneedles are used to probe interstitial fluid, then fluid access is improved, but mechanical stability of the substrate deteriorates and fabrication complexity increases
Solution Approach 1:
The device segments the fluid access function from the structural support function by using separate components: solid microneedles for mechanical stability and adjacent vias with apertures for fluid access. This segmentation allows each component to optimize its respective function without compromising the other.
Solution Approach 2:
The vias act as intermediary structures that facilitate fluid access without requiring hollow microneedles. The apertures in the vias provide a pathway for interstitial fluid to reach the electrodes, serving as a mediator between the external environment and the sensing elements.
2Manufacturing precision
If complex pre-patterning of electrode materials is used, then electrode precision is improved, but manufacturing scalability deteriorates
Solution Approach 1:
The electrode materials are pre-patterned on a sacrificial layer before the microneedle structure is formed. This preliminary action allows precise electrode positioning to be established early in the fabrication process, simplifying subsequent steps and enabling better scalability.
Solution Approach 2:
The fabrication process uses a mold that copies the microneedle pattern onto the polymer substrate. This copying approach, combined with the pre-patterned electrodes on the sacrificial layer, enables precise replication of the device structure while maintaining manufacturing scalability through mold reuse.
3Stability of the object's composition
If solid microneedles with adjacent vias are used, then mechanical stability is improved, but electrode coating complexity increases
Solution Approach 1:
The fabrication process merges the formation of microneedles, vias, and electrode coatings into a single integrated process. The sacrificial layer technique allows all three features to be created simultaneously in one fabrication sequence, reducing overall process complexity despite the multi-component structure.
Solution Approach 2:
The sacrificial layer automatically defines the electrode boundaries and positions during the coating process. As the conductive material is deposited, it naturally conforms to the regions defined by the sacrificial layer's pattern, eliminating the need for complex masking or alignment steps.
4Ease of operation
If sweat sensing is used, then non-invasive monitoring is improved, but sample volume generation deteriorates
Solution Approach 1:
The device extracts interstitial fluid directly from beneath the skin through the microneedle array, bypassing the need to rely on sweat production. This extraction approach provides adequate sample volume without requiring substantial physical activity or sweat-inducing interventions.
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 design simplifies the fabrication process, enhances mechanical stability, and allows for efficient detection of physiological fluids, making the sensor devices more user-friendly and suitable for extended wear, while being scalable for mass production.
Implementation Method 1
Each electrode comprises an electrically conductive material layer that coats a region of the substrate, so as to coat at least some of the microneedles and neighboring portions of said base surface
Data Source
AI summary
A sensor device, such as a biosensor, may comprise a polymer substrate, which is structured so as to form sets of microneedles and respective vias. The microneedles extend, each, from a base surface of the substrate. Each of the vias extends through a thickness of the substrate, thereby forming a corresponding set of apertures on the base surface. Each of the apertures is adjacent to a respective one of the microneedles. The device further may comprise two or more electrodes, these including a sensing electrode and a reference electrode. Each electrode may comprise an electrically conductive material layer that coats a region of the substrate, so as to coat at least some of the microneedles and neighboring portions of said base surface. Related devices, apparatuses, and methods of fabrication and use of such devices may be provided.