Microneedle Biosensor Interfaces with Isolated Posterior Electrical Routing
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Solution Overview
Problem
Current chip-scale packaging techniques for microneedle-based electrochemical biosensors, such as wire-bonding and flip-chip methods, obstruct the microneedle surface and prevent reliable penetration due to increased standoff or misorientation, making it difficult to establish a spatially-defined electrical conduit between the microneedle and the substrate.
Innovation Solution
Implementing insulating barriers to circumscribe and electrically isolate microneedles from the substrate, allowing for a spatially-defined conductive conduit from the microneedle tip to the substrate's posterior surface, enabling unobstructed insertion and electrical probing without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire-bonding or flip-chip methods are used to establish electrical contact with the microneedle, then electrical interface is achieved, but the microneedle surface is obstructed and penetration of the stratum corneum is prevented
Solution Approach 1:
The substrate is divided into two separate surfaces: the anterior surface containing the microneedle array for skin penetration, and the posterior surface containing the electrical interface for wire-bonding or flip-chip attachment. This spatial segmentation allows both functions to operate independently without interference.
Solution Approach 2:
The electrical interface is moved from the same plane as the microneedles to the opposite side of the substrate, transitioning the problem from a two-dimensional surface conflict to a three-dimensional spatial arrangement. This allows the microneedles to extend forward while electrical contacts are established on the rear surface.
2Reliability
If conductive traces are routed on the same surface as the microneedles, then electrical communication is established, but standoff is increased and microneedle insertion is interfered with
Solution Approach 1:
Conductive traces and electrical pads are relocated from the anterior surface to the posterior surface of the substrate, utilizing the third dimension (substrate thickness) to separate the electrical routing path from the microneedle insertion path. This eliminates the need for long surface traces and reduces standoff distance.
3Ease of manufacture
If the substrate is flipped to facilitate electrical interface, then wire-bonding or flip-chip attachment is enabled, but the microneedle structure is oriented away from the application site
Solution Approach 1:
The substrate functions are segmented into distinct surfaces: the anterior surface maintains permanent orientation toward the skin application site with microneedles extending forward, while the posterior surface serves as the manufacturing interface for packaging operations. This allows the device to be packaged in the flipped state while remaining oriented correctly during use.
Solution Approach 2:
The conventional approach of routing electrical contacts on the same side as the active elements is inverted. Instead, electrical contacts are placed on the opposite side of the substrate, allowing the substrate to be flipped during packaging while the active microneedle surface maintains its correct orientation toward the application site.
Data Source
AI summary
A method for circumscribing an insulating barrier region around a singular conductive microneedle structure or plurality of conductive microneedle structures adhered to a fixed substrate for the purpose of spatially defining a conduit for the routing of an electrical signal from the surface of said microneedle or microneedles to the posterior surface of the substrate is disclosed herein. A microneedle-based electrochemical biosensors structure comprises a substrate, a microneedle biosensor, a primary electrically conductive element, a secondary electrically conductive element and an electrically insulative annular barrier.