Cross-Linked Sensor Membrane for Stable Analyte Diffusion Control

The patent employs a composite membrane structure consisting of a hydrogel layer combined with a diffusion barrier layer made from zwitterionic polymer. This composite approach allows the hydrogel to provide biocompatibility and moisture retention while the zwitterionic polymer layer provides selective diffusion control. The synergistic combination resolves the contradiction by maintaining both measurement specificity through the diffusion barrier and long-term stability through the biocompatible hydrogel base layer, enabling stable in vivo measurements over extended periods.

The patent utilizes zwitterionic polymers with specific amino acid side chains that exhibit parameter changes in response to pH variations. These polymers undergo conformational changes or solubility transitions at different pH levels, allowing the membrane to dynamically adjust its permeability and exclusion properties. This parameter-based adaptation enables the membrane to maintain optimal performance by reducing interference from body fluid components while preserving necessary analyte diffusion, thereby resolving the contradiction between interference reduction and performance stability.

The patent implements a multi-layer membrane structure where different regions perform different functions: the hydrogel layer provides biocompatibility and mechanical stability, while the zwitterionic polymer diffusion barrier layer provides selective analyte transport. This local differentiation of functional properties allows the sensor to achieve accurate analyte measurements through the diffusion barrier while the hydrogel layer maintains sensor durability and biocompatibility during prolonged in vivo operation, resolving the contradiction between measurement accuracy and sensor durability.