Biofouling and Foreign Body Response (FBR) Mitigation

The longevity and accuracy of Continuous Glucose Monitors (CGMs) are strictly limited by Biofouling and the Foreign Body Response (FBR). Upon insertion, the body coats the sensor in proteins, followed by immune cell attack (inflammation) and collagen encapsulation (fibrosis). This creates a barrier that delays glucose diffusion and consumes local oxygen, leading to signal drift and the "first-day dip" in accuracy.

Key Mitigation Strategies:

Passive Coatings: Use of Zwitterionic polymers and Hydrogels (e.g., PEG, phosphorylcholine) to create a hydration shell that resists protein adhesion.
Active Release: Incorporation of Nitric Oxide (NO) donors to mimic blood vessels and Dexamethasone elution to suppress local inflammation.
Membrane Engineering: Use of Nafion and mass-transport limiting layers to block interferents while regulating glucose/oxygen flux.

Despite these innovations, the "run-in" period and eventual fibrous encapsulation remain the primary technical hurdles preventing long-term (30+ day) implantable sensors.

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Biofouling and Foreign Body Response (FBR) Mitigation in Continuous Glucose Monitors

Introduction

The longevity and accuracy of Continuous Glucose Monitors (CGMs) are limited by two major factors: Biofouling and the Foreign Body Response (FBR) [1]. Upon insertion, the body's natural response involves coating the sensor with proteins, followed by an immune cell attack (inflammation) and collagen encapsulation (fibrosis) [2]. This creates a barrier that delays glucose diffusion and consumes local oxygen, leading to signal drift and the "first-day dip" in accuracy [3].

Key Mitigation Strategies

Several strategies have been developed to mitigate the effects of biofouling and FBR:

Passive Coatings: The use of Zwitterionic polymers and Hydrogels (e.g., PEG, phosphorylcholine) to create a hydration shell that resists protein adhesion [4].
Active Release: Incorporation of Nitric Oxide (NO) donors to mimic blood vessels and Dexamethasone elution to suppress local inflammation [5].
Membrane Engineering: Use of Nafion and mass-transport limiting layers to block interferents while regulating glucose/oxygen flux [6].

Challenges and Future Directions

Despite these innovations, the "run-in" period and eventual fibrous encapsulation remain the primary technical hurdles preventing long-term (30+ day) implantable sensors [7]. Further research is needed to overcome these challenges and develop more effective mitigation strategies.