Microfabricated Neural Biosensors for Detection of Neurotransmitters, Biomarkers, and Small Molecules: Emerging Trends on Self‐Sustained Systems and Energy Harvesting

ABSTRACT The rapid evolution of neuroscience and bioelectronics has intensified the demand for highly sensitive, selective, and miniaturized biosensors capable of monitoring neurochemical activity with high spatial and temporal resolution. Among these, microfabricated thin‐film biosensors have emerged as a powerful platform for the detection of neurotransmitters and small molecules, owing to their ultrathin form factor, mechanical flexibility, and compatibility with implantable systems. Design strategies, material innovations, and functional surface chemistries are now central to enabling real‐time, in vivo monitoring with minimal tissue disruption and long‐term stability. This review covers the recent progress in microfabricated biosensors, focusing on electrochemical, optical, acoustic, and magnetic modalities for the detection of key neurotransmitters, such as dopamine, serotonin, glutamate, and acetylcholine, as well as biologically relevant small molecules, including glucose, lactate, hydrogen peroxide, and nitric oxide. The integration of thin‐film sensors for inflammatory and neurodegenerative disease biomarkers, such as cytokines (e.g., IL‐6, TNF‐α), amyloid‐β, and tau proteins, is also discussed. Key challenges such as drift, biofouling, and signal specificity are critically examined alongside emerging solutions. Finally, current and future applications ranging from fundamental neuroscience and brain‐machine interfaces to personalized medicine emphasize the potential of thin‐film biosensing technologies in real‐world biomedical scenarios.