Chitosan Films for Micro- and Nanosensors: A Systematic Evidence Map and Curated Critical Review of Functional Roles, Transduction, and Device Readiness

Chitosan films and interfaces are increasingly used in micro- and nanosensors, yet the contribution of chitosan is often obscured by hybrid architectures. This systematic evidence map and curated critical review evaluated fabrication routes, micro-/nanoscale structures, functional roles, transduction mechanisms, analytical validation, reporting completeness, and device readiness. Searches of Scopus, PubMed, and IEEE Xplore yielded 15,058 database records. After deduplication, 8832 unique database-derived records underwent rule-based evidence mapping: Core Primary Candidate (n = 2617), Contextual Evidence (n = 3096), Manual Review (n = 1318), and Exclude (n = 1801). A separately assembled curated full-text subset contained 73 unique records, including 32 unique additions to the database-derived corpus. Full-text adjudication of this curated subset identified 26 studies meeting the strict CORE criteria, 17 boundary experimental studies, eight contextual experimental/material studies, 18 review/contextual sources, two methodological sources, and two exclusions. The detailed critical synthesis and reporting-completeness assessment were restricted to the 26 CORE studies assessed within this curated subset and should not be interpreted as an exhaustive synthesis of all 2617 automated candidate records. Within the 26-study curated CORE subset, reporting completeness was highest for response definition (26/26, 100.0%) and functional-role reporting (25/26, 96.2%), but lower for chitosan identity and selectivity/interference (17/26, 65.4% each) and stability (13/26, 50.0%). The assessed studies indicate that strong analytical performance in hybrid architectures generally reflected the complete sensing system rather than chitosan alone. The proposed role–structure–transduction–evidence framework supports clearer component attribution, within-platform comparison, validation, and device-readiness assessment within the evidence set examined.