Analytical Validation of Low-Cost Optical Sensors for Freshwater Monitoring: A Scoping Review of Current Gaps and a Proposed Framework. - Cirrone, Riccardo Gaetano; Boldrini, Amedeo; Polvani, Alessio; Liu, Xinyu; Vesprini, Francesco; Galgani, Luisa; Witter, Anna; González, Óscar; Tamasi, Gabriella; Loiselle, Steven Arthur (Sensors (14248220), 2026)