Exploration on Solvatochromic Sensing Probe of Phenol Blue for L‐Lactic Acid Detection: Effective Strategy to Obtain Reliable Capacitive Sensor. (1st November 2022)

• Record Type: Journal Article
• Authors: Seo, Jungyoon; Hwang, Taehoon; Ko, Eun; Oh, Seungtaek; Tsogbayar, Dashdendev; Khan, Md Rajibur Rahaman; Cho, Jeong Ho; Park, Yeong Don; Lee, Hwa Sung
• Is Part Of: Advanced functional materials. Volume 33:Number 2(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-01
• Subjects: capacitive sensors -- L‐Lactic acid -- phenol blue -- sensing mediums -- solvatochromism; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202211253
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: This study systematically investigates a capacitive sensor applied with phenol blue (PhB)‐based sensing medium for detection of L‐lactic acid (LA), as a health monitoring indicator. PhB is a substance with solvatochromic effect, inducing the change in capacitance by exposure to polar molecules. However, the capacitive LA sensor with a flat‐structured PhB/polyvinylchloride (PVC) composite‐sensing medium is observed to have a problem in that sensing capacitance variation saturate quickly with increasing the LA solution concentration. This main cause can be analyzed that the interaction of proton from LA molecule with the lone pair electrons of the PhB molecule acts as a major factor on the sensing characteristics rather than the solvatochromic behavior of PhB molecule. Therefore, a strategy is adopted to introduce a porous structure to the PhB/PVC composite‐sensing medium to maximize the interaction of PhB with protons, which is implemented through solvent and non‐solvent exchange methods. Consequently, the sensitivity and linearity of the porous‐structured LA sensor are 2.99 pF mm −1 and 0.966 over LA concentrations ranging from 0 to 100 mm, respectively, which is a significant improvement over that of the flat‐structured one. Notably, the sensing performance remained unchanged even after a month of storage under normal ambient conditions. Abstract : Capacitive sensor applied with phenol blue‐based sensing medium is studied for detection of lactic acid used as a health monitoring indicator. The sensor demonstrates excellent sensing linearity or reliability over a wide range of lactic acid concentrations by applying a porous sensing medium, which are maintained even after 1 month of storage under normal ambient condition.