To the best of our knowledge, very few works have been done on the continuous real-time monitoring of proton exchange membrane fuel cells (PEMFCs) membrane degradation based on fluoride-specific electrochemical microsensors. PEMFCs are eco-smart energy sources for efficient transportation but experience variable degradation rates that wear the membrane electrode assembly (MEA), a critical component of the fuel cell's functionality. Current market options lack specific diagnostics and legitimate indication of when exactly the membrane must be replaced. As such, this work focused on manufacturing a sensor for measuring MEA degradation in real-time by selectively monitoring fluoride concentration in effluent water, a signature PEMFCs degradation status, through functionalized LaF3:(Au nanoparticle) thin films (~60 nm). The sensor’s exceptional specificity/sensitivity has been achieved in real-time at a sub 10 ppb level, optimized through spin-coating deposition and post-annealing process. Its multimodal readout has been achieved and studied through the characterizations of open circuit potential, cyclic voltammetry, chronoamperometry and differential pulse voltammetry, revealing a consistent linear decrease of 15.7 mA/cm2 at 0 ppb to 10.2 mA/cm2, while also maintaining its low-cost, small size, and robustness.

In previous studies of the folate content of human milk, samples were prepared for assay by a method that resulted in a turbid solution that was then assayed by a turbidimetric microbiological method. We have used an improved microbiological assay in which the milks were treated with rennin to precipitate casein and heated in a buffered ascorbate to coagulate lactalbumin and lactoglobulin. Milks were obtained serially from nursing mothers for periods ranging from 1 day to 6 months postpartum. The results showed that the folate in human milk has few glutamate residues since treatment with a purified folate conjugase preparation release no additional folate activity for Lactobacillus casei. Colostrum is relatively low in folate, but milk folate increases as lactation proceeds. During each stage of lactation there was great variation in milk folate content among the women. In the case of a folate-deficient woman, supplementation with folic acid resulted in a prompt increase in milk folate level.

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