biostudies-literatureLi YUniversity of Pennsylvania The Orphan Disease CenterNIBIB NIH HHSVirginia Commonwealth UniversityNational Institutes of HealthNational Institute of Biomedical Imaging and Bioengineering129358https://www.ebi.ac.uk/biostudies/studies/S-EPMC12949671biostudies-literatureUnknown302Measurement of urinary calcium concentration is essential for the diagnosis and management of various disorders related to calcium metabolism, including kidney stones, hypoparathyroidism, and hyperparathyroidism. Current testing protocols require patients to visit clinical laboratories or hospitals, and no at-home devices are currently approved for quantitative self-testing of urinary calcium. In this work, we report a low-cost and user-friendly colorimetric sensor for urinary calcium measurement. The sensor consists of a segment of sensing oil contained within a millifluidic channel, such as a pipette tip. The oil incorporates hydrophobic sensing chemicals typically used in ion-selective optodes, including a chromoionophore, an ion exchanger, and an ionophore. It is specially formulated tTalantaMillifluidic ion-selective optodes with integrated optical detection for colorimetric quantification of urinary calcium.PMC12949671HYPOPARA-20-003-02R01EB036599R01 EB036599Patel ALi YGoodhart RWang XfalseMillifluidic ion-selective optodes with integrated optical detection for colorimetric quantification of urinary calcium.Measurement of urinary calcium concentration is essential for the diagnosis and management of various disorders related to calcium metabolism, including kidney stones, hypoparathyroidism, and hyperparathyroidism. Current testing protocols require patients to visit clinical laboratories or hospitals, and no at-home devices are currently approved for quantitative self-testing of urinary calcium. In this work, we report a low-cost and user-friendly colorimetric sensor for urinary calcium measurement. The sensor consists of a segment of sensing oil contained within a millifluidic channel, such as a pipette tip. The oil incorporates hydrophobic sensing chemicals typically used in ion-selective optodes, including a chromoionophore, an ion exchanger, and an ionophore. It is specially formulated t2026-01-01T00:00:00Z2026 May2026-07-16T23:14:43.668Z2026-07-12T03:10:53.409ZS-EPMC129496714151903310.1016/j.talanta.2026.129358