MICROFLUIDIC DEVICE FOR RAPID SOIL pH ASSESSMENT USING AN OPTIMIZED INDICATOR MIXTURE

H.M.C. S. Wijerathne, N.D. Tissera, G. Priyadarshana, R.N. Wijesena

Abstract: Soil pH monitoring is critical in agriculture as it directly affects the plant nutrient absorption and microbial activity, including a number of chemical and biochemical reactions. Although various pH assessment methods exist, a clear gap remains in achieving rapid, on-site soil pH measurement with current techniques, where microfluidic devices show a remarkable impact. This study presents the development of a microfluidic pH sensor unit incorporating an optimized indicator mixture for enhanced accuracy and range. The indicator mixture is composed of five sulphonephthalein indicators, which have an improved linear response over a broad range from pH 2 to 10. The prototype microfluidic pH sensing platform enables rapid, on-site, and continuous soil pH measurement, is low-cost and easy to operate, and effectively fulfills the pH monitoring requirements of precision agriculture.

Keywords: Soil pH, Microfluidic device, Indicator mixture, Precision Agriculture, On-site monitoring

DOI: 10.24874/PES08.02B.014

Recieved: 21.12.2025  Revised: 12.02.2026  Accepted: 13.04.2026  
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