Development of a smartphone based spectrometer for high-resolution urinalysis

Chronic kidney disease (CKD) affects millions worldwide but remains under-diagnosed, especially in resource-limited settings. Current diagnostic methods, including visual and dipstick urinalysis, lack quantitative accuracy, while laboratory-based tests remain inaccessible for routine or remote monitoring. Here we present SpectraPhone, a smartphone-integrated, portable spectrometer designed for quantitative, point-of-care urinalysis. Leveraging the smartphone's built-in camera and flashlight, SpectraPhone captures high-resolution spectral data to accurately quantify hematuria and albuminuria, which are both biomarkers of CKD. Through rigorous optical characterization and empirical validation, SpectraPhone demonstrates superior quantification performance, accurately measuring red blood cell concentrations ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>R</mml:mi> <mml:mn>2</mml:mn></mml:msup> </mml:math> = 0.9913, RMSE = 61.6086 RBC/ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>μ</mml:mi></mml:math> L, MAE = 43.9077 RBC/ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>μ</mml:mi></mml:math> L) and albumin levels ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>R</mml:mi> <mml:mn>2</mml:mn></mml:msup> </mml:math> = 0.9981, RMSE = 11.8525 mg/dL, MAE = 8.4985 mg/dL), significantly surpassing the capabilities of conventional qualitative methods. With the addition of bromophenol blue reagent, SpectraPhone achieves more accurate urine albumin measurements ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>R</mml:mi> <mml:mn>2</mml:mn></mml:msup> </mml:math> = 0.9997, RMSE = 4.2583 mg/dL, MAE = 3.2625 mg/dL), enabling clinical-grade albuminuria detection. SpectraPhone's affordability, ease of use, and robust performance highlight its potential to transform routine CKD screening, facilitate early detection, improve disease management, and increase healthcare access globally.