1：Experimental Design and Method Selection:

The study designed a compact fluorescence polarization (FP) detector using a 3D-printed housing and off-the-shelf optical components, integrated with a smartphone camera. Optical design software (LightTools 8.5) was used for simulation and optimization. The method involves measuring FP by detecting parallel and perpendicular polarized emissions simultaneously.

2：5) was used for simulation and optimization. The method involves measuring FP by detecting parallel and perpendicular polarized emissions simultaneously. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Samples included Rhodamine 6G and Coumarin 540A dyes dissolved in methanol with varying glycerol concentrations to adjust viscosity, and Prostaglandin E2 (PGE2) samples for immunoassay validation. Dyes were purchased from Exciton, and PGE2 kit from Enzo Life Sciences.

3：List of Experimental Equipment and Materials:

Equipment includes a smartphone (HTC One M8), 3D-printed housing, excitation sources (DJ532-10 or L462P1400MM lasers, blue LED), optical components (collimation lens LJ1402L1, linear polarizer 40-990, plano-convex lens LA154-A, polarizing beam splitter 49-001, mirrors 43-790, bandpass filters 1005190B and FF02-485/20-25), microfluorescence cuvette (Type 507), and Android app for image processing. Materials include dyes, methanol, PBS, glycerol, and PGE2 assay kit reagents.

4：Experimental Procedures and Operational Workflow:

For dye experiments, samples were prepared with different glycerol concentrations, inserted into the cuvette, and FP measured using the smartphone system with appropriate excitation and filters. For PGE2 assay, samples were mixed with labeled PGE2 and antibody, incubated for 30 minutes, and measured. The app captured images, calculated intensities, and computed FP values.

5：Data Analysis Methods:

FP values were calculated using the formula (I_parallel - I_perpendicular) / (I_parallel + I_perpendicular). Data were analyzed with exponential curve fitting, and limit of detection was determined based on standard deviation. Coefficient of variation was calculated for replicated samples.