## 3 Results and Discussion  
### Measurement of Fluorophore Emission  
To verify that the proposed detection platform (GGP-GMR/CCD system) can detect both the intensity and peak wavelength, one fluorescent dye that is commonly used in the polymerase chain reaction for DNA detection was tested. The performance of the GGP-GMR/CCD system was compared with that of a commercial spectrometer to demonstrate its capability and flexibility for general fluorescence detection in liquid assays.  
Figure 3a,b presents the fluorescence intensities measured using a spectrometer and the GGP-GMR/CCD system, respectively, for five concentrations (\(10^{-3}\) to \(10^{-7}\) M in 10-fold dilution) of TAMRA (5-carboxytetramethylrhodamine, Abcam, Cambridge, UK) in methanol. A 458-nm LED was used as the excitation source, and the fluorescence emission collected by the ball lens was coupled to the \(2\times 1\) fiber for the measurement (Figure 2c).  
Figure 2: (a) Illustration of the incident spectrum for the GGP-GMR device, (b) intensity distribution on the CCD of the GGP-GMR device, and (c) experimental setup for the fluorescence and colorimetric assay measurement.  
The results presented in Figure 3a indicate that the fluorescence intensity increased with increases in the analyte concentration from the spectrometer measurement, as expected. In addition, the intensity at the MICP measured by the GGP-GMR/CCD system also increased with the aforementioned concentration, as indicated in Figure 3b (explained in the previous section as well as in Figure 2a,b).  
Experiments were performed three times to obtain a quantitative measurement. For each run, the intensities were normalized to that measured at the highest concentration. The dose response curves measured using the GGP-GMR/CCD system and spectrometer are displayed in Figure 4a,b, respectively. A comparison of the results (normalized intensity of the peak wavelength vs. the normalized intensity of the MICP) is illustrated in Figure 4c, where both the slope of the regression line and the coefficient of determination (R2) approach 1, which indicates that the measurements obtained with the GGP-GMR/CCD system agree well with those obtained with a commercial spectrometer.  
In addition to the intensity, the peak wavelength and MICP shifted with changes in the concentration, as displayed in Figure 2a,b. The peak wavelength shifted from 600 to 566 nm when the concentration decreased from \(10^{-3}\) to \(10^{-6}\) M, as depicted in Figure 3a. According to the calibration diagram presented in Figure 1e, the MICP should correspond to pixel numbers of 2199-2154, which is close to the observation in Figure 3b, where the MICP corresponds to pixel numbers of 2201-2160. The variations in the peak wavelength and MICP with the concentration obtained from the three experimental runs are illustrated as blue and orange curves in Figure 5a, respectively.  
Moreover, on the basis of the calibration diagram presented in Figure 1e, the calibrated MICPs are plotted as a gray curve in Figure 5a. A comparison of the results between the measured MICPs and peak wavelength measured by the spectrometer is presented in Figure 5b, where the large value of the coefficient of determination (0.9825) indicates a strong correlation between the MICP and the peak wavelength. These fluorescence measurement results indicate that the location and intensity of the MICP can be used to correlate the peak wavelength and its intensity appropriately. Similar results (Figures S3-S5) were obtained from another commonly used fluorophores, FAM (6-carboxyfluorescein, Merck, Darmstadt, Germany), which can be found in Supplementary Material.  
Figure 3: Fluorescence emission from different concentrations of TAMRA (5-carboxytetramethyl-rhodamine) measured using (**a**) a spectrometer and (**b**) the proposed GGP-GMR/CCD system.