We modified the original chamber design to include a blue excitation light source at a right angle to the absorbance photo sensor.
The absorbance, intensity and sensor response time of the MMF fiber optic sensor with gold and palladium nanocomposite with ratio of 2: 0.7 (Au to Pd) are shown in Fig. 7a-c below while Fig. 7d-f show the result obtained from the fourth sensor, coated with gold and palladium nanocomposite with ratio 2: 1 (Au to Pd).
The fluorescence intensity and absorbance for the sensor showed a good linearity with the concentration of Al3+ in the range of 0 12.5 μM and 8 44 μM, respectively, with detection limits of 0.23 μM and 1.90 μM.
The fluorescence intensity and absorbance of the sensor showed a good linearity with the concentration of Pd2+ in the range of 0 15 μM and 0 17 μM, respectively, with detection limits of 0.015 μM and 0.200 μM.
b Calibration curve for variamine blue-oxidized sensor, absorbance recorded at 550 nm.
As a colorimetric sensor, the absorbance peak centered at 315 nm and 400 nm enhanced after the addition of Al3+, while the absorbance peak centered at 275 nm and 344 nm gradually decreased.
The absorbance of each ROS sensor was measured by an UV-1650PC UV-Visible Shimadzuhotometer (Shimadzu, Japan).
Fig. 5 a Absorbance spectrum of tapered fiber sensor towards Ethanol concentrations, (b) Intensity spectrum of tapered fiber sensor towards Ethanol concentrations, (c) Dynamic response of 2.0 mg/mol Au coated tapered fiber.
Fig. 6 a Absorbance spectrum of coating fiber sensor with 1.0 mg/mol palladium towards Ethanol concentrations, (b) Intensity spectrum of tapered fiber sensor towards Ethanol concentrations, (c) Dynamic response of Pd coated MMF sensor towards different concentration of Ethanol.
A dedicated data acquisition system is designed and fabricated using a LPC2106 microcontroller with light emitting diode (LED) as source and photodiode as sensor to measure absorbance and to calculate the calcium concentration.
In environmentally friendly media (50% (v/v) water/ethanol and 10 mM NaAc HAc neutral buffer (pH 7.0)), the sensor exhibited selective absorbance enhancement to Cu2+ over other metal ions at 529 nm, with a dynamic working range of 0.05 5.00 μM and a detection limit of 10 nM Cu2+, respectively.
