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Highly pH-responsive sensor based on amplified spontaneous emission coupled to colorimetry

View Article: PubMed Central - PubMed

ABSTRACT

We demonstrated a simple, directly-readable approach for high resolution pH sensing. The method was based on sharp changes in Amplified Spontaneous Emission (ASE) of a Stilbene 420 (ST) laser dye triggered by the pH-dependent absorption of Bromocresol Green (BG). The ASE threshold of BG:ST solution mixtures exhibited a strong dependence on BG absorption, which was drastically changed by the variations of the pH of BG solution. As a result, ASE on-off or off-on was observed with different pH levels achieved by ammonia doping. By changing the concentration of the BG solution and the BG:ST blend ratio, this approach allowed to detect pH changes with a sensitivity down to 0.05 in the 10–11 pH range.

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pH values required for ASE recovery as a function of BG concentration in BG:ST blend solutions (pH resolution up to 0.05 ± 0.003). The inset is the standard color chart for the wide range of pH test strips. pH value for ASE recovery stand for the minimum pH required to reach ASE at lowest threshold level in certain mixture. The sensor added value stands on the fact that colorimetric evaluation to the naked eye is no longer feasible in the pH 9 to 14.
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f4: pH values required for ASE recovery as a function of BG concentration in BG:ST blend solutions (pH resolution up to 0.05 ± 0.003). The inset is the standard color chart for the wide range of pH test strips. pH value for ASE recovery stand for the minimum pH required to reach ASE at lowest threshold level in certain mixture. The sensor added value stands on the fact that colorimetric evaluation to the naked eye is no longer feasible in the pH 9 to 14.

Mentions: In Fig. 4 we recorded the pH values required to reach ASE at lowest threshold level in mixtures as a function of ST ratio against BG (BG:ST = 1:X). We define the resolution of the sensor as the minimum pH change that the sensor can discriminate. From the figure we infer a maximum pH resolution as low as 0.05 ± 0.003 in the 10.28–10.93 sensing range. The resolution of this sensor can be further improved by adjusting the BG:ST ratio. For each BG:ST content the minimum pH value necessary to recover ASE is displayed in Fig. 4 which constitutes the calibration curve of the pH sensor. The protocol to determine the unknown pH of a given sample would consist of screening a set of BG:ST mixtures (i.e. doping BG:ST solutions with a fixed volume of sample and adjust the pump power for different mixtures) and detecting presence/absence of ASE. As the amount of BG in solutions rises, ASE will no longer be feasible for BG contents above a certain BG:ST level, (called here the vanish point). Then, by using the calibration curve displayed in Fig. 4, the pH of the sample will correspond to the one for BG:ST ratio just before the vanish point.


Highly pH-responsive sensor based on amplified spontaneous emission coupled to colorimetry
pH values required for ASE recovery as a function of BG concentration in BG:ST blend solutions (pH resolution up to 0.05 ± 0.003). The inset is the standard color chart for the wide range of pH test strips. pH value for ASE recovery stand for the minimum pH required to reach ASE at lowest threshold level in certain mixture. The sensor added value stands on the fact that colorimetric evaluation to the naked eye is no longer feasible in the pH 9 to 14.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5384246&req=5

f4: pH values required for ASE recovery as a function of BG concentration in BG:ST blend solutions (pH resolution up to 0.05 ± 0.003). The inset is the standard color chart for the wide range of pH test strips. pH value for ASE recovery stand for the minimum pH required to reach ASE at lowest threshold level in certain mixture. The sensor added value stands on the fact that colorimetric evaluation to the naked eye is no longer feasible in the pH 9 to 14.
Mentions: In Fig. 4 we recorded the pH values required to reach ASE at lowest threshold level in mixtures as a function of ST ratio against BG (BG:ST = 1:X). We define the resolution of the sensor as the minimum pH change that the sensor can discriminate. From the figure we infer a maximum pH resolution as low as 0.05 ± 0.003 in the 10.28–10.93 sensing range. The resolution of this sensor can be further improved by adjusting the BG:ST ratio. For each BG:ST content the minimum pH value necessary to recover ASE is displayed in Fig. 4 which constitutes the calibration curve of the pH sensor. The protocol to determine the unknown pH of a given sample would consist of screening a set of BG:ST mixtures (i.e. doping BG:ST solutions with a fixed volume of sample and adjust the pump power for different mixtures) and detecting presence/absence of ASE. As the amount of BG in solutions rises, ASE will no longer be feasible for BG contents above a certain BG:ST level, (called here the vanish point). Then, by using the calibration curve displayed in Fig. 4, the pH of the sample will correspond to the one for BG:ST ratio just before the vanish point.

View Article: PubMed Central - PubMed

ABSTRACT

We demonstrated a simple, directly-readable approach for high resolution pH sensing. The method was based on sharp changes in Amplified Spontaneous Emission (ASE) of a Stilbene 420 (ST) laser dye triggered by the pH-dependent absorption of Bromocresol Green (BG). The ASE threshold of BG:ST solution mixtures exhibited a strong dependence on BG absorption, which was drastically changed by the variations of the pH of BG solution. As a result, ASE on-off or off-on was observed with different pH levels achieved by ammonia doping. By changing the concentration of the BG solution and the BG:ST blend ratio, this approach allowed to detect pH changes with a sensitivity down to 0.05 in the 10–11 pH range.

No MeSH data available.


Related in: MedlinePlus