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Ratiometric optical temperature sensor using two fluorescent dyes dissolved in an ionic liquid encapsulated by Parylene film.

Kan T, Aoki H, Binh-Khiem N, Matsumoto K, Shimoyama I - Sensors (Basel) (2013)

Bottom Line: The sensor can measure the temperature of such microregions with an accuracy of 1.9 °C, a precision of 3.7 °C, and a fluorescence intensity change sensitivity of 1.0%/K.The sensor can measure temperatures at different sensor depths in water, ranging from 0 to 850 µm.The droplet sensor is fabricated using microelectromechanical system (MEMS) technology and is highly applicable to lab-on-a-chip devices.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo, Japan. kan@leopard.t.u-tokyo.ac.jp

ABSTRACT
A temperature sensor that uses temperature-sensitive fluorescent dyes is developed. The droplet sensor has a diameter of 40 µm and uses 1 g/L of Rhodamine B (RhB) and 0.5 g/L of Rhodamine 110 (Rh110), which are fluorescent dyes that are dissolved in an ionic liquid (1-ethyl-3-methylimidazolium ethyl sulfate) to function as temperature indicators. This ionic liquid is encapsulated using vacuum Parylene film deposition (which is known as the Parylene-on-liquid-deposition (PoLD) method). The droplet is sealed by the chemically stable and impermeable Parylene film, which prevents the dye from interacting with the molecules in the solution and keeps the volume and concentration of the fluorescent material fixed. The two fluorescent dyes enable the temperature to be measured ratiometrically such that the droplet sensor can be used in various applications, such as the wireless temperature measurement of microregions. The sensor can measure the temperature of such microregions with an accuracy of 1.9 °C, a precision of 3.7 °C, and a fluorescence intensity change sensitivity of 1.0%/K. The sensor can measure temperatures at different sensor depths in water, ranging from 0 to 850 µm. The droplet sensor is fabricated using microelectromechanical system (MEMS) technology and is highly applicable to lab-on-a-chip devices.

No MeSH data available.


(a) Schematic of the droplet sensor, (b) fabrication process of the droplet sensor, (c) temperature measurement method using fluorescence intensity, and (d) image of fabricated droplet sensors.
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f1-sensors-13-04138: (a) Schematic of the droplet sensor, (b) fabrication process of the droplet sensor, (c) temperature measurement method using fluorescence intensity, and (d) image of fabricated droplet sensors.

Mentions: In the developed sensor, the liquid in which the temperature sensitive dyes are dissolved was coated with a Parylene thin film (Figure 1(a)). The quantum yield Φ of a fluorescent dye is temperature dependent; therefore, a temperature change modulated the fluorescence intensity [11], which decreased with increasing temperature (see Figure 1(c)). We used a ratiometric method to determine the temperature from the fluorescence intensity using two dyes, Rhodamine B (RhB) and Rhodamine 110 (Rh110) [12]. The fluorescence of these two dyes could be measured independently because the dyes have different excitation/emission wavelengths. The temperature could also be measured ratiometrically because the dyes exhibited different thermal dependences. The ratiometric method is robust to artifacts from optical losses by the absorption of medium because any optical loss is cancelled out during the ratiometric operation. These dyes were activated as fluorescent materials by dissolution in an ionic liquid; we previously confirmed that the dyes behaved similarly in the ionic liquid as in water. The ionic liquid had a very low vapor pressure, was nonvolatile, and could be encapsulated using chemical vapor deposition, as we reported previously [9,10]. The Parylene-C film coating prevented liquid leakage, enabling the application of the sensor to aqueous environments.


Ratiometric optical temperature sensor using two fluorescent dyes dissolved in an ionic liquid encapsulated by Parylene film.

Kan T, Aoki H, Binh-Khiem N, Matsumoto K, Shimoyama I - Sensors (Basel) (2013)

(a) Schematic of the droplet sensor, (b) fabrication process of the droplet sensor, (c) temperature measurement method using fluorescence intensity, and (d) image of fabricated droplet sensors.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3673075&req=5

f1-sensors-13-04138: (a) Schematic of the droplet sensor, (b) fabrication process of the droplet sensor, (c) temperature measurement method using fluorescence intensity, and (d) image of fabricated droplet sensors.
Mentions: In the developed sensor, the liquid in which the temperature sensitive dyes are dissolved was coated with a Parylene thin film (Figure 1(a)). The quantum yield Φ of a fluorescent dye is temperature dependent; therefore, a temperature change modulated the fluorescence intensity [11], which decreased with increasing temperature (see Figure 1(c)). We used a ratiometric method to determine the temperature from the fluorescence intensity using two dyes, Rhodamine B (RhB) and Rhodamine 110 (Rh110) [12]. The fluorescence of these two dyes could be measured independently because the dyes have different excitation/emission wavelengths. The temperature could also be measured ratiometrically because the dyes exhibited different thermal dependences. The ratiometric method is robust to artifacts from optical losses by the absorption of medium because any optical loss is cancelled out during the ratiometric operation. These dyes were activated as fluorescent materials by dissolution in an ionic liquid; we previously confirmed that the dyes behaved similarly in the ionic liquid as in water. The ionic liquid had a very low vapor pressure, was nonvolatile, and could be encapsulated using chemical vapor deposition, as we reported previously [9,10]. The Parylene-C film coating prevented liquid leakage, enabling the application of the sensor to aqueous environments.

Bottom Line: The sensor can measure the temperature of such microregions with an accuracy of 1.9 °C, a precision of 3.7 °C, and a fluorescence intensity change sensitivity of 1.0%/K.The sensor can measure temperatures at different sensor depths in water, ranging from 0 to 850 µm.The droplet sensor is fabricated using microelectromechanical system (MEMS) technology and is highly applicable to lab-on-a-chip devices.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo, Japan. kan@leopard.t.u-tokyo.ac.jp

ABSTRACT
A temperature sensor that uses temperature-sensitive fluorescent dyes is developed. The droplet sensor has a diameter of 40 µm and uses 1 g/L of Rhodamine B (RhB) and 0.5 g/L of Rhodamine 110 (Rh110), which are fluorescent dyes that are dissolved in an ionic liquid (1-ethyl-3-methylimidazolium ethyl sulfate) to function as temperature indicators. This ionic liquid is encapsulated using vacuum Parylene film deposition (which is known as the Parylene-on-liquid-deposition (PoLD) method). The droplet is sealed by the chemically stable and impermeable Parylene film, which prevents the dye from interacting with the molecules in the solution and keeps the volume and concentration of the fluorescent material fixed. The two fluorescent dyes enable the temperature to be measured ratiometrically such that the droplet sensor can be used in various applications, such as the wireless temperature measurement of microregions. The sensor can measure the temperature of such microregions with an accuracy of 1.9 °C, a precision of 3.7 °C, and a fluorescence intensity change sensitivity of 1.0%/K. The sensor can measure temperatures at different sensor depths in water, ranging from 0 to 850 µm. The droplet sensor is fabricated using microelectromechanical system (MEMS) technology and is highly applicable to lab-on-a-chip devices.

No MeSH data available.