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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.


Variation in the fluorescence intensity of the sensor with the droplet number.
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f4-sensors-13-04138: Variation in the fluorescence intensity of the sensor with the droplet number.

Mentions: Fluorescent dyes may be photobleached by continuous illumination by exciting light. To inhibit the photobleaching effect, pulse illuminations were used for the droplet sensor. The duration of a single pulse was 0.75 s, which was adequate for the temperature measurements. Figure 3 shows the fluorescence intensity of each dye versus the pulse count. The fluorescence intensity was normalized by the initial intensity for each dye. The fluorescence intensities of RhB and Rh110 after 20 pulses were 101% and 98% of the initial dye intensities, respectively. Thus, almost no photobleaching occurred using pulse excitation for several tens of pulses. Consequently, pulse excitation was used in the temperature measurements. The uniformity of the fabricated temperature sensors was also evaluated. The fluorescence intensities of RhB and Rh110 were measured for 25 droplets, and the ratio of the two intensities was calculated for each droplet (see Figure 4). The intensity of each droplet was normalized by that of the first droplet, which was selected arbitrarily. Although the individual droplet intensities of the RhB and Rh110 exhibited relatively large fluctuations of up to 30% of the initial droplet intensity, the variation in the ratio of the RhB and Rh110 intensities was as small as 6%.


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)

Variation in the fluorescence intensity of the sensor with the droplet number.
© Copyright Policy
Related In: Results  -  Collection

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

f4-sensors-13-04138: Variation in the fluorescence intensity of the sensor with the droplet number.
Mentions: Fluorescent dyes may be photobleached by continuous illumination by exciting light. To inhibit the photobleaching effect, pulse illuminations were used for the droplet sensor. The duration of a single pulse was 0.75 s, which was adequate for the temperature measurements. Figure 3 shows the fluorescence intensity of each dye versus the pulse count. The fluorescence intensity was normalized by the initial intensity for each dye. The fluorescence intensities of RhB and Rh110 after 20 pulses were 101% and 98% of the initial dye intensities, respectively. Thus, almost no photobleaching occurred using pulse excitation for several tens of pulses. Consequently, pulse excitation was used in the temperature measurements. The uniformity of the fabricated temperature sensors was also evaluated. The fluorescence intensities of RhB and Rh110 were measured for 25 droplets, and the ratio of the two intensities was calculated for each droplet (see Figure 4). The intensity of each droplet was normalized by that of the first droplet, which was selected arbitrarily. Although the individual droplet intensities of the RhB and Rh110 exhibited relatively large fluctuations of up to 30% of the initial droplet intensity, the variation in the ratio of the RhB and Rh110 intensities was as small as 6%.

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.