Local temperature measurement using specrta shift of quantum-dot hydrogel sensor

In this paper, we proposed a long-lifetime temperature measurement using color shift of the fluorescence from the quantum dots. The cell investigation tool encapsulates the quantum dots and can adhere to the cell membrane. These tools can be manipulated in a solution by optical tweezers. We used image processing of fluorescent image of the tools to acquire the color information from the fluorescent image. We calibrated the temperature using the tool containing quantum dots by several color spaces such as HSV and YCrCb. (H: hue, S: saturation, V: values (brightness). Y: brightness, Cr: color difference of red, Cb: color difference of blue) Y and Cr decrease monotonically with increasing temperature, whereas H and Cb do not vary monotonically with temperature. Temperature measurements based on Cr are more stable than measurements based on Y and V because the color difference is robust against brightness fluctuations. These results demonstrate that measuring temperature using Cr information is suitable for cell analysis. This method has a sensitivity of -1.3 %/K and an accuracy of 0.3 K.