Fig. 3: Temperature response behavior of LIBRA.
a Schematic of temperature response of LIBRA. The sensitivity of temperature response can be enhanced by bidirectional changes of the luminescence intensities at 980 and 1550 nm. b NIR luminescence spectra of LIBRA@PEG in aqueous dispersion at 10 to 90 °C by external heating. The emission at 980 nm decreased and the emission at 1550 nm increased with temperature elevation. c The ratio of emissions at 1550 and 980 nm (Ratio (I1550/I980)) versus temperature (given in K) for temperature calibration. Data were presented as mean values based on three individual measurements (n = 3) by spectrometry. Error bars were defined as standard deviation. d Relative thermal sensitivity (Sr) of LIBRA@PEG based on ratio of 980 and 1550 nm emissions and single emission intensity. The temperature range was from 283 to 363 K. e Repeatability of the ratio of emissions at 1550 and 980 nm (Ratio (I1550/I980)) with 4 cycles of heating and cooling between 293 and 323 K. Data were presented as mean values based on three individual measurements (n = 3) by spectrometry. Error bars were defined as standard deviation. f Ratio of emissions at 1550 and 980 nm (Ratio (I1550/I980)) under the excitation of 808 nm laser with varied power densities at room temperature. Data were presented as mean values based on three individual measurements (n = 3) by spectrometry. Error bars were defined as standard deviation.
