Ratiometric highly sensitive luminescent nanothermometers working in the room temperature range. Applications to heat propagation in nanofluids.

نویسندگان

  • Carlos D S Brites
  • Patrícia P Lima
  • Nuno J O Silva
  • Angel Millán
  • Vitor S Amaral
  • Fernando Palacio
  • Luís D Carlos
چکیده

There is an increasing demand for accurate, non-invasive and self-reference temperature measurements as technology progresses into the nanoscale. This is particularly so in micro- and nanofluidics where the comprehension of heat transfer and thermal conductivity mechanisms can play a crucial role in areas as diverse as energy transfer and cell physiology. Here we present two luminescent ratiometric nanothermometers based on a magnetic core coated with an organosilica shell co-doped with Eu(3+) and Tb(3+) chelates. The design of the hybrid host and chelate ligands permits the working of the nanothermometers in a nanofluid at 293-320 K with an emission quantum yield of 0.38 ± 0.04, a maximum relative sensitivity of 1.5% K(-1) at 293 K and a spatio-temporal resolution (constrained by the experimental setup) of 64 × 10(-6) m/150 × 10(-3) s (to move out of 0.4 K--the temperature uncertainty). The heat propagation velocity in the nanofluid, (2.2 ± 0.1) × 10(-3) m s(-1), was determined at 294 K using the nanothermometers' Eu(3+)/Tb(3+) steady-state spectra. There is no precedent of such an experimental measurement in a thermographic nanofluid, where the propagation velocity is measured from the same nanoparticles used to measure the temperature.

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عنوان ژورنال:
  • Nanoscale

دوره 5 16  شماره 

صفحات  -

تاریخ انتشار 2013