Dual sensing of temperature and oxygen using PtTFPP-doped CdSe/SiO2 core–shell nanoparticles

A sensor comprising doped core–shell nanoparticles embedded in a sol–gel matrix is proposed for the dual sensing of temperature and oxygen. The nanoparticles comprise a CdSe quantum dot (QD) core and a silica shell doped with platinum(II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP). The core–shell nanoparticles provide a temperature sensing function while the platinum dye provides an oxygen sensing function. Both indicators are excited using a wavelength of 409 nm. The doped nanoparticles are embedded in an n-propyltrimethoxysilane (n-propyl-TriMOS)/3,3,3-trifluoropropyltrimethoxysilane (TFP-TriMOS) composite xerogel and coated on the end of an optical fiber. The experimental results show that the shift in the emission wavelength has the thermal sensitivity of ∼0.095 nm/°C over temperatures ranging from 30 to 100 °C. Moreover, it is shown that the sensor enables the reliable measurement of oxygen concentrations in the range of 0–100% with a response (I0/I) of approximately 18 under room temperature conditions. The response time was 0.37 s when switching from nitrogen to oxygen, and 4.7 s when switching in the reverse direction. Overall, the results presented in this study show that the proposed sensor provides an ideal solution for the dual sensing of oxygen and temperature in such applications as (micro)biological, medical and environmental fields.