Preparation of Self-Assembled π-Conjugated Polymer Microlaser Sensor and Its Application in Detection of Acetone in Exhaled Gas of Diabetes Patients

Given that most existing blood glucose detection methods are invasive tests, the study mentioned by the title was conducted. Poly2-methoxy-5-(2-ethylhexoxy)-1,4-phenylacetylene (MEH-PPV) microspheres were prepared by the lotion-solvent evaporation method, which had perfect circular boundaries and super smooth surfaces, emitting uniform red fluorescence at 330-380 nm of UV excitation wavelength, with emission peaks at 601 nm and 638 nm. By changing the diameter of the microspheres excited by femtosecond laser at a pump power density of 160 nJ·cm⁻², it was found that the effective refractive index (2.04) of the microspheres was consistent with the intrinsic refractive index (1.85) of the MEH-PPV polymer, indicating that laser modulation was caused by the resonance of the spherical whispering gallery cavity, which was beneficial for sensing very small changes at the resonance wavelength with the sensor. Using a self-built gas sensor to detect different volume fractions of acetone gas, the volume fraction of acetone gas within (2.0-4.0)×10⁻⁵ was linearly related to the change Δλ_s in laser wavelength before and after exposure to acetone gas (the laser wavelength λ₀ before exposure was about 621 nm), with detection limit of 9.0×10⁻⁸ (volume fraction), and the sensor had good selectivity for acetone. The proposed method was used to analyze the exhaled gas of simulated diabetes patients containing 2×10⁻⁶ (volume fraction, the same below) acetone. The detected amount of acetone was 4.05 times of that in the 2×10⁻⁶ acetone gas, and 78% of that in the healthy individuals exhale gas. It was shown that the sensor could provide a new method for non-invasive diagnosis of diabetes mellitus.