Titanium dioxide-polyaniline/silk fibroin microfiber sensor for pork freshness evaluation

A novel and low-cost micro-sensor with a diameter of 12 μm was developed based on Titanium dioxide-Polyaniline/Silk fibroin fiber (TiO₂-PANI/SFF). TiO₂-PANI composites were deposited on surfaces of SFFs by in-situ polymerization. The microfibers were characterized by Scanning electron microscopy (SEM), Energy dispersive spectrometer (EDS), Raman spectrometer, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD), and the formation mechanism of them was illustrated in detail. With ammonia (NH₃) as model gas, the TiO₂-PANI/SFF micro-sensor showed good sensing performance with response value of 0.82 and response time of 10 s to NH₃ of 100 μg/L. When the micro-sensors were applied for pork freshness evaluation, the output response values showed good correlation with the total volatile basic nitrogen (TVB-N) levels in pork (R² = 0.990), and the discriminant results of the micro-sensors for pork freshness based on linear discriminant analysis (LDA) showed the prediction accuracy of calibration and prediction set was 90.73% and 86.38%, respectively, which indicated the great potential of TiO₂-PANI/SFF micro-sensor for pork freshness evaluation.