Strain engineered biocompatible h-WO3 nanofibers based highly selective and sensitive chemiresistive platform for detection of Catechol in blood sample.

In this work, we demonstrate a simple, low-cost biocompatible 1D-WO3 electrospun nanofibers based strain-induced high-performance chemiresistive catechol sensor. WO3 nanofibers were synthesized using e-spinning, annealed and drop-casted on to flexible PET substrate. X-Ray Diffraction (XRD) studies confirm the formation of Hexagonal phase-WO3 and Raman spectroscopy proved the presence of O-W-O bending modes. Field emission scanning electron microscopy (FESEM) images displayed the random orientation of dense WO3 nanofibers on PET substrate. Hall measurements confirmed the formation of n-type WO3 nanofibers with carrier density of 1019 cm-3. The sensor responded to a broad dynamic range of catechol concentrations from 1 μM to 100 μM with sensitivity of 51.29 μM-1 cm-2 and limit of detection of 0.52 μM which are better than previously reported catechol sensors. Interestingly, upon application of compressive strain to the flexible sensor, a remarkable increase in sensitivity to 88.34 μM-1 cm-2 was observed with further reduction of the limit of detection to 42 nM. Upon subjecting the sensor to strain ranging from 3.14% to 47.6%, an increase in sensitivity to catechol was observed due to the increase in the exposed surface area of interconnected WO3 nanofibers which enhances the active sites for catechol oxidation by enhancing the tunneling current. The sensor could detect catechol in simulated blood samples with excellent selectivity against AA, UA, Na+, Ca+, hydroquinone and glucose.