TAILORING ZnO-BASED PIEZOTRONIC SENSORS BY CHEMICAL SPECIATION

Abstract

This work shows the potentiality of analytical speciation as a precious tool in the hands of a chemist to design ZnO nanostructures (n-ZnO)1 and tune the performances of the resulting sensors (Figure 1). This principle was firstly applied to 1D n-ZnO piezotronics wearable heartbeat piezotronic detectors, prepared at mild conditions (85°C, 12 hours) on flexible circuit boards2 and to the seamless integration of 2D n-ZnO (85°C, 24 hours) onto flexible ITO/PET strain sensors devices3 . The strain sensors show better performances in comparison to 1D ZnO based devices along with self-cleaning properties triggered by the ZnO photocatalytic effect. These devices are easily wearable and indeed allow for the real time piezoresistive monitoring of finger and elbow bending (Figure 1). The resistance variation upon bending (about 4-fold) outperforms similar devices based on 1D -ZnO. Lastly, the two-fold increase of the zinc ions concentrations and the extension of the reaction time to 60 hours, leads to 3D n-ZnO structures, namely ZnO cauliflowers. These systems show excellent photocatalytic activity and are fully integrable into cellulose acetate films to obtain nanocomposite suitable for regenerative medicine platforms.