Exfoliation in water of heaxgonal Boron Nitride (h-BN), Mxene and InSe was successfully achieved. The dispersions are stable for several weeks and have concentrations above 0.1 mg/mL. The ink was characterized with several techniques, such as XPS, FTIR, SEM, and EDS. The lateral size and thickness distributions of the flakes was measured by AFM, showing that most nanosheets have thickness below 15 nm, indicating efficient exfoliation.
The dispersions were made inkjet printable by performing solvent exchange with a printable water-based solvent developed in our group. The ink was deposited on silicon and on paper at different printing passes and the thickness vs number of printing passes relationship was extracted. The printed features are unform and sharp, indicating excellent printability.
The h-BN ink was used to demonstrate a wearable and wireless impedance-based humidity sensor, which shows enhanced sensitivity towards relative humidity, fast response, no appreciable hysteresis and cross-sensitivity in the range of 25–60°C. We finally demonstrate that the h-BN based sensor is able to monitor the whole breathing cycle process of exhaling and inhaling, hence enabling to record in real time the subtlest changes of respiratory signals associated with different daily activities as well as various symptoms of flu, without requiring any direct contact with the individual. A wireless demonstrator was made by integrating the device onto a face mask. The same approach was then extended to 2D Titanium Oxide inks, previously developed in our group.
The Mxene and inSe inks were used to demonstrate fully printed photodetectors with relatively good performance - further optimization is needed.
Due to the lockdown and maternity leave, the dissemination was somehow limited. The work was presented as poster and oral in few conferences and a press release was made after publication and shared on Linkedin.
