Transparent and flexible tactile sensors based on graphene films designed for smart panels

With the development of the human–computer interaction, smart panel requires more of lightweight and transparency. However, most smart panels have been developed based on bulky metal materials and integrated external circuits, which lack flexibility and transparency. Here we demonstrate an ultrathin and flexible tactile sensor based on few-layer graphene films (GFs). The optical transmittance of the sensor is up to 80% in the visible range, which provides optical transparency enough for an aesthetic view. The sensor is assembled through a very simple method consisted a polyethylene terephthalate substrate and two unconnected GFs. The as-assembled sensors can reflect one-dimensional (1D) touch position with a high sensitivity of 0.23 mm−1. The tactile sensor can be used in the monitoring of finger touch, as well as in the detection of liquid temperature. The GFs-based tactile sensor was transferred on the glass substrate to form a smart window, which can warn of a rainy weather coming without sacrificing the window visual functionalities. In addition, a flexible smart panel has been assembled only connect two external circuits and succeed in reappearing the 2D touch path.