An All-Inkjet-Printed Photosensor on Flexible Plastic Substrate for the Detection of Ultraviolet Radiation

Due to the demand of low-cost sensor applications and new technologies for efficient production, the printing of functional inks is one of the most sustainable and fastest-growing markets in the electronic industry. This statement is confirmed by the "Roadmap for Organic and Printed Electronics", which predicts that the global market value of this sector will increase by about 50% to about 43 billion USD by 2020. The reason for this enormous growth is the continuous development of various nanomaterials, with the possibilities to bind smallest particles of a material in a solvent and to apply the resulting inks with different printing techniques on temperature-sensitive large substrates. These comparatively simple additive processes allow for example a combination of conductive polymers and inorganic materials, to manufacture cost-efficient electronic systems. This work presents the development of a 2D-printed photosensor for the detection of ultraviolet radiation in the wavelength range of 310 nm - 390 nm for wearable applications. This interdigitated electrode sensor can be completely realized by applying inkjet printing technology with nanoparticle-based inks. It detects electromagnetic radiation resistively. The semiconductor layer (ZnO-based) reacts on the UV radiation. Figure 1 shows a schematic representation of the sensor structure and figure 2 the printed sensor. Due to the transparency of zinc oxide in the visible range of the electromagnetic spectrum, the printed sensing material is marked with a red square.