4.10 A paper based human-machine interface: Towards fully green and recyclable Internet of Things

The transition to a sustainable society is driving the development of green electronic solutions which are designed to have a minimal environmental impact. One promising route to achieve this goal is to construct electronics from biobased materials like cellulose which is carbon neutral, non-toxic, and which can be recycled. This is especially true for IoT devices which are rapidly growing in number and are becoming embedded in every aspect of our lives. Here, we demonstrate a paper-based electronic “book” which uses triboelectric pressure sensors to help elderly people communicate with the digital world using an interface which is more intuitive to them. The sensors were manufactured by screen printing onto flexible paper substrates, using in-house developed cellulose-based inks with non-hazardous solvents. The triboelectric sensor signal, generated by the contact between a finger and chemically modified cellulose, could reach several volts which could be registered by a portable microcontroller card and transmitted by Bluetooth to any device with an internet connection. Apart from the MCU card (which can be easily removed), the whole system can be put in paper recycling at end of life.