Hybrid Materials for Wearable Electronics and Electrochemical Systems

Abstract: Flexible electronic systems such as wearable devices, sensors and electronic skin require power sources and sensing units that are mechanically robust, operational at low bending radius, and environmentally friendly. Recently, there has been an enormous interest in active materials such as thin film semiconductors, conductive polymers, and ion-electron conductors. These materials can be deposited with both printing and microfabrication techniques onto the flexible substrates such as plastics and paper. In addition, paper-based composites with nanofibrillated cellulose are favorable due to their mechanical strength, porosity, and solution-processability. Printing of such systems enables mass-production of large area electrochemical devices i.e., batteries, supercapacitors and fuel cells. Moreover, designing ultrathin devices for such concepts are promising for implantable and skin-like conformable electronics.The aim of this thesis is the development of flexible electronic devices where, both organic and inorganic materials are explored, and examples of smart packaging and wearable electronics are demonstrated. Within the thesis, two different fabrication approaches are presented to achieve flexible electronics: (1) fabrication of porous paper electrodes for printable, wearable supercapacitor applications, where our efforts towards sustainable solutions for energy storage and (2) development of ultraflexible devices for electronic skin and implantable electronics to attain miniaturized, ultrathin device concepts. Overall, high performance electronic devices and demonstrators shown here have a significant impact on portable hybrid systems and flexible electronics applications.