UC Berkeley

Recently, form factors of electronics have been changing from conventional rigid electronics to more novel and complex form factors including soft, flexible, and even stretchable forms. These unique form factors are lightweight and enable conformal interfaces between electronics and the objects they rest upon. Printing is a commercially viable manufacturing technology for fabricating these types of electronics, capable of depositing materials including conducting, insulating, and semiconducting materials. However, printed flexible electronics are not as efficient as silicon integrated circuits (ICs) in certain regimes, such as computation or communication. Flexible hybrid electronics (FHE) leverage the benefits of flexible printed electronics and ICs by combining the two onto flexible substrates.

In this dissertation, I will discuss the various components of an FHE system and the range of printing techniques that are used to fabricate them. This dissertation will also overview specific works highlighting advancements in developing FHE systems. For passive sensing applications, I will focus on our work on screen-printed thermistor arrays, and their applications in battery health monitoring. For active sensing applications, I will discuss our work using doctor-blade coated arrays of organic light-emitting diodes (OLEDs) and organic photodiodes (OPDs) for reflection mode blood oximetry, which accurately measures pulse rate and oxygenation. In addition to the discussion of the flexible sensor composed of OLEDs and OPDs, I will present our work on various unique geometries of optoelectronics and their significance in improving sensor efficiency. For power sources, I will present our work on screen-printed Zn-Ag2O battery arrays, and the scalability of these devices. Finally, I will discuss other techniques to develop robust conformal electronics, using a class of FHE systems called in-mold electronics.