Ultra-conformal drawn-on-skin electronics for multifunctional motion artifact-free sensing and point-of-care treatment

An accurate extraction of physiological and physical signals from human skin is crucial for health monitoring, disease prevention, and treatment. Recent advances in wearable bioelectronics directly embedded to the epidermal surface are a promising solution for future epidermal sensing. However, the existing wearable bioelectronics are susceptible to motion artifacts as they lack proper adhesion and conformal interfacing with the skin during motion. Here, we present ultra-conformal, customizable, and deformable drawn-on-skin electronics, which is robust to motion due to strong adhesion and ultra-conformality of the electronic inks drawn directly on skin. Electronic inks, including conductors, semiconductors, and dielectrics, are drawn on-demand in a freeform manner to develop devices, such as transistors, strain sensors, temperature sensors, heaters, skin hydration sensors, and electrophysiological sensors. Electrophysiological signal monitoring during motion shows drawn-on-skin electronics' immunity to motion artifacts. Additionally, electrical stimulation based on drawn-on-skin electronics demonstrates accelerated healing of skin wounds. Designing efficient wearable bioelectronics for health monitoring, disease prevention, and treatment, remains a challenge. Here, the authors demonstrate an ultra-conformal, customizable and deformable drawn-on-skin electronics which is robust to motion artifacts and resistant to physical damage

P3HT-Based Solar Cells: Structural Properties and Photovoltaic Performance

Each year we are bombarded with B.Sc. and Ph.D. applications from students that want to improve the world. They have learned that their future depends on changing the type of fuel we use and that solar energy is our future. The hope and energy of these young people will transform future energy technologies, but it will not happen quickly. Organic photovoltaic devices are easy to sketch, but the materials, processing steps, and ways of measuring the properties of the materials are very complicated. It is not trivial to make a systematic measurement that will change the way other research groups think or practice. In approaching this chapter, we thought about what a new researcher would need to know about organic photovoltaic devices and materials in order to have a good start in the subject. Then, we simplified that to focus on what a new researcher would need to know about poly-3-hexylthiophene:phenyl-C61-butyric acid methyl ester blends (P3HT: PCBM) to make research progress with these materials. This chapter is by no means authoritative or a compendium of all things on P3HT:PCBM. We have selected to explain how the sample fabrication techniques lead to control of morphology and structural features and how these morphological features have specific optical and electronic consequences for organic photovoltaic device applications

Organic Semiconductors

One of the most exciting opportunities in electronics, optoelectronics or flexible electronics is to be able to make devices based on organic semiconductors. Organic active materials can exhibit many advantages such as lower demands on processing technology with less sensitivity to the processing environment, flexibility, and the opportunity to apply the simplicity of organic synthesis to tailoring the properties of the materials for specific applications [1]. Depending on their vapor pressure and solubility, organic semiconductors are deposited either from a vapor or solution phase. In this section, some of the organic semiconductor deposition methods are discussed. Similar to its inorganic counterparts, organic semiconductors have been the subject of extensive research to produce organic electronic devices such as organic photovoltaic cells (OPV), organic field-effect transistors (OFET), and organic lightemitting diodes (OLED) [2, 3, 73–77, 82]. However, organic semiconductors have certain limitations such as a short lifetime, degradation byUVlight, temperature sensitivity, low efficiency compared to inorganic semiconductors, and not well understood charge transfer mechanisms. Despite these limitations, advantages like their lightweight, transparency, flexibility, and lower production cost make them candidates for the development of novel electronic devices fomenting research in this area. It is worthwhile to note that organic semiconductors have been combined with other carbon nanomaterials like carbon nanotubes, fullerenes, and graphene, to improve their charge carrier mobility, which is one of the limitations of polymers and oligomers