Using Polarized Spectroscopy to Investigate Order in Thin-Films of Ionic Self-Assembled Materials Based on Azo-Dyes

Three series of ionic self-assembled materials based on anionic azo-dyes and cationic benzalkonium surfactants were synthesized and thin films were prepared by spin-casting. These thin films appear isotropic when investigated with polarized optical microscopy, although they are highly anisotropic. Here, three series of homologous materials were studied to rationalize this observation. Investigating thin films of ordered molecular materials relies to a large extent on advanced experimental methods and large research infrastructure. A statement that in particular is true for thin films with nanoscopic order, where X-ray reflectometry, X-ray and neutron scattering, electron microscopy and atom force microscopy (AFM) has to be used to elucidate film morphology and the underlying molecular structure. Here, the thin films were investigated using AFM, optical microscopy and polarized absorption spectroscopy. It was shown that by using numerical method for treating the polarized absorption spectroscopy data, the molecular structure can be elucidated. Further, it was shown that polarized optical spectroscopy is a general tool that allows determination of the molecular order in thin films. Finally, it was found that full control of thermal history and rigorous control of the ionic self-assembly conditions are required to reproducibly make these materials of high nanoscopic order. Similarly, the conditions for spin-casting are shown to be determining for the overall thin film morphology, while molecular order is maintained

GrowBot: An Educational Robotic System for Growing Food

We present the GrowBot as an educational robotic system to facilitate hands-on experimentation with the control of environmental conditions for food plant growth. The GrowBot is a tabletop-sized greenhouse automated with sensors and actuators to become a robotic system for the control of plant’s growth. The GrowBot includes sensors for humidity, CO2, temperature, water level, RGB camera images, and actuators to control the grow conditions, including full spectrum lights, IR lights, and UV lights, nutrients pump, water pump, air pump, air change pump, and fan. Inspired by educational robotics, we developed user-friendly graphical programming of the GrowBots on several means: a touch display, a micro:bit, and a remote webserver interface. This allows school pupils to easily program the GrowBots to different growth conditions for the natural plants in terms of temperature, humidity, day light cycle, wavelength of LED light, nutrient rate, etc. The GrowBot system also allows the user to monitor the environmental conditions, such as CO2 monitoring for photosynthesis understanding, on both the touch display and the remote web–interface. An experiment with nine GrowBots shows that the different parameters can be controlled, that this can control the growth of the food plants, and that control to make an environmental condition with blue light results in higher and larger plants than red light. Further, the pilot experimentation in school settings indicates that the comprehensive system design method results in a deployable system, which can become well adopted in the educational domain