Predicting the potential of capacitive deionization for the separation of pH‐dependent organic molecules

One of the main steps in the biotechnological production of chemical building blocks, such as, e.g. bio-based succinic acid which is used for lubricants, cosmetics, food, and pharmaceuticals, is the isolation and purification of the target molecule. A new approach to isolate charged, bio-based chemicals is by electrosorption onto carbon surfaces. In contrast to ion exchange, electrosorption does not require additional chemicals for elution and regeneration. However, while the electrosorption of inorganic salts is well understood and in commercial use, the knowledge about electrosorption of weak organic acids including the strong implications of the pH-dependent dissociation and their affinity towards physical adsorption must be expanded. Here, we show a detailed discussion of the main pH-dependent effects determining the achievable charge efficiencies and capacities. An explicit set of equations allows the fast prediction of the named key figures for constant voltage and constant current operation. The calculated and experimental results obtained for the electrosorption of maleic acid show that the potential-free adsorption of differently protonated forms of the organic acid play a dominating role in the process. At pH 8 and a voltage threshold of 1.3 V, charge efficiencies of 25% and capacities around 40 mmol/kg could be reached for a constant current experiment. While this capacity is clearly below that of ion exchange resins, the required carbon materials are inexpensive and energy costs are only about 0.013 €/mol. Therefore, we anticipate that electrosorption has the potential to become an interesting alternative to conventional unit operations for the isolation of charged target molecules

Microfiber-microcavity system for efficient single photon collection

Funded by the National Research Foundation of Korea (NRF) grant (MSIP) (NRF-2007-341-C00018, NRF-2014M3C1A3052567); State of Bavaria.Single photon sources are key components for various quantum information processing. For practical quantum applications, bright single photon sources with efficient fiber-optical interfaces are highly required. Here, bright fiber-coupled single photon sources based on InAs quantum dots are demonstrated through the k-vector matching between a microfiber mode and a normal mode of the linear photonic crystal cavity. One of the modes of the linear photonic crystal cavity whose k-vector is similar to that of the microfiber mode is employed. From independent transmission measurement, the coupling efficiency directly into the fiber of 58% is obtained. When the quantum dot and cavity system is non-resonantly pumped with 80 MHz pulse train, a raw count rate of 1.81 MHz is obtained with g(2)(0) = 0.46. Resonant pump is expected to improve the rather high g(2)(0) value. Time-resolved photoluminescence is also measured to confirm the three-fold Purcell enhancement. This system provides a promising route for efficient direct fiber collections of single photons for quantum information processing.PostprintPeer reviewe

Sensors and actuators

This chapter addresses sensors and actuators for three main sensory modalities: hearing, vision, and touch. Technology in recent years was often focused on flat displays, e.g., or smartwatches. In contrast, the focus of this chapter is on wearable technologies of the post-smartphone area, allowing rich sensory input and output modalities. New approaches for tactile feedback include fiber-based sensors and actuators for e-textiles as well as complex 3D-fiber structures. Wearable sound sources and innovative sound-projection solutions using perceptual knowledge can replace complex distributed channel systems. One way to reduce latencies in vision are Organic Light-Emitting Diode (OLED) eyeables, that have the potential to significantly improving reaction time and power consumption. Combining the expertise of human perception and action with that on sensors and actuators contributes to augmented perception and interaction to exchange perceptual knowledge, which is needed for holistic sensor and actuator development. Moreover, sensors and actuators combined with tactile electronics in terms of flexible electronics and circuits for interfacing/processing explore new technologies for haptic and robotic systems