Abstract: Electrospinning is a versatile technology for the production of polymer micro/nanoscale fibers. It provides the direct addition of bioactive payloads into micro/nanofibers thus improving the encapsulation efficiency and reducing the burst release via proper selection of drug-polymer-solvent system or electrospinning setup. In addition, since electrospun fibers have one dimension at the microscopic scale but another dimension at the macroscopic one, it is possible to combine the advantages possessed by functional materials on the nanometer scale. A large surface to volume ratio, with the properties of conventional solid membranes, such as ease of manipulation and applicability in any size and shape, making them suitable for biomedical or healthcare applications both topically (i.e. skin) and locally (i.e. tumor). This communication deals with electrospun fibrous systems containing active compounds extracts from plants such as Artemisinin and Propolis; these systems have been properly realized to preserve the pharmacological activity of drugs and evaluated as potential delivery systems for vector-born deseases and cancer, reducing the damage to non-target organism and environment.
Abstract: Alternating-current (AC) electroluminescent (EL) devices on fabrics with high brightness are presented. The EL-devices were fabricated via knife coating; inorganic luminous pigments are based on zinc sulfide. Effects of parameters influencing the brightness were investigated. These parameters are the AC-voltage, AC-frequency, AC-waveform, layer composition of the luminous capacitor and the fabric. Introducing a flexible reflecting dielectric layer enhances the light yield on fine woven fabrics with green luminous pigment. This can be achieved with small concentrations of reflective white pigments such as titanium dioxide, maintaining the flexibility and bendability of the textile substrate. The produced luminous textiles are investigated as a possible replacement for light boxes used in the therapy of seasonal affective disorder (SAD). A high luminous emittance and a high portion of short and energy rich wavelengths are necessary for the treatment. Contrarily to state-of-the-art light boxes a higher acceptance of light therapy is expected, because a luminous textile can be integrated easily and unremarkably into the living environment.
Abstract: Textile band structures with integrated soft condensed matter sensor (SCMS) can be used as a vital function monitor device to detect pulse wave and breathing on the human body. A textile an elastic band was used as a support material and the U-shaped SCMS fiber sensor was bonded on the surface with elastic band with a liquid rubber bonding material. The sensor signal and gauge factor of the textile sensor structure was investigated using tensile testing experiments. The resistivity of the sensor structure increased linearly within a strain of 10 to 50%, and a slope of 8 (kOhm/% strain) could be detected. The sensor had a gauge factor of 4-5 from 10 to 50% between strain. Using the integrated SCMS sensor textile band around the chest, it was possible to detect talking, normal breathing and coughing. In collaboration with Rice University the textile sensor was tested for proof-of-concept for use in a battery-powered monitor for apnea of premature infants.
Abstract: We study the influence of ripple waves on graphene sheets and graphene nanoribbons. Such waves are originating from the electromechanical effects, among other possible mechanisms. By considering variations in the in-plane and out-of-plane displacement vector, we show that the spontaneous generation of ripple waves has no preferred orientation. Intrinsic properties of ripple waves induce a large pseudopotential that in its turn is to induce large pseudomagentic fields that can be implemented into the band engineering of graphene structures.
Abstract: In this paper we presented the synthesis of TEOS with photoresist in order to use it like a hybrid material for 3D printer on the micrometer scale by means of the two-photon polymerization process, in which two photon are absorbed simultaneously by the material using an ultrafast laser causing its polymerization. We analyzed the mix of TEOS and photoresist with UV-VIS and FTIR spectrometers, checking that complies with two important conditions: has an optical transmission at 780 nm and absorbs at 390 nm. Finally we fabricated micro-structures with a new hybrid material; TEOS does not absorb the laser in this system and does not interfere with the formation of a three-dimensional structure. After formation the 3D microstructure, samples were heated to form the SiO. These samples of microstructures were observed under digital microscope and SEM.
Abstract: The bursting wireless communication market, including 5G, advanced satellite communication systems and COTM (Communication On The Move) terminals, require ever more sophisticated functions, from multi-band and multi-function operations to electronically steerable and reconfigurable antennas, pushing technological developments towards the use of tunable microwave components and circuits. Reconfigurability allows indeed for reduced complexity and cost of the apparatuses. In this context, RF MEMS (Micro-Electro-Mechanical-Systems) technology has emerged as a very attractive solution to realize both tunable devices (e.g. variable capacitors, inductors and micro-relays), as well as complex circuits (e.g. tunable filters, reconfigurable matching networks and reconfigurable beam forming networks for phased array antennas). High linearity, low loss and high miniaturization are the typical advantages of RF MEMS over conventional technologies. Micromechanical components fabricated via IC-compatible MEMS technologies and capable of low-loss filtering, switching and frequency generation allow for miniaturized wireless front-ends via higher levels of integration. In addition, the inherent high linearity of the MEMS switches enables carrier aggregations without introducing intermodulation distortions. This paper will review the recent advances in the development of the RF MEMS to RF tunable circuits and systems.
Abstract: Manufacture of piezoelectric energy harvesters typically assumes bulk piezoelectric material for the transducer until the reduction in size of the device prevents this. However when designing piezoelectric harvesters, the complete system must be taken into account including the transducer, power circuit, and battery, as these will impose restrictions on what can be achieved. Therefore a comparison between MEMS and meso-scale piezoelectric energy harvesting systems using a fully parametrised model is required. The comparison was restricted to a piezoelectric beam with a mass at the end connected to a single supply pre-biasing circuit to provide the optimal damping force and rectification. A buck converter was used to transfer extracted energy to a 1.5V battery. The results indicate that for devices with a volume side length less than 16.25 mm, no device using meso-scale properties can be made to resonant at 100 Hz or less due to the length and stiffness of the beam. Whereas above this limit, the voltage required to damp devices with MEMS scale properties causes a breakdown in the dielectric. We present a comparison of the theoretical limits of MEMS and meso-scale piezoelectric harvesters to provide design insight for future devices to maximise power generation.
Abstract: We present a novel structure to supply gases to microchambers in microfluidic chips. An exemplary application is the continuous feeding of oxygen and CO2 for on-chip cell cultivation of mammalian cells. In our device, the surrounding air diffuses into the culture medium inside the chip through a porous wall of agarose hydrogel resulting in an easy and robust design.
One common method is the usage of gas permeable PDMS chips. However, liquid medium in which the cells grow is absorbed by PDMS causing unknown concentrations and memory effects. Another possibility is a complex setup where medium with already dissolved gas is pumped constantly through the chip.
We designed and realized a silicon and borosilicate glass chip containing a gas permeable wall of agarose preventing leakage of medium. In order to precisely position the walls in the chip, we made use of surficial phaseguides (50nm high).
The blue-bottle-experiment makes the effective dissipation of oxygen visible when the colorless leucomethylen-blue reacts to methylene-blue. Successful results were achieved when applying 0.5 g/l methylene blue, 10 g/l glucose and a pH of 12.6 set by a buffer solution. As a result a continuous color gradient through the chip was obtained, which reflects the oxygen gradient and confirms the oxygen diffusion.
Abstract: Obesity and dysphagia are of potential and direct serious harm to the human body health. A commonly used method is controlling food intake to avoid obesity or determining if dysphagia exists by monitoring the swallow . This paper proposes a swallow detecting principle based on nanometer materials sensor, and implements a wearable detecting system with advantage of improved DTW algorithm. The system efficiently detects and faithfully identifies swallowing. In addition, it reduces the demand for hardware computing power. The system meets the features of a wearable system, such as soft and comfortable, lightweight, portable, and noninvasive.
Abstract: Fungi growth on bananas during transportation not only results in loss of food but it also incurs considerable transport losses. To investigate the influence of spores on the development of fungi growth on the bananas we present a sensor sticker. The sticker can be put on the banana surface for the detection of spore concentration. The designed sensor comprises of a thin layer of culture medium (PDA agarose) coated on a capacitive sensor fabricated on a polyimide foil (5 μm). As spores germinate, the capacitance of the culture medium changes which is measured by the interdigital capacitive element that contains 2 electrodes (with 428 fingers) that have a length of 3 mm, a width and a gap of 7 μm. In addition to the culture medium one of the major requirements for the fungi to grow is air. As air cannot diffuse through the sticker, air cavities are integrated in the culture medium layer to provide the necessary amount of air for fungi growth. This method was successfully applied to determine different concentrations of Fusarium Oxysporum, a major fungi species responsible for banana contamination. Measured capacitance change after a fixed time interval depends on the initial concentration of spores. The measurement takes typically 6 hours.