Highly Transparent and Tunable Antenna Window Using Saltwater for UHF Band Applications

This paper presents a highly optical transparent and tunable liquid antenna for applications on the UHF band. The antenna has high transparency (> 91%), which is achieved through its use of salty water as a conductive medium held within a clear and hollow acrylic rectangular prism, allowing its use as an optical window. To achieve frequency- and beam-tunable characteristics, two advanced configurations of the antenna using dual-port feeding are proposed. The antenna’s performance is simulated and then verified through experiments. Measurement results show that for a basic configuration using single-port feeding, the antenna has a −6 dB bandwidth ranging from 350 to 675 MHz and efficient radiation efficiency (> 60%) over the band. For advanced configurations, a tunable frequency and directional radiation pattern can be achieved with enhancing gain compared to the basic configuration. These results demonstrate the proposed antenna can be used as a bi-functional device, i.e., as atunable antenna and optical window.

First Principle Study of Salinity Measurement by 2D Material

By using first principle calculations, a simple model of salinity sensor based on graphene electrode is constructed and its electron transport property is systematically investigated. It is found that all saltwater clusters at different salinity exhibit an obvious increase of the current while the saltwater to be detected is passing through the device. Moreover, only changing one Na atom acted as the conductive medium, and the electron transport behaviors could be clearly distinguished among the saltwater by negative differential resistance phenomenon, which demonstrates that the graphene-based salinity sensor could be capable of distinguishing saltwater at different salinity efficiently and accurately. This study provides a new path for the creation of the novel salinity sensor by graphene and other 2D material electrode.

Uniform null controllability for a parabolic equations with discontinuous diffusion coefficient

In this article, we study the null-controllability of a heat equation in a domain composed of two media of different constant conductivities. In particular, we are interested in the behavior of the system when the conductivity of the medium on which the control does not act goes to infinity, corresponding at the limit to a perfectly conductive medium. In that case, and under suitable geometric conditions, we obtain a uniform null-controllability result. Our strategy is based on the analysis of the controllability of the corresponding wave operators and the transmutation technique, which explains the geometric conditions.

Dielectrophoresis Prototypic Polystyrene Particle Synchronization toward Alive Keratinocyte Cells for Rapid Chronic Wound Healing

Diabetes patients are at risk of having chronic wounds, which would take months to years to resolve naturally. Chronic wounds can be countered using the electrical stimulation technique (EST) by dielectrophoresis (DEP), which is label-free, highly sensitive, and selective for particle trajectory. In this study, we focus on the validation of polystyrene particles of 3.2 and 4.8 μm to predict the behavior of keratinocytes to estimate their crossover frequency (fXO) using the DEP force (FDEP) for particle manipulation. MyDEP is a piece of java-based stand-alone software used to consider the dielectric particle response to AC electric fields and analyzes the electrical properties of biological cells. The prototypic 3.2 and 4.8 μm polystyrene particles have fXO values from MyDEP of 425.02 and 275.37 kHz, respectively. Fibroblast cells were also subjected to numerical analysis because the interaction of keratinocytes and fibroblast cells is essential for wound healing. Consequently, the predicted fXO from the MyDEP plot for keratinocyte and fibroblast cells are 510.53 and 28.10 MHz, respectively. The finite element method (FEM) is utilized to compute the electric field intensity and particle trajectory based on DEP and drag forces. Moreover, the particle trajectories are quantified in a high and low conductive medium. To justify the simulation, further DEP experiments are carried out by applying a non-uniform electric field to a mixture of different sizes of polystyrene particles and keratinocyte cells, and these results are well agreed. The alive keratinocyte cells exhibit NDEP force in a highly conductive medium from 100 kHz to 25 MHz. 2D/3D motion analysis software (DIPP-MotionV) can also perform image analysis of keratinocyte cells and evaluate the average speed, acceleration, and trajectory position. The resultant NDEP force can align the keratinocyte cells in the wound site upon suitable applied frequency. Thus, MyDEP estimates the Clausius–Mossotti factors (CMF), FEM computes the cell trajectory, and the experimental results of prototypic polystyrene particles are well correlated and provide an optimistic response towards keratinocyte cells for rapid wound healing applications.