Mohamed Serry

A New Sensor for Heavy Metals Detection in Aqueous Media

A novel technique for rapid and ultrahigh sensing of heavy metals in aqueous media based on microfluidic platform integrated with porous anodic alumina (PAA) membrane and functionalized with ultrathin porous layer of highly ordered hexagonal arrays of Au nanoparticles with 25 nm sub-gaps is proposed. The sensor function is based on both chemical and electromagnetic enhancement. Both were achieved by increasing the number of hot spots and by increasing the density of the Au-nanoparticles at the surface of the PAA membrane up to 7 × 1010 cm-2. The sensor demonstrated high selectivity between three different heavy metal ions ( Hg2+, Cd2+, Pb2+, Cu2+, Co2+, and Ni2+) with concentrations varied from 1 to 20 ppb (1 × 10-3 to 20 × 10-3 μg/ml). The platform provides an instant and fully integrated detection method that is based on in-situ surface-enhanced Raman scattering (SERS) spectroscopy. The observed Raman enhancement is due to the excitation and interference of surface plasmon waves, which are highly dependent on the type and concentration of the heavy metal. Therefore, the proposed sensor is an unprecedented fully integrated platform that is easy to fabricate and seamlessly integrated with an in-situ signal detection device for added functionality.

Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation

We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed.

Excitonic Optical Tamm States: A Step toward a Full Molecular–Dielectric Photonic Integration

We report the first experimental observation of an Excitonic Optical Tamm State supported at the interface between a periodic multilayer dielectric structure and an organic dye-doped polymer layer. The existence of such states is enabled by the metal-like optical properties of the excitonic layer based on aggregated dye molecules. Experimentally determined dispersion curves, together with simulated data, including field profiles, allow us to identify the nature of these new modes. Our results demonstrate the potential of organic excitonic materials as a powerful means to control light at the nanoscale, offering the prospect of a new alternative type of nanophotonics based on molecular materials.

A new sensor for heavy metals detection in aqueous media

A novel technique for rapid and ultrahigh sensing of heavy metals in aqueous media based on microfluidic platform coated with Porous Anodic Alumina (PAA) membrane and functionalized with ultrathin porous layer of highly ordered hexagonal arrays of Au nanoparticles with 25nm sub-gaps is proposed. The sensor demonstrated high selectivity between three different heavy metals (Hg, Cd, and Pb) with concentrations varied from 1 to 20 ppb. The platform provides an instant and fully integrated detection method that is based on in situ surface-enhanced Raman scattering (SERS) spectroscopy. The observed Raman enhancement is due to the excitation and interference of surface plasmon waves, which are highly dependent on the type and concentration of the heavy metal. As a result, the proposed sensor is an unprecedented fully integrated platform that is easy to fabricate and can be seamlessly integrated with an in situ signal detection device for added functionality.

Micromachined On-Chip Dielectric Resonator Antenna Operating at 60 GHz

This paper presents a novel cylindrical dielectric resonator antenna (DRA) suitable for millimeter-wave (mm-wave) on-chip systems. The antenna was fabricated from a single high-resistivity silicon wafer via micromachining technology. The new antenna was characterized using HFSS and experimentally with good agreement been found between the simulations and experiment. The proposed DRA has good radiation characteristics, where its gain and radiation efficiency are 7 dBi and 79.35%, respectively. These properties are reasonably constant over the working frequency bandwidth of the antenna. The return loss bandwidth was 2.23 GHz, which corresponds to 3.78% around 60 GHz. The antenna was primarily a broadside radiator with -15dB cross-polarization level.

Silicon Germanium as a Novel Mask for Silicon Deep Reactive Ion Etching

This paper reports on the use of p-type polycrystalline Silicon Germanium (poly-Si1-xGex) thin films as a new masking material for cryogenic silicon deep reactive ion etching (DRIE). The proposed masking material can be deposited at CMOS backend compatible temperatures and demonstrates high etching selectivity towards silicon (>;1:270). Moreover, SiGe etches 37 times faster than SiO2 or SiN masks in SF6/O2 plasma resulting in a major reduction in the processing time without the need for a dedicated etcher. Selectivity tests revealed that the etching selectivity of the SiGe mask towards silicon strongly depends on the Ge content, boron concentration and etching temperature. This was attributed to chemical and thermodynamic stability of the SiGe film, as well as the electronic properties of the mask.

77-GHz MEMS brick-wall antenna fed by coupled microstrip lines

Micromachining technology is very attractive for integrated antennas as it offers efficient packaging, high radiation efficiency, wide impedance bandwidth, and less mutual coupling between antenna elements. These advantages are more difficult to be achieved using the conventional planar technology especially at high frequencies such as 77 GHz. Research carried out on MEMS antennas can be classified into two main categories. The first category features a flat antenna, such as patch, realized on a thin membrane [1]. The membrane is fabricated by etching silicon under the patch. This results in reducing the effective dielectric constant of the medium surrounding the antenna and consequently increases the bandwidth and radiation efficiency. The second category features a 3D antenna, such as horn or waveguide, realized by etching grooves in a number of silicon wafers [2]. The walls of these grooves are covered with metal. Each groove represents part of the desired 3D structure. The wafers are bonded together to form the complete antenna.

High performance NEMS ultrahigh sensitive radiation sensor based on platinum nanorods capacitor

A novel NEMS radiation sensor optimized for ultrahigh sensitive and isotropic detection of gamma irradiation is presented. The sensor is designed as a 3D symmetrical array of nanostructured platinum nanorod capacitor with 20 to 50 nm silicon oxide dielectric layer and a surface to volume ratio magnified by a factor of 5 × 10³ to 8 × 10⁵ as compared to bulk capacitor electrodes. For wide range gamma radiation doses from 5 to 35 kG using a Co⁶⁰ source in the ±90° angle range, the detected sensitivity is evaluated in the range of 800 nf/G compared to 1.1 pf/G for conventional bulk capacitive sensors, a factor of ~ 8 × 10⁵ improvement.

Robust and Optimal Control of Magnetic Microparticles inside Fluidic Channels with Time-Varying Flow Rates

Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For example, magnetic particles need to be navigated controllably in vessels against flowing streams of body fluid. This paper describes the motion control of paramagnetic microparticles in the flowing streams of fluidic channels with time-varying flow rates (maximum flow is 35 ml.hr−1). This control is designed using a magnetic-based proportional-derivative (PD) control system to compensate for the time-varying flow inside the channels (with width and depth of 2 mm and 1.5 mm, respectively). First, we achieve point-to-point motion control against and along flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1. The average speeds of single microparticle (with average diameter of 100 μm) against flow rates of 6 ml.hr−1 and 30 ml.hr−1 are calculated to be 45 μm.s−1 and 15 μm.s−1, respectively. Second, we implement PD control with disturbance estimation and compensation. This control decreases the steady-state error by 50%, 70%, 73%, and 78% at flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1, respectively. Finally, we consider the problem of finding the optimal path (minimal kinetic energy) between two points using calculus of variation, against the mentioned flow rates. Not only do we find that an optimal path between two collinear points with the direction of maximum flow (middle of the fluidic channel) decreases the rise time of the microparticles, but we also decrease the input current that is supplied to the electromagnetic coils by minimizing the kinetic energy of the microparticles, compared to a PD control with disturbance compensation.

Targeting of cell mockups using sperm-shaped microrobots in vitro

Sperm-shaped microrobots are controlled under the influence of weak oscillating magnetic fields (milliTesla range) to selectively target cell mockups (i.e., gas bubbles with average diameter of 200 μm). The sperm-shaped microrobots are fabricated by electrospinning using a solution of polystyrene, dimethylformamide, and iron oxide nanoparticles. These nanoparticles are concentrated within the head of the microrobot, and hence enable directional control along external magnetic fields. The magnetic dipole moment of the microrobot is characterized (using the flip-time technique) to be 1.4×10-11 A.m2, at magnetic field of 28 mT. In addition, the morphology of the microrobot is characterized using Scanning Electron Microscopy images. The characterized parameters and morphology are used in the simulation of the locomotion mechanism of the microrobot to prove that its motion depends on breaking the time-reversal symmetry, rather than pulling with the magnetic field gradient. We experimentally demonstrate that the microrobot can controllably follow S-shaped, U-shaped, and square paths, and selectively target the cell mockups using image guidance and under the influence of the oscillating magnetic fields.